eMedicine Specialties > Pediatrics: General Medicine > Gastroenterology

Appendicitis

Author: Michael S Katz, MD, Research Fellow, Department of Pediatric Surgery, St Christopher's Hospital for Children
Coauthor(s): Michael Stephen Freitas, MS, State University of New York at Buffalo School of Medicine and Biomedical Sciences; Jeffrey R Tucker, MD, Assistant Professor, Department of Pediatrics, Division of Emergency Medicine, University of Connecticut and Connecticut Children's Medical Center; Philip Glick, MD, MBA, Professor, Departments of Surgery, Pediatrics, and Gynecology and Obstetrics, Vice-Chairperson for Research and Development, Department of Surgery, State University of New York at Buffalo
Contributor Information and Disclosures

Updated: Jan 7, 2009

Introduction

Background

Appendicitis is acute inflammation and infection of the vermiform appendix, which is most commonly referred to simply as the appendix. The appendix is a blind ending structure arising from the cecum. Acute appendicitis is one of the most common causes of abdominal pain and the most frequent condition leading to emergent abdominal surgery in children.

Pathophysiology

Appendicitis is due to a closed-loop obstruction of the appendix. Most commonly, the obstruction is due to either lymphoid hyperplasia within the appendix or impacted fecal matter, referred to as a fecalith. Obstruction of the appendix leads to bacterial overgrowth and an increase in intraluminal pressure. The increased intraluminal pressure obstructs the venous blood flow in the appendix and leads to congestion in the appendix. Over time, this congestion leads to ischemia in the appendix, allowing for bacterial translocation and infection. The ischemia and the bacterial infection cause the inflammation of the appendix. As the disease progresses, the inflammation progresses from a mild inflammation to a gangrenous appendix. When the appendix becomes gangrenous, it may perforate. This process usually takes place over 72 hours. This is an important point when considering the patient’s history.

When the appendix perforates, inflammatory fluid and bacterial contents are released into the abdominal cavity. This fluid may infect the peritoneum, and the patient may develop generalized peritonitis. Concomitantly, the patient develops more intense and generalized abdominal pain. However, the omentum and loops of small bowel may wall off the fluid and form an abscess. In this case, the patient may continue to have localized abdominal pain in the area of the abscess.

Frequency

United States

Appendicitis occurs in all age groups but is rare in infants. If an infant has appendicitis, the diagnosis of Hirschsprung disease should also be considered. The incidence in the United States is 4 cases per 1000 children. Overall, 7% of people in the United States have their appendix removed during their life.

Mortality/Morbidity

At the time of diagnosis, the rate of perforation is 20-35%. Younger children have a higher rate of perforation, with reported rates of 50-85%. The mortality rate for children with appendicitis is 0.1-1%. This is most commonly seen in neonates and infants. This is due to 2 factors. First, appendicitis is rare in this age group; thus, unless the physician’s index of suspicion is high, appendicitis is often low on the list of suspected differential diagnoses. Second, very young patients are unable to communicate the location and nature of their pain. Some neonates may not even become febrile. Often, the patient’s only symptom is irritability or inconsolability.

Sex

The male-to-female ratio is approximately 2:1.

Age

Appendicitis occurs in all age groups. The mean age in the pediatric population is 6-10 years. Appendicitis is rare in the neonate, and the diagnosis is typically made after perforation for the reasons discussed above (see Mortality/Morbidity). Younger children have a higher rate of perforation (50-85% reported).

Clinical

History

As with almost any clinical entity, the best place to start is with the patient’s history. The classic description of appendicitis is a patient who develops vague periumbilical pain, followed by nausea, vomiting, and anorexia. Over time, the pain migrates to the right lower quadrant. If the appendix perforates, an interval of pain relief is followed by development of generalized abdominal pain and peritonitis. Although some patients progress in the classical fashion, some patients deviate from the classic model. Fifteen percent of patients have a retrocecal appendix, and their signs and symptoms may not localize to the right lower quadrant, localizing instead to the psoas muscle. Other patients may have the tip of their appendix deep in the pelvis, and their signs and symptoms localize to the rectum or bladder.

• Pain: The initial symptom is poorly defined periumbilical pain. Acute onset of severe pain is not typically present in acute appendicitis but is seen with acute ischemic conditions such as volvulus, testicular torsion, ovarian torsion, or intussusception.  If the pain is initially located in the right lower quadrant, severe constipation should be considered.
• Nausea and vomiting: Generally, vomiting that occurs prior to pain is unusual. However, in retrocecal appendices, particularly those that extend cephalad along the posterior surface of the right colon, inflammation of the appendix irritates the nearby duodenum, resulting in nausea and vomiting prior to the onset of right lower quadrant pain.
• Diarrhea: Likewise, significant diarrhea is atypical in appendicitis, and the physician should consider other diagnoses, while not ruling out appendicitis. In patients with an appendix in a pelvic location, inflammation of the appendix occasionally results in an irritative stimulation of the rectum. These patients often report diarrhea. However, upon closer questioning, such patients relate symptoms of frequent, small-volume, soft stools and usually not true diarrhea.
• Shift to right lower quadrant pain: After a few hours, pain shifts to the right lower quadrant because of inflammation of the parietal peritoneum. This pain is more intense, continuous, and localized.
• Fever: Most children with appendicitis are afebrile or have a low-grade fever and characteristic flushness of their cheeks. Severe fever is not a common presenting feature unless perforation has occurred and may still be a rare finding. According to one study, vomiting and fever are more frequent findings in children with appendicitis than in children with other causes of abdominal pain.

