Fig. 3From: Diagnosis at gut point: rapid identification of pneumoperitoneum via point-of-care ultrasounda Patient placed in the supine position for an initial sonographic assessment for free intraperitoneal air. b Patient placed in the lateral decubitus position to allow free intraperitoneal air to accumulate anterior to the hepatic parenchyma. c Sonographic output of a patient with free intraperitoneal air. Air is a strong reflector of ultrasound waves. Reflection produces bright focal lines (A-lines, red arrow) with dark shadowing in betweenBack to article page