Perforated sigmoid colon diverticulitis initially presenting with pneumoperitoneum, pneumoretroperitoneum, and pneumomediastinum: A case report.

BACKGROUND: Complications occur in approximately 12% of cases of diverticulitis, with perforation occurring in up to 10% of complications. Typically, patient with perforated diverticulitis present intraperitoneally with abdominal pain and peritoneal signs. By contrast, pneumoretroperitoneum and pneumomediastinum are rare complications and lack typical symptoms, making their diagnosis difficult and often delayed, leading to increased morbidity and mortality.

CASE SUMMARY: A 66-year-old man presented with lower abdominal pain for 3 days. On examination, his vital signs were stable, and the abdomen was soft with mild distension and left lower quadrant tenderness, but no peritoneal signs were noted. Laboratory tests indicated leukocytosis and a markedly elevated C-reactive protein level. Abdominal computed tomography (CT) revealed focal wall thickening and fat stranding near the rectosigmoid junction as well as pneumoretroperitoneum, pneumomediastinum, and minor pneumoperitoneum. Suspecting hollow organ perforation, an emergent exploratory laparotomy was performed which revealed a retroperitoneal abscess with mesocolonic necrosis, likely due to perforated sigmoid diverticulitis. The patient underwent sigmoid resection with Hartmann's procedure and retroperitoneal drainage. Follow-up CT on postoperative day 14 confirmed resolution of the free air, and the patient was discharged on postoperative day 40 with an uneventful recovery.

CONCLUSION: Pneumoretroperitoneum and pneumomediastinum are rare complications of perforated diverticulitis, often with delayed diagnosis due to the absence of peritoneal signs. CT aids detection, and timely surgical intervention is crucial.