Characterization of subendometrial myometrial contractions throughout the menstrual cycle in normal fertile women.

The objective was to study the characteristics of ultrasonographically detected subendometrial myometrial contractions. The contractions were evaluated by 328 ultrasound scans throughout the menstrual cycle. Reproducibility of these findings were studied in consecutive cycles. Eighteen healthy ovulatory volunteers with proven fertility were evaluated for at least one complete menstrual cycle in the follicular, periovulatory, and luteal phases. Multiple cycles were studied in 10 volunteers. The results showed that the contractions increase in frequency, amplitude, and percentage toward the fundus throughout the follicular and periovulatory phases. The pattern is essentially reversed in the luteal phase. There is reproducibility of these patterns from cycle to cycle. We conclude that there is a definite identifiable pattern of subendometrial myometrial contractility that varies with the phases of the normal menstrual cycle and recurs in a similar fashion from cycle to cycle.