Prospective randomized study of x-ray pelvimetry in the primigravida. Vaginal delivery after previous caesarean section: is X-ray pelvimetry necessary?
A prospective randomized study was performed to determine the usefulness of x-ray pelvimetry before oxytocin induction or augmentation. Two hundred primiparous women were entered into this study. Agreement on pelvic size by the clinical and radiologic assessment occurred in 76.5% of the cases. When the total groups were compared, there were no differences in pregnancy outcome. In the induction of labor subgroups there were less forcep deliveries and lower five-minute Apgar scores in the pelvimetry group. In the augmentation subgroups there were no differences. The subgroup of patients diagnosed clinically to have a borderline pelvis, had a higher incidence of cesarean section (P less than .05) if they had x-ray pelvimetry. These results suggest that the elimination of x-ray pelvimetry in primigravida women does not lead to a compromise in infant outcome when electronic fetal monitoring is used. To determine whether antepartum X-ray pelvimetry (XRP) reliably identified women suitable for a trial labour or repeat elective caesarean section after one previous section.
                A prospective controlled trial in which women were randomly allocated to either an antepartum XRP group who had XRP at 36 weeks gestation to determine mode of delivery, or a control group who had a trial labour without antepartum XRP. Following delivery, all controls had postpartum XRP.
                Department of Obstetrics and Gynaecology, King Edward VIII Hospital, Durban, South Africa.
                Three hundred-six women with a history of one previous caesarean section.
                Mode of delivery, birthweight and maternal and perinatal mortality and morbidity in the two groups.
                In the antepartum XRP group, 23 of 144 (16%) of women delivered vaginally compared with 60 of 144 (42%) controls (P < 0.0001). Of the 84 women with adequate antepartum XRP only 23 (27.7%) delivered vaginally. In the control group, 33 of 60 (55%) women who had vaginal deliveries had inadequate postpartum XRP and would have had a caesarean section if this information was known in the antepartum period; 62 of 84 (74%) caesarean sections in the control group had adequate postpartum XRP. Birthweight of the infants was similar in the two groups. There were no maternal or perinatal deaths. Maternal morbidity was similar in the two groups. Neonatal morbidity was minimal.
                Antepartum XRP is not necessary prior to a trial labour in women with one previous caesarean section. It increases the caesarean section rate and is a poor predictor of the outcome of labour.
There is not enough evidence to support the use of x-ray pelvimetry in women whose fetuses have a cephalic presentation.