A 22-year-old man is brought to the emergency department with abdominal pain that started around his belly button, then moved to the right lower abdominal quadrant. After initial evaluation, laparotomy is performed, and the surgical specimen is shown in the image below:
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Which of the following most likely initiated this patient's condition?
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This patient with abdominal pain has gross pathologic findings consistent with acute appendicitis. Acute appendicitis typically occurs in children and young adults and is often initiated by obstruction of the appendiceal lumen. The most common obstructing agents are fecaliths, hyperplastic lymphoid follicles (eg, following infection), tumors (eg, carcinoid), and nematodes.
Mucus accumulates in the lumen of the obstructed appendix, which causes increased pressure, appendiceal wall distension, and impaired venous outflow. The resulting ischemia and associated bacterial proliferation (Choice B) lead to inflammation of the appendiceal wall, causing edema (with further distension), serosal erythema, and purulent exudate. Necrosis of the wall with rupture may follow, and inflammatory fluid and bacterial contents may spill into the peritoneal cavity, causing peritonitis.
Patients typically experience abdominal pain, which may migrate over time. Distension of the appendix triggers afferent pain fibers that enter at the T10 level in the spinal cord, producing vague, referred pain at the umbilicus. As the inflammatory reaction advances, the appendix irritates the parietal peritoneum, causing more severe somatic pain that shifts to the right lower quadrant.
(Choices A and E) Both arterial spasm and venous thrombosis can cause mesenteric ischemia, which often presents with severe, diffuse abdominal pain. Gross examination of the affected bowel segment would show dusky red serosa, edema, and hemorrhagic mucosa.
(Choice D) Meckel diverticula often contain ectopic gastric mucosa, which may lead to peptic ulceration of the surrounding small intestinal tissue and subsequent lower intestinal bleeding. Gross examination would show an intestinal outpouching within 2 feet of the ileocecal valve.
Educational objective:
Obstruction of the appendiceal lumen (eg, fecalith, lymphoid hyperplasia) is frequently the inciting event in pathogenesis of acute appendicitis, which typically presents with periumbilical pain that shifts to the right lower quadrant. Gross pathologic examination often shows an edematous, erythematous appendix with purulent exudate.