Appendicitis, Acute

Michael P. D'Alessandro, M.D.
Peer Review Status: Internally Peer Reviewed

Etiology/Pathophysiology:
Caused by obstruction of the appendiceal lumen by a fecalith, inspissated material, a foreign body or lymphoid hyperplasia which causes progressive inflammation, ischemia and necrosis of the appendiceal wall. The disease progresses more rapidly in children than in adults. If perforation occurs the young infant is more likely to get generalized peritonitis because they have a diminished capacity to wall off the infection than older children.

Pathology:
Not applicable

Imaging Findings:
Plain abdominal film findings are variable. A calcified appendicolith is seen in 8-10% of cases and is highly specific for acute appendicitis. Indirect signs of peritoneal inflammation can be seen and include deficient bowel gas and air fluid levels in the right lower quadrant associated with localized cecal and small bowel ileus, scoliosis with concavity to the right, or edema with focal obliteration of the properitoneal fat line due to adjacent inflammation.

The appendix can also be directly imaged under ultrasound using a linear transducer.

A perforated appendicitis with an associated abscess may be seen on abdominal plain film as a mass displacing the cecum that may have air within it and that may cause a small bowel obstruction. The abscess is best imaged with ultrasound or computed tomography.

DDX:

• Right lower lobe pneumonia
• Ovarian torsion
• Ovarian cyst
• Tubo-ovarian abscess

References:

• Correlapedia

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