There has been a lack of randomised controlled trials comparing the outcomes of planned repeat caesarean with planned trial of labour after caesarean (TOLAC).[1, 2] We are left with a literature that primarily estimates the risks and benefits of vaginal birth after caesarean (VBAC), and with guidelines that have changed over the years. Doctors and patients are often in a quandary about whether, when, or where to attempt TOLAC, and these questions have been largely unresolved for several decades. It has also become a very contentious issue with a wide spectrum of views, from advocates who believe that VBAC can be safely attempted outside a hospital,[3-5] to those who believe VBAC should never be offered at all.
I have had a long-standing interest in VBAC, and it is clear to me that no single set of rules or recommendations will work for women and their doctors in all situations. The systematic reviews and guidelines available are based primarily on observational studies performed in tertiary-care centres, and they cannot always be translated into practice in other settings. They rarely provide definitive answers to the questions and concerns that doctors and patients encounter in practice, particularly in rural and low-resource situations. Even when the decision is made to proceed with an attempted VBAC, there are conflicting recommendations about how to manage both the labour and the delivery. This is largely because external influences, including economic, logistic, and medical legal issues, as well as doctor and patient preferences, become important in actual practice.[7-11] My objective is to provide a practical and evidence-based approach for the practitioner for the intrapartum management of TOLAC and VBAC.
Assessment of evidence
English language MEDLINE, PubMed, and COCHRANE databases were searched in collaboration with a professional librarian in February 2013, and again in April 2013, for original studies including randomised controlled trials, systematic reviews, updates, and guidelines comparing specific methods for managing TOLAC and VBAC. The search terms used were ‘management of trial of labor after cesarean’ and ‘management of vaginal birth after cesarean section or cesarean delivery’. The search generated 59 pertinent full-text articles, including one randomised controlled trial, nine systematic reviews, five national society guidelines, and a report from a US National Institutes of Health (NIH) Consensus Development Conference. Additional articles that reported on various aspects of intrapartum management of TOLAC and VBAC were obtained from references listed in the selected work. There was a wide range in the level of evidence used in these documents, and heterogeneity of studies was common in those included in systematic reviews. The lack of randomised trials on management of labour and delivery precluded reliable meta-analysis. The best evidence from studies judged to be informative and clinically useful form the basis for this article.
Prelabour counselling is an important component of the intrapartum management of TOLAC and VBAC. The preponderance of literature and most guidelines indicate that TOLAC is relatively safe under normal circumstances for women who have had one low transverse caesarean.[12-18] Nevertheless, much of the controversy surrounding TOLAC and VBAC is about the risk of uterine rupture and its adverse outcomes for mother and infant. The latest Practice Bulletin from the American College of Obstetricians and Gynecologists (ACOG) encourages VBAC, but recommends 24–hour obstetric and anaesthesia coverage in order to deliver the infant immediately by emergency caesarean should uterine rupture occur. Conversely, it was recognised that some doctors and patients may elect to proceed with TOLAC even if all recommended conditions cannot be met; however, the safety of TOLAC in settings where resources are limited remains a topic of debate.
The overall success rate of having a vaginal delivery after caesarean is approximately 75%, with a range of 60–80%.[13, 14, 18] Short interpregnancy interval, single-layer closure, and labour induction and augmentation have all been suggested in studies as factors that may increase the rate of uterine rupture, but the infrequency of uterine rupture and the relatively weak associations limits their usefulness in counselling women. Algorithms have been devised to help in counselling and predicting vaginal birth, but careful consideration of favourable versus unfavourable conditions in an individual patient may be just as useful. Factors associated with higher and lower success rates are shown in Box 1. Clinical judgment has a place. For example, it is likely that a woman in spontaneous labour with a normal-sized fetus in cephalic presentation, whose first caesarean was for a breech presentation, will have a much better chance of a successful VBAC than a secundagravida who is obese and of less than 5 feet in height, whose caesarean was for a failed forceps delivery, and whose infant is suspected to be larger than the first.
