Trial of labor refers to a planned attempt to have a vaginal birth after a previous cesarean section, often called a Trial of Labor After Cesarean (TOLAC). The goal of a TOLAC is to achieve a Vaginal Birth After Cesarean (VBAC). This approach represents a shift from the historical view that “once a cesarean, always a cesarean,” offering an alternative for those who meet specific medical criteria.
Understanding Trial of Labor
Trial of Labor After Cesarean (TOLAC) is a structured medical process where a person who has had a prior C-section attempts a vaginal birth. This allows for a different birthing experience and can potentially avoid another abdominal surgery. This approach emerged as a viable option as increasing C-section rates highlighted the need for alternatives that could reduce maternal morbidity and healthcare costs associated with repeat procedures.
Studies from the 1960s began to challenge the notion that all subsequent deliveries after a C-section must also be by C-section. By the 1980s, medical panels questioned the necessity of routine repeat C-sections, leading to a growing interest in promoting VBAC and recognizing its benefits for qualified individuals.
Determining Candidacy
Candidacy for a trial of labor involves a thorough assessment by a healthcare provider, considering factors that influence the likelihood of a successful VBAC and minimize risks. The type of uterine incision from the previous C-section is a significant factor. A low transverse incision, a horizontal cut across the lower uterus, is most favorable for TOLAC due to its lower risk of uterine rupture compared to a classical (vertical) incision. Individuals with a previous low vertical incision or an unknown incision type may still be candidates if a classical incision is not strongly suspected.
The reason for the previous C-section also plays a role in candidacy. If the prior C-section was due to a non-recurring issue, such as a breech presentation or fetal distress, it may increase the chances of a successful TOLAC. Conversely, if the previous C-section was due to labor not progressing, sometimes called labor dystocia, the chance of success may be lower. The number of previous C-sections is another consideration; individuals with one prior low transverse C-section are generally considered suitable candidates, and those with two previous low transverse C-sections may also be considered in certain circumstances.
Maternal health conditions are also evaluated; individuals with severe medical disorders like uncontrolled diabetes or severe hypertension may not be suitable candidates. Fetal factors are assessed, including the baby’s estimated size and position; a fetus with an estimated weight greater than 3.5 kg or a breech presentation may reduce the chances of a successful TOLAC. However, external cephalic version (ECV) may be an option for breech presentation in otherwise suitable candidates. A short interval between pregnancies, typically less than 18 months, can also increase the risk of uterine rupture.
Navigating the Process
During a trial of labor, continuous monitoring of both the birthing person and the baby is a standard practice to ensure safety. This involves continuous electronic fetal heart rate monitoring to detect any early signs of fetal distress, allowing for prompt intervention if needed. The medical team closely observes labor progression, regularly assessing cervical dilation and effacement to identify any potential issues early.
Intravenous access is typically established to facilitate fluid administration and provide immediate access for medications if required. Pain management options are available, similar to those offered during any vaginal birth, including epidural anesthesia. While spontaneous labor onset is often preferred, labor induction may be considered for maternal or fetal indications, though caution is exercised with certain methods like prostaglandin analogs, which can increase the risk of uterine rupture. Throughout the process, the medical team remains ready for a potential C-section, with anesthesia and surgical teams immediately available on-site.
Outcomes and Considerations
The potential outcomes of a trial of labor vary, with the overall success rate of achieving a Vaginal Birth After Cesarean (VBAC) typically ranging from 60% to 80% for appropriate candidates. This success rate can be influenced by several factors, including a history of a previous vaginal birth, which significantly increases the likelihood of a successful VBAC, with rates potentially reaching over 80%. Conversely, factors like increased maternal age, a gestational age beyond 40 weeks, or a prior C-section due to labor not progressing can decrease the chances of a successful VBAC.
If the trial of labor is unsuccessful, it results in a repeat C-section, sometimes referred to as a Cesarean Birth After Cesarean (CBAC). While a successful VBAC offers benefits such as avoiding abdominal surgery, a quicker recovery, reduced risk of infection, and less blood loss, an unsuccessful TOLAC carries its own considerations. The most significant concern is uterine rupture, where the C-section scar on the uterus tears during labor. This is a rare but serious complication, occurring in less than 1% of TOLAC attempts, but it can be life-threatening for both the birthing person and the baby, necessitating an emergency C-section.
Compared to a planned repeat C-section, an unsuccessful TOLAC may also have a slightly higher risk of complications like increased blood loss or infection. However, a successful VBAC can reduce the risk of future complications associated with multiple C-sections, such as problems with the placenta growing too deeply into the uterine wall. Discussions with a healthcare provider about individualized risk assessment for VBAC likelihood and the comparative risks of both TOLAC and planned repeat C-section are important for informed decision-making.