TIMING OF THE ENDOMETRIAL BIOPSY MAY BE CRITICAL FOR THE ACCURATE DIAGNOSIS OF LUTEAL-PHASE DEFICIENCY

Objective: To determine the optimal time to perform the endometrial bi opsy for the detection of ''out-of-phase'' endometrium. Design: Two en dometrial biopsies were performed during a single menstrual cycle in e ach subject. The patient's chronological day was determined by countin g forward from the midcycle LH surge, as assessed by urinary LH detect ion. The ''early'' biopsy was done on day LH + 7.4 +/- 0.8, and the '' late'' biopsy on day LH + 11.6 +/- 0.7. Each biopsy was independently read by two pathologists and was considered out of phase if the histol ogic date was greater than or equal to 3 days delayed compared with th e chronological date. Setting: Infertility practice of an academic tea ching hospital. Patients: Thirty-three ovulatory women seeking evaluat ion for infertility. Main Outcome Measure: Number of patients with out -of-phase endometrium detected by the early versus the late biopsy. Re sults: There was a significantly greater detection rate for out-of-pha se endometrium using the early biopsy (12.1% to 18.2% incidence depend ing on the observer) compared with the later biopsy (6.1% to 9.1% inci dence). A majority of the early out-of-phase biopsies corrected by the time of the later biopsy. Conclusion: Our findings indicate that an e ndometrial biopsy performed in the midluteal phase may detect a greate r number of women with delayed endometrial maturation during the tempo ral window of embryo implantation. The observation that most of the wo men with out-of-phase midluteal biopsies had normal late luteal endome trium may represent a cryptic form of luteal phase deficiency.