Pneumoperitoneum: a review of nonsurgical causes.

OBJECTIVE To review causes of nonsurgical pneumoperitoneum (NSP), identify nonsurgical etiologies, and guide conservative management where appropriate. DATA SOURCE We conducted a computerized MEDLINE database search from 1970 to 1999 by using key words pneumoperitoneum and benign, nonsurgical, spontaneous, iatrogenic, barotrauma, pneumatosis, diaphragmatic defects, free air, mechanical ventilation, gynecologic, and pelvic. We identified 482 articles by using these keywords and reviewed all articles. Additional articles were identified and selectively reviewed by using key words laparotomy, laparoscopy, and complications. STUDY SELECTION We reviewed all case reports and reviews of NSP, defined as pneumoperitoneum that was successfully managed by observation and supportive care alone or that required a nondiagnostic laparotomy. DATA SYNTHESIS Each unique cause of nonsurgical pneumoperitoneum was recorded. When available, data on nondiagnostic exploratory laparotomies were noted. Case reports were organized by route of introduction of air into the abdominal cavity: abdominal, thoracic, gynecologic, and idiopathic. CONCLUSIONS Most cases of NSP occurred as a procedural complication or as a complication of medical intervention. The most common abdominal etiology of NSP was retained postoperative air (prevalence 25% to 60%). NSP occurred frequently after peritoneal dialysis catheter placement (prevalence 10% to 34%) and after gastrointestinal endoscopic procedures (prevalence 0.3% to 25%, varying by procedure). The most common thoracic causes included mechanical ventilation, cardiopulmonary resuscitation, and pneumothorax. One hundred ninety-six case reports of NSP were recorded, of which 45 involved surgical exploration without evidence of perforated viscus. The clinician should maintain a high index of suspicion for nonsurgical causes of pneumoperitoneum and should recognize that conservative management may be indicated in many cases.