The American College of Obstetricians and Gynecologists (ACOG) has issued a new practice bulletin on vaginal birth after previous cesarean (VBAC) delivery. The new statement, published in the July 1999 issue of Obstetrics and Gynecology, replaces an earlier version published in 1998. The focus of the new practice bulletin remains the same. The new report clarifies ACOG's position on the need for institutions offering VBAC to have the facilities and personnel, including obstetric, anesthesia and nursing personnel, immediately available to perform emergency cesarean delivery when conducting a trial of labor for women with an existing uterine scar. While strongly supporting the concept of VBAC delivery, ACOG recommends a cautious approach and consideration of individual risk factors before attempting a trial of labor.

The report discusses the background of VBAC, clinical considerations and recommendations, selection of candidates for a trial of labor, risks and benefits, contraindications to VBAC, patient counseling and management of labor. An algorithm for determining the feasibility of VBAC in a patient is also included in the ACOG practice bulletin.

According to ACOG, no randomized trials have proved that maternal and neonatal outcomes are better with VBAC than with repeat cesarean delivery. Published evidence suggests that the benefits of VBAC outweigh the risks in most women. However, reports note that maternal and infant complications also are associated with an unsuccessful trial of labor. These developments have led to a more circumspect approach to a trial of labor than was previously indicated.

ACOG emphasizes that it is ultimately up to the physician and patient to decide whether to attempt VBAC. The following are the criteria that ACOG lists for identifying a candidate for VBAC:

• One or two previous low-transverse cesarean deliveries.

• Clinically adequate pelvis.

• No other uterine scars or previous rupture.

• Physician immediately available throughout active labor capable of monitoring labor and performing an emergency cesarean delivery.

• Availability of anesthesia and personnel for emergency cesarean delivery.

VBAC should not be undertaken in women who have had a previous classic or T-shaped incision or other transfundal uterine surgery. Other contraindications for VBAC are a contracted pelvis; medical or obstetric complication that precludes vaginal delivery; and inability to perform emergency cesarean delivery because of the lack of an available surgeon, appropriate anesthesia, sufficient staff or appropriate facility.

The following recommendations from ACOG, based on consistent scientific evidence, have been excerpted from the practice pattern:

• Most women with one previous cesarean delivery with a low-transverse incision are candidates for VBAC and should receive counseling about VBAC and be offered a trial of labor.

• Epidural anesthesia may be used for VBAC.

• A previous uterine incision extending into the fundus is a contraindication to VBAC.

The following recommendations, according to ACOG, are based on limited or inconsistent scientific evidence:

• Women with two previous low-transverse cesarean deliveries and no contraindications who wish to attempt

• VBAC may be allowed a trial of labor. They should be advised that the risk of uterine rupture increases as the number of cesarean deliveries increases.

• Use of oxytocin or prostaglandin gel for VBAC requires close patient monitoring.

• Women with a vertical incision within the lower uterine segment that does not extend into the fundus are candidates for VBAC.

The following recommendations are based primarily on consensus and expert opinion:

• Because uterine rupture may be catastrophic, VBAC should be attempted in institutions equipped to respond to emergencies with physicians immediately available to provide emergency care.

• After thorough counseling that weighs the individual benefits and risks of VBAC, the ultimate decision to attempt this procedure or undergo a repeat cesarean delivery should be made by the patient and her physician.