Appendicitis 

Updated: Jul 23, 2018
Author: Sandy Craig, MD; Chief Editor: Barry E Brenner, MD, PhD, FACEP 

Overview

Practice Essentials

Appendicitis is defined as an inflammation of the inner lining of the vermiform appendix that spreads to its other parts. Despite diagnostic and therapeutic advancement in medicine, appendicitis remains a clinical emergency and is one of the more common causes of acute abdominal pain. See the image below.

Transverse graded compression transabdominal sonog Transverse graded compression transabdominal sonogram of an acutely inflamed appendix. Note the targetlike appearance due to thickened wall and surrounding loculated fluid collection.

See Appendicitis: Avoiding Pitfalls in Diagnosis, a Critical Images slideshow, to help make an accurate diagnosis.

Also, see the Can't-Miss Gastrointestinal Diagnoses slideshow to help diagnose the potentially life-threatening conditions that present with gastrointestinal symptoms.

Signs and symptoms

The clinical presentation of appendicitis is notoriously inconsistent. The classic history of anorexia and periumbilical pain followed by nausea, right lower quadrant (RLQ) pain, and vomiting occurs in only 50% of cases. Features include the following:

  • Abdominal pain: Most common symptom

  • Nausea: 61-92% of patients

  • Anorexia: 74-78% of patients

  • Vomiting: Nearly always follows the onset of pain; vomiting that precedes pain suggests intestinal obstruction

  • Diarrhea or constipation: As many as 18% of patients

Features of the abdominal pain are as follows:

  • Typically begins as periumbilical or epigastric pain, then migrates to the RLQ[1]

  • Patients usually lie down, flex their hips, and draw their knees up to reduce movements and to avoid worsening their pain

  • The duration of symptoms is less than 48 hours in approximately 80% of adults but tends to be longer in elderly persons and in those with perforation.

Physical examination findings include the following:

  • Rebound tenderness, pain on percussion, rigidity, and guarding: Most specific finding

  • RLQ tenderness: Present in 96% of patients, but nonspecific

  • Left lower quadrant (LLQ) tenderness: May be the major manifestation in patients with situs inversus or in patients with a lengthy appendix that extends into the LLQ

  • Male infants and children occasionally present with an inflamed hemiscrotum

  • In pregnant women, RLQ pain and tenderness dominate in the first trimester, but in the latter half of pregnancy, right upper quadrant (RUQ) or right flank pain may occur

The following accessory signs may be present in a minority of patients:

  • Rovsing sign (RLQ pain with palpation of the LLQ): Suggests peritoneal irritation

  • Obturator sign (RLQ pain with internal and external rotation of the flexed right hip): Suggests the inflamed appendix is located deep in the right hemipelvis

  • Psoas sign (RLQ pain with extension of the right hip or with flexion of the right hip against resistance): Suggests that an inflamed appendix is located along the course of the right psoas muscle

  • Dunphy sign (sharp pain in the RLQ elicited by a voluntary cough): Suggests localized peritonitis

  • RLQ pain in response to percussion of a remote quadrant of the abdomen or to firm percussion of the patient's heel: Suggests peritoneal inflammation

  • Markle sign (pain elicited in a certain area of the abdomen when the standing patient drops from standing on toes to the heels with a jarring landing): Has a sensitivity of 74%[2]

See Clinical Presentation for more detail.

Diagnosis

The following laboratory tests do not have findings specific for appendicitis, but they may be helpful to confirm diagnosis in patients with an atypical presentation:

  • CBC

  • C-reactive protein (CRP)

  • Liver and pancreatic function tests

  • Urinalysis (for differentiating appendicitis from urinary tract conditions)

  • Urinary beta-hCG (for differentiating appendicitis from early ectopic pregnancy in women of childbearing age)

  • Urinary 5-hydroxyindoleacetic acid (5-HIAA)

CBC

  • WBC >10,500 cells/µL: 80-85% of adults with appendicitis

  • Neutrophilia >75-78% of patients

  • Less than 4% of patients with appendicitis have a WBC count less than 10,500 cells/µL and neutrophilia less than 75%

In infants and elderly patients, a WBC count is especially unreliable because these patients may not mount a normal response to infection. In pregnant women, the physiologic leukocytosis renders the CBC count useless for the diagnosis of appendicitis.

C-reactive protein

  • CRP levels >1 mg/dL are common in patients with appendicitis

  • Very high levels of CRP in patients with appendicitis indicate gangrenous evolution of the disease, especially if it is associated with leukocytosis and neutrophilia

  • In adults who have had symptoms for longer than 24 hours, a normal CRP level has a negative predictive value of 97-100% for appendicitis[3, 4, 5]

Urinary 5-HIAA

HIAA levels increase significantly in acute appendicitis and decrease when the inflammation shifts to necrosis of the appendix.[6] Therefore, such decrease could be an early warning sign of perforation of the appendix.

CT scanning

  • CT scanning with oral contrast medium or rectal Gastrografin enema has become the most important imaging study in the evaluation of patients with atypical presentations of appendicitis

  • Low-dose abdominal CT may be preferable for diagnosing children and young adults in whom exposure to CT radiation is of particular concern[7]

Ultrasonography

  • Ultrasonography may offer a safer alternative as a primary diagnostic tool for appendicitis, with CT scanning used in those cases in which ultrasonograms are negative or inconclusive

  • In pediatric patients, American College of Emergency Physicians (ACEP) clinical policy recommends ultrasonography for confirmation, but not exclusion, of acute appendicitis; to definitively exclude acute appendicitis, the ACEP recommends CT[8, 9]

  • A healthy appendix usually cannot be viewed with ultrasonography; when appendicitis occurs, the ultrasonogram typically demonstrates a noncompressible tubular structure of 7-9 mm in diameter

  • Vaginal ultrasonography alone or in combination with transabdominal scan may be useful to determine the diagnosis in women of childbearing age[10]

Other imaging studies

  • Kidneys-ureters-bladder radiographs: Insensitive, nonspecific, and not cost-effective

  • Barium enema study: Has essentially no role in the diagnosis of acute appendicitis

  • Radionuclide scanning: Localized uptake of tracer in the RLQ suggests appendiceal inflammation

  • MRI: Useful in pregnant patients if graded compression ultrasonography is nondiagnostic

See Workup for more detail.

Management

Emergency department care is as follows:

  • Establish IV access and administer aggressive crystalloid therapy to patients with clinical signs of dehydration or septicemia

  • Keep patients with suspected appendicitis NPO

  • Administer parenteral analgesic and antiemetic as needed for patient comfort; no study has shown that analgesics adversely affect the accuracy of physical examination[11]

Appendectomy remains the only curative treatment of appendicitis, but management of patients with an appendiceal mass can usually be divided into the following 3 treatment categories:

  • Phlegmon or a small abscess: After IV antibiotic therapy, an interval appendectomy can be performed 4-6 weeks later

  • Larger well-defined abscess: After percutaneous drainage with IV antibiotics is performed, the patient can be discharged with the catheter in place; interval appendectomy can be performed after the fistula is closed

  • Multicompartmental abscess: These patients require early surgical drainage

Antibiotics

  • Antibiotic prophylaxis should be administered before every appendectomy

  • Preoperative antibiotics should be administered in conjunction with the surgical consultant

  • Broad-spectrum gram-negative and anaerobic coverage is indicated

  • Cefotetan and cefoxitin seem to be the best choices of antibiotics

  • In penicillin-allergic patients, carbapenems are a good option

  • Pregnant patients should receive pregnancy category A or B antibiotics

  • Antibiotic treatment may be stopped when the patient becomes afebrile and the WBC count normalizes

See Treatment and Medication for more detail.

Background

Appendicitis is defined as an inflammation of the inner lining of the vermiform appendix that spreads to its other parts. This condition is a common and urgent surgical illness with protean manifestations, generous overlap with other clinical syndromes, and significant morbidity, which increases with diagnostic delay (see Presentation). In fact, despite diagnostic and therapeutic advancement in medicine, appendicitis remains a clinical emergency and is one of the more common causes of acute abdominal pain.

No single sign, symptom, or diagnostic test accurately confirms the diagnosis of appendiceal inflammation in all cases, and the classic history of anorexia and periumbilical pain followed by nausea, right lower quadrant (RLQ) pain, and vomiting occurs in only 50% of cases (see Presentation).

Appendicitis may occur for several reasons, such as an infection of the appendix, but the most important factor is the obstruction of the appendiceal lumen (see Pathophysiology and Etiology). Left untreated, appendicitis has the potential for severe complications, including perforation or sepsis, and may even cause death (see Prognosis). However, the differential diagnosis of appendicitis is often a clinical challenge because appendicitis can mimic several abdominal conditions (see Diagnostic Considerations .[12]

Appendectomy remains the only curative treatment of appendicitis (see Treatment ). The surgeon's goals are to evaluate a relatively small population of patients referred for suspected appendicitis and to minimize the negative appendectomy rate without increasing the incidence of perforation. The emergency department (ED) clinician must evaluate the larger group of patients who present to the ED with abdominal pain of all etiologies with the goal of approaching 100% sensitivity for the diagnosis in a time-, cost-, and consultation-efficient manner.

