The Acute Stomach and Duodenum

Abstract

Perforation of peptic ulcer is the most common cause of pneumoperitoneum. Anterior wall ulcers of the stomach and duodenal bulb usually perforate freely into the intraperitoneal space, whereas posterior wall gastric ulcers perforate into the lesser sac. However, a significant proportion of perforated gastric and duodenal ulcers seal off immediately, and free intraperitoneal air can be detected on plain radiography in only 70% of the patients (Rubesin and Levine 2003). An erect chest radiograph and a supine abdominal radiograph are usually obtained if perforation is suspected. Both are very sensitive, and as little as 1 ml of free air can be detected on the horizontal beam examination, which may be aided by the use of a decubitus abdominal radiograph (Fig. 12.1a,b) (Levine et al. 1991). On the erect chest radiograph, air may be shown under one or other diaphragmatic surfaces but rarely both are outlined by air, hence the “continuous diaphragm” sign (Fig. 12.2). Signs of free intraperitoneal air on a supine abdominal radiograph include the “lucent liver” sign, which is air overlying the liver (Fig. 12.3), the “Doges’ cap” sign due to a triangle of air in Morrison’s pouch (Fig. 12.4), and the “falciform ligament” sign.