VBAC Safe for Women With Twin Pregnancies

OB/GYN News, August 15, 2000 by Sherry Boschert

SAN FRANCISCO - Vaginal birth after cesarean section is a viable option for women with twin pregnancies, Dr. Thomas D. Myles said at the annual meeting of the American College of Obstetricians and Gynecologists.

Many physicians avoid vaginal birth after C-section (VBAC) for twins because they fear that the risks are too high, although the medical literature provides no evidence of worse outcomes, noted Dr. Myles of the University of Illinois, Chicago.

In his retrospective study of 76 attempted VBACs, twins did as well as singletons.

He compared records for all twin deliveries attempting VBAC at a single institution between 1993 and 1999. Each twin VBAC attempt was compared with the next three singleton VBAC attempts at the same institution. Sixteen (84%) of 19 twin pregnancies and 43 (75%) of 57 singletons succeeded in delivering vaginally. VBACs were considered successful when both twins were delivered vaginally.

The rate of postpartum hemorrhage was 5% in both groups. There also were no significant differences between groups in other parameters: uterine rupture, estimated blood loss with either successful or failed VBAC, 1-minute and 5-minute Apgar scores, umbilical artery pH levels, or neonatal intensive care unit admissions.

The only uterine rupture occurred in a singleton pregnancy Dr. Myles noted.

Based on these findings, VBAC "should be offered to patients with twin pregnancies who are eligible" for it, Dr. Myles advised.

For inclusion in the study, the first twin had to be in a vertex presentation. The method of delivery for the second twin was left to the discretion of the attending physician, as was the use of cervical ripentug agents and oxytocin for induction augmentation. "VBAC can be offered to [women with] twin pregnancies regardless of the lie of the second twin," he added.

Women with twins were excluded from the study if they had obstetrical contraindications for labor, a previous uterine debiscence, or a vertical uterine scar. A uterine scar of indeterminate characteristics did not mean automatic exclusion. If the scar was believed to be from a low transverse C-section, the patient was offered VBAC.

The current results support two previous studies that found comparable success rates in twin and singleton VBACs. A 1989 study of VBAC in twins found a 72% success rate, and a 1996 study found a 71% success rate. In singletons, VBAC generally succeeds in 70%-80% of cases.