Go to Pediatric Appendicitis for more information on this topic.

For patient education information, see the Digestive Disorders Center as well as Appendicitis and Abdominal Pain in Adults.

Anatomy

The appendix is a wormlike extension of the cecum and, for this reason, has been called the vermiform appendix. The average length of the appendix is 8-10 cm (ranging from 2-20 cm). The appendix appears during the fifth month of gestation, and several lymphoid follicles are scattered in its mucosa. Such follicles increase in number when individuals are aged 8-20 years. A normal appendix is seen below.

Normal appendix; barium enema radiographic examina Normal appendix; barium enema radiographic examination. A complete contrast-filled appendix is observed (arrows), which effectively excludes the diagnosis of appendicitis.

The appendix is contained within the visceral peritoneum that forms the serosa, and its exterior layer is longitudinal and derived from the taenia coli; the deeper, interior muscle layer is circular. Beneath these layers lies the submucosal layer, which contains lymphoepithelial tissue. The mucosa consists of columnar epithelium with few glandular elements and neuroendocrine argentaffin cells.

Taenia coli converge on the posteromedial area of the cecum, which is the site of the appendiceal base. The appendix runs into a serosal sheet of the peritoneum called the mesoappendix, within which courses the appendicular artery, which is derived from the ileocolic artery. Sometimes, an accessory appendicular artery (deriving from the posterior cecal artery) may be found.

Appendiceal vasculature

The vasculature of the appendix must be addressed to avoid intraoperative hemorrhages. The appendicular artery is contained within the mesenteric fold that arises from a peritoneal extension from the terminal ileum to the medial aspect of the cecum and appendix; it is a terminal branch of the ileocolic artery and runs adjacent to the appendicular wall. Venous drainage is via the ileocolic veins and the right colic vein into the portal vein; lymphatic drainage occurs via the ileocolic nodes along the course of the superior mesenteric artery to the celiac nodes and cisterna chyli.

Appendiceal location

The appendix has no fixed position. It originates 1.7-2.5 cm below the terminal ileum, either in a dorsomedial location (most common) from the cecal fundus, directly beside the ileal orifice, or as a funnel-shaped opening (2-3% of patients). The appendix has a retroperitoneal location in 65% of patients and may descend into the iliac fossa in 31%. In fact, many individuals may have an appendix located in the retroperitoneal space; in the pelvis; or behind the terminal ileum, cecum, ascending colon, or liver. Thus, the course of the appendix, the position of its tip, and the difference in appendiceal position considerably changes clinical findings, accounting for the nonspecific signs and symptoms of appendicitis.

Congenital appendiceal disorders

Appendiceal congenital disorders are extremely rare but occasionally reported (eg, agenesis, duplication, triplication).

Pathophysiology

Reportedly, appendicitis is caused by obstruction of the appendiceal lumen from a variety of causes (see Etiology). Independent of the etiology, obstruction is believed to cause an increase in pressure within the lumen. Such an increase is related to continuous secretion of fluids and mucus from the mucosa and the stagnation of this material. At the same time, intestinal bacteria within the appendix multiply, leading to the recruitment of white blood cells (see the image below) and the formation of pus and subsequent higher intraluminal pressure.

Technetium-99m radionuclide scan of the abdomen sh Technetium-99m radionuclide scan of the abdomen shows focal uptake of labeled WBCs in the right lower quadrant consistent with acute appendicitis.

If appendiceal obstruction persists, intraluminal pressure rises ultimately above that of the appendiceal veins, leading to venous outflow obstruction. As a consequence, appendiceal wall ischemia begins, resulting in a loss of epithelial integrity and allowing bacterial invasion of the appendiceal wall.

Within a few hours, this localized condition may worsen because of thrombosis of the appendicular artery and veins, leading to perforation and gangrene of the appendix. As this process continues, a periappendicular abscess or peritonitis may occur.

Etiology

Appendicitis is caused by obstruction of the appendiceal lumen. The most common causes of luminal obstruction include lymphoid hyperplasia secondary to inflammatory bowel disease (IBD) or infections (more common during childhood and in young adults), fecal stasis and fecaliths (more common in elderly patients), parasites (especially in Eastern countries), or, more rarely, foreign bodies and neoplasms.

Fecaliths form when calcium salts and fecal debris become layered around a nidus of inspissated fecal material located within the appendix. Lymphoid hyperplasia is associated with various inflammatory and infectious disorders including Crohn disease, gastroenteritis, amebiasis, respiratory infections, measles, and mononucleosis.

Obstruction of the appendiceal lumen has less commonly been associated with bacteria (Yersinia species, adenovirus, cytomegalovirus, actinomycosis, Mycobacteria species, Histoplasma species), parasites (eg, Schistosomes species, pinworms, Strongyloides stercoralis), foreign material (eg, shotgun pellet, intrauterine device, tongue stud, activated charcoal), tuberculosis, and tumors.

Epidemiology

Appendicitis is one of the more common surgical emergencies, and it is one of the most common causes of abdominal pain. In the United States, 250,000 cases of appendicitis are reported annually, representing 1 million patient-days of admission. The incidence of acute appendicitis has been declining steadily since the late 1940s, and the current annual incidence is 10 cases per 100,000 population. Appendicitis occurs in 7% of the US population, with an incidence of 1.1 cases per 1000 people per year. Some familial predisposition exists.

In Asian and African countries, the incidence of acute appendicitis is probably lower because of the dietary habits of the inhabitants of these geographic areas. The incidence of appendicitis is lower in cultures with a higher intake of dietary fiber. Dietary fiber is thought to decrease the viscosity of feces, decrease bowel transit time, and discourage formation of fecaliths, which predispose individuals to obstructions of the appendiceal lumen.

In the last few years, a decrease in frequency of appendicitis in Western countries has been reported, which may be related to changes in dietary fiber intake. In fact, the higher incidence of appendicitis is believed to be related to poor fiber intake in such countries.

There is a slight male preponderance of 3:2 in teenagers and young adults; in adults, the incidence of appendicitis is approximately 1.4 times greater in men than in women. The incidence of primary appendectomy is approximately equal in both sexes.

The incidence of appendicitis gradually rises from birth, peaks in the late teen years, and gradually declines in the geriatric years. The mean age when appendicitis occurs in the pediatric population is 6-10 years. Lymphoid hyperplasia is observed more often among infants and adults and is responsible for the increased incidence of appendicitis in these age groups. Younger children have a higher rate of perforation, with reported rates of 50-85%. The median age at appendectomy is 22 years. Although rare, neonatal and even prenatal appendicitis have been reported. Clinicians must maintain a high index of suspicion in all age groups.

Go to Pediatric Appendicitis for more information on this topic.

Prognosis

Acute appendicitis is the most common reason for emergency abdominal surgery. Appendectomy carries a complication rate of 4-15%, as well as associated costs and the discomfort of hospitalization and surgery. Therefore, the goal of the surgeon is to make an accurate diagnosis as early as possible. Delayed diagnosis and treatment account for much of the mortality and morbidity associated with appendicitis.

The overall mortality rate of 0.2-0.8% is attributable to complications of the disease rather than to surgical intervention. The mortality rate in children ranges from 0.1% to 1%; in patients older than 70 years, the rate rises above 20%, primarily because of diagnostic and therapeutic delay.

Appendiceal perforation is associated with increased morbidity and mortality compared with nonperforating appendicitis. The mortality risk of acute but not gangrenous appendicitis is less than 0.1%, but the risk rises to 0.6% in gangrenous appendicitis. The rate of perforation varies from 16% to 40%, with a higher frequency occurring in younger age groups (40-57%) and in patients older than 50 years (55-70%), in whom misdiagnosis and delayed diagnosis are common. Complications occur in 1-5% of patients with appendicitis, and postoperative wound infections account for almost one third of the associated morbidity.

In a multivariable analysis, independent factors predictive of complicated appendicitis in children were as follows[13] :

  • Age younger than 5 years
  • Symptom duration longer than 24 hours
  • Hyponatremia
  • Leukocytosis
 

Presentation

History

Variations in the position of the appendix, age of the patient, and degree of inflammation make the clinical presentation of appendicitis notoriously inconsistent. Statistics report that 1 of 5 cases of appendicitis is misdiagnosed; however, a normal appendix is found in 15-40% of patients who have an emergency appendectomy.

Niwa et al reported an interesting case of a young woman with recurrent pain in who was referred for appendicitis, treated with antibiotics, and was found to have an appendiceal diverticulitis associated with a rare pelvic pseudocyst at laparotomy after 12 months.[14] Her condition was probably due to diverticular perforation of the pseudocyst.

