Natural history and clinical significance of postoperative pneumoperitoneum: a systematic review and meta-analysis

Postoperative pneumoperitoneum is a common radiological finding after abdominal surgery. Pneumoperitoneum is often benign but may be a sign of an anastomotic leak or other complications. This systematic review synthesises data on the prevalence, volume, and clinical implications of postoperative pneumoperitoneum.

A systematic search identified studies reporting postoperative pneumoperitoneum prevalence and volume following abdominal surgery. Data were extracted on pneumoperitoneum rates by postoperative day (POD), imaging modality, surgical approach, and association with clinical factors. Meta-analysis and meta-regression were used to analyse trends over the postoperative period.

Forty studies (3,342 patients) met the inclusion criteria. Pneumoperitoneum was detected in 93% (95% CI: 36-100%) on POD1 using computed tomography (CT), compared with 62% (95% CI: 48-74%) using radiographs (XR). The pooled pneumoperitoneum volume on POD1 was 21 mL (95% CI: 5-38 mL). Pneumoperitoneum prevalence and volume gradually declined over time but showed significant heterogeneity. Greater volumes of pneumoperitoneum were predictive of complications in several studies, but no consistent threshold was identified. Pneumoperitoneum was associated with shoulder pain, male sex, and drain use in several studies, whereas obesity was negatively associated with pneumoperitoneum.

Pneumoperitoneum is common after abdominal surgery and varies by imaging modality and time. While persistence and high volume on XR may indicate complications, considerable overlap with normal findings limits diagnostic utility. Prospective validation using standardised definitions is needed to better define the normal postoperative course of benign pneumoperitoneum and clarify the association with postoperative complications.