Physiology of the menstrual cycle by ultrasonography.

The aim of this was to study the physiologic changes occurring during the menstrual cycle in 39 healthy women as they appear ultrasonographically. We investigated the following parameters: serum progesterone level, endometrial thickness, and uterine artery pulsatility index. Endometrial thickness was measured at the widest point in the longitudinal plane, including all of the highly reflective endometrium. Uterine arterial Doppler velocimetry was evaluated at the level of the uterine cornua by the pulsatility index. Ovulation was documented by transvaginal determinations of follicle development and progesterone level in each cycle. This prospective study shows that ultrasonographically determined endometrial thickness and uterine artery pulsatility index depend on the phase of the menstrual cycle. Endometrial thickness steadily increases throughout the menstrual cycle whereas the pulsatility index of both uterine arteries tends to decrease after ovulation. This decrease is larger in the uterine artery ipsilateral to the site where ovulation took place.