Small bowel obstruction from signet-ring cell appendiceal carcinoma

To illustrate the diagnostic challenge that arises in patients presenting with symptoms due to small bowel obstruction (SBO) whose initial cross-sectional imaging does not reveal the site or etiology of obstruction, and to review the pathophysiologic mechanisms by which SBO can evade radiographic detection.

A man in his 80s with a remote history of intraabdominal surgeries presented with abdominal pain, bloating, and emesis. Non-contrast enhanced computed tomography (CT) imaging of the abdomen and pelvis showed distended small bowel loops with air-fluid levels, but no transition point or distal decompression. He was initially treated with isotonic fluids and a nasogastric tube to suction with resolution of symptoms, and he was discharged with a diagnosis of ileus of unclear etiology. However, approximately one month later, his symptoms recurred, and repeat CT imaging showed potential SBO at the terminal ileum. Exploratory laparotomy was performed for failure of conservative management, which ultimately revealed appendiceal mucinous adenocarcinoma with peritoneal carcinomatosis as the cause of the patient's initial presentation.

CT findings of obstruction without an identifiable transition point may not reliably distinguish SBO from ileus, and symptom resolution with conservative management may falsely lead to an ileus diagnosis and drive premature closure. Because ileus requires an explanatory trigger, its diagnosis in the absence of one should prompt consideration of low-grade partial SBO as well as intermittent and functional pathophysiology.