BACKGROUND: The dichotomy between ovulation rates and pregnancy rates for women with polycystic ovary syndrome (PCOS) treated with clomiphene citrate (CC) prompted the present study to determine the effect of CC on endometrial maturity. METHODS: Retrospective case-control study of anovulatory women with PCOS (n = 119) on their third ovulatory cycle of CC and controls, 238 healthy regularly ovulating women whose partners had abnormal sperm, all of whom had an endometrial biopsy in the late luteal phase. RESULTS: Endometrial histology classified according to the classical Noyes criteria revealed out-of-phase endometrium in 19/119 (16%) of the CC group compared with 7/238 (3%) in controls (p < 0.0001). Duration of the luteal phase was not influenced by histological age of the endometrium. Endometrial biopsy performed during 138 conception cycles extracted from the database did not increase the miscarriage rate significantly (23.9%). CONCLUSIONS: CC treatment significantly increases the prevalence of out-of-phase endometrium and this could explain, in part, the large difference between ovulation and pregnancy rates. There was no correlation between the results of the endometrial biopsy and the duration of the luteal phase. Performing an endometrial biopsy during a conception cycle does not seem to have a significant negative effect on the outcome of pregnancy.
BACKGROUND: The dichotomy between ovulation rates and pregnancy rates for women with polycystic ovary syndrome (PCOS) treated with clomiphene citrate (CC) prompted the present study to determine the effect of CC on endometrial maturity. METHODS: Retrospective case-control study of anovulatory women with PCOS (n = 119) on their third ovulatory cycle of CC and controls, 238 healthy regularly ovulating women whose partners had abnormal sperm, all of whom had an endometrial biopsy in the late luteal phase. RESULTS: Endometrial histology classified according to the classical Noyes criteria revealed out-of-phase endometrium in 19/119 (16%) of the CC group compared with 7/238 (3%) in controls (p < 0.0001). Duration of the luteal phase was not influenced by histological age of the endometrium. Endometrial biopsy performed during 138 conception cycles extracted from the database did not increase the miscarriage rate significantly (23.9%). CONCLUSIONS: CC treatment significantly increases the prevalence of out-of-phase endometrium and this could explain, in part, the large difference between ovulation and pregnancy rates. There was no correlation between the results of the endometrial biopsy and the duration of the luteal phase. Performing an endometrial biopsy during a conception cycle does not seem to have a significant negative effect on the outcome of pregnancy.