Infection rates are somewhat higher in women who fail TOLAC and require a repeat caesarean delivery, but the morbidity for mother and infant overall is low, and is a less important consideration than the possibility of uterine rupture.[14, 21-23]
Factors to consider when deciding on a trial of labour after caesarean (modified from Scott)
Successful VBAC most likely when
- prior caesarean incision was low transverse
- clinically adequate pelvis and normal fetal size
- no other uterine scars, anomalies, or previous rupture
- previous vaginal delivery
- patient enthusiasm and informed consent
- spontaneous labour
- dilated cervix
- doctor available and able to monitor labour, the fetus, and perform a caesarean
- anaesthesia, blood bank, and staff are available
- simulation training for emergency caesarean delivery
Caution and contraindications
- prior classical or T–shaped incision, or previous fundal surgery
- contracted pelvis, macrosomia, or both
- recurrent indication for initial caesarean delivery
- morbid obesity
- short interpregnancy interval
- medical or obstetric condition precluding vaginal delivery
- patient refusal
- induction of labour and unfavourable cervix
- augmentation of labour
- inability to perform emergency caesarean delivery
Factored into the contemporary decision for TOLAC should be a consideration of increased risk of abnormal placentation with each repeat caesarean. The disadvantages of multiple caesareans are now well recognised, and it is essential to inform the patient of the dramatic rise in the incidence of placenta praevia and accreta, and their consequences, with each subsequent delivery.[24-26] To put this into perspective, in a patient with placenta praevia, the risk of placenta accreta in the subsequent first, second, third, fourth, and fifth repeat caesarean delivery is 3, 11, 40, 61, and 67%. Placenta accreta leads to dangerous complications, including difficult surgery, excessive blood loss, hysterectomy, and even maternal death. The emergency nature and severity of these complications are certainly appreciated by doctors who have had to deal with them. Some have minimised the risk of repeat caesarean in women, particularly in women who plan on having only one or two children; however, unanticipated life changes occur, including divorce and remarriage, financial status, and death of children, and almost half of pregnancies are unintended.[27, 28] Consequently, women are frequently unable to correctly predict their total number of pregnancies.
The importance of and variation in non-medical factors in the decision process regarding TOLAC has been understudied, and is consequently underemphasised. In the USA, a significant number of community hospitals are unable to provide adequate 24-hour personnel and anaesthesia services to handle the rare possibility of uterine rupture,[29-33] and this also holds for many obstetric care facilities in developing nations. Estimates of the anaesthesia workforce in the USA indicate that a requirement for in-house anaesthesia is not practical for rural hospitals from staffing and financial perspectives.[9, 30] Because of the staffing prerequisites and medical legal risks, many smaller hospitals and insurance companies have prohibited TOLAC and VBAC.[4, 10, 29-32] This has led to criticism and defence of these policies, and outspoken advocates both for and against VBAC.
Patients vary in their desire for VBAC, and a non-judgmental and fact-based conversation that provides practical information but honours patient autonomy is the best approach. Each case is unique, and it is important to tactfully but honestly discuss the current issues with each patient. These include the facilities, availability of personnel, preparation, and protocols for emergency caesarean, the chance of a successful VBAC, her understanding of failed TOLAC, and the rare possibility of uterine rupture. It may be unwise to persuade a patient who wants a repeat caesarean to attempt VBAC, and vice versa. A woman who had a long and difficult labour before delivery by caesarean is often reluctant to experience that again.
Basically, the patient needs to know: (1) what are my options; and (2) what are the outcomes with each option? After careful counselling, the decision for TOLAC is ultimately the patient's, and this informed consent should be documented in writing. Realistically, there are two different clinical scenarios that affect decisions.
The first involves hospitals with 24–hour in-house obstetric and anaesthesia coverage. This setting offers the best chance to avoid a poor maternal or fetal outcome should uterine rupture occur. Most patients with no contraindications can be encouraged to proceed with TOLAC.
The second involves hospitals that do not have 24–hour in-house staffing, and they vary in what they provide.[4, 29-33] In this situation, the decision for TOLAC requires a careful evaluation of benefits compared with risks. Counselling should take into account the patient's wishes and her risk tolerance for the rare uterine rupture, and its potential outcome. Decision options include a plan for attempted VBAC at the hospital, delivery by repeat caesarean at the hospital, or, preferentially, referral to another hospital that can provide 24–hour in-house services.
The previous obstetric records and operative notes should be obtained and reviewed for the indication for the initial caesarean, to document the type of uterine incision, and any complications encountered, and to make sure that there are no unanticipated contraindications to VBAC. Consultation with the anaesthesiologist, either antepartum or when the patient is admitted to the labour and delivery suite, and with the other doctors and personnel who will be involved, is also essential. A complete intrapartum management plan should be documented in writing, and reviewed periodically with the woman and her partner during the course of the pregnancy.
Clinical management of labour
The key to a successful VBAC includes planning, preparation, and presence, and each hospital needs a well-defined protocol for TOLAC patients. The patient should be evaluated for fetal presentation and position as soon as she is admitted in labour, the signed consent form and the plan verified, and all team members notified. Personnel familiar with TOLAC and who are vigilant for possible signs and symptoms of complications should be present throughout labour.
Analgesia and anaesthesia
Epidural anaesthesia is a very good technique for TOLAC. There are few contraindications, and adequate pain relief is helpful in encouraging women to choose a trial of labour. Epidural analgesia has not been found to mask the signs and symptoms of uterine rupture, and success rates for VBAC are similar to those experienced by women who receive other types of pain relief.[14, 18, 35] It is appropriate to consider an early placement of the epidural catheter so that it can be used later for labour analgesia or for anaesthesia should an operative delivery become necessary. Clear liquids and ice chips during labour are acceptable, but solid foods are best avoided.
