Globally, the cesarean delivery (CD) rate has plateaued at 32%; it is higher in developed nations and urban areas in less developed nations. Concurrently, after peaking in the mid-1990s, trial of labor after cesarean (TOLAC) rates show a declining trend, even though many women are anxious to have a normal birth, especially in countries like India where the economic costs are much higher and access to facilities providing CD is limited. Less than 25% of women with a prior cesarean delivery attempt a future TOLAC. The cause of this decreasing trend in TOLAC is explained by inadequate resource availability, malpractice concerns, and lack of knowledge in patients and providers regarding the perceived risks and benefits.
Trial of labor after cesarean delivery (TOLAC) is a planned attempt to deliver a woman with a previous cesarean section (CS) vaginally, regardless of the outcome. This method provides a choice to women with a previous CD to attempt to deliver vaginally—a vaginal birth after cesarean delivery (VBAC). Even as it fulfills a patient’s preference for vaginal delivery at an individual level, VBAC is also associated with decreased maternal morbidity and blood loss, as well as a decreased risk of complications associated with multiple CD in future pregnancies. It also leads to a decrease in the overall cesarean delivery rate at the population level with immense socio-economic benefits.
Though TOLAC may be appropriate for many women, several factors increase the likelihood of a failed trial of labor followed by a CD. A failed trial leading to a repeat CD is associated with increased maternal and perinatal morbidity when compared with a successful trial of labor (i.e.VBAC) as well as an elective repeat cesarean delivery (ERCD). To minimize these risks, It is vital to assess the likelihood of a successful VBAC, as well as the individual risks when determining which woman is an appropriate candidate for TOLAC. The American College of Obstetricians and Gynecologists has come out with guidelines on these aspects in 2017, as given below.
American College of Obstetricians and Gynecologists Guidelines on VBAC
- From 60 to 80% of women who attempt a trial of labor after cesarean delivery (TOLAC) achieve a successful vaginal birth.
- Conditions that can make VBAC less likely if TOLAC is attempted include:
- advanced maternal age
- a high body mass index
- a high birth weight
- a previous CS that resulted because the cervix failed to dilate.
- Recommend that TOLAC be attempted in facilities that can provide cesarean delivery for situations that are immediate threats to the life of the woman or fetus.
- Women undergoing TOLAC should not attempt to deliver at home.
- Several advantages associated with VBAC include allowing women to avoid major abdominal surgery and lowering their risk for hemorrhage, blood clots, and infection. It also shortens the recovery period and reduces women’s risk for experiencing maternal morbidity or mortality during delivery in a future pregnancy as a result of repeated cesarean deliveries.
- The number of previous cesarean deliveries, the reasons for them, and the types of surgical incisions used should all be considered when making decisions regarding VBAC and TOLAC.
- Most women with one previous cesarean delivery with a low-transverse incision are safe candidates for TOLAC.
- Planned TOLAC is generally not recommended for women with high risk for uterine rupture and women in whom vaginal delivery is contraindicated, such as those with placenta previa.
- Do not use misoprostol for cervical ripening or labor induction in term patients with prior cesarean delivery or major uterine surgery. Epidural analgesia for labor may be used during TOLAC.
- Women with one previous cesarean delivery with a low-transverse incision, who are otherwise appropriate candidates for twin vaginal delivery, are considered candidates for TOLAC.
- Induction of labor remains an option in women undergoing TOLAC.
- External cephalic version of infants with breech presentation is not contraindicated in women with a prior low transverse uterine incision who are candidates for external cephalic version and TOLAC. These women should undergo continuous fetal heart rate monitoring during TOL.
The critical words in the Indian context are that TOLAC should only be attempted in facilities that can provide cesarean delivery for situations that are immediate threats to the life of the woman or fetus. This essentially implies that onsite availability of close and expert monitoring, and facility for a CD within 30 minutes or so, with an experienced Ob/Gyn, anesthetist, neonatologist and ICU is critical, as uterine rupture is life threatening for both mother and baby. This is possible in most tertiary care medical colleges or private tertiary care hospitals where such facilities exist.
