RELATIONSHIP OF BIOCHEMICAL PREGNANCY TO PREOVULATORY ENDOMETRIAL THICKNESS AND PATTERN IN PATIENTS UNDERGOING OVULATION INDUCTION

In order to assess the relationship between pre-ovulatory endometrial thickness and pattern and biochemical pregnancy, the pregnancy outcome was retrospectively analysed in 81 patients undergoing ovulation induction evaluated by vaginal ultrasound on the day of human chorionic gonadotrophin (HCG) administration or luteinizing hormone (LH) surge. Biochemical pregnancies occurred in 7/32 (21.9%) pregnancies when endometrial thickness was <9 mm, compared to 0/49 when endometrial thickness was greater-than-or-equal-to 9 mm on the day of HCG administration or LH surge (P < 0.0025). Clinical abortions occurred in 5/32 (15.6%) pregnancies when endometrial thickness was 6 - 8 mm, compared to 6/49 (12.2%) when endometrial thickness was 6-8 mm (NS). Endometrial thickness was related to the cycle day of HCG or LH surge (r = 0.37, P < 0.001) but was unrelated to oestradiol level on the day of HCG administration or LH surge (r = 0.12). Biochemical pregnancies were related to endometrial pattern (r = - 0.22, P = 0.02) but were unrelated to maternal age or previous abortions. Clinical abortions were related to age (r = 0.26, P = 0.01) and to previous abortion (r = - 0.25, P = 0.013) but were unrelated to endometrial pattern. Neither biochemical pregnancy nor clinical abortion was related to oestradiol or LH levels on the day of HCG administration or LH surge. These findings suggest that the majority of biochemical pregnancies do not result from karyotypically abnormal embryos, as do clinical abortions.