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4/1/2017

Trial of Labor after Cesarean (TOLAC)

Author: Sarah Shaffer, DO

Mentor: Thomas M. Gellhaus, MD
Editor: Abimbola Famuyide, MD, MBBS

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Options following a cesarean delivery include elective repeat cesarean delivery and trial of labor after cesarean (TOLAC).  Successful TOLAC results in vaginal birth after cesarean (VBAC).  No large, randomized trials have compared outcomes of TOLAC and elective repeat cesarean delivery.

A successful VBAC may decrease the potential risks associated with multiple cesarean deliveries, including abnormal placentation. Benefits of elective repeat cesarean delivery include predictable timing, access for sterilization procedures and minimization of uterine rupture risk.

Although uterine rupture is a rare complication of TOLAC, approximately 25% will undergo a hysterectomy. Neonatal neurologic morbidity and neonatal death are also important considerations (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 an appreciable difference in risk to neonates born by VBAC and elective repeat cesarean delivery.

Characteristics of an optimal TOLAC candidate include a single prior low transverse cesarean delivery, with anticipated success rate of greater than 60% 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, and inter-pregnancy interval.

Absolute contraindications for TOLAC include a classical, “T” or “J” hysterotomy, extensive transfundal surgery or any incision that extends through the active portion of the myometrium.  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 or 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, although mechanical cervical ripening (e.g., transcervical foley catheter) may be offered to ripen an unfavorable cervix. Prostaglandin induction may be considered in the setting of fetal demise given the altered fetal risk profile.

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 tracing.  ACOG recommends TOLAC be undertaken where immediate emergency cesarean delivery can be performed.

Options including TOLAC and elective repeat cesarean delivery should be discussed early during prenatal care allowing time for consideration of resources, counseling, addressing questions or changes in status.  Calculators predicting the likelihood of achieving VBAC no longer include race and ethnicity in an effort to mitigate risks of health disparities.

Further Reading:

American College of Obstetricians and Gynecologists, ACOG Practice Bulletin No. 205: Vaginal Birth After Cesarean Delivery. Obstet Gynecol. 2019 Feb;133(2):e110-e127. doi: 10.1097/AOG.0000000000003078.

Grobman WA, Sandoval G, Rice MM, Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. et al. Prediction of vaginal birth after cesarean delivery in term gestations: a calculator without race and ethnicity. Am J Obstet Gynecol. 2021 May 24:S0002-9378(21)00587-1. doi: 10.1016/j.ajog.2021.05.021. Epub ahead of print. PMID: 34043983.  Full version also available at: https://www.ajog.org/article/S0002-9378(21)00587-1/pdf

Initial Approval:  January 2017; Revised July 2018; Revised/Minor Update January 2020; Revised September 2021

 

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