Induction and augmentation of labour
The most consistent intrapartum factors associated with successful VBAC are the onset of spontaneous labour and advanced cervical dilatation. Induction of labour becomes an issue when the patient presents with spontaneous ruptured membranes or is at term or post-term with an unfavourable cervix and not in labour.
Evidence regarding the effectiveness and safety of prostaglandins and transcervical catheters for cervical ripening and induction of labour in VBAC patients is conflicting,[14-17, 36-41] and a recent Cochrane review concluded that there was insufficient information available from randomised controlled trials on which to base clinical decisions regarding the optimal method of induction in VBAC patients. A number of guidelines conclude that they are permissible options, but that the use of misoprostol is contraindicated.[14-17] A systematic review showed that induction of labour was more likely to result in caesarean delivery than spontaneous labour. One large population-based cohort study with data from a total of 20 095 primiparous women who gave birth to a live singleton infant by caesarean, and later delivered a second singleton infant, reported a uterine rupture rate of 5.2 per 1000 for spontaneous labour, and 24.5 per 1000 for labour induced with the use of prostaglandins, and a similar population-based study of 35 854 women also confirmed an increased risk with induction. Oxytocin has also been used both for induction and augmentation, and remains an option.[14, 36, 38] However, the higher doses of oxytocin used for failure to progress place women at increased risk of uterine rupture, and doses exceeding 20 mU/min increase the risk of uterine rupture at least four-fold.
In my view, despite a number of favourable published results and guideline recommendations regarding induction and augmentation in TOLAC patients, caution is warranted. The fact remains that the majority of poor outcomes and malpractice claims are prevented when: (1) labour is spontaneous; (2) labour is continued only when a normal, non-augmented labour curve is followed; and (3) labour is continued only in the absence of significant fetal heart rate abnormalities or other indicators of fetal compromise.
As 20–40% of TOLACs are unsuccessful, it is prudent to consider the VBAC patient as being at high risk for labour abnormalities and deserving of close surveillance. Progress in labour in women with no previous vaginal births should be similar to labour in normal nulliparous women, and labour patterns in women who have delivered vaginally are comparable with those in multigravidas. Generally accepted standards of labour progress in the active phase should be followed, and the decision to continue should be reviewed with inadequate progress. Most authorities recommend continuous fetal heart rate monitoring to detect significant fetal heart rate decelerations or bradycardia in order to diagnose the earliest signs of uterine rupture; however, intrauterine pressure catheters have not been found to be superior to external monitoring or to assist in preventing or detecting uterine rupture.
Surveillance for uterine rupture
The rare but potentially catastrophic outcome from uterine rupture cannot be ignored, and it is an important reason that many hospitals and doctors are not offering VBAC.[9-11, 29, 31-33, 47, 48] Antepartum rupture is rare, and imaging studies of the previous caesarean scar are unreliable to forecast which patient will rupture intrapartum. The reported prevalence of rupture ranges from 0.5 to 1.0%, and it can occur even in good candidates for VBAC.[12, 18, 46, 50-52] Although rupture can result in significant maternal morbidity, including transfusions and hysterectomy, it is the risk of neonatal death or neurologic injury that is the major concern for doctors and patients. The chance for a poor infant outcome depends on a number of factors, including the extent of rupture and umbilical cord compression (Figure 1), whether the placenta and/or fetus are extruded into the maternal abdomen, and the time from diagnosis to delivery. Approximately 6% of uterine ruptures will result in perinatal death. Estimates for the risk of hypoxic encephalopathy with long-term disability range from 0.5 to 19%.[11, 36, 53-56] Neurologic injury is rare if the infant is delivered within 18 minutes, and in many cases the outcome has been good when delivered within 30 minutes.[39, 56] Nevertheless, obstetricians should proceed with emergent caesarean as quickly as possible in any patient with suspected uterine rupture.
The diagnosis of uterine rupture is a clinical one that depends on observant attendants who maintain a high index of suspicion. Non-reassuring fetal heart rate tracings, significant variable decelerations, and bradycardia are characteristic findings, and bradycardia is the pattern most diagnostic of uterine rupture.[46, 57, 58] Other less frequent findings include abdominal pain, most commonly in the area of the prior caesarean incision, recession of the presenting vertex, and vaginal bleeding. With concealed intraperitoneal bleeding, the patient may exhibit shoulder pain, anxiety, restlessness, dizziness, and shock.
The second stage of labour is conducted in the same manner as with the non-VBAC patient, and there is nothing unique about the actual delivery. Accepted obstetric indications for the use of vacuum delivery and forceps are appropriate in these patients. There is no evidence that an asymptomatic uterine scar should be routinely examined after delivery of the placenta, or that the uterus should be explored; however, in the case of a postpartum haemorrhage, it is important to make sure the bleeding is not from the previous low transverse incision.