Introduction
In 1886, Reginald H. Fitz, a Harvard pathologist, first described the clinical condition of acute appendicitis.1 He correctly pointed out the importance of its early diagnosis and timely treatment, based on his analysis of 257 cases of perforating inflammation of the appendix and 209 cases of typhlitis or perityphlitis.2
A few years later, Charles McBurney described the clinical findings prior to rupture and advocated early surgical intervention. Despite aggressive intervention, mortality and morbidity rates remained high through the rest of the 19th century and the first half of the 20th century. The mortality rate associated with appendicitis declined with the introduction of antibiotics and with the development of anesthesia and better perioperative care.
Currently, the diagnosis of acute appendicitis remains a challenge. Only slightly more than half of patients present with classic signs and symptoms of acute appendicitis. Atypical presentations often lead to a delay in diagnosis, perforation, prolonged hospitalization, and increased morbidity.3 Thus, all clinicians must be knowledgeable about diagnosing and managing this disease process.
For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education articles, Appendicitis and Abdominal Pain in Adults.
History of the Procedure
The appendix was probably first noted as early as the Egyptian civilization (3000 BC). During the mummification process, abdominal parts were removed and placed in Coptic jars with inscriptions describing the contents. When these jars were uncovered, inscriptions referring to the "worm of the intestine" were discovered.4
Aristotle and Galen did not identify the appendix because they both dissected lower animals, which do not have appendices. Celsus, however, probably discovered the appendix because he was allowed to dissect criminals executed by Caesar.4 Leonardo da Vinci first depicted the appendix in anatomic drawings in 1492.5 In 1521, Jacopo Beregari da Capri, a professor of anatomy in Bologna, identified the appendix as an anatomic structure. In the 1500s, Vesalius (1543) and Pare (1582) referred to the appendix as the caecum. Laurentine compared the appendix to a twisted worm in 1600, and Phillipe Verheyen coined the term appendix vermiformis in 1710.4Problem
Acute appendicitis remains one of the most common surgical diseases encountered by physicians. When appendicitis manifests in its classic form, it is easily diagnosed and treated. Unfortunately, these classic symptoms occur in just over half of patients with acute appendicitis; therefore, an accurate and timely diagnosis of atypical appendicitis remains clinically challenging and one of the most commonly missed problems in the emergency department. Furthermore, the consequence of missing appendicitis, thus leading to perforation, significantly increases morbidity and prolongs hospitalization.6
Frequency
In Western countries, approximately 7% of individuals develop appendicitis at some time during their lives. Approximately 200,000 appendectomies are performed annually in the United States.1
The peak incidence of acute appendicitis has gradually declined to about half of its peak incidence in the early 20th century, with the current annual incidence of 1 per 1000 population in the United States and 86 cases for every 100,000 persons worldwide.7,8
Acute appendicitis is less common in Africa and in parts of Asia because of the high-residue diets of the inhabitants.
Etiology
Appendicitis results from obstruction of the lumen of the appendix. Obstruction may be from lymphoid hyperplasia (60%), fecalith or fecal stasis (35%), foreign body (4%), and tumors (1%).9
Pathophysiology
The basic pathophysiology of appendicitis is obstruction of the lumen of the appendix followed by infection. In 60% of patients, obstruction is caused by hyperplasia of the submucosal follicles. This form of obstruction is mostly observed in children and is known as catarrhal appendicitis. A fecalith or fecal stasis causes luminal obstruction 35% of the time and is usually observed in adults. Obstruction may also be caused by foreign bodies (4%) and tumors (1%).
Following obstruction, an increase in mucous production occurs, and this leads to increased pressure. With increased pressure and stasis from obstruction, bacterial overgrowth ensues. The mucus then turns into pus that causes a further increase in luminal pressure. This leads to distention of the appendix and visceral pain, which is typically located in the epigastric or periumbilical region.
As the luminal pressure continues to increase, lymphatic obstruction occurs, leading to an edematous appendix. This stage is known as acute or focal appendicitis. The overlying parietal peritoneum becomes irritated, and the pain now localizes to the right lower quadrant (RLQ). This series of events results in the classic migrating abdominal pain described in patients with appendicitis.
Further increase in pressure leads to venous obstruction, causing edema and ischemia of the appendix. At this stage, bacterial invasion of the wall of the appendix occurs and is known as acute suppurative appendicitis. Finally, with continued pressure increases, venous thrombosis and arterial compromise occur, leading to gangrene and perforation.9 If the body successfully walls off the perforation, the pain may actually improve. However, symptoms do not completely resolve. Patients may still have underlying right lower quadrant pain, decreased appetite, change in bowel habits (eg, diarrhea, constipation), or intermittent low-grade fever. If the perforation is not successfully walled off, then diffuse peritonitis will develop.
