https://orcid.org/0000-0003-0566-3746
Abstract
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.
Introduction
Pneumatosis cystoides intestinalis (PCI) is defined by the presence of gas within the submucosal or subserosal layers of the gastrointestinal tract [1–3]. Secondary PCI accounts for ~85% of cases and is associated with intestinal obstruction, inflammatory bowel disease, pulmonary disorders, medications, and iatrogenic procedures [4, 5]. The mechanical theory attributes PCI to increased intraluminal pressure forcing gas through microscopic mucosal defects, allowing dissection within the bowel wall [4, 5]. PCI typically occurs in proximity to the causative lesion; therefore, distal colonic PCI secondary to proximal duodenal stenosis is highly unusual.
We report a surgically confirmed case of sigmoid PCI presenting as massive pneumoperitoneum in a patient with previously unrecognized post-ulcer duodenal bulb stenosis, with acute decompensation temporally associated with endoscopic insufflation.
Case presentation
A 65-year-old chronic smoker with a history of surgery for perforated gastroduodenal ulcer (primary repair and omentoplasty) presented with one week of progressive abdominal pain, mild anorexia, and minimal rectal bleeding. He was haemodynamically stable, afebrile, and without peritoneal signs.
Laboratory investigations were unremarkable: C-reactive protein of 1 mg/L, white blood cell count of 6010/mm3, haemoglobin of 13.2 g/dL, and normal renal and hepatic function, as well as normal tumour markers.
Rectosigmoidoscopy performed the day before admission revealed multiple sessile lesions with contact bleeding between 40 and 70 cm from the anal verge; no biopsies were obtained. Computed tomography (CT) demonstrated massive pneumoperitoneum with moderate peritoneal effusion, initially interpreted as perforated peptic ulcer disease. Expert radiological review identified no definite perforation and suggested perforated sigmoid volvulus as an alternative diagnosis (Fig. 1).
Abdominal CT scan showing multiple cystic gas collections within the sigmoid colonic wall. (a) Axial sections demonstrating massive pneumoperitoneum; (b) axial sections in lung window setting highlighting intramural gaseous cysts; (c) axial contrast-enhanced axial sections.
Emergency laparotomy revealed abundant sterile serous peritoneal fluid without evidence of gastrointestinal perforation. The stomach was markedly distended, and a severe fibrotic narrowing of the duodenal bulb consistent with chronic post-ulcer stenosis was identified. The sigmoid colon contained multiple thin-walled, translucent, crepitant subserosal cysts arranged in grape-like clusters, consistent with PCI, without necrosis or diverticular disease (Figs 2–4).
Intraoperative image of a sigmoid resection specimen showing multiple subserosal and mural gas-filled cysts.
Surgical resection specimen showing bowel pneumatosis.
Macroscopic section of a sigmoid colon resection specimen demonstrating multiple intramural gas-filled cysts within the colonic wall, consistent with pneumatosis cystoides intestinalis.
A controlled insufflation test via a nasogastric tube demonstrated free gas passage from the stomach to the sigmoid colon without extraluminal leakage, excluding perforation and supporting a pressure-mediated mechanism. Given diagnostic uncertainty and the inability to exclude malignancy intraoperatively, segmental sigmoid resection with primary anastomosis was performed. Histopathology confirmed benign secondary PCI without malignancy, inflammatory bowel disease, ischemia, or mucosal injury. The postoperative course was uneventful.
Discussion
The mechanical theory best explains this presentation [2, 3]. Chronic post-ulcer duodenal bulb stenosis likely resulted in sustained intraluminal pressure elevation. A redundant dolichosigmoid may have acted as a low-resistance distal reservoir, favouring gas accumulation and mural dissection. Intraoperative insufflation demonstrated uninterrupted gas transmission from the stomach to the sigmoid colon, supporting this mechanism.
Chronic smoking may have contributed to ulcer persistence and progression of stenosis through impaired mucosal defence, increased acid secretion, and delayed healing [6, 7].
The temporal relationship between sigmoidoscopy and symptom onset suggests a possible triggering role of endoscopic insufflation. In a bowel chronically exposed to elevated intraluminal pressure, sudden overdistension may facilitate gas dissection through microscopic mucosal defects, precipitating expansion or rupture of PCI cysts [8]. This supports the hypothesis of an ‘iatrogenic pressure trigger.’ In patients with suspected or known gastrointestinal obstruction, CO₂ insufflation is preferred due to its rapid absorption and reduced risk of sustained distension [9, 10].
PCI may closely mimic gastrointestinal perforation but represents a benign cause of pneumoperitoneum due to cyst rupture [4, 11]. CT features suggestive of benign PCI include absence of bowel wall thickening, preserved mural enhancement, and a disproportion between radiological severity and clinical presentation [12]. In this case, normal inflammatory markers, absence of peritoneal signs, and haemodynamic stability contrasted markedly with extensive free intraperitoneal gas. This radio-clinical dissociation should prompt consideration of PCI and may help avoid unnecessary laparotomy. Sterile ascites may represent chemical peritonitis following cyst rupture [13].
Sigmoid involvement remote from the duodenal stenosis likely reflects combined distal transmission of pressure waves and preferential gas trapping within a redundant dolichosigmoid acting as a pressure reservoir. Intraoperative insufflation confirmed a continuous pressure conduit between proximal obstruction and distal cystic segment.
Endoscopic findings of sessile, contact-bleeding lesions corresponded to intraluminal manifestations of subserosal cysts. The absence of biopsy is a limitation, as histological confirmation could have established the diagnosis earlier.
No post-ulcer surveillance had been undertaken, allowing silent progression of cicatricial duodenal stenosis. Although not addressed during emergency surgery, definitive management by endoscopic dilation or surgical bypass remains necessary to prevent recurrence [14, 15].
Conclusions
This case highlights four key lessons. First, PCI is an important mimic of gastrointestinal perforation, and marked radiological abnormalities with reassuring clinical findings should prompt diagnostic caution. Second, endoscopic insufflation may exacerbate underlying pressure-related pathology, and CO₂ should be preferred in patients with suspected obstruction. Third, recognition of characteristic grape-like subserosal cysts is diagnostic and may allow limited or conservative surgical management. Finally, secondary PCI reflects an underlying pathology requiring definitive treatment to prevent recurrence.
To our knowledge, this is the first reported case in which endoscopic insufflation was the most likely precipitating factor for acute decompensation of sigmoid PCI in the setting of chronic, previously unrecognized post-ulcer duodenal bulb stenosis. This observation expands the mechanical theory of PCI and supports the concept of an iatrogenic pressure-trigger mechanism.
Conflicts of interest
None declared.
Funding
None declared.
Data availability
Not applicable.
Consent
Written informed consent was obtained from the patient for publication.
