A controlled study of human chorionic gonadotrophin induced ovulation versus urinary luteinizing hormone surge for timing of intrauterine insemination.

Forty-eight patients in a programme of intrauterine insemination (IUI) were randomized in a cross-over study. All were stimulated with clomiphene citrate (CC) and inseminated either after follicular rupture induced by human chorionic gonadotrophin (HCG) or after a spontaneous urinary luteinizing hormone (LH) surge. The HCG was administered when follicles of 18-22 mm in diameter were observed on ultrasound and IUI was performed 37-40 h thereafter. The monitoring of a urinary LH peak was carried out using a rapid urinary LH test. IUI took place approximately 22 h after detection of the LH surge. Overall, the pregnancy rates were 9.3% (4/43) after HCG induced ovulation and 20.5% (9/44) after spontaneous ovulation (P = 0.12). Analysis of mid-cycle events showed that following sonographic criteria, the HCG injection was performed significantly earlier in the cycle compared with the spontaneous LH surge. In addition, the mean diameter of the preovulatory follicles was significantly smaller and insemination was substantially earlier in the HCG induced cycles. These findings suggest that a beneficial effect arises from allowing the natural process of final follicular maturation to occur.