This study aimed to evaluate the sensitivity of the erect chest X-ray for diagnosing subdiaphragmatic free air. Furthermore, we examined the effects of different parameters, including sex, age, size of perforation, and the location of perforation on the sensitivity of the erect CXR.

This study included all patients with perforated peptic ulcer (107 cases) referred to the Shahid Rajaei hospital of Tonekabon from April 2015 to August 2020. The perforated peptic ulcer was confirmed by laparotomy, and the erect chest X-ray was performed as a preoperative procedure. The collected checklist was analyzed using the IBM SPSS Statistics V22.0 software.

Achieved results showed total sensitivity of 86% for the erect chest X-ray. The sensitivity of the erect CXR was calculated, 88.5% and 82.6% at males and females, respectively. However, the sensitivity for different age groups was about 86%. The larger perforations resulted in higher sensitivity. Furthermore, the erect chest X-ray sensitivity for duodenal perforations (92.5%) was significantly greater than the gastric perforations (75%).

Based on this study, the erect chest X-ray could be utilized as a preoperative procedure with total sensitivity of 86% for gastroduodenal perforations. Patients' age and sex have no significant impact on the sensitivity (P-value > 0.05). However, the size and location of perforation significantly influenced the sensitivity (P-value < 0.05). The results demonstrated that larger perforations and duodenal perforations lead to the higher erect CXR sensitivity.

The erect chest X-ray is used as a routine procedure to detect subdiaphragmatic free air in gastroduodenal perforations. The effects of different factors such as age, sex, size of perforation, and the location of perforation on the sensitivity of the erect chest X-ray are discussed for the first time in this study.