Presentation
The classic presentation of a patient with appendicitis includes a history of initial periumbilical or epigastric abdominal pain migrating to the RLQ. The pain is gradual in onset and progressively worsens. Anorexia, nausea, and vomiting are typically associated with the disease. In early appendicitis, the patient is initially afebrile or has a low-grade fever. Higher fevers are associated with a perforated appendix.3
On physical examination, the patient is usually lying still, as movement worsens the pain. Having the patient cough elicits localized pain in the RLQ. Local tenderness to palpation is usually observed. Percussion tenderness is also noted in this area. Tenderness on the right side during rectal examination may occur, whereas pelvic and testicular examination findings are normal. Other signs (eg, Rovsing, psoas, obturator) are unreliable and typically occur late in the disease process.3
Unfortunately, only 55% of patients with appendicitis present with classic history and physical findings. This is because the early signs and symptoms are primarily dependent upon the location of the tip of the appendix, which is highly variable.9
Indications
Indications for surgical consultation
A surgeon should evaluate any patient with classic migrating abdominal pain and RLQ tenderness. Because only a little more than half of patients with appendicitis present with a classic history and physical findings, acute appendicitis should be on the list of possible diagnoses for any patient with abdominal pain. Thus, a surgeon should also evaluate patients with focal RLQ tenderness or progressively worsening abdominal pain.
To minimize the time between presentation and appendectomy, obtain surgical consultation prior to performing additional diagnostic studies, such as CT scan, ultrasound, and technetium (Tc)-labeled WBC scan.3
Indications for operation
Any patient with suspected appendicitis who has (1) persistent pain and becomes febrile, (2) an increasing WBC count, or (3) worsening clinical examination findings should undergo appendectomy or at least diagnostic laparoscopy. In patients with an atypical presentation, the most important determination for appendectomy is serial physical examinations. The WBC count often does not increase after the patient is admitted and hydrated; therefore, any patient sent home from the emergency department should undergo a follow-up evaluation the next day.3
Relevant Anatomy
Embryologically, the appendix is a continuation of the cecum and is first delineated during the fifth month of gestation. The appendix does not elongate as rapidly as the rest of the colon, thus forming a wormlike structure.1
The appendix averages 10 cm in length but can range from 2-20 cm. The wall of the appendix consists of 2 layers of muscle, an inner circular and outer longitudinal. The longitudinal layer is a continuation of the taeniae coli. The appendix is lined by colonic epithelium.1
Few submucosal lymphoid follicles are noted at birth. These follicles enlarge, peak from 12-20 years, and then decrease. This correlates with the incidence of appendicitis.
Blood supply to the appendix is mainly from the appendicular artery, a branch of the ileocolic artery. This artery courses through the mesoappendix posterior to the terminal ileum. An accessory appendicular artery can branch from the posterior cecal artery. This artery can lead to significant intraoperative and postoperative hemorrhage and should be searched for carefully and ligated once the main appendicular artery is controlled.9
The base of the appendix is fairly constant and is located at the posteromedial wall of the cecum about 2.5 cm below the ileocecal valve. This is also where the taeniae converge.9
The base is at a constant location, whereas the position of the tip of the appendix varies. In 65% of patients, the tip is located in a retrocecal position; in 30%, it is located at the brim or in the true pelvis; and, in 5%, it is extraperitoneal, situated behind the cecum, ascending colon, or distal ileum. The location of the tip of the appendix determines early signs and symptoms.
Contraindications
No contraindications to performing an appendectomy in patients with suspected appendicitis exist; however, patients with a well-developed abscess (detected on CT scan) following perforated appendicitis may be initially treated with percutaneous drainage and intravenous antibiotics.
Once bowel function resumes, the patient may be discharged on oral antibiotics (total IV plus PO antibiotics for 7-10 d) with consideration for interval appendectomy in 6 weeks.10
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References
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Goldin AB, Sawin RS, Garrison MM, et al. Aminoglycoside-based triple-antibiotic therapy versus monotherapy for children with ruptured appendicitis. Pediatrics. May 2007;119(5):905-11. [Medline].
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Further Reading
Keywords
vermiform appendix, acute appendicitis, suppurative appendicitis, gangrenous appendicitis, perforated appendicitis, lymphoid hyperplasia, fecaliths, fecal stasis
