Natural History of Pneumoperitoneum After Laparotomy: Findings on Multidetector-Row Computed Tomography

Postoperative pneumoperitoneum after abdominal surgery represents a diagnostic challenge. This study was designed to analyze the appearance of pneumoperitoneum on computed tomography after uncomplicated abdominal surgery through laparotomy.

The database of the department of digestive surgery was retrospectively queried to identify all patients who underwent abdominal surgery through laparotomy during a 13-month period. This initial search retrieved a total of 384 consecutive patients. Criteria for inclusion in this study were: (a) the operation was performed in our institution, (b) the patient had computed tomography examination postoperatively, and (c) the patient had no postoperative grade ≥3 complication.

Postoperative pneumoperitoneum was visible in 38/80 patients (47.5 %), with a mean volume of 15 ± 22.8 (SD) cm³ and multiple locations in 32/38 patients (84 %). Postoperative pneumoperitoneum was observed in 22/26 patients (85 %) until day 5 postoperative, 14/34 patients (41 %) between day 6 and day 15 postoperative, and in 2/21 patients (9.5 %) after day 15 postoperative. Its volume decreased when the time interval between surgery and computed tomography increased. Results of multivariate analysis showed that the time interval between surgery and computed tomography was the single independent variable that was associated with the presence of postoperative pneumoperitoneum.

Postoperative pneumoperitoneum is a frequent finding on computed tomography in the early period following abdominal surgery and commonly with multiple locations. Although commonly observed before day 5 postoperative, its presence must be considered as an alarming finding after day 7 postoperative, if present in a single location with a volume >20 cm³.