FREQUENCY OF AIR UNDER THE DIAPHRAGM IN PATIENTS WITH PERFORATED GASTRIC AND DUODENAL ULCER

Abstract

Objective: To determine the frequency of air under the diaphragm on erect chest X-ray in patients with intra-operatively confirmed perforated gastric and duodenal ulcer, and to compare this frequency between gastric and duodenal perforation.

Study Design: Descriptive, cross-sectional study.

Setting: Department of Surgery, Jinnah Postgraduate Medical Centre (JPMC), Karachi.

Period: January 2025 to April 2025.

Material & Methods: Non-probability purposive sampling method was used to recruit 129 patients aged 18-70 years with operative proof of perforated gastric and duodenal ulcers. Before an exploratory laparotomy, all patients underwent a standardized erect postero-anterior chest radiograph. The consultant radiologist who reported the radiographs was blind to the operative findings. The presence, laterality, and size of pneumoperitoneum were documented and analyzed against the intra-operative finding of perforation. SPSS version 26 was used to analyze data. The age, gender, BMI, duration of symptoms, and site of perforation were controlled through stratification, and the Chi-square test was performed after stratification. A p-value less than 0.05 was considered significant.

Results: Air under the diaphragm was evident in 110 of 129 (85.3%) participants (exact binomial p < 0.001 on the null proportion (P) of 50%). The frequency was higher in duodenal perforation (86 of 96 = 89.6%) compared to gastric perforation (24 of 33 = 72.7%) (χ² = 5.556, p = 0.018). In the 110 participants who were X-ray positive, the free air was predominantly on the right side (61.8%) and was moderately sized (49.1%); neither factor was significantly different with respect to side (p = 0.922) and size (p = 0.066) of the free air. Overall, the frequency of pneumoperitoneum was not significantly associated. Age, gender, BMI and duration of symptoms did not significantly modify the overall frequency, although the site–pneumoperitoneum association strengthened with age, reaching significance in patients aged >55 years (χ²=8.889, p=0.003).