The guidelines for clinical practice from the French College of Gynecologists and Obstetricians by Sentilhes L et al released in 2013 were also based on professional consensus as well as analysis of data. They also opined that the risk-benefit ratio considering the risks of short- and long-term maternal complications is favorable to TOLAC in most cases. The risks of fetal, perinatal, and neonatal mortality during TOLAC are low but are significantly higher than those associated with an elective CD (ERCD). The risks of mask ventilation, intubation for meconium-stained amniotic fluid, and neonatal sepsis all increase in TOLAC, though the risk of transient respiratory distress increased in ERCD. To reduce this risk, unless otherwise indicated, ERCD must not be performed before 39 weeks. The guidelines state that TOLAC is possible for women with a previous cesarean before 37 weeks, with two previous cesareans, with a uterine malformation, and a low vertical incision, but this is doubtful in the Indian scenario of unassured facilities, and an ERCD may be a better option. There was professional consensus that ERCD is recommended in women with a scar in the uterine body and a history of three or more cesareans. There was also professional consensus that Ultrasound assessment of the risk of uterine rupture in women with uterine scars has not been shown to have any clinical utility; it is not recommended during pregnancy to help decide the mode of delivery.
Another important point recommended was that in the active phase, the total duration of failure to progress should not exceed 3 hours, at which point cesarean should be performed (professional consensus). Epidural analgesia must be encouraged. Induction of labor in a woman with a previous cesarean should be done only for medical indications, as it increases the risk of uterine rupture, which can be estimated at 1% if oxytocin (it is dose dependent) is used and 2% with vaginal prostaglandins.
A study on 400 patients on TOLAC by Soni et al in Kangra Medical College in rural India concluded that “Under strict supervision, TOLAC is a reasonable option even in rural India”. However, this study was conducted in a medical college and cannot be applied to even the district level hospitals, most of which lack tertiary care faculties.
TOLAC should be encouraged for women with a previous vaginal delivery either before or after the cesarean, a favorable Bishop score or spontaneous labor, and for preterm births. For women with a fetus with an estimated weight of more than 4500 g, especially in the absence of a previous vaginal delivery and those with supermorbid obesity (BMI>50), ERCD must be planned from the outset. For all of the other clinical situations envisioned (maternal age>35 years, diabetes, morbid obesity, prolonged pregnancy, breech presentation and twin pregnancy), TOLAC is possible at the treating Ob/Gyn discretion to assess risk/benefits. The decision about planned mode of delivery must be shared by the patient and her physician by the 8th month, taking into account the individual risk factors for TOLAC failure and uterine rupture.
Therefore, TOLAC in anticipation of VBAC is the preferred choice only for women who do not have several risk factors. The treating doctors need to conduct a very careful assessment of patient and available emergency facilities, and discuss potential outcomes for TOLAC/VBAC with the patient, before proceeding for a TOLAC, to achieve optimal outcomes for the mother and baby.
- Brown T. Updated Guidelines on VBAC Released by ACOG. Medscape News. WebMD Inc. November 7, 2017. https://www.medscape.com/viewarticle/888126
- Practice Bulletin No. 184: Vaginal Birth After Cesarean Delivery. Committee on Practice Bulletins-Obstetrics. Obstet Gynecol.2017 Nov;130(5):e217-e233. https://insights.ovid.com/pubmed?pmid=29064970
- Sentilhes L. et al. Delivery for women with a previous cesarean: guidelines for clinical practice from the French College of Gynecologists and Obstetricians (CNGOF). Eur J Obstet Gynecol Reprod Biol.2013 Sep;170(1):25-32. doi: 10.1016/j.ejogrb.2013.05.015. Epub 2013 Jun 28.
- Soni A. Int J Gynaecol Obstet. 2015 May; 129(2):156-60. doi: 10.1016/j.ijgo.2014.11.007. Epub 2015 Jan 7.
Dr. Sunanda Gupta
The author MBBS & MD, MPH (Obstetrics & Gynaecology) and is Head of Department, Obs/Gyn, World College of Medical Sciences and Research, Haryana. She is a member Editorial Board, Obstetrics & Gynaecology at Specialty Medical Dialogues.