What is the pathophysiology of pediatric appendicitis?

Updated: Oct 25, 2018
  • Author: Adam C Alder, MD; Chief Editor: Carmen Cuffari, MD  more...
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Answer

Tradition holds that once the appendix becomes obstructed, bacteria trapped within the appendiceal lumen begin to multiply, and the appendix becomes distended. The increased intraluminal pressure obstructs venous drainage, and the appendix becomes congested and ischemic.

The combination of bacterial infection and ischemia produce inflammation, which progresses to necrosis and gangrene. When the appendix becomes gangrenous, it may perforate. The progression from obstruction to perforation usually takes place over 72 hours.

One study noted that appendiceal perforation is more common in children, specifically younger children, than in adults. A substantial risk of perforation within 24 hours of onset was noted (7.7%) and was found to increase with duration of symptoms. While perforation was directly related to the duration of symptoms before surgery, the risk was associated more with prehospital delay than with in-hospital delay. [1]

During the initial stage of appendicitis, the patient may feel only periumbilical pain due to the T10 innervation of the appendix. As the inflammation worsens, an exudate forms on the appendiceal serosal surface. When the exudate touches the parietal peritoneum, a more intense and localized pain develops.

Perforation results in the release of inflammatory fluid and bacteria into the abdominal cavity. This further inflames the peritoneal surface, and peritonitis develops. 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 localized to the abscess site. If the contents are not walled off and the fluid is able to travel throughout the peritoneum, the pain and tenderness become generalized.


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