A 76-year-old man has abdominal pain and constipation after eating popcorn. What condition does he likely have?

The condition likely present in this scenario is acute diverticulitis. In older adults, particularly those with a history of constipation or dietary habits that lead to the formation of diverticula, inflammation of these small pouches can occur when they become obstructed or infected. Popcorn, being high in fiber and difficult to digest, could contribute to the irritation or blockage of diverticula, especially if consumed in larger quantities.

Patients with acute diverticulitis typically present with abdominal pain, which is often localized in the left lower quadrant, and they may experience changes in bowel habits, such as constipation. The acute onset following a particular dietary choice, like popcorn, supports this diagnosis.

While intestinal obstruction can also result in abdominal pain and constipation, it is often accompanied by additional symptoms such as nausea, vomiting, and more severe abdominal distension. Gastroenteritis usually involves diarrhea rather than constipation, and appendicitis is less likely in this age group and typically presents with more localized pain and systemic symptoms, such as fever. Therefore, the symptoms and historical context strongly suggest acute diverticulitis as the most fitting condition in this case.