Longitudinal study of the uterine body and cavity with three-dimensional ultrasonography in the puerperium

Objective: To describe uterine involution in the puerperium with three-dimensional ultrasound.

Design: Prospective, longitudinal study.

Setting: Fetal medicine unit, department of obstetrics and gynecology, university referral hospital, Uppsala, Sweden.

Population: Fifty women with uncomplicated deliveries and puerperium between February 2009 and February 2010.

Methods: Three-dimensional ultrasound was used to measure the uterine body and cavity volumes. The volume data set was analysed using virtual organ computer-aided analysis (VOCAL) with a 30 degree rotation step. Measurements were performed transabdominally on days 1, 7 and 14 and transvaginally on days 28 and 56 postpartum. Parity, gestational age, birthweight, smoking, breastfeeding and blood loss were recorded.

Main outcome measures: Uterine body and cavity volumes.

Results: Median uterine body volume was 756 cm(3) on day 1, 440 cm(3) on day 7, 253 cm(3) on day 14, 125 cm(3) on day 28 and 68 cm(3) on day 56. Median cavity volume was 22 cm(3) on day 1, 18 cm(3) on day 7, 6 cm(3) on day 14, 1 cm(3) on day 28 and not measurable on day 56. The interindividual variation of uterine body and cavity volumes was most pronounced on day 1 and decreased throughout the observation period. Intrauterine content was found in 36% of the women on day 1, 95% on day 7, 87% on day 14 and 28% on day 28.

Conclusions: Three-dimensional ultrasound is a non-invasive tool suitable for measurement of the uterine body and cavity volumes during the puerperium. The volumes decreased in a similar pattern in the study population.