• abdomen- non trauma
• abdomen- non trauma, gastro-intestinal
• imaging, x-ray

A 79-year-old woman complained of sharp epigastric pain for 2 days. She also had fever with chills before being brought to the emergency department. At arrival, her vital signs were stable, and haemogram showed leucocytosis (white cell count, 18.3×10⁹/litre; normal range in our institution, 4–10×10⁹/litre). The level of C reactive protein was 8.9 mg/dl (normal range, 0–1.0 mg/dl). Diffuse abdominal tenderness with muscle guarding was detected on physical examination. Supine plain film of the abdomen revealed an obvious linear density at the upper abdomen (figure 1A, black arrows), known as the falciform ligament sign and Rigler sign (figure 1A, arrowheads), indicating the presence of air on both sides of the bowel wall. Besides, the radiography also demonstrated gas accumulating at the subphrenic area, extending into the fissure for the ligamentum teres (figure 1A, white arrows). Computed tomography revealed the falciform ligament (figure 1B, arrowheads) enhanced by intraperitoneal free air and air in the fissure for the ligamentum teres (figure 1B, arrows). Laparotomy confirmed the diagnosis of pneumoperitoneum caused by duodenal perforation.

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Figure 1

A) Plain film of the abdomen showed intraperitoneal air, falciform ligament sign and Rigler sign of pneumoperitoneum. (B) CT confirmed pneumoperitoneum and air in the fissure for the ligamentum teres.

Supine plain film of the abdomen is always the first choice of radiological examination of acute abdominal pain because it is simple, timely, non-invasive and cheap. Although supine radiography of the abdomen is generally thought to have limited value in diagnosing pneumoperitoneum, physicians need to be aware of these various signs of life-threatening situation.1