Vaginal Birth After Cesarean Delivery (VBAC)

Delivering a baby through vaginal birth after a previous Cesarean section can lead to complications such as uterine rupture, but it's possible under the right conditions.

Is it possible to have a normal delivery after a C-section?

• Formerly, women who had given birth by Cesarean section (C-section) were always managed with a Cesarean birth in subsequent pregnancies.
• Today, it is understood that many women can undergo a healthy vaginal birth after a previous C-section (VBAC).
• Woman who wishes to attempt VBAC will be evaluated to determine if she is a suitable candidate.
• Most women who attempt VBAC are successful.
• Women attempting VBAC must be carefully monitored during labor, and if complications arise, a C-section must be performed.

What are the risks of a vaginal birth after a C-Section?

• Some factors make a successful VBAC less likely, including large infant size, women weighing over 200 pounds, and women over the age of 35.
• The risk of uterine rupture is the principal risk of VBAC.
• The type of incision used during a previous C-section is important to determine whether a woman should be offered VBAC.

Under certain conditions, it is now acceptable for women to attempt a trial of labor (an attempt to deliver the baby vaginally after a previous C-section) in order to complete a vaginal delivery. Many women now have a successful vaginal birth after cesarean (known as VBAC). If the trial of labor is unsuccessful, the woman then undergoes a cesarean birth. Studies have shown that the majority of women who attempt VBAC will be successful. However, the number of babies born vaginally after C-section appears to have peaked, and the percentage of cesarean deliveries is again on the rise.

Factors affecting whether a woman may be offered an attempt at VBAC include:

• If a doctor has experienced complications with other women attempting VBAC, he/she may be reluctant to recommend a trial of labor. Women who wish to attempt a trial of labor should factor this consideration into their choice of a physician.
• ACOG guidelines require the presence of an obstetrician, anesthesiologist, and staff capable of performing an emergency cesarean delivery during a woman's entire active phase of labor. Academic centers and larger community hospitals typically offer such services. However, smaller hospitals with a lower obstetrical volume may not be able to justify these requirements. So this requirement is more difficult to comply with in smaller hospitals. For women who want a trial of labor after C-section, this factor must be acknowledged in their choice of a hospital.
• If the reason for the initial C- section is recurrent in subsequent pregnancies (for example, very small maternal pelvic dimensions), then an attempt to have a VBAC is inadvisable and may be dangerous to both mother and baby.
• Some women may not be a candidate for a vaginal birth after a prior cesarean delivery if the uterine incision was not a low-transverse incision. In cases in which the uterine incision included the upper muscular component of the uterus, attempting a vaginal delivery is associated with a greater risk for uterine scar separation and an increased risk of fetal and maternal death.
• Women should be counseled regarding the risks of a trial of labor following a previous C-section. Uterine rupture can occur in a small percentage of cases in which the uterine incision was of the low-transverse variety.
• Women attempting VBAC should be monitored closely during labor. Signs of uterine rupture can be difficult to detect, and at times, a rapid change in the fetal heart rate or loss of contractions on the monitor represents the first sign of a uterine rupture.

The decision to undergo a trial of labor after cesarean is serious, and it should only be made after a complete discussion of this option between the patient and her doctor. The doctor will review the medical information in regard to woman's previous deliveries (both vaginal and C-section) and subsequently estimate her risk for uterine rupture during her anticipated labor.

Although each woman's pregnancy is unique, and no one factor can predict with certainty who will achieve a vaginal birth after cesarean, certain factors aid in predicting who will be successful.

• VBAC is less successful in women weighing over 200 pounds.
• Women over 35 years of age have higher rates of cesarean delivery, and women older than 40 years have a 3-fold higher risk of requiring a repeat C-section.
• The greater the infant's birthweight, the less the likelihood of successful VBAC.
• Women who had their first C-section following a prolonged second stage of labor (i.e. the stage of labor after the cervix has completely dilated) are unlikely to deliver vaginally in a subsequent pregnancy.
• The reason for a previous cesarean delivery can help in decision making. The doctor will carefully examine medical records of previous births to find out why a woman had her initial C- section.

Women who are more likely to have a successful VBAC include those who have had a prior had a prior C-section because of fetal breech position or placenta previa, or have had a prior VBAC.

Having a VBAC allows a woman to avoid a major abdominal surgery and the risks of surgery, including bleeding and infection. A VBAC also typically means a shorter hospital stay and easier recovery than with a C-section.

Uterine rupture is a tear in the uterus, and is a rare and very serious medical situation that is potentially life-threatening for both mother and fetus.

