Chronic Benign Pneumoperitoneum

Abstract

Introduction: Pneumoperitoneum is encountered in the setting of perforation of a hollow viscus in over 90 percent of cases.1 A perforated ulcer is the most common cause, followed by iatrogenic interventions2. Case: We report a 78 year old Caucasian male with atrial fibrillation, prostate cancer, asymptomatic cholelithiasis, diverticulosis with prior diverticulitis and osteoarthritis who underwent a CT of his chest to evaluate a pulmonary nodule in 2011, with the incidental discovery of intraperitoneal free air. He had not had previous abdominal/surgical interventions that could cause a pneumoperitoneum and a CT obtained a year ago was negative for intraperitoneal free air. Physical exam showed him to be afebrile, alert and oriented with clear lungs and a non-tender abdomen. A follow up CT of his abdomen with contrast was performed noting multifocal intraperitoneal free air with extensive diverticular disease. Four years later a chest x-ray was obtained prior to knee replacement surgery and again, air was present under the diaphragm, leading to another CT of his abdomen. Similar to the prior CT scan, pneumatosis in a short segment of small bowel in the right mid to upper quadrant without any wall thickening or surrounding stranding was identified. He remains without abdominal symptoms. Discussion: Pneumoperitoneum generally elicits an urgent surgical evaluation and can require operation. An uncommon cause of pneumoperitoneum is intestinal pneumatosis which consists of gas located in the bowel wall, whatever the cause or location. It can occur idiopathically (primary form in 15 % cases) or secondarily in 85 % of cases3. Pneumatosis cystoides intestinalis (PCI) is another rare disease characterized by the presence of gaseous cysts in the intestinal wall. Rupture of PCI can also lead to pneumoperitoneum4. Chandler et al report a laparotomy rate of 28 % for patients with pneumoperitoneum without overt peritoneal signs5. We often encounter the same diagnostic and management dilemma in patients free of peritoneal signs. A complete history and physical are important for further evaluation of a benign pneumoperitoneum and avoidance of unnecessary laparotomy. Additionally, CT scanning, especially with the use of oral and/or rectal contrast is very sensitive in detecting even tiny visceral perforations. This case is unusual due to the absence of symptoms, lack of a surgical history and the incidental discovery of intraperitoneal air and intestinal pneumatosis during a preoperative risk assessment, with similar findings four years earlier.Figure 1