The application of letrozole for ovulation induction in clomiphene resistant patients with polycystic ovary syndrome

Objective To evaluate the clinical effect and safety of letrozole (LE) for ovulation induction in clomiphene resistant patients with polycystic ovary syndrome (PCOS).Methods 125 ovulation induction cycles in 42 clomiphene resistant patients with PCOS were analyzed retrospectively.Patients were divided into control group [20 cases,63 cycles,human menopausal gonadotropin (HMG)] and observation group (22 cases,62 cycles,sequential therapy with LE and HMG).The ovulation effects and safety were compared.Results Patients in control group showed shorter ovulation duration and more HMG consumption.Patients in two groups showed similar ovulation rate,but patients in observation group showed higher mono-follicle rate and lower multi-follicle rate.Patients in control group showed higher E2 level,but there was no statistical difference in depth of endometrium between two groups on HCG,day.There were no statistical differences in clinical pregnancy rate and miscarriage rate between two groups (22.2％ in control group vs.21.0％ in observation group; 14.3％ in control group vs.15.4％ in observation group).The incidence rates of ovarian cyst,OHSS and multiple pregnancy in control group were higher,while there was no statistical difference in the incidence rate of multiple pregnancy between two groups because of few cases.Conclusion Sequential therapy with LE and HMG shows similar clinical effect and higher safety compared with HMG therapy. Key words: Letrozole;  Clomiphene resistance;  Polyeystic ovary syndrome;  Ovulation induction; Ovarian hyperstimulation syndrome