Comparison of serum progesterone and endometrial biopsy for confirmation of ovulation and evaluation of luteal function

An endometrial biopsy and a blood sample for progesterone determination obtained simultaneously in the midluteal phase of the cycles of 55 infertile women were compared for reliability for confirmation of presumptive ovulation and evaluation of luteal function. Progesterone levels of 3 ng/ml or greater were found in 90.5% of the cycles. Secretory endometrium was identified in 81% of the cycles. Thirty-three cycles yielded sufficient information to compare the two methods for evaluation of luteal function. Histology and progesterone levels were consistent with each other and the presumed time of ovulation in only 11 cycles. Histology was inconsistent with the presumed time of ovulation in 20 cycles, while progesterone was inconsistent in only two cycles. Additional samples for progesterone determinations were obtained during the biopsy cycles of 15 patients who presented adequate data for evaluation of luteal function. A single, well-timed progesterone determination appeared adequately to reflect the data obtained from serial samples in the same cycle. These results support the thesis that a single, well-timed serum progesterone determination is superior to a single endometrial biopsy as a screening method for confirmation of presumptive ovulation and for evaluation of luteal function. An attempt to determine how accurate serum progesterone as compared with endometrial biopsy is in confirming that ovualtion has taken place, and what is the value of each method for assessing luteal function in infertile women is presented. Subjects were 55 women who were undergoing evaluation for infertility. Only patients who were presumed to be ovulatory were included. The maximum duration of infertility had been 10 years, with a mean of 3.9 years. Blood samples were obtained at the time of biopsy. Some additional blood samples were taken during the presumed luteal cycles. Progesterone serum levels of 3 ng/ml or higher were found in 90.5% of cycles. Secretory endometrium was found in 81% of cycles. There was a positive correlation between biopsy findings and serum progesteone in only 75% of cases. Only 33 cycles in 32 patients were suitable for luteal function determination. Retarded endometrial histology did not necessarily reflect insufficient progesterone secretion but low serum values during expected periods of peak progesterone secretion usually showed retarded endometrium. These findings had little prognostic value regarding future fertility. A single progesterone sample was as accurate as endometrial histology in confirming presumptive ovulation and was superior as an indication of corpus luteum function. In some cases a combination of well-timed biopsy and 3 or 4 serial progesterone values might be better to evaluate the interaction between corpus luteum function and histologic response.