Fig. 2
From: Imaging the postoperative patient: long-term complications of gastrointestinal surgery
a, b Patient with abdominal pain because of a closed-loop SBO. Both ends of a fluid-filled distended closed loop taper fusiformly, in a way similar to a beak—the beak sign (arrows in a). Mesenteric edema (star in a), peritoneal fluid and reduced enhancement of the bowel wall comparatively to other small-bowel loops (arrowhead in a) are also evident, findings that suggest strangulation. A slightly cranial image shows the twisting of the mesenteric vessels at the mesenteric root—whirl sign (curved arrow in b)