To explore the key points of ultrasound diagnosis of adnexal torsion (AT) in patients with ovarian hyperstimulation (OHSS).

A retrospective analysis was carried out on the clinical medical records and ultrasonic features of 15 patients diagnosed with OHSS with AT at Chongqing Maternal and Child Health Hospital from January 2016 to April 2020. Their outcomes were followed, and the causes of misdiagnosis were analyzed. The difference between the affected ovary and contralateral ovary was compared by two-sample paired Wilcoxon test.

Among the 15 patients included, 12 were treated by surgery (1 case was misdiagnosed), and 3 underwent follow-up observation. Eleven of the patients treated by surgery were diagnosed with AT, with torsion angle ranging from 180° to 1080°. All of them had unilateral onset, including 7 cases (63.6%) on the right side and 4 (36.4%) on the left side. There were 2 cases (18.2%) with ovarian torsion alone, and 9 cases (81.8%) with fallopian tube, ligament, and ovarian torsion. The symptoms of 3 patients improved or disappeared after clinical follow-up observation. One case was misdiagnosed as intrauterine complicated with extrauterine pregnancy. In the patients diagnosed with AT, ultrasonography showed significant enlargement of the ovary on the affected side [8.5 (7.5, 10.3) cm vs 5.8 (4.3, 7.3) cm], the difference was statistically significant (Z=-2.58, P=0.010 ). The torsion pedicle structure showed the "vortex sign", decreased or disappeared blood flow signals, and pelvic effusion compared with the opposite side. The "vortex sign" of the torsion pedicle structure can be a direct and specific sign of AT in OHSS patients.

Ultrasound can be used to diagnose OHSS with AT and preliminarily judge the ovarian activity. During scanning, clinical history and ultrasonic characteristics should be combined to avoid misdiagnosis, so as to give timely clinical treatment for patients.