Outcomes of Neuraxial Anesthetic Technique on the Trial of Labor After Cesarean (TOLAC)

Though it has been said, "once a cesarean, always a cesarean," the current medical stance has changed and now encourages vaginal birth after cesaren (VBAC) in a select population of patients. VBAC has several advantages over a repeat cesarean including decreased recovery period, decreased risk of infection, avoidance of major abdominal surgery, and lessened blood loss. Predictors for success of VBAC include previous spontaneous vaginal birth, singleton pregnancy, and previous low transverse scar for C-section delivery. TOLAC is a reasonable option for select pregnant women and is associated with a 74% likelihood of VBAC. Risk factors for failure of VBAC include labor dystocia, advanced maternal age, maternal obesity, fetal macrosomia, gestational age (GA) >40 weeks, short inter pregnancy interval, and preeclampsia.

While success of VBAC is associated with fewer complications, failure of VBAC may be associated with increased complications. A major concern for VBAC is the possibility for uterine rupture, which may result in hysterectomy and intrapartum fetal hypoxia/death. According to the American College of Obstetricians and Gynecologists (ACOG) guidelines, effective regional analgesia should not be expected to mask the signs and symptoms of uterine rupture, particularly because the most common sign of rupture is fetal heart tracing abnormalities. Adequate pain relief achieved with either CSE or epidurals may even encourage more women to opt for VBAC. The decision to proceed with TOLAC should occur only after appropriate discussion of the risks and benefits has occurred between the patient and her obstetrician and as long as no other contraindications exist. The final decision should be left up to the patient. There is no reliable way to predict risk of uterine rupture, but it may be associated with classical and low vertical uterine scars, induction of labor, and increased number of prior cesarean deliveries and risk may be decreased by previous vaginal birth. Other aspects of VBAC versus repeat cesarean pertaining to the fetus to consider include respiratory function, mother-infant contact, and initiation of breastfeeding, which may be delayed in cesarean deliveries.

There is very little research concerning the effects of CSEs and epidurals on women undergoing TOLAC.There have been multiple studies comparing CSE and epidurals on nulliparous and multiparous women, but none have been done specifically on patients undergoing TOLAC. According to the American Society of Anesthesiologists (ASA) practice guidelines for obstetric anesthesia "nonrandomized comparative studies suggest that epidural analgesia may be used in a trial of labor for previous cesarean delivery patients without adversely affecting the incidence of vaginal delivery. Randomized comparison of epidural versus other anesthetic techniques were not found." They agree that neuraxial techniques improve the likelihood of vaginal delivery for patients attempting VBAC and suggest neuraxial catheter be placed in event of operative delivery. Because no study to date has compared CSEs and epidurals and their effects on the success of VBAC, this study aims to further investigate this arena.

Inclusion criteria

• all patients meeting ACOG guidelines for TOLAC
• at least one previous elective cesarean delivery
• <40 weeks gestational age (GA)
• vertex singleton pregnancy with use of continuous fetal monitoring

Exclusion criteria

• Patient refusal of regional anesthetic or with contraindication for regional anesthesia
• BMI >40
• associated comorbidities such as gestational diabetes, preeclampsia, abnormal placentation