Diagnostic value of pneumoperitoneum on plain abdominal film in patients with suspected visceral perforation at Bugando Medical Centre, Mwanza, Tanzania

Abstract

Background:  The presence of pneumoperitoneum on plain abdominal film has been widely used in many centres in Tanzania as primary diagnostic imaging in patients with suspected visceral perforation. However, its diagnostic value has not yet been assessed in any hospital in the country including Bugando Medical Centre (BMC), and therefore its use as a diagnostic tool in these patients is not justified. This existing knowledge gap prompted the author to conduct this study. The study aimed to determine the diagnostic value of pneumoperitoneum on plain abdominal film in patients with suspected visceral perforation in our local setting.

Methods: This was a prospective cross-sectional study among patients with suspected visceral perforation at BMC from June 2017 to May 2018. Pneumoperitoneum on plain abdominal radiography was evaluated, and the findings were cross-tabulated against operative findings, the gold standard. Then, the sensitivity, specificity, accuracy, Positive Predictive Value, Negative Predictive Value and accuracy were calculated to determine the diagnostic value of pneumoperitoneum on plain abdominal film. The Kappa statistic (қ) was calculated to determine the degree of agreement with operative findings.

Results: A total of 132 patients were studied. The median age of patients was 35 years. The diagnostic accuracy of pneumoperitoneum on plain abdominal film in the detection of perforation was 90.9% with sensitivity, specificity, PPV and NPV of 90.1%, 92.7%, 96.5% and 80.9% respectively. There was good agreement with operative findings (κ = 0.86). The perforations of the ileum, gastric, duodenum, colon and appendix accounted for 36.3%, 22.0%, 19.8%, 11.0% and 11.0% of cases, respectively. The sensitivity, specificity, PPV, NPV and accuracy perforations of the ileum, gastric, duodenum, colon and appendix were 61.5-100%, 31.7-46.5%, 10.6-37.7%, 85.1-100% and 38.6-59.1% respectively.  The kappa statistics showed good agreement with the operative findings (ķ = 0.76-0.89).

Conclusion: The presence of pneumoperitoneum on plain abdominal film provides high diagnostic value in the detection of visceral perforation and can be employed at BMC to improve the diagnostic value in patients with suspected visceral perforation and subsequently reduce negative laparotomy and complication rates.