Midluteal phase endometrial biopsy does not accurately predict luteal function

Objective: To investigate whether a midluteal phase endometrial biopsy accurately predicts luteal function. Design: One nonpregnant menstrual cycle was evaluated in a prospective fashion. Setting: Outpatient Clinic of the Clinical Center of the National Institutes of Health. Participants: Fifty healthy, normally cycling women. Interventions: Serum progesterone (P) was measured daily throughout the luteal phase. An endometrial biopsy was performed 7 to 9 days after the luteinizing hormone (LH) surge, as detected by rapid plasma assays, and dated histologically according to Noyes' criteria. Main Outcome Measure: To correlate endometrial maturation with luteal P secretion. Results: Mean integrated P measurements were reduced only when the lag between histologic and chronological dating was ≥3 days or ≥4 days, depending on whether chronological dates were assigned prospectively from the LH surge or retrospectively from the onset of next menses, respectively. However, these lags did not consistently predict deficient luteal function because subnormal integrated P secretion was seen in only 14% of women with these delays in endometrial maturation. Conclusions: Midluteal phase endometrial biopsy provides a crude test of luteal function that does not precisely distinguish luteal insufficiency.