Follicular ring sign: a simple sonographic sign for early diagnosis of ovarian torsion.

The follicular ring sign is a novel, easily identifiable sonographic finding of ovarian torsion consisting of hyperechoic rings around the antral follicles. In a retrospective analysis of 15 consecutive patients with torsion undergoing surgery, the follicular ring sign was frequently present, starting early in the disease course. This sign could be valuable for accurate and early diagnosis of torsion in the absence of specific conventional sonographic features.