Symptoms

The classic history of anorexia and periumbilical pain followed by nausea, right lower quadrant (RLQ) pain, and vomiting occurs in only 50% of cases. Nausea is present in 61-92% of patients; anorexia is present in 74-78% of patients. Neither finding is statistically different from findings in patients who present to the emergency department with other etiologies of abdominal pain. In addition, when vomiting occurs, it nearly always follows the onset of pain. Vomiting that precedes pain is suggestive of intestinal obstruction, and the diagnosis of appendicitis should be reconsidered. Diarrhea or constipation is noted in as many as 18% of patients and should not be used to discard the possibility of appendicitis.

The most common symptom of appendicitis is abdominal pain. Typically, symptoms begin as periumbilical or epigastric pain migrating to the right lower quadrant (RLQ) of the abdomen. This pain migration is the most discriminating feature of the patient's history, with a sensitivity and specificity of approximately 80%, a positive likelihood ratio of 3.18, and a negative likelihood ratio of 0.5.[1] Patients usually lie down, flex their hips, and draw their knees up to reduce movements and to avoid worsening their pain. Later, a worsening progressive pain along with vomiting, nausea, and anorexia are described by the patient. Usually, a fever is not present at this stage.

The duration of symptoms is less than 48 hours in approximately 80% of adults but tends to be longer in elderly persons and in those with perforation. Approximately 2% of patients report duration of pain in excess of 2 weeks. A history of similar pain is reported in as many as 23% of cases, but this history of similar pain, in and of itself, should not be used to rule out the possibility of appendicitis.

In addition to recording the history of the abdominal pain, obtain a complete summary of the recent personal history surrounding gastroenterologic, genitourinary, and pneumologic conditions, as well as consider gynecologic history in female patients. An inflamed appendix near the urinary bladder or ureter can cause irritative voiding symptoms and hematuria or pyuria. Cystitis in male patients is rare in the absence of instrumentation. Consider the possibility of an inflamed pelvic appendix in male patients with apparent cystitis. Also consider the possibility of appendicitis in pediatric or adult patients who present with acute urinary retention.[15]

Physical Examination

It is important to remember that the position of the appendix is variable. Of 100 patients undergoing 3-dimensional (3-D) multidetector computed tomography (MDCT) scanning, the base of the appendix was located at the McBurney point in only 4% of patients; in 36%, the base was within 3 cm of the point; in 28%, it was 3-5 cm from that point; and, in 36% of patients, the base of the appendix was more than 5 cm from the McBurney point.[16]

The most specific physical findings in appendicitis are rebound tenderness, pain on percussion, rigidity, and guarding. Although RLQ tenderness is present in 96% of patients, this is a nonspecific finding. Rarely, left lower quadrant (LLQ) tenderness has been the major manifestation in patients with situs inversus or in patients with a lengthy appendix that extends into the LLQ. Tenderness on palpation in the RLQ over the McBurney point is the most important sign in these patients.

A careful physical examination, not limited to the abdomen, must be performed in any patient with suspected appendicitis. Gastrointestinal (GI), genitourinary, and pulmonary systems must be studied. Male infants and children occasionally present with an inflamed hemiscrotum due to migration of an inflamed appendix or pus through a patent processus vaginalis. This is often initially misdiagnosed as acute testicular torsion. In addition, perform a rectal examination in any patient with an unclear clinical picture, and perform a pelvic examination in all women with abdominal pain.

According to the American College of Emergency Physicians (ACEP) 2010 clinical policy update, clinical signs and symptoms should be used to stratify patient risk and to choose next steps for testing and management.[8, 9]

Accessory signs

In a minority of patients with acute appendicitis, some other signs may be noted. However, their absence never should be used to rule out appendiceal inflammation. The Rovsing sign (RLQ pain with palpation of the LLQ) suggests peritoneal irritation in the RLQ precipitated by palpation at a remote location. The obturator sign (RLQ pain with internal and external rotation of the flexed right hip) suggests that the inflamed appendix is located deep in the right hemipelvis. The psoas sign (RLQ pain with extension of the right hip or with flexion of the right hip against resistance) suggests that an inflamed appendix is located along the course of the right psoas muscle.

The Dunphy sign (sharp pain in the RLQ elicited by a voluntary cough) may be helpful in making the clinical diagnosis of localized peritonitis. Similarly, RLQ pain in response to percussion of a remote quadrant of the abdomen, or to firm percussion of the patient's heel, suggests peritoneal inflammation.

The Markle sign, pain elicited in a certain area of the abdomen when the standing patient drops from standing on toes to the heels with a jarring landing, was studied in 190 patients undergoing appendectomy and found to have a sensitivity of 74%.[2]

Rectal examination

There is no evidence in the medical literature that the digital rectal examination (DRE) provides useful information in the evaluation of patients with suspected appendicitis; however, failure to perform a rectal examination is frequently cited in successful malpractice claims. In 2008, Sedlak et al studied 577 patients who underwent DRE as part of an evaluation for suspected appendicitis and found no value as a means of distinguishing patients with and without appendicitis.[17]

Appendicitis and Pregnancy

The incidence of appendicitis is unchanged in pregnancy relative to the general population, but the clinical presentation is more variable than at other times.

During pregnancy, the appendix migrates in a counterclockwise direction toward the right kidney, rising above the iliac crest at about 4.5 months' gestation. RLQ pain and tenderness dominate in the first trimester, but in the latter half of pregnancy, right upper quadrant (RUQ) or right flank pain must be considered a possible sign of appendiceal inflammation.

Nausea, vomiting, and anorexia are common in uncomplicated first trimester pregnancies, but their reappearance later in gestation should be viewed with suspicion.

Diagnostic Scoring

Several investigators have created diagnostic scoring systems to predict the likelihood of acute appendicitis. In these systems, a finite number of clinical variables is elicited from the patient and each is given a numeric value; then, the sum of these values is used.

The best known of these scoring systems is the MANTRELS score, which tabulates migration of pain, anorexia, nausea and/or vomiting, tenderness in the RLQ, rebound tenderness, elevated temperature, leukocytosis, and shift to the left (see Table 1, below).[18]

Table 1. MANTRELS Score (Open Table in a new window)

Characteristic

Score

M = Migration of pain to the RLQ

1

A = Anorexia

1

N = Nausea and vomiting

1

T = Tenderness in RLQ

2

R = Rebound pain

1

E = Elevated temperature

1

L = Leukocytosis

2

S = Shift of WBCs to the left

1

Total

10

Source: Alvarado.[18]

RLQ = right lower quadrant; WBCs = white blood cells

Clinical scoring systems are attractive because of their simplicity; however, none has been shown prospectively to improve on the clinician's judgment in the subset of patients evaluated in the emergency department (ED) for abdominal pain suggestive of appendicitis. The MANTRELS score, in fact, was based on a population of patients hospitalized for suspected appendicitis, which differs markedly from the population seen in the ED.

In reviewing the records of 150 ED patients who underwent abdominopelvic computed tomography (CT) scanning to rule out appendicitis, McKay and Shepherd suggested that patients with an MANTRELS score of 0-3 could be discharged without imaging, that those with scores of 7 or above receive surgical consultation, and those with scores of 4-6 undergo CT evaluation.[19] The investigators found that patients with a MANTRELS score of 3 or lower had a 3.6% incidence of appendicitis, patients with scores of 4-6 had a 32% incidence of appendicitis, and patients with scores of 7-10 had a 78% incidence of appendicitis.[19]

In another study, Schneider et al concluded that the MANTRELS score was not sufficiently accurate to be used as the sole method for determining the need for appendectomy in the pediatric population.[20] These investigators, studied 588 patients aged 3-21 years and found that a MANTRELS score of 7 or greater had a positive predictive value of 65% and a negative predictive value of 85%.

Scoring systems and computer-aided diagnosis

Computer-aided diagnosis consists of using retrospective data of clinical features of patients with appendicitis and other causes of abdominal pain and then prospectively assessing the risk of appendicitis. Computer-aided diagnosis can achieve a sensitivity greater than 90% while reducing rates of perforation and negative laparotomy by as much as 50%.

However, the principle disadvantages to this method are that each institution must generate its own database to reflect characteristics of its local population, and specialized equipment and significant initiation time are required. In addition, computer-aided diagnosis is not widely available in US EDs.

Stages of Appendicitis

The stages of appendicitis can be divided into early, suppurative, gangrenous, perforated, phlegmonous, spontaneous resolving, recurrent, and chronic.

Early stage appendicitis

In the early stage of appendicitis, obstruction of the appendiceal lumen leads to mucosal edema, mucosal ulceration, bacterial diapedesis, appendiceal distention due to accumulated fluid, and increasing intraluminal pressure. The visceral afferent nerve fibers are stimulated, and the patient perceives mild visceral periumbilical or epigastric pain, which usually lasts 4-6 hours.

Suppurative appendicitis

Increasing intraluminal pressures eventually exceed capillary perfusion pressure, which is associated with obstructed lymphatic and venous drainage and allows bacterial and inflammatory fluid invasion of the tense appendiceal wall. Transmural spread of bacteria causes acute suppurative appendicitis. When the inflamed serosa of the appendix comes in contact with the parietal peritoneum, patients typically experience the classic shift of pain from the periumbilicus to the right lower abdominal quadrant (RLQ), which is continuous and more severe than the early visceral pain.

