RESUMO
Assisted reproduction is a risk factor for adnexal torsion due to ovarian hyperstimulation and increased incidence of twin pregnancy. Both risk factors can be eliminated in frozen embryo transfers, but in our case ovarian torsion occurred after the use of an aromatase inhibitor (Femara) in endometrium preparation due to the presence of corpus luteum. Case presentation: G2P1+0 presented at 7 weeks gestation after vitrified-warmed embryo transfer with right loin pain and mild right iliac pain and tenderness. Ultrasound examination revealed transient or incomplete ovarian torsion. The presentation of the case was somewhat misleading and the transient nature of the torsion provided an opportunity for the conservative management of the case. In conclusion, ovarian torsion is still an undesired event, even after single embryo transfers and in vitrified-warmed cycles. Clinical and ultrasound follow-up precluded the need for surgery in our case.