Free Air in the Postoperative CT Patient: Observe or Operate?

Abstract

The finding of free air on postoperative imaging creates a difficult scenario for the clinician triggering immediate action. A quick decision needs to be made to determine whether the free air is related to a GI perforation and whether surgical intervention is required. In select cases, some patients can undergo expectant observation. There have been numerous studies both retrospective and prospective, attempting to determine the incidence, duration, and characteristics of “benign,” postoperative pneumoperitoneum. Overall, the duration of a benign postoperative pneumoperitoneum can vary greatly but often tends to reabsorb within 1–2 weeks and is usually of a small volume. It is also important to remember that CT scans are much more sensitive for picking up free air than plain films so the finding of “benign” free air on a postoperative CT scan is much more likely than on plain films. The most important general conclusion from the literature is that there is a percentage of patients with free air found on imaging that can be observed; however, observing for, and consideration of surgical peritonitis should be an ongoing concern and continuously reassessed.