Anatomic changes in the pelvis after uncomplicated vaginal delivery: a CT study on 14 women

Abstract

We analyzed CT scans of the pelvis made within 24 hr of an uncomplicated term vaginal delivery in 14 women to document the anatomic changes that occur in the immediate postpartum period. Scans were interpreted by three radiologists, and the results were compared with those from pelvic CT scans made from normal, age-matched, nonpregnant women. In addition to soft-tissue windows, bone windows also were obtained to assess the pubic symphysis and sacroiliac joints in both the postpartum women and the control subjects. The mean uterine length, transverse width, and anteroposterior diameter in the postpartum women (14 +/- 1.4, 12 +/- 1.5, and 9 +/- 1.6 cm, respectively) were significantly larger than in the nonpregnant women (7 +/- 1.4, 5 +/- 0.8, and 4 +/- 0.9 cm) (p less than .0001). CT scans showed intrauterine blood in nine of the postpartum women (64%), and three (21%) had intrauterine gas. There was widening of the sacroiliac joint in one (7%) of the postpartum women compared with none of the control subjects. Widening of the pubic symphysis was present in six (42%) of the postpartum women and in none of the control subjects. Six (42%) of the postpartum women had gas in the sacroiliac joints, 33% of which occurred bilaterally; gas in the pubic symphysis was seen in four (28%) of the postpartum scans. In one patient, an asymptomatic muscle hematoma was discovered. We conclude that normal changes in the pelvis after uncomplicated term vaginal delivery include enlargement of the uterus, intrauterine blood, widening of the symphysis and sacroiliac joints, and gas in the sacroiliac joints.