Physical

The physical examination findings in children may vary depending on age. Irritability may be the only sign of appendicitis in a neonate. Older children often seem uncomfortable or withdrawn. They may prefer to lie still because of peritoneal irritation. Teenaged patients often present in a classic or near-classic fashion.

• General examination: Patient’s general state should be observed before interacting with them. The patient’s state of activity or withdrawal may lend information into their state. A patient in obvious distress with abdominal pain gives the impression of an infectious process; however, other causes must be ruled out.
• Cardiac and pulmonary examination: The evaluation of the heart and lungs of the patient reflects the overall state more than suggests the appendix as a cause. Patients are often dehydrated or in pain and may be tachycardic or tachypneic. Pediatric patients have great physiological reserve and may not show any general symptoms until they are very ill.
• Abdominal examination
  • The child's abdomen should be examined in the same way an adult's abdomen is examined. Full exposure of the abdomen is key. Localization of the pain is also key but may depend on the position of the appendix.
  • Observing the patient cough and asking them to localize their pain with one finger often localizes their discomfort to the right lower quadrant. Typically, maximal tenderness can be found at the McBurney point in the right lower quadrant. However, the appendix may lie in many positions.
    • A medially positioned appendix may present as suprapubic tenderness.
    • Patients with a laterally positioned appendix often have flank tenderness.
    • Patients with a retrocecal appendix may not have any tenderness until it is advanced or perforated.
  • Palpation of the abdomen should be performed with a gentle and light touch, searching for involuntary guarding of the rectus or oblique muscles. Eliciting rebound tenderness is an unnecessary part of the abdominal examination. 
  • The Rovsing sign is pain in the right lower quadrant in response to left-sided palpation or percussion and strongly suggests peritoneal irritation.
  • To perform the psoas sign, place the child on the left side and hyperextend the right leg at the hip. A positive response suggests an inflammatory mass overlying the psoas muscle (retrocecal appendicitis).
  • Perform the obturator sign by internally rotating the flexed right thigh. A positive response suggests an inflammatory mass overlying the obturator space (pelvic appendicitis).
• Rectal examination
  • A rectal examination is important and should be performed in all patients who are evaluated for appendicitis.
  • The caliber of the patient's anus should be taken into consideration, and smaller digits should be used for examining younger patients.
  • The rectal examination in a young child may be completely objective because they may not be able to communicate variations in tenderness or may have general discomfort from the examination.
  • Objective information to ascertain includes impacted stool or an inflammatory mass.
  • A patient able to communicate should be asked if they have tenderness in different areas of the rectum. 
  • Right-sided tenderness of the rectum is the classic finding in pelvic appendicitis or in pus that pools in the pelvis from an inflamed appendix elsewhere in the abdomen.

Causes

• Appendicitis is caused by a closed-loop obstruction of the appendix. Most cases are caused either by impacted fecal material, called a fecalith or appendicolith, or by hyperplasia of submucosal lymphoid follicles. Rarely, foreign objects or nematodes may cause luminal obstruction.
• Obstruction leads to increasing intraluminal pressure from bacterial overgrowth. This increase in pressure leads to vascular compression initially on the venous side. This causes congestion and decreased wall perfusion. This decreased perfusion leads to necrosis and inflammation of the appendix. 
• During this initial stage the patient feels only periumbilical pain due to the T10 innervation of the appendix. As the inflammation continues, an exudate forms on the appendiceal serosal surface. When the exudate touches the parietal peritoneum, a more intense and localized pain develops. The location of this pain has been described above (see History).
• As the obstruction continues, bacteria within the appendix proliferate and increase intraluminal pressure. The bacteria then infiltrate the wall of the appendix. If the diagnosis is not made early, the obstruction progresses, and the wall of the appendix stretches. 
• Over time, the intraluminal pressure in the appendix increases and the strength of the appendiceal wall decreases due to the necrosis, and perforation occurs. At this point, inflammatory fluid and bacterial contents release into the abdominal cavity. This further inflames the peritoneal surface, and peritonitis develops. At this point, the location and extent of peritonitis (diffuse or localized) depends on the degree to which the omentum and adjacent bowel loops can contain the spillage of luminal contents. 
• If the contents become walled off and form an abscess, the pain and tenderness may be very localized to the abscess. If the contents are not walled off and the fluid is able to travel throughout the peritoneum, a general peritonitic state is observed.

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