Sigmoid pneumatosis cystoides intestinalis secondary to chronic digestive hyperpressure on post-ulcer duodenal bulb stenosis, decompensated following recent endoscopic insufflation.

Pneumatosis cystoides intestinalis (PCI) is a rare condition characterised by gas-filled cysts within the intestinal wall. Distal colonic PCI secondary to proximal duodenal stenosis is exceptionally uncommon. We report a 65-year-old chronic smoker with prior surgery for perforated duodenal ulcer presenting with acute abdominal pain and minimal rectal bleeding. Computed tomography (CT) showed massive pneumoperitoneum suggestive of gastrointestinal perforation, but clinical and laboratory findings were reassuring. Exploratory laparotomy revealed no perforation but identified an unrecognized post-ulcer duodenal bulb stenosis associated with extensive sigmoid PCI. The condition was linked to air insufflation during sigmoidoscopy. Intraoperative insufflation demonstrated gas passage from stomach to sigmoid colon without leakage, supporting a pressure-mediated mechanism. Segmental sigmoid resection was performed, and histopathology confirmed benign secondary PCI. This case highlights a rare aetiology and iatrogenic trigger. The discordance between imaging severity and clinical findings should suggest PCI and may avoid unnecessary surgery. CO₂ insufflation is recommended in obstructive settings.