Ultrasonographic Evaluation of Uterine Involution in the Early Puerperium.

Purpose Our aim was to describe the changes observed by ultrasonography in uterine dimensions during the early puerperium among women who experienced an uncomplicated puerperium. Additionally, the influence of parity, mode of delivery, breastfeeding and birth weight on uterine involution was evaluated. Methods Ninety-one patients underwent an ultrasound examination on days 1 (D1), 2 (D2) and 7 (D7) of the postpartum period. The longitudinal, anteroposterior and transverse uterine diameters were measured, and the uterine volume was calculated by the formula: longitudinal diameter (LD) X anteroposterior diameter (APD) X transverse diameter (TD) X 0.45. The thickness and length of the uterine cavity were also measured. Results The uterine volume and the LD, APD and TD decreased by 44.8%, 20.9%, 11.8% and 20.0% respectively. The uterine cavity thickness was reduced by 23%, and the length of the cavity was reduced by 27.2% on D7. Uterine involution was correlated inversely with parity when the day of the postpartum period was not taken into account (p = 0.01). However, when the uterine involution was correlated to parity separately, with D1, D2 or D3, no correlations were found. A significant difference occurred at D2, when it was found that the uterus had a smaller volume following cesarean section compared with vaginal delivery (p = 0.04). The high birth weight and breastfeeding were significantly related to uterine involution (p ≤ 0.01 and p = 0.04). Conclusion The sonographic evaluation of the uterus in the early puerperium should consider birth weight, breastfeeding and parity, as well as the delivery route on D2, to identify abnormalities related to uterine involution.