Gangrenous appendicitis

Intramural venous and arterial thromboses ensue, resulting in gangrenous appendicitis.

Perforated appendicitis

Persisting tissue ischemia results in appendiceal infarction and perforation. Perforation can cause localized or generalized peritonitis.

Phlegmonous appendicitis or abscess

An inflamed or perforated appendix can be walled off by the adjacent greater omentum or small-bowel loops, resulting in phlegmonous appendicitis or focal abscess.

Spontaneously resolving appendicitis

If the obstruction of the appendiceal lumen is relieved, acute appendicitis may resolve spontaneously.[21, 22] This occurs if the cause of the symptoms is lymphoid hyperplasia or when a fecalith is expelled from the lumen.

Recurrent appendicitis

The incidence of recurrent appendicitis is 10%. The diagnosis is accepted as such if the patient underwent similar occurrences of RLQ pain at different times that, after appendectomy, were histopathologically proven to be the result of an inflamed appendix.

Chronic appendicitis

Chronic appendicitis occurs with an incidence of 1% and is defined by the following: (1) the patient has a history of RLQ pain of at least 3 weeks’ duration without an alternative diagnosis; (2) after appendectomy, the patient experiences complete relief of symptoms; (3) histopathologically, the symptoms were proven to be the result of chronic active inflammation of the appendiceal wall or fibrosis of the appendix.

 

DDx

Diagnostic Considerations

The overall accuracy for diagnosing acute appendicitis is approximately 80%, which corresponds to a mean negative appendectomy rate of 20%. Diagnostic accuracy varies by sex, with a range of 78-92% in male patients and 58-85% in female patients.

The classic history of anorexia and periumbilical pain followed by nausea, right lower quadrant (RLQ) pain, and vomiting occurs in only 50% of cases. Vomiting that precedes pain is suggestive of intestinal obstruction, and the diagnosis of appendicitis should be reconsidered.

The differential diagnosis of appendicitis is often a clinical challenge because appendicitis can mimic several abdominal conditions (see the Differentials section).[12] Patients with many other disorders present with symptoms similar to those of appendicitis, such as the following:

  • Pelvic inflammatory disease (PID) or tubo-ovarian abscess

  • Endometriosis

  • Ovarian cyst or torsion

  • Ureterolithiasis and renal colic

  • Degenerating uterine leiomyomata

  • Diverticulitis

  • Crohn disease

  • Colonic carcinoma

  • Rectus sheath hematoma

  • Cholecystitis

  • Bacterial enteritis

  • Mesenteric adenitis and ischemia

  • Omental torsion

  • Biliary colic

  • Renal colic

  • Urinary tract infection (UTI)

  • Gastroenteritis

  • Enterocolitis

  • Pancreatitis

  • Perforated duodenal ulcer

Other problems that should be considered in a patient with suspected appendicitis include appendiceal stump appendicitis, typhlitis, epiploic appendagitis, psoas abscess, and yersiniosis.

Misdiagnosis in women of childbearing age

Appendicitis is misdiagnosed in 33% of nonpregnant women of childbearing age. The most frequent misdiagnoses are PID, followed by gastroenteritis and urinary tract infection. In distinguishing appendiceal pain from that of PID, anorexia and onset of pain more than 14 days after menses suggests appendicitis. Previous PID, vaginal discharge, or urinary symptoms indicates PID. On physical examination, tenderness outside the RLQ, cervical motion tenderness, vaginal discharge, and positive urinalysis support the diagnosis of PID.

Although negative appendectomy does not appear to adversely affect maternal or fetal health, diagnostic delay with perforation does increase fetal and maternal morbidity. Therefore, aggressive evaluation of the appendix is warranted in pregnant women.

The level of urinary beta–human chorionic gonadotropin (beta-hCG) is useful in differentiating appendicitis from early ectopic pregnancy. However, with regard to the WBC count, physiologic leukocytosis during pregnancy makes this study less useful in the diagnosis than at other times, and no reliable distinguishing WBC parameters are cited in the literature.

Misdiagnosis in children

Appendicitis is misdiagnosed in 25-30% of children, and the rate of initial misdiagnosis is inversely related to the age of the patient. The most common misdiagnosis is gastroenteritis, followed by upper respiratory infection and lower respiratory infection.

Children with misdiagnosed appendicitis are more likely than their counterparts to have vomiting before pain onset, diarrhea, constipation, dysuria, signs and symptoms of upper respiratory infection, and lethargy or irritability. Physical findings less likely to be documented in children with a misdiagnosis than in others include bowel sounds; peritoneal signs; rectal findings; and ear, nose, and throat findings.

Considerations in elderly patients

Appendicitis in patients older than 60 years accounts for 10% of all appendectomies. The incidence of misdiagnosis is increased in elderly patients.

Older patients tend to seek medical attention later in the course of illness; therefore, a duration of symptoms in excess of 24-48 hours should not dissuade the clinician from the diagnosis. In patients with comorbid conditions, diagnostic delay is correlated with increased morbidity and mortality.

Differential Diagnoses

 

Workup

Approach Considerations

Patients with appendicitis may not have the reported classic clinical picture 37-45% of the time, especially when the appendix is located in an unusual place (see Anatomy). In such cases, imaging studies may be important but not always available. However, patients with appendicitis usually have accessory signs that may be helpful for diagnosis (see Physical Examination). For example, the obturator sign is present when the internal rotation of the thigh elicits pain (ie, pelvic appendicitis), and the psoas sign is present when the extension of the right thigh elicits pain (ie, retroperitoneal or retrocecal appendicitis).

Laboratory tests are not specific for appendicitis, but they may be helpful to confirm diagnosis in patients with an atypical presentation.For example, liver and pancreatic function tests (eg, transaminases, bilirubin, alkaline phosphatase, serum lipase, amylase) may be helpful to determine the diagnosis in patients with an unclear presentation. For women of childbearing age, the level of urinary beta–human chorionic gonadotropin (beta-hCG) is useful in differentiating appendicitis from early ectopic pregnancy.

Complete Blood Cell Count

Studies consistently show that 80-85% of adults with appendicitis have a white blood cell (WBC) count greater than 10,500 cells/µL. Neutrophilia greater than 75% occurs in 78% of patients. Less than 4% of patients with appendicitis have a WBC count less than 10,500 cells/µL and neutrophilia less than 75%.

Dueholm et al further delineated the relationship between the WBC count and the likelihood of appendicitis by calculating likelihood ratios for defined intervals of the WBC count.[23]

Table 2. WBC Count and Likelihood of Appendicitis (Open Table in a new window)

WBC (× 10,000)

Likelihood Ratio (95% CI)

4-7

0.10 (0-0.39)

7-9

0.52 (0-1.57)

9-11

0.29 (0-0.62)

11-13

2.8 (1.2-4.4)

13-15

1.7 (0-3.6)

15-17

2.8 (0-6.0)

17-19

3.5 (0-10)

19-22

Source: Dueholm et al.[23]

CI = confidence interval; WBC = white blood cell.

Complete blood cell (CBC) tests are inexpensive, rapid, and widely available; however, the findings are nonspecific. In infants and elderly patients, a WBC count is especially unreliable because these patients may not mount a normal response to infection. In pregnant women, the physiologic leukocytosis renders the CBC count useless for the diagnosis of appendicitis.

C-Reactive Protein

C-reactive protein (CRP) is an acute-phase reactant synthesized by the liver in response to infection or inflammation and rapidly increases within the first 12 hours. CRP has been reported to be useful in the diagnosis of appendicitis; however, it lacks specificity and cannot be used to distinguish between sites of infection.

