The Mesenteric Whirl Sign: A Surgical Decision Signal for Bowel-Threatening Mechanical Disease.

The mesenteric whirl sign on computed tomography (CT) should be approached as a surgical decision signal for potentially bowel-threatening mechanical disease rather than as an isolated radiologic label. Not every whirl pattern represents fixed active volvulus; however, underestimating a true whirl sign can delay recognition of closed-loop obstruction, internal hernia, strangulation, bowel necrosis, perforation, sepsis, and death. This review reframes the sign around the management question most relevant to general surgeons: when should imaging evidence of mesenteric rotation alter care before frank ischemia is visible? We review the differential diagnosis of actionable whirl-pattern disease, including small-bowel volvulus, adhesive closed-loop obstruction and band disease, post-Roux-en-Y gastric bypass internal hernia, transmesenteric and paraduodenal hernias, cecal volvulus, sigmoid volvulus, malrotation-associated midgut volvulus, and other torsion syndromes with vascular compromise. We then organize CT risk features into mechanical and ischemic constellations and propose a practical bedside assessment incorporating serial abdominal examination, systemic inflammatory or septic physiology, complete blood count, lactate, metabolic and acid-base status, peritonitis, tachycardia, persistent vomiting, progressive distention, and overall trajectory. A non-confirmatory exploration is often recoverable; missed bowel-threatening mechanical disease may not be.