Small Bowel Obstruction Secondary to Sigmoid Diverticulitis With Reactive Enteritis: Diagnosis via CT and Successful Conservative Management.

Small bowel obstruction (SBO) is a common cause of acute abdominal presentation. While most cases are mechanical, secondary functional obstruction from inflammatory processes is rare. Inflammation of the sigmoid colon can, in some instances, extend to adjacent small bowel loops, resulting in reactive changes and transient obstruction. A man in his 60s presented with abdominal pain, distension, and fever. Contrast-enhanced CT of the abdomen and pelvis demonstrated sigmoid diverticulitis with localized perforation and pericolic inflammation, surrounded by mildly dilated small bowel loops showing subtle mural enhancement, consistent with reactive change. He was managed conservatively with nasogastric decompression, IV fluids, and broad-spectrum antibiotics as per local guidelines. Total parenteral nutrition was commenced after five days of no oral intake to prevent nutritional deterioration. A water-soluble contrast study was performed for diagnostic and therapeutic purposes, confirming bowel continuity and promoting resolution of the obstruction. The patient improved clinically, resumed oral intake, and was discharged after seven days with complete recovery. This case highlights a rare mechanism of SBO secondary to sigmoid diverticulitis, in which reactive inflammatory changes in the adjacent small bowel caused functional narrowing, without evidence of a discrete mechanical transition point. Prompt recognition of reactive enteric changes on CT allows appropriate conservative management. Control of the primary colonic inflammation led to resolution of the reactive changes and restoration of bowel function without surgical intervention.