CRP levels of greater than 1 mg/dL are commonly reported in patients with appendicitis, but very high levels of CRP in patients with appendicitis indicate gangrenous evolution of the disease, especially if it is associated with leukocytosis and neutrophilia. However, CRP normalization occurs 12 hours after onset of symptoms. Several prospective studies have shown that, in adults who have had symptoms for longer than 24 hours, a normal CRP level has a negative predictive value of 97-100% for appendicitis.[3, 4, 5] Thimsen et al noted that a normal CRP level after 12 hours of symptoms was 100% predictive of benign, self-limited illness.[3]

CRP sensitivity

Multiple studies have examined the sensitivity of CRP level alone for the diagnosis of appendicitis in patients selected to undergo appendectomy. Gurleyik et al noted a CRP sensitivity of 96.6% in 87 of 90 patients with histologically proven disease.[24] Similarly, Shakhetrah found a CRP sensitivity of 95.5% in 85 of 89 patients with histologically proven appendicitis.[25] Asfar et al reported a CRP sensitivity of 93.6% in 78 patients undergoing appendectomy,[26] and Erkasap et al found a CRP sensitivity of 96% in a group of 102 adult patients with right lower quadrant (RLQ) pain, 55 of whom proceeded to appendectomy.[27]

Sensitivity of WBC count and CRP level in combination

Investigators have also studied the ability of combinations of white blood cell (WBC) count and CRP to reliably rule out the diagnosis of appendicitis. Gronroos and Gronroos found that the WBC count or CRP level was abnormal in all 200 patients with appendicitis in their cohort of 300 patients operated for suspected appendicitis.[28] Ortega-Deballon et al found that a normal WBC count and CRP level had a negative predictive value of 92.3% for the presence of appendicitis in prospectively studied patients referred to a surgeon for RLQ pain.[29]

Some studies have examined the sensitivity of a combined WBC count and CRP level in the subpopulation of patients older than 60 years. Gronroos studied 83 patients older than 60 years who underwent appendectomy (73 found to have appendicitis) and found that no patient with appendicitis had both a normal WBC count and CRP level.[30] Yang et al retrospectively studied 77 patients older than 60 years with histologically proven appendicitis and found that only 2 had a normal "triple screen" (see below).[31]

Several studies also examined the accuracy of the WBC count and CRP level in the subpopulation of pediatric patients with suspected appendicitis. Gronroos evaluated 100 children with pathology-proven appendicitis and found that both the WBC count and CRP level were normal in 7 of 100 patients.[32] Stefanutti et al prospectively studied more than 100 children undergoing surgery for suspected appendicitis and found that either the WBC count or CRP level was elevated in 98% of those with pathology-proven appendicitis.[33]

Triple screen of WBC count, CRP level, and neutrophilia

Mohammed et al prospectively studied 216 children admitted for suspected appendicitis and found a triple screen sensitivity of 86% and a negative predictive value of 81.[34] However, Yang et al found that only 6 of 740 patients with appendicitis had a WBC count less than 10,500 cells/μ L AND neutrophilia that was less than 75%, AND a normal CRP level, yielding a sensitivity of 99.2% for the "triple screen."[35]

Urinalysis and Urinary 5-HIAA

Urinalysis

Urinalysis may be useful in differentiating appendicitis from urinary tract conditions. Mild pyuria may occur in patients with appendicitis because of the relationship of the appendix with the right ureter. Severe pyuria is a more common finding in urinary tract infections (UTIs). Proteinuria and hematuria suggest genitourinary diseases or hemocoagulative disorders.

One study of 500 patients with acute appendicitis revealed that approximately one third reported urinary symptoms, most commonly dysuria or right flank pain.[36] One in 7 patients had pyuria greater than 10 WBCs per high power field (hpf), and 1 in 6 patients had greater than 3 red blood cells (RBCs) per hpf. Thus, the diagnosis of appendicitis should not be dismissed due to the presence of urologic symptoms or abnormal urinalysis.[36]

Urinary 5-hydroxyindoleacetic acid

According to a report by Bolandparvaz et al, measurement of the urinary 5-hydroxyindoleacetic acid (U-5-HIAA) levels could be an early marker of appendicitis.[6]  The rationale of such measurement is related to the large amount of serotonin-secreting cells in the appendix. The investigators noted that U-5-HIAA levels increased significantly in acute appendicitis, decreasing when the inflammation shifted to necrosis of the appendix.[6]  Therefore, such decrease could be an early warning sign of perforation of the appendix.

Computed Tomography Scanning

Computed tomography (CT) scanning with oral contrast medium or rectal Gastrografin enema has become the most important imaging study in the evaluation of patients with atypical presentations of appendicitis. Intravenous contrast is usually not necessary.

Studies have found a decrease in negative laparotomy rate and appendiceal perforation rate when pelvic CT imaging was used in selected patients with suspected appendicitis.[37, 38, 39, 40] An enlarged appendix is shown in the CT below.

CT scan reveals an enlarged appendix with thickene CT scan reveals an enlarged appendix with thickened walls, which do not fill with colonic contrast agent, lying adjacent to the right psoas muscle.

The use of CT has dramatically increased since the introduction of multidetector CT (MDCT) scanners. A large, single center study found that MDCT has a high rate of sensitivity and specificity (98.5% and 98%, respectively) for diagnosing acute appendicitis.[41]

In adults with appendicitis, the diagnostic performance of CT scans with intravenous contrast alone is comparable to that of scans with both intravenous and oral contrast, and patients who receive CT scans with intravenous contrast alone are discharged more quickly from the emergency department.[42]

CT scanning may also be used to detect atypically located acute appendicitis, including inguinal or femoral canal, subhepatic, retrocecal, intraperitoneal abdominal midline as well as left side in situs inversus or intestinal malrotation patients.[43] In this setting, patients may have an atypical presentation that causes a misleading or confusing diagnosis.

Concerns have grown over the possible adverse effects on patients from exposure to radiation from CT scanning. Low-dose abdominal CT allows for a 78% reduction in radiation exposure compared to traditional abdominopelvic CT and may be preferable for diagnosing children and young adults in whom exposure to CT radiation is of particular concern.[7] Ultrasonography may offer a safer alternative as a primary diagnostic tool for appendicitis, with CT scanning used in those cases in which ultrasonograms are negative or inconclusive.

An algorithm for screening pediatric patients (≤18 y) with suspected appendicitis appears to reduce the use of CT scanning without affecting diagnostic accuracy.[44, 45]  This tool also has implications for reducing the levels of radiation exposure and the cost of using this imaging modality. The algorithm includes pediatric surgery consultation without imaging studies in patients with an unequivocal history; for those with an equivocal history, physical examination, and ultrasonographic findings, the algorithm includes consultation and physical examination before obtaining CT studies.[45]

Investigators analyzed data from 331 pediatric patients with suspected appendicitis 2 years before (41%; n = 136) and 3 years after (59%; n = 195) implementation of the new algorithm and found a significant decrease in the use of CT scanning from 39% to 18%, respectively.[44, 45]  Moreover, although the negative appendectomy rate rose from 9% pre-implementation of the algorithm to 11% post-implementation, this increase was not significant and there was no association between negative appendectomy and CT scan utilization.[44, 45]

Go to Imaging of Appendicitis for more information on this topic.

Ultrasonography

Because of concerns about patient exposure to radiation during computed tomography (CT) scans, ultrasonography has been suggested as a safer primary diagnostic modality for appendicitis, with CT scanning used secondarily when ultrasonograms are negative or inconclusive.[46, 47, 48]

A healthy appendix usually cannot be viewed with ultrasonography. When appendicitis occurs, the ultrasonogram typically demonstrates a noncompressible tubular structure of 7-9 mm in diameter (see the images below).

Sagittal graded compression transabdominal sonogra Sagittal graded compression transabdominal sonogram shows an acutely inflamed appendix. The tubular structure is noncompressible, lacks peristalsis, and measures greater than 6 mm in diameter. A thin rim of periappendiceal fluid is present.
Transverse graded compression transabdominal sonog Transverse graded compression transabdominal sonogram of an acutely inflamed appendix. Note the targetlike appearance due to thickened wall and surrounding loculated fluid collection.

In pediatric patients, the American College of Emergency Physicians (ACEP) 2010 clinical policy update recommends using ultrasonography for confirmation, but not exclusion, of acute appendicitis. To definitively exclude acute appendicitis, CT is recommended.[8, 9]

Ultrasonography followed by magnetic resonance imaging (MRI) appears to be an effective combination for accurately diagnosing appendicitis in children.[49, 50] In a retrospective study of 662 patients younger than age 18 years presenting to the emergency department with abdominal pain, ultrasonography/MRI was performed in 397 patients and CT scanning was used in 265. In the ultrasonography/MRI group, ultrasound was positive for appendicitis in 19.7% of patients, and MRI identified an additional 62 cases, of which 7 (11.3%) were complicated. In the CT group, 55.4% of patients positive for appendicitis, of which 19.4% were complicated.[49, 50]

The false-positive rate was similar in the two groups (1.4% in the ultrasonography/MRI group and 2.5% in the CT group), and there were no false-negatives in either group.[49, 50] No significant differences between groups were observed in mean overall length of hospital stay, time to antibiotic administration, time to appendectomy, or perforation rate.[49, 50]

Vaginal ultrasonography alone or in combination with transabdominal scan may be useful to determine the diagnosis in women of childbearing age. One study of 22 pregnant women in the first and second trimesters showed that graded compression ultrasonography had a sensitivity of 66% and specificity of 95%.[10]

Ultrasonography findings may also aid clinicians in differentiating complicated from uncomplicated appendicitis, which in turn guides the decision making regarding whether to administer antibiotic therapy first or initiate and perform appendectomy.[51] In a retrospective, blinded study, the medical records of 119 patients with acute appendicitis were reviewed, of which 32 patients had complicated appendicitis (including gangrenous, with or without perforation). Investigators found that the only significant independent predictor of complicated appendicitis was loss of the normally echogenic submucosal layer, with 100% sensitivity and 92.0% specificity.[51]

Go to Imaging of Appendicitis for more information on this topic.

