Ultrasonic evaluation of the uterus and uterine cavity after normal, vaginal delivery

Objective To describe uterine and uterine cavity changes throughout the pue rperium, as revealed by ultrasound. Methods This was a prospective, longitudinal study in which 42 women with u ncomplicated vaginal term deliveries were examined serially by ultrasound o n postpartum days 1, 3, 7, 14, 28 and 56. The first four examinations were performed transabdominally and the last two transvaginally. The involution process of the uterus was assessed by measuring the anteroposterior diamete r of the uterus and uterine cavity. Morphological findings were recorded. T he influence on the involution process of parity, breast-feeding, maternal smoking and infant's birth weight were also evaluated. Results The maximum anteroposterior diameter of the uterus diminished subst antially and progressively from 92.0 mm on day 1 postpartum to 38.9 mm on d ay 56. The maximum anteroposterior diameter of the uterine cavity diminishe d from 15.8 mm on day 1 to 4.0 mm. on day 56. However, the anteroposterior diameter of the uterine cavity, 5 cm. from the fundus, typically increased on days 7 and 14 postpartum. The position of the uterus and the shape and t he appearance of the cavity change in a unique way during the normal puerpe rium. The uterus was most often retroverted and empty in the early puerperi um. Fluid and debris in the whole cavity were seen in the middle part of th e puerperium. In late puerperium the cavity was empty and appeared as a thi n white line. Endometrial gas was occasionally visualized. No correlation w as found between the involution of the uterus and parity, breast-feeding an d the infant's birth weight. Conclusion Transabdominal sonography is suitable for examination of the ute rus during the first 14 days postpartum but from day 28 the transvaginal ro ute is preferable. The uterine body and position, as well as the cavity, ar e easy to examine by ultrasound. Accumulation of fluid and debris in the ut erine cavity is a common and insignificant finding of the involuting uterus . It is located in the cervical area in the early puerperium and in the who le uterine cavity in the middle part of the puerperium. Findings from uncom plicated vaginal deliveries are needed as a reference when the diagnostic e fficacy of ultrasound for pathological conditions is to be tested.