Ultrasound appearance of the ovaries during the pill-free interval.

Abstract

Breakthrough ovulation and sometimes pregnancy which may occur in women taking the combined oral contraceptive (OC) is most likely to occur in women who inadvertently lengthen their pill-free interval. The authors studied 120 women ages 18-30 who had taken the low-dose OC for at least 6 months. All had a pelvic ultrasound scan performed on the 7th day of their pill-free interval (day 28 of the cycle). Significant ultrasound follicular activity (considered as follicles >10 mm in diameter) was present in 23% of the women studied. 22% demonstrated a polycystic ovarian pattern on ultrasound; 50% had quiescent ovaries and 5% had ovarian cysts (defined as a fluid-filled structure >30 mm in diameter). In this cross-sectional study it was considered that the subgroup of women with follicles of >10 mm in diameter were likely to be at risk for further follicular growth and ovulation if the pill-free interval were lengthened. Further studies are indicated in order to determine if ovulation would in fact occur. (authors modified)