Abdominal Radiography

The kidneys-ureters-bladder (KUB) radiographic view is typically used to visualize an appendicolith in a patient with symptoms consistent with appendicitis. This finding is highly suggestive of appendicitis, but appendicoliths also occur in fewer than 10% of cases. The consensus in the literature is that plain radiographs are insensitive, nonspecific, and not cost-effective.

Go to Imaging of Appendicitis for more information on this topic.

Barium Enema Study

In the past, barium enema examination was used to diagnose appendicitis; in the era of ultrasonography and CT scanning, barium enema study has essentially no role in the diagnosis of acute appendicitis.

A single-contrast study can be performed on an unprepared bowel. Absent or incomplete filling of the appendix coupled with pressure effect or spasm in the cecum suggests appendicitis. The typical radiologic sign of appendicitis is the "reverse 3," which typically manifests as an indentation of the cecum. However, the appendix cannot be visualized in 50% of healthy individuals; therefore, barium enema lacks reliability.

Go to Imaging of Appendicitis for more information on this topic.

Radionuclide Scanning

Whole blood is withdrawn for radionuclide scanning. Neutrophils and macrophages are labeled with technetium Tc 99m (99m Tc) albumin and administered intravenously. Then, images of the abdomen and pelvis are obtained serially over 4 hours. Localized uptake of tracer in the RLQ suggests appendiceal inflammation; this is shown in the image below.

Technetium-99m radionuclide scan of the abdomen sh Technetium-99m radionuclide scan of the abdomen shows focal uptake of labeled WBCs in the right lower quadrant consistent with acute appendicitis.

Go to Imaging of Appendicitis for more information on this topic.

Magnetic Resonance Imaging

Traditionally, magnetic resonance imaging (MRI) has played a relatively limited role in the evaluation of appendicitis because of its high cost, long scan times, and limited availability. However, the lack of ionizing radiation makes it an attractive modality in pregnant patients. In fact, Cobben et al showed that MRI is far superior to transabdominal ultrasonography in evaluating pregnant patients with suspected appendicitis.[52]  Moreover, the sensitivity and specificity of MRI for appendicitis appears to be similar to those of computed tomography (CT) scanning.[53]

Nonetheless, when evaluating pregnant patients with suspected appendicitis, graded compression ultrasonography should be the imaging test of choice. If ultrasonography demonstrates an inflamed appendix, the patient should undergo appendectomy. If graded compression ultrasonography is nondiagnostic, the patient should undergo MRI of the abdomen and pelvis.

When used for evaluating pediatric patients, MRI has a higher sensitivity than ultrasound. In a prospective comparison of ultrasound and MRI in 104 children with suspected appendicitis, researchers found that MRI had a sensitivity of 100% compared to ultrasound which had a sensitivity of 76%. Tolerance of MRI was comparable to that of tolerance for ultrasound.[54]

A retrospective study of 662 patients younger that age 18 years who presented to the emergency department with abdominal pain found that ultrasound followed selectively by MRI accurately diagnosed pediatric appendicitis.[49, 50]

Go to Imaging of Appendicitis for more information on this topic.

Gross and Microscopic Evaluation

In the early stages of appendicitis, the appendix grossly appears edematous with dilation of the serosal vessels. Microscopy demonstrates neutrophil infiltrate of the mucosal and muscularis layers extending into the lumen. As time passes, the appendiceal wall grossly appears thickened, the lumen appears dilated, and a serosal exudate (fibrinous or fibrinopurulent) may be observed as granular roughening. At this stage, mucosal necrosis may be observed microscopically.

At the later stages of appendicitis, the appendix grossly shows marked signs of mucosal necrosis extending into the external layers of the appendiceal wall that can become gangrenous. Sometimes, the appendix may be found in a collection of pus. At this stage of appendicitis, microscopy may demonstrate multiple microabscesses of the appendiceal wall and severe necrosis of all layers.

 

Treatment

Approach Considerations

Appendectomy remains the only curative treatment of appendicitis, but management of patients with an appendiceal mass can usually be divided into the following 3 treatment categories:

  • Patients with a phlegmon or a small abscess: After intravenous (IV) antibiotic therapy, an interval appendectomy can be performed 4-6 weeks later.

  • Patients with a larger well-defined abscess: After percutaneous drainage with IV antibiotics is performed, the patient can be discharged with the catheter in place. Interval appendectomy can be performed after the fistula is closed.

  • Patients with a multicompartmental abscess: These patients require early surgical drainage.

Although many controversies exist over the nonoperative management of acute appendicitis, antibiotics have an important role in the treatment of patients with this condition. Antibiotics considered for patients with appendicitis must offer full aerobic and anaerobic coverage. The duration of the administration is closely related to the stage of appendicitis at the time of the diagnosis, considering either intraoperative findings or postoperative evolution. According to several studies, antibiotic prophylaxis should be administered before every appendectomy. When the patient becomes afebrile and the white blood cell (WBC) count normalizes, antibiotic treatment may be stopped. Cefotetan and cefoxitin seem to be the best choices of antibiotics. (See Medication).

Go to Pediatric Appendicitis for more information on this topic.

Emergency Department Care

The emergency department (ED) clinician must evaluate the larger group of patients who present to the ED with abdominal pain of all etiologies with the goal of approaching 100% sensitivity for the diagnosis in a time-, cost-, and consultation-efficient manner.

Establish IV access and administer aggressive crystalloid therapy to patients with clinical signs of dehydration or septicemia. Patients with suspected appendicitis should not receive anything by mouth.

Administer parenteral analgesic and antiemetic as needed for patient comfort. The administration of analgesics to patients with acute undifferentiated abdominal pain has historically been discouraged and criticized because of concerns that they render the physical findings less reliable.[55] However, at least 8 randomized controlled studies have demonstrated that administering opioid analgesic medications to adult and pediatric patients with acute undifferentiated abdominal pain is safe; no study has shown that analgesics adversely affect the accuracy of physical examination.[11]  Factors associated with prescription of any analgesia and opioids are older age and payment source; in addition, use of computed tomography (CT) scanning  was associated with prescription of analgesics.[55]

Consider ectopic pregnancy in women of childbearing age, and obtain a qualitative beta–human chorionic gonadotropin (beta-hCG) measurement in all cases.

Administer intravenous antibiotics to those with signs of septicemia and to those who are to proceed to laparotomy.

Nonsurgical Treatment

Nonsurgical treatment may be useful when appendectomy is not accessible or when it is temporarily a high-risk procedure. Anecdotal reports describe the success of IV antibiotics in treating acute appendicitis in patients without access to surgical intervention (eg, submariners, individuals on ships at sea).

In a prospective study of 20 patients with ultrasonography-proven appendicitis, symptoms resolved in 95% of patients receiving antibiotics alone, but 37% of these patients had recurrent appendicitis within 14 months.[56]

The Appendicitis Acuta (APPAC) trial, which compared antibiotic therapy with appendectomy in the treatment of 530 patients with uncomplicated acute appendicitis confirmed by computed tomography (CT), was not able to demonstrate noninferiority of antimicrobial management versus surgery.[57]

Bonadio et al reported that of 203 children with perforated appendicitis, those who underwent early appendectomy (n = 122) had significantly better outcomes than those who received medical management (n = 81).[58] The early appendectomy group had shorter hospitalization stays, received fewer parenteral antibiotics, underwent fewer radiologic studies and other invasive procedures (percutaneous drainage, central venous catherization), and had fewer inpatient febrile episodes, as well as had fewer postadmission intraabominal complications and/or fewer unscheduled postdischarge readmissions.[58]

Preoperative Antibiotics

Preoperative antibiotics have demonstrated efficacy in decreasing postoperative wound infection rates in numerous prospective controlled studies, and they should be administered in conjunction with the surgical consultant. Broad-spectrum gram-negative and anaerobic coverage is indicated (see Medication).

Penicillin-allergic patients should avoid beta-lactamase type antibiotics and cephalosporins. Carbapenems are a good option in these patients.

Pregnant patients should receive pregnancy category A or B antibiotics.

Urgent Versus Emergent Appendectomy

A retrospective study suggested that the risk of appendiceal rupture is minimal in patients with less than 24-36 hours of untreated symptoms,[59] and another retrospective study suggested that appendectomy within 12-24 hours of presentation is not associated with an increase in hospital length of stay, operative time, advanced stages of appendicitis, or complications compared with appendectomy performed within 12 hours of presentation.[60]

Fair et al used data from the American College of Surgeons National Surgical Quality Improvement Project to evaluate 30-day morbidity and mortality of intervention (laparoscopic and open appendectomy) at different time periods (adjusted for preoperative risk factors) and found similar outcomes between when appendectomy was performed within 24 hours and when it was performed between 24-48 hours.[61]  However, a delay of operative intervention longer than 48 hours was associated with doubling of complication rates.

In a separate study, Boomer et al reported that delaying appendectomy (16 hours from presentation in the emergency department or 12 hours from inpatient admission) in children did not result in higher rates of surgical site infections.[62]

Additional studies are needed to demonstrate whether initiation of antibiotic therapy followed by urgent appendectomy is as effective as emergent appendectomy for patients with unperforated appendicitis.

