Transvaginal color blood flow imaging of the periovulatory follicle

To assess intrafollicular blood flow in relation to ovarian morphology and function during the periovulatory period.

A prospective, longitudinal study of random, natural ovarian cycles.

The Ovarian Screening Clinic and Endocrine Laboratory of the Department of Obstetrics and Gynaecology, King's College Hospital, London, United Kingdom.

Women with apparently normal ovarian function awaiting treatment for infertility by IVF-ET during subsequent natural cycles.

All women were examined by transvaginal ultrasonography with color flow imaging and had a sample of peripheral venous blood taken at each scan for hormone analysis.

The minimum pulsatility index (PI) and maximum peak systolic velocity from vessels within the dominant follicle; the maximum follicular diameters (and hence volume); serum FSH, E2, LH, and P.

The dominant follicle ruptured in 10 of 11 women. The median interval between the two scans that delineated the time of follicular rupture was 9.5 hours (range, 0.0 to 24.5 hours). These cycles appeared to be morphologically and endocrinologically normal. There was an apparent increase in intrafollicular blood flow over the periovulatory period with an insignificant trend toward lower values for the mean PI and a significant increase in the peak systolic velocity. These changes appeared to follow the rise in circulating LH.

Indexes of blood flow at a given site within the leading follicle can be monitored by transvaginal ultrasonography with color Doppler imaging over the periovulatory period. The increase in the peak systolic velocity and the relatively constant PI suggest a marked increase in blood flow at this time during the ovarian cycle.