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Trial of Labor after Cesarean (TOLAC)

4/1/2017 - Sarah Shaffer, DO

Mentor:  Thomas M. Gellhaus, MD

Editor:  Roger Smith, MD

Options following a cesarean delivery include elective repeat cesarean delivery (ERCD) and trial of labor after cesarean (TOLAC).  Successful TOLAC results in vaginal birth after cesarean (VBAC).  No large randomized trials have yet been done to compare outcomes of TOLAC and ERCD.

A successful VBAC may decrease the potential risks associated with multiple cesarean deliveries, including placenta accreta.  Benefits of ERCD include predictable timing, access for sterilization procedures, and minimization of uterine rupture risk.

Uterine rupture is a rare complication of TOLAC.  Risks of uterine rupture include hysterectomy (14-33%), neonatal neurologic morbidity, and death (3-6%).  If TOLAC is unsuccessful requiring an intrapartum cesarean delivery, the risks of infection and blood transfusion increase.  There does not appear to be appreciable difference in risk to neonates born by TOLAC without uterine rupture and ERCD.

Characteristics of an optimal TOLAC candidate include a single prior low transverse cesarean delivery, with anticipated success rate of 60-80% and 0.5% uterine rupture risk.  Other predictors of success include a history of vaginal delivery or VBAC, spontaneous onset of labor, and a non-recurring indication for the primary cesarean delivery.  An unknown uterine scar performed in the setting of usual indications for a low transverse cesarean is not a contraindication to a TOLAC.  Consideration should be given to gestational age, estimated fetal weight, inter-pregnancy interval and maternal demographic factors.

Absolute contraindications for TOLAC include a classical or “T” or “J” hysterotomy, a transfundal myomectomy incision. or one that extends through the active segment to the endometrium.  The risk of uterine rupture in this setting is 4-9%.  Patients with a history of uterine rupture or an obstetrical contraindication to vaginal delivery should not be offered the option for TOLAC.

There is insufficient data to know with certainty if TOLAC success or uterine rupture risk is altered with a prior low vertical hysterotomy, two or more low transverse hysterotomies, and twin gestation.  While the need for induction or augmentation of labor decreases VBAC success, TOLAC may still be offered and undertaken in certain circumstances.  Prostaglandins should be avoided due to the increased risk of uterine rupture.  TOLAC should be offered for a fetal demise requiring induction as there is no risk to the fetus.

Epidural analgesia does not mask signs or symptoms of uterine rupture or decrease the risk of successful TOLAC.  The most common sign of uterine rupture is a change in fetal heart rate.  ACOG recommends TOLAC be undertaken where immediate emergency cesarean delivery can be performed.

Options including TOLAC and ERCD should be discussed early during the course of prenatal care allowing time for consideration of resources, counseling, addressing questions, or considering changes in status.  Predictors of success are available and can assist in the counseling of patients regarding their likelihood of achieving a VBAC. The final plan for delivery should be a well-documented collaborative process.

Further Reading:

National Institutes of Health Consensus Development Conference Statement – Vaginal Birth After Cesarean: New Insights March 8-10,2010. Obstet Gynecol. 2010;115:1279-95.

Vaginal birth after previous cesarean delivery. Practice Bulletin No. 115. American College of Obstetricians and Gynecologists. Obstet Gynecol 2010;116:450–63.

Maternal-Fetal Medicine Units Network (MFMU), "Development of a nomogram for prediction of vaginal birth after cesarean delivery," Obstet Gynecol. 2007;109:806-12. Available at:

Initial Approval:  January 2017


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