Go to Appendectomy and Pediatric Appendectomy for more information on these topics.

Emergent Versus Interval Surgery for Perforated Appendicitis

Historically, immediate (emergent) appendectomy was recommended for all patients with appendicitis, whether perforated or unperforated. More recent clinical experience suggests that patients with perforated appendicitis with mild symptoms and localized abscess or phlegmon on abdominopelvic computed tomography (CT) scans can be initially treated with IV antibiotics and percutaneous or transrectal drainage of any localized abscess. If the patient's symptoms, WBC count, and fever satisfactorily resolve, therapy can be changed to oral antibiotics and the patient can be discharged home. Then, delayed (interval) appendectomy can be performed 4-8 weeks later.

The above approach is successful in the vast majority of patients with perforated appendicitis and localized symptoms. Some have suggested that interval appendectomy is not necessary, unless the patient presents with recurrent symptoms. Further studies are needed to clarify not only whether routine interval appendectomy is indicated but also to identify the optimal treatment strategy in patients with perforated appendicitis

Go to Appendectomy and Pediatric Appendectomy for more information on these topics.

Laparoscopic Appendectomy

Initially performed in 1987, laparoscopic appendectomy has been performed in thousands of patients and is successful in 90-94% of attempts. It has also been demonstrated that laparoscopic appendectomy is successful in approximately 90% of cases of perforated appendicitis. However, this procedure is contraindicated in patients with significant intra-abdominal adhesions.

According to the 2010 Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) guideline, the indications for laparoscopic appendectomy are identical to those for open appendectomy.[63]

The 2010 SAGES guideline lists the following conditions as suitable for laparoscopic appendectomy[63] :

  • Uncomplicated appendicitis

  • Appendicitis in pediatric patients

  • Suspected appendicitis in pregnant women

According to the SAGES guideline, laparoscopic appendectomy may be the preferred approach in the following cases[63] :

  • Perforated appendicitis

  • Appendicitis in elderly patients

  • Appendicitis in obese patients

The SAGES guideline states that the laparoscopic approach should be preferred in women of childbearing age with presumed appendicitis.[63]

Diagnostic laparoscopy may be useful in selected cases (eg, infants, elderly patients, female patients) to confirm the diagnosis of appendicitis. This procedure has been suggested for pregnant patients in the first trimester with suspected appendicitis. If findings are positive, such procedures should be followed by definitive surgical treatment at the time of laparoscopy. Although negative appendectomy does not appear to adversely affect maternal or fetal health, diagnostic delay with perforation does increase fetal and maternal morbidity. Therefore, aggressive evaluation of the appendix is warranted in this group.

In a systematic review and meta-analysis of 11 studies on laparoscopic versus open appendicectomy for suspected appendicitis in pregnancy, Wilasrusmee et al found that laparoscopic appendicectomy in pregnant women was associated with a significantly greater risk of fetal loss.[64] According to the SAGES guideline, if findings are negative (normal appendix) on laparoscopic approach, removal should be considered based on the patient’s clinical situation.[63]

Advantages of laparoscopic appendectomy include increased cosmetic satisfaction and a decrease in the postoperative wound-infection rate. Some studies show that laparoscopic appendectomy shortens the hospital stay and convalescent period compared with open appendectomy.

Disadvantages of laparoscopic appendectomy are increased cost and an operating time approximately 20 minutes longer than that of an open appendectomy; however, the latter may resolve with increasing experience with laparoscopic technique. The SAGES guideline recommends practicing a consistent operative method to reduce cost, operating time, and complications.[63]

Go to Appendectomy and Pediatric Appendectomy for more information on these topics.

Complications

Complications of appendicitis may include wound infection, dehiscence, bowel obstruction, abdominal/pelvic abscess, and, rarely, death. Stump appendicitis also occurs rarely; however, at least 36 reported cases of appendicitis in the surgical stump after previous appendectomy exist.[65]

Consultations

In cases of suspected appendicitis, consult a general surgeon. The surgeon's goals are to evaluate a relatively small population of patients referred for suspected appendicitis and to minimize the negative appendectomy rate without increasing the incidence of perforation.

 

Medication

Medication Summary

The goals of therapy are to eradicate the infection and to prevent complications. Thus, antibiotics have an important role in the treatment of appendicitis, and all such. Agents under consideration must offer full aerobic and anaerobic coverage. The duration of the administration is closely related to the stage of appendicitis at the time of the diagnosis.

Antibiotic agents are effective in decreasing the rate of postoperative wound infection and in improving outcome in patients with appendiceal abscess or septicemia. The Surgical Infection Society recommends starting prophylactic antibiotics before surgery, using appropriate spectrum agents for less than 24 hours for nonperforated appendicitis and for less than 5 days for perforated appendicitis. Regimens are of approximately equal efficacy, so consideration should be given to features such as medication allergy, pregnancy category (if applicable), toxicity, and cost.

Penicillins

Class Summary

The penicillins are bactericidal antibiotics that work against sensitive organisms at adequate concentrations and inhibit the biosynthesis of cell wall mucopeptide.

Piperacillin and tazobactam sodium (Zosyn)

This agent is a drug combination of beta-lactamase inhibitor with piperacillin. It has activity against some gram-positive organisms, gram-negative organisms, and anaerobic bacteria. When used as a single agent, it inhibits biosynthesis of cell wall mucopeptide and is effective during active multiplication stages.

Ampicillin and sulbactam (Unasyn)

This agent is a drug combination of beta-lactamase inhibitor with ampicillin. It is used as a single agent and interferes with bacterial cell wall synthesis during active replication, causing bactericidal activity against susceptible organisms. Ampicillin/sulbactam also has activity against some gram-positive organisms, gram-negative organisms (nonpseudomonal species), and anaerobic bacteria.

Ticarcillin/clavulanate (Timentin)

Ticarcillin/clavulanate inhibits biosynthesis of cell wall mucopeptide and is effective during the stage of active growth. It is an antipseudomonal penicillin plus beta-lactamase inhibitor that provides coverage against most gram-positive organisms, most gram-negative organisms, and most anaerobic organisms.

Cephalosporins

Class Summary

Cephalosporins are structurally and pharmacologically related to penicillins. They inhibit bacterial cell wall synthesis, resulting in bactericidal activity.

Cefotetan (Cefotan)

Cefotetan is a second-generation cephalosporin that is used as single-drug therapy for broad gram-negative and anaerobic coverage. Administer cefotetan with cefoxitin to achieve the effectiveness of single dose. Its half-life is 3.5 hours.

Cefoxitin (Mefoxin)

This drug is also a second-generation cephalosporin that is indicated as single agent for the management of infections caused by susceptible gram-positive cocci and gram-negative rods. It has a half-life of 0.8 hours.

Cefepime

Cefepime is a fourth-generation cephalosporin. It has gram-negative coverage comparable to ceftazidime but has better gram-positive coverage. Cefepime is a zwitter ion that rapidly penetrates gram-negative cells.

Aminoglycosides

Class Summary

Aminoglycosides have concentration-dependent bactericidal activity. These agents work by binding to the 30S ribosome, inhibiting bacterial protein synthesis.

Gentamicin (Gentacidin, Garamycin)

Gentamicin is an aminoglycoside antibiotic used for gram-negative coverage, as well as in combination with an agent against gram-positive organisms and another one against anaerobes. Gentamicin is not the drug of choice, but consider using this drug if penicillins or other less toxic drugs are contraindicated, when it is clinically indicated, and in mixed infections caused by susceptible staphylococci and gram-negative organisms. This agent may be administered intravenously or intramuscularly and has numerous regimens; the dose must be adjusted for creatinine clearance and changes in volume of distribution.

Carbapenems

Class Summary

Carbapenems are structurally related to penicillins and have broad-spectrum bactericidal activity. The carbapenems exert their effect by inhibiting cell wall synthesis, which leads to cell death. They are active against gram-negative, gram-positive, and anaerobic organisms.

Meropenem (Merrem)

Meropenem is a bactericidal broad-spectrum carbapenem antibiotic that inhibits cell wall synthesis. It is used as a single agent and is effective against most gram-positive and gram-negative bacteria.

Ertapenem

Ertapenem has bactericidal activity that results from the inhibition of cell wall synthesis and is mediated through ertapenem binding to penicillin-binding proteins. It is stable against hydrolysis by a variety of beta-lactamases, including penicillinase, cephalosporinase, and extended-spectrum beta-lactamases.

Fluoroquinolones

Class Summary

These agents can be used to relieve acute undifferentiated abdominal pain in patients presenting to the ED.

Ciprofloxacin (Cipro)

Ciprofloxacin is a fluoroquinolone that inhibits bacterial DNA synthesis and, consequently, growth, by inhibiting DNA gyrase and topoisomerase, which are required for replication, transcription, and translation of genetic material. Quinolones have broad activity against gram-positive and gram-negative aerobic organisms.

Levofloxacin (Levaquin)

Levofloxacin is used for infections caused by various gram-negative organisms, antipseudomonal infections due to multidrug resistant gram-negative organisms.

