The temporal relation between the urine LH surge and sonographic evidence of ovulation: determinants and clinical significance.

OBJECTIVES

1. To define the temporal relation between self-detection of the urine LH surge and sonographic evidence of ovulation, 2) to identify clinical factors that affect this interval, and 3) to determine whether differences in the day of sonographic detection of ovulation could potentially influence pregnancy rates during timed supracervical insemination cycles.

METHODS

Two hundred sixty-nine cycles in 145 women treated in an infertility center were analyzed. The subjects were referred for urine LH-timed supracervical insemination and were managed prospectively by protocol, including transvaginal sonographic confirmation of ovulation. Unstimulated and clomiphene citrate cycles were studied.

RESULTS

Sonographic evidence of ovulation was detected by the first day after the urine LH surge (day +1) in 95 cycles (35%, 95% confidence interval [CI] 29-41) and not until day +2 in 165 cycles (61%, 95% CI 55-67). Further analyses indicated that cycles with two or more ovulations were associated with a significantly greater percentage of cases in which ovulation was not demonstrated until day +2 (81%, 95% CI 76-86) compared with mono-ovulatory cycles (52%, 95% CI 46-58) (P < .001). Multivariate analysis revealed that the day of sonographic detection of ovulation was linked with clinical pregnancy rates during these insemination cycles (P < .05).

CONCLUSIONS

A substantial number of women, especially those with multiple ovulations, will not demonstrate sonographic evidence of ovulation until the second morning after detection of the urine LH surge. This temporal relation may exert an impact on pregnancy rates during supracervical insemination cycles.