A supine abdominal radiograph of a patient with suspected perforated peptic ulcer shows gas outlining both the inner and outer walls of a bowel loop, making the wall clearly visible as a discrete line. What is this sign called?

• A Sentinel loop sign
• B String sign
• C Coffee bean sign
• D Rigler sign ✓

Explanation

Rigler sign, or the double wall sign, is seen when free intraperitoneal gas outlines the serosal (outer) surface of bowel while intraluminal gas outlines the mucosal (inner) surface, rendering the bowel wall visible as a thin radiopaque line. It is highly specific for pneumoperitoneum and is useful on supine films where subdiaphragmatic air cannot be assessed. The coffee bean sign describes sigmoid volvulus, and the sentinel loop is a localized segment of dilated bowel adjacent to inflammation.

Reference: Grainger and Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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