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 biopsy for the detection of "out-of-phase" endometrium.

DESIGN

Two endometrial biopsies were performed during a single menstrual cycle in each subject. The patient's chronological day was determined by counting forward from the midcycle LH surge, as assessed by urinary LH detection. 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 histologic date was > or = 3 days delayed compared with the chronological date.

SETTING

Infertility practice of an academic teaching hospital.

PATIENTS

Thirty-three ovulatory women seeking evaluation for infertility.

MAIN OUTCOME MEASURE

Number of patients with out-of-phase endometrium detected by the early versus the late biopsy.

RESULTS

There was a significantly greater detection rate for out-of-phase endometrium using the early biopsy (12.1% to 18.2% incidence depending on the observer) compared with the later biopsy (6.1% to 9.1% incidence). A majority of the early out-of-phase biopsies corrected by the time of the later biopsy.

CONCLUSION

Our findings indicate that an endometrial biopsy performed in the midluteal phase may detect a greater number of women with delayed endometrial maturation during the temporal window of embryo implantation. The observation that most of the women with out-of-phase midluteal biopsies had normal late luteal endometrium may represent a cryptic form of luteal phase deficiency.