Value of “protruding lips” sign in malignant bowel obstructions

ObjectiveThis study aims to evaluate the diagnostic accuracy of a new CT sign in order to define or exclude a malignant aetiology of bowel obstruction.Materials and methodsCT scans of 137 patients affected by bowel obstruction were reviewed. Colonic obstruction occurred in 47 (34%) cases, small bowel obstruction in 90 (66%). Neoplastic aetiology was found in 42 cases (31%), while in the remaining 95 (69%) obstruction was caused by non-neoplastic conditions. Definitive diagnosis was surgically confirmed in all patients. CT images were evaluated searching for bowel obstruction's signs and for the presence of the “protruding lips” sign on the proximal surface of stenosis, which is represented by the evidence of a protrusion within the dilated loop.ResultsThe sign was found in 31 (23%) cases, all of neoplastic origin. When malignant obstruction was diagnosed, sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy values of the described sign were 74%, 100%, 100%, 90% and 92%, respectively.ConclusionsThe “protruding lips” sign represents an alteration to be searched when bowel obstruction is diagnosed by CT examination. Its evidence correlates to a malignant condition with a 100% probability and when it is not found, the probability of a non-neoplastic condition is 90%.