obturator sign

To elicit the obturator sign, the examiner flexes the patient's right hip and knee to 90 degrees, then internally rotates the hip. A positive test produces pain in the hypogastric or right lower quadrant region due to stretching and irritation of the obturator internus muscle, which lies close to the pelvic appendix. This occurs because inflammatory processes (such as appendicitis) in a retrocecal or pelvic location can irritate this muscle when it is stretched.

The obturator sign is one of several classic peritoneal irritation signs used in the evaluation of suspected appendicitis, alongside the psoas sign (pain on hip extension due to iliopsoas irritation, suggesting retrocecal appendix) and Rovsing's sign (RLQ pain elicited by palpation of the LLQ). While historically taught as important diagnostic maneuvers, these signs have relatively low sensitivity and specificity for appendicitis and should not replace clinical judgment, imaging (CT or ultrasound), and laboratory findings (leukocytosis) in diagnosis.

Clinically, a positive obturator sign should raise suspicion for appendicitis with a pelvic location, though it can also be seen with other pelvic inflammatory processes such as pelvic abscess, diverticulitis with pelvic extension, or other conditions causing irritation near the obturator internus muscle. Understanding these signs is important for Step 2 CK surgical and clinical diagnosis questions, though modern practice relies more heavily on imaging for definitive diagnosis.