With the implementation of the two-child policy, many women who had a cesarean delivery are faced with the choice of delivery method when they have another baby. Whether to have another cesarean or vaginal delivery. Here are the recommendations from foreign authorities. Vaginal birth after cesarean section (VBAC)
Clinical considerations and recommendations
Who is a good candidate for a vaginal trial of labor?
The preponderance of evidence suggests that those who have undergone a low transverse uterine section and have no contraindications to vaginal birth are mostly suitable for vaginal trial of labor. The following selection criteria are helpful in identifying those who are suitable for VBAC.
● previous 1 low transverse cesarean section
● Adequate clinical demonstration of a large transverse pelvic diameter.
● absence of other uterine scarring or previous history of uterine rupture
● Physician availability to monitor labor and perform emergency cesarean delivery throughout spontaneous labor
● Ability to be anesthetized immediately and have emergency cesarean staff readily available.
According to the results of several retrospective studies, women with the following other special obstetric conditions may also undergo vaginal trial of labor
those who have had more than 1 previous cesarean delivery
Those who are more than 40 weeks of gestation
Those waiting for spontaneous delivery beyond 40 weeks of gestation have a decreased probability of successful VBAC but no increased risk of uterine rupture. In a study of more than 1200 vaginal trial of labor after 40 weeks of gestation, only induction of labor was associated with an increased risk of uterine rupture.
Previous low level longitudinal hysterectomy
The success rate of VBAC in those with previous low longitudinal hysterectomy is the same as that of those with previous low transverse hysterectomy. In addition, there was no increase in maternal or perinatal complications.
Uterine scar type unknown
In 2 case series conducted in large tertiary hospitals, the success rate of VBAC and the incidence of uterine rupture in those with unknown type of uterine scar were the same as those reported in other contemporaneous studies of those who had undergone low transverse hysterectomy. Those who had 1 previous cesarean delivery with unknown scar type had cases with scar rupture at the time of hypospadias and cases without scar rupture without hypospadias.
What are the risks and benefits associated with VBAC?
There are risks associated with either elective repeat cesarean delivery or VBAC. Overall, successful VBAC is associated with a shorter hospital stay for the mother, less blood loss and transfusion, fewer infections and fewer thromboembolic events compared to cesarean delivery for the former. However, failed vaginal attempts were associated with serious complications for the mother, such as uterine rupture, hysterectomy, surgical injury, maternal infection and increased need for blood transfusion. If vaginal attempts fail, there is also an increased rate of neonatal complications, as evidenced by umbilical artery blood gas pH levels below 7, 5-minute Apgar scores less than 7, and an increased incidence of infection. However, there are also risks to the mother from multiple cesarean deliveries, including an increased risk of placenta previa and placental implantation. Based on these risk factors, a decision model analysis found that vaginal trial of labor may be considered for those with a ≥50% chance of success and a desired likelihood of a repeat pregnancy of 10% to 20% or more after cesarean delivery.
Maternal mortality at the time of VBAC is extremely low. Although the perinatal mortality rate (<1%) is low, the mortality rate at the time of vaginal trial of labor is higher than at the time of elective repeat cesarean. Uterine rupture is associated with fetal death and neonatal neurological damage. Uterine rupture during vaginal trial of labor in a previous cesarean section is a life-threatening complication. The risk of uterine rupture depends mainly on the type and location of the previous incision. The incidence of uterine rupture in those with previous conventional and T-shaped incisions ranges from 4% to 9%.
The risk of uterine rupture is also influenced by obstetric history. A history of vaginal delivery significantly reduces the risk of uterine rupture. The longer the interval between births, the lower the risk of uterine rupture. The risk of uterine rupture is two to three times higher in women who have had a VBAC less than 24 months after their most recent delivery than in those who have had a VBAC more than 24 months apart. The risk of uterine rupture during subsequent vaginal trial of labor was 4 times higher in those who had a single suture during direct cesarean hysterotomy compared with those who had a double suture.
Did the previous cesarean section result in induction or dilation of labor during the vaginal trial of labor?
Natural birth is more likely to result in a successful VBAC than induced or induced labor. Dilation with prostaglandin preparations has been well documented to increase the probability of uterine rupture. The use of prostaglandins for induction of labor is discouraged in most patients who have undergone cesarean delivery.
What are the contraindications to VBAC?
Trial of labor is not recommended in patients with a high risk of uterine rupture. Conditions in which vaginal trial of labor cannot be performed include
● Previous conventional or T-shaped incision or extensive trans-uterine fundoplication.
● A history of uterine rupture.
● medical or obstetric complications that prevent vaginal delivery.
● inability to perform an emergency cesarean section due to unavailability of surgeons, anesthesiologists, adequate number of staff or facilities
2 previous uterine scarring and no previous vaginal delivery.
In addition, there are factors that may preclude direct cesarean delivery when they are present alone, but when they are present together, consider a repeat cesarean delivery rather than a VBAC.
Recommendations and Summary
The following recommendations are based on consistent good academic evidence (Level A??)
Most patients who have had 1 previous low transverse cesarean section are suitable for VBAC and should be counseled about VBAC and have a vaginal trial of labor.
● Epidural anesthesia may be used during VBAC.
The following recommendations are based on limited inconsistent academic evidence (grade B?)
Women with a longitudinal incision located in the lower uterus and not extending to the fundus are suitable for VBAC.
● For most women who have had a previous cesarean section, the use of prostaglandins to promote cervical maturation or to induce labor is discouraged.
The following recommendations are based primarily on consensus opinion and expert opinion (Level C).
● Because uterine rupture can be catastrophic, VBAC should be tried only in hospitals where emergency measures are available and physicians can provide immediate emergency care.
● The final decision to try VBAC or to accept another cesarean section should be made by the patient and physician only after a thorough consultation weighing the benefits and risks of VBAC in each case. The outcome of the discussion must be documented.
VBAC is contraindicated in patients who have had a conventional hysterotomy or extensive fundoplication