Functional three-dimensional sonographic study of the postpartum uterus.

<bold>Objective: </bold>To demonstrate sequential changes of the postpartum uterus using two- and three-dimensional (2D and 3D) ultrasounds and Doppler studies.<bold>Methods: </bold>Eighty-one women who delivered a singleton at term were recruited for this prospective longitudinal study. Manual and ultrasound examinations of the uterus were performed for seven consecutive weeks. Sequential changes in size of the uterus, endometrial thickness and appearances and Doppler indices of the uterine and arcuate arteries were analyzed.<bold>Results: </bold>Complete follow ups were achieved in 71 women who had an uncomplicated postpartum course. 2D and 3D ultrasound estimations of uterine volume are highly correlated with each other (r > 0.7), but not manual estimations (r < 0.3). Data generated from 497 3D observations demonstrated rapid involution of the uterus in the first two weeks after delivery. Breastfeeding and parity did not affect uterine involution (r < 0.2). Resistance index (RI) of the uterine artery started to elevate at four weeks after delivery (r > 0.7). RI of the arcuate artery was not significantly changed during the study period (r < 0.2). Uterine involution was independent from progressive thinning of the endometrium and elevation of uterine artery RI. (r < 0.1 and 0.2, respectively).<bold>Conclusion: </bold>Longitudinal sonographic study showed independent physiologic reversals of uterine volume, endometrium and vascular supply in the first seven weeks following vaginal delivery. Standardization of measurement techniques is essential to apply this information for an early detection of postpartum uterine complications. [ABSTRACT FROM AUTHOR]