During the last 20 years, studies have shown that women who have had a prior cesarean delivery with a low transverse incision may, depending on the reason for the initial C-section, safely attempt VBAC. The same cannot be said of women who have had prior vertical incisions made on the uterus.

• Women with a prior history of more than one low transverse cesarean delivery are at slightly increased risk for uterine rupture. This risk increases significantly when the woman has had three or more cesarean deliveries.
• In about 10% of women with vertical uterine incisions, the uterus will rupture.
• In some cases, the uterus may rupture prior to the onset of labor.
• Uterine rupture can be devastating to the fetus, even if delivery is accomplished immediately following its occurrence.
• Induction of labor with prostaglandin agents (used for cervical ripening) is inadvisable, as these agents have been associated with an increase in the risk of uterine rupture. Inducing labor when the cervix is dilated using low-dose oxytocin (Pitocin) does not appear to increase the risk of rupture.

How is uterine rupture diagnosed?

Diagnosing a uterine rupture can be difficult. Signs of rupture include the following:

• Acute onset of severe abdominal pain
• A "loss of fetal station" as determined by vaginal examination. In such instances the fetal presenting part (usually the head) will feel, on pelvic examination, as though it has moved upward in the vagina.
• Increased vaginal bleeding
• Ominous fetal heart rate changes.
• Uterine rupture mandates immediate delivery of the infant by emergency C-section.

What are the complications of uterine rupture?

If uterine rupture occurs, additional serious complications may ensue. These include:

• Hypoxic ischemic encephalopathy (brain damage to the fetus caused by lack of oxygen).
• Infection of the inner lining of the uterus (endometritis).
• Excessive blood loss necessitating transfusion.
• Hysterectomy (surgical removal of the uterus).
• Maternal and/or fetal death.

For women who have had C-sections, a vaginal delivery in subsequent pregnancies is often possible, depending on the type of incision that was made on the uterus and the reason for the initial C-section. This information is available from the medical records of their initial C-sections. Hysterotomy is the general medical term for an incision into the uterus.

There are three types of uterine incisions.

1. A classical incision wherein a deep vertical incision is made through the thick upper portion of the uterine wall. Although seldom used today, this incision may occasionally be necessary if the fetus is found to be in an unusual position; with twins or premature infants; and in the case of placenta previa. This type of incision is associated with a higher likelihood of uterine rupture during subsequent pregnancies, and any decision to attempt VBAC should be discouraged.
2. A low vertical incision, which is similar to a classical incision except that it is made lower on the uterine wall. Some studies have indicated a lower risk of uterine rupture with a low vertical incision than with a classical incision. Again, with this type of incision, a repeat C-section is preferred to VBAC with subsequent deliveries.
3. A low transverse incision, wherein the lower uterine wall is entered horizontally in an area where the uterine wall is thinner, and there is usually less bleeding. This is the type of incision that is most commonly used in obstetrical practice today. In most cases in which this incision has been used, VBAC may be attempted, but close monitoring of both mother and fetus is imperative.

The direction of the first incision on the skin (up and down or side to side) does not necessarily coincide with the direction of the incision made in the uterus.

Many women who have had a previous cesarean delivery can successfully deliver their next babies vaginally if they:

• had low-transverse uterine incisions with previous cesarean deliveries;
• are closely monitored by skilled medical staff in a facility with the capability of performing an emergency cesarean; or
• are at low risk for uterine rupture.

In 1916 Dr. E. B. Cragin advised the New York Association of Obstetricians and Gynecologists, "Once a cesarean, always a cesarean." Over the next 60 years, most obstetricians advised their patients accordingly. This was believed to be the safest management for women who had undergone a prior a cesarean delivery.

Cesarean delivery, also known as cesarean section, is a major abdominal operation involving two incisions. The first is an incision through the skin and abdominal wall and the second is an incision into the uterus to deliver the baby. While at times necessary to insure the safety of the mother or the baby, cesarean childbirth is not a procedure to be undertaken lightly by either the doctor or the expectant mother. Many women who have had prior cesarean sections wish to deliver their next baby vaginally. Vaginal childbirth occurs when the baby is delivered normally through the vagina canal.

By 1988, a quarter of all infants were delivered by cesarean section. Very few babies were delivered vaginally if the mother had undergone a previous cesarean. To curb the increasing rate of cesarean birth, both the U.S. National Institutes of Health (NIH) and the American College of Obstetricians and Gynecologists (ACOG) encouraged doctors to allow women to try to deliver her baby vaginally if she had undergone a prior cesarean delivery.