Background and aim. Pneumoperitoneum following a recent abdominal surgery is a diagnostic dilemma. The aim of the study was to determine the diagnostically significant amount of free air in the peritoneal cavity, evaluating probable complications that are associated with a break of gastrointestinal (GI) integrity and to identify clinical, laboratory and demographic impact on the results.
Materials and methods. 50 patients who underwent abdominal operations were examined, 30 had an uneventful postoperative period (the first group) and 20 developed complications (the second group). The abdominal radiographies (AXR) were performed on the fifth postoperative day as well as the complete blood count and C-reactive protein (CRP) tests. Pneumoperitoneum diagnosis was based on finding free air under the diaphragm.
Results. The average amount of free air in the first group was 6.59 mm, and in the second – 29.57 mm. Postoperative complications were correctly diagnosed in 70% of cases, and correctly denied in 60% of cases. Using a cutoff point of 9.65 mm, complications were diagnosed correctly in 70% of cases, and correctly denied in 83.33%. The amount of free air has a significant correlation with the body mass index (r = -0.620; <0.001) and CRP (r = 0.596; p = 0.006). No statistically significant difference of amount of free air between operated in an open manner and laparoscopically was observed.
Conclusions. AXR has limited specificity and sensitivity for diagnosing postoperative complications that are associated with a break of GI integrity; however, if the results are combined with CRP values, AXR remains a solid alternative to computed tomography scan.
Keywords: postoperative pneumoperitoneum, free air, radiography, perforation, anastomotic leak.