Moxifloxacin (Avelox)

Moxifloxacin is a fluoroquinolone that inhibits A subunits of DNA gyrase, inhibiting bacterial DNA replication and transcription.

Anti-infective Agents

Class Summary

Anti-infectives such as metronidazole and tigecycline are effective against many types of bacteria that have become resistant to other antibiotics.

Metronidazole (Flagyl)

Metronidazole has broad gram-negative and anaerobic coverage and is used in combination with aminoglycosides (eg, gentamicin). This agent appears to be absorbed into cells; intermediate metabolized compounds bind DNA and inhibit protein synthesis, causing cell death.

Tigecycline (Tygacil)

Tigecycline is a glycylcycline antibiotic that is structurally similar to tetracycline antibiotics. It inhibits bacterial protein translation by binding to the 30S ribosomal subunit, and it blocks entry of amino-acyl tRNA molecules into the ribosome A site.

Analgesics

Class Summary

These agents can be used to relieve acute undifferentiated abdominal pain in patients presenting to the ED.

Morphine sulfate (Astramorph, Duramorph, MS Contin, MSIR, Oramorph)

Morphine sulfate is the drug of choice for analgesia because of its reliable and predictable effects, safety profile, and ease of reversibility with naloxone. Various intravenous doses are used; morphine sulfate is commonly titrated to the desired effect.

 

Questions & Answers

Overview

What is appendicitis?

What are the signs and symptoms of appendicitis?

What are the features of abdominal pain in appendicitis?

Which physical findings suggest appendicitis?

What are the less common signs of appendicitis?

Which lab tests may be helpful in the diagnosis of appendicitis in patients with an atypical presentation?

Which CBC count findings suggest appendicitis in patients with atypical presentation?

What is the significance of C-reactive protein levels in appendicitis?

What is the role of urinary 5-HIAA levels in the diagnosis of appendicitis?

What is the role of CT scanning in the diagnosis of appendicitis?

What are the ACEP recommendations for use of ultrasonography in the diagnosis of appendicitis?

Which imaging studies may be useful for the diagnosis of appendicitis?

How is appendicitis managed in the emergency department (ED)?

How is appendicitis treated?

Which antibiotics may be used in the treatment of appendicitis and how are they administered?

What is appendicitis?

Can appendicitis be diagnosed based on signs and symptoms?

What is the disease course of untreated appendicitis?

What are the diagnostic and surgical goals concerning appendicitis in the emergency department (ED)?

What is the anatomy of the appendix?

How can intraoperative hemorrhages be avoided in appendicitis?

Where the appendix located?

How often do congenital appendiceal disorders occur?

What causes appendicitis?

What is the role of appendiceal obstruction in the pathogenesis of appendicitis?

What are the most common causes of appendicitis?

What is the role of fecaliths in the pathogenesis of appendicitis?

What are the less common causes of appendicitis?

What is the incidence of appendicitis in the US?

What is the global incidence of appendicitis?

Is appendicitis more common in males or females?

How does the incidence of appendicitis vary among age groups?

What is the complication rate of appendectomy?

What is the mortality rate associated with appendicitis?

What is the rate of appendiceal perforation in patients with appendicitis?

What factors are predictive of complicated appendicitis in children?

Presentation

Which factors lead to inconsistent clinical presentation of appendicitis?

What is the focus of the history in suspected appendicitis?

What is the most common symptom of appendicitis and how does it progress?

Why is gastroenterologic and genitourinary history needed in suspected appendicitis?

Where is the appendix positioned?

What physical findings suggest appendicitis?

In addition to the abdomen, what should be included in the physical exam of a patient with suspected appendicitis?

Which signs should be noted in patients with suspected acute appendicitis?

How useful is digital rectal exam (DRE) in the evaluation of suspected appendicitis?

How does pregnancy affect the clinical presentation of appendicitis?

What is computer-aided diagnosis for appendicitis?

How is the MANTRELS score used in the diagnosis of appendicitis?

How effective is the MANTRELS score in diagnosing appendicitis?

How are the stages of appendicitis?

What are the characteristics of the early stage of appendicitis?

What are the characteristics of the suppurative stage of appendicitis?

What are the characteristics of the gangrenous, perforated, phlegmonous, and spontaneously resolving stages of appendicitis?

What is the incidence of recurrent appendicitis?

How is chronic appendicitis defined?

DDX

How accurate is the diagnosis of acute appendicitis?

What are the classic symptoms of appendicitis?

Which disorders should be included in the differential diagnoses of appendicitis?

How often is appendicitis misdiagnosed in women and what are the most common misdiagnoses?

During pregnancy, how does appendectomy affect maternal or fetal health?

How is appendicitis differentiated from ectopic pregnancy?

How often is appendicitis misdiagnosed in children and what are the most common misdiagnoses?

What physical findings are more likely to be present in children with misdiagnosed appendicitis?

What is the incidence of appendicitis in patients older than 60 years?

What are the differential diagnoses for Appendicitis?

Workup

How is appendicitis diagnosed in patients lacking a classic clinical presentation?

What is the role of lab tests in the diagnosis of appendicitis?

Which WBC count and neutrophilia levels suggest appendicitis?

Is a CBC count useful in the diagnosis of appendicitis?

What is the role of C-reactive protein (CRP) in the diagnosis of appendicitis?

What C-reactive protein (CRP) levels are suggest appendicitis?

What is the sensitivity of C-reactive protein level (CRP) in the diagnosis of appendicitis?

How effective are WBC count and C-reactive protein (CRP) in ruling out the diagnosis of appendicitis?

Is a triple screen of WBC count, CRP level, and neutrophilia effective in diagnosing appendicitis?

What is the role of urinalysis in differentiating appendicitis from UTIs?

What urinalysis results suggest appendicitis?

Can urinary 5-hydroxyindoleacetic acid (U-5-HIAA) be used as an early marker of appendicitis?

How effective is CT scanning when evaluating atypical presentations of appendicitis?

What is the role of multidetector CT (MDCT) in the diagnosis of acute appendicitis?

Are CT scans beneficial in the diagnosis of appendicitis?

How is CT scanning used in the diagnosis of appendicitis?

What are the adverse effects of CT scans in the diagnosis of appendicitis?

How effective is a screening algorithm for pediatric patients with suspected appendicitis?

What is the role of ultrasonography in the diagnosis of appendicitis?

When is ultrasonography recommended in the workup of appendicitis by the ACEP?

Can ultrasonography be used to diagnose appendicitis in women of childbearing age?

Can ultrasonography be used to differentiate complicated from uncomplicated appendicitis?

What is the role of abdominal X-ray in the diagnosis of appendicitis?

What is the role of barium enema exam in the diagnosis of appendicitis?

What is the role of radionuclide scanning in the diagnosis of appendicitis?

What is the role of MRI in the diagnosis of appendicitis?

How effective is MRI compared with ultrasonography in the diagnosis of appendicitis?

How do the microscopic findings change from the early stages to the later stages of appendicitis?

Treatment

How is an appendiceal mass managed?

What is the role of antibiotic therapy in the treatment of acute appendicitis?

What is the goal of the emergency department (ED) clinician when evaluating abdominal pain?

What treatment should be given in the emergency department (ED) for suspected appendicitis?

When should analgesics and antiemetics be administered to patients with acute undifferentiated abdominal pain in the emergency department (ED)?

What test should be obtained for all women of childbearing age with suspected appendicitis?

When is nonsurgical treatment indicated in patients with appendicitis?

How effective is nonsurgical treatment in comparison to an appendectomy for appendicitis?

When are preoperative antibiotics indicated in the treatment of appendicitis?

When is an immediate (emergent) appendectomy indicated in the treatment of appendicitis?

What is the risk of an appendiceal rupture in appendicitis?

Is a laparoscopic appendectomy effective and when is it contraindicated in the treatment of appendicitis?

According to the SAGES guidelines, when is laparoscopic appendectomy the preferred approach in the treatment of appendicitis?

Which patients should undergo a laparoscopy to confirm the diagnosis of appendicitis?

What are the adverse effects of a laparoscopic appendectomy in the treatment of appendicitis?

What are the advantages and disadvantages of a laparoscopic appendectomy in the treatment of appendicitis?

What are the possible complications of appendicitis?

When should a general surgeon be consulted in the treatment of appendicitis?

Medications

What are the goals of therapy for appendicitis?

How effective are antibiotics in the treatment of appendicitis and what are the recommended regimens?

Which medications in the drug class Penicillins are used in the treatment of Appendicitis?

Which medications in the drug class Cephalosporins are used in the treatment of Appendicitis?

Which medications in the drug class Aminoglycosides are used in the treatment of Appendicitis?

Which medications in the drug class Carbapenems are used in the treatment of Appendicitis?

Which medications in the drug class Fluoroquinolones are used in the treatment of Appendicitis?

Which medications in the drug class Anti-infective Agents are used in the treatment of Appendicitis?

Which medications in the drug class Analgesics are used in the treatment of Appendicitis?