BACKGROUND: Women with polycystic ovary syndrome (PCOS) undergoing in vitro fertilization (IVF) are given letrozole before a trigger injection of human chorionic gonadotropin (hCG) to lower estrogen (E2) levels, but can experience ovarian hyperstimulation syndrome (OHSS). The aim of this study was to evaluate the effect of oral letrozole, prior to administration of hCG, on the outcome of IVF and development of OHSS.

MATERIAL AND METHODS: Retrospective clinical review included 181 cases of women with PCOS who underwent IVF cycles with intracytoplasmic sperm injection (ICSI) and embryo transfer (ET) (IVF/ICSI-ET). The day before the use of hCG, cases were divided into a letrozole-treated group (N=78) and a non-letrozole group (N=103). An oral dose of 2.5 mg qd of letrozole was given when the peak level of E2 was ≥4000 pg/ml during ovarian stimulation and ceased before the day of egg retrieval.

RESULTS: The letrozole-treated group had a significant increase in the number of retrieved oocytes, viable embryos, and fresh ET rate (P>0.05); peak levels of E2, and E2 levels on the day of the egg retrieval, were significantly higher, and the fertilization rate was significantly lower (P<0.001). No significant differences were found in the rates of pregnancy, abortion, or ectopic pregnancy between the two groups (P>0.05). The incidence OHSS was lower in the letrozole-treated group, but this difference did not reach statistical significance (P>0.05).

CONCLUSIONS: Women with PCOS who underwent IVF, oral treatment with letrozole a day prior to treatment with hCG lowered E2 levels, but did not significantly reduce the incidence of OHSS.

Keywords: Fertilization in Vitro, Ovarian Hyperstimulation Syndrome