During a cesarean section an infant is delivered by cutting through the mother's abdominal wall and then cutting into the uterus right underneath and delivering the baby through the incisions. Once a woman has had a cesarean, she is often counseled not to attempt vaginal delivery for any future pregnancies.

That picture is likely to change somewhat, thanks to a Practice Bulletin published in the August issue of Obstetrics and Gynecology by the American College of Obstetrics and Gynecology. The bulletin provides doctors with clear guidelines for what needs to be considered when weighing the trials of labor and vaginal delivery and risk of C-section following Cesarean section.

The medical community has had widely varying opinions as to the safety of a normal labor and vaginal delivery once a woman has had a cesarean. And it is this issue that the recent American College of Obstetrics and Gynecology Practice Bulletin addresses.

The decision to perform a caesarean may be made at the beginning or during labor if it appears that proceeding with a vaginal delivery will be risky to the baby or mother. Or, they may be planned well in advance of labor.

There are many reasons for emergency cesareans. The baby may be too large to pass through the birth canal; there may be an abnormality of the placenta which may cause excessive bleeding or loss of blood supply to the baby or mother; the baby's heart rate may have become abnormally low and doesn't improve with normal measures; there may be a risk of infection. There are other reasons as well.

Cesarean sections may also be planned ahead of time because of pre-identified risk factors that make a vaginal delivery dangerous for the mother or baby. Another common reason for a prescheduled cesarean section is that the woman has previously delivered an infant by C-section.

This last reason – a previous C-section automatically pre-determining that a mother's future births will also have to be by that method – has been controversial. The medical community has had widely varying opinions as to the safety of a normal labor and vaginal delivery once a woman has had a cesarean. And it is this issue that the recent American College of Obstetrics and Gynecology Practice Bulletin addresses.

The main concern regarding vaginal delivery after a C-section has been that once the uterus has been cut open and repaired, it may not be able to withstand the strong contractions that occur during labor. Either the labor may be ineffective, or the uterus may actually rupture during the birth process, a potentially catastrophic outcome for mother and infant.

But on the other side of the issue, C-sections also pose certain risks for mothers and infants, from both a physical and emotional perspective. Those who advocate trying labor and birth canal delivery after a cesarean believe that the much-publicized risks have prevented doctors from making decisions on an individual basis.

As a result, many normal vaginal deliveries that could occur safely following cesarean have never happened, they believe. The idea is that with clearer delineation of the degree of risk within populations of women, and better ways of assessing a woman individually based on the specifics of her health and obstetric history, vaginal delivery may not be so risky.

Among the factors the American College of Obstetrics and Gynecology believes need to be considered when determining whether a woman who has had a C-section could deliver her next child vaginally are the outcome of the initial cesarean section and the woman's medical and obstetrical history. The guidelines review the most likely issues that led to the original C-section and their recommendations are based on the most current reviews of the evidence garnered from studies of delivery outcomes.

These guidelines will provide the basis for clear conversations between doctors and mothers-to-be as they figure out the best route to the common goal of the best outcome for mother and infant.

Among the most strongly stated, and perhaps the most difficult to follow of the guidelines is the recommendation that, "because of the risks associated with trial of labor after cesarean and that uterine rupture and other complications may be unpredictable, the College recommends that TOLAC (trial of labor after cesarean) be undertaken in facilities with staff immediately available to provide emergency care...[If this is not possible] the best alternative may be to steer patients to a facility with available resources."

The guidelines review the most likely issues that led to the original C-section and their recommendations are based on the most current reviews of the evidence garnered from studies of delivery outcomes.

Realizing that this would make it difficult for women in rural and underserved medical areas to have access to trials of labor after cesarean, the authors propose such facilities have emergency drills to practice calling needed staff in to the hospital should the need arise, as well as establishing regional centers to provide the necessary services.

Probably most important is for the discussion and decision to try labor after cesarean to occur well before delivery so that all the safest arrangements can be planned for and both patient needs and doctor needs are met. Here are some other considerations discussed in the report:

What not just have another Cesarean?
Cesarean sections are major abdominal surgery. They can be complicated by bleeding, and infection. Multiple cesarean sections can lead to hysterectomy, bowel or bladder injuries, and abnormalities in the way the placenta implants within the uterus during future pregnancies. Women who have sections take longer to recover from delivery. Some women experience additional psychological and emotional stress after delivering by cesarean and some experts believe this can make mother-infant bonding more difficult. Breast-feeding may be more challenging initially because of the mother's postoperative pain and need for medications.

What are the risks of a trial of labor?
If a woman who has had a previous cesarean undergoes a trial of labor, and there are problems that lead to another cesarean, she and her infant are at risk for serious complications. When a trial of labor following section fails, the labor has been physically and physiologically stressful for the mother and fetus and their health may be in jeopardy.

The most catastrophic outcome is uterine rupture that occurs when the uterus tears open causing bleeding, lack of blood and oxygen to the mother and baby and rapid blood loss. Investigators have tried to assess which women, who have had previous cesareans were at increased risk for this outcome.

Who are the best candidates?
The location on the uterus of the cut made to surgically delivery the fetus has been considered a pivotal factor in deciding which women have the best chance of a successful vaginal delivery after a C-section. The evidence shows that women with only one previous section, with a low transverse incision have a high likelihood of a successful vaginal delivery. Conversely, women with other types of uterine incisions, or prior uterine rupture have a much lower chance of successful vaginal delivery.

What if a woman has more than one section?
The data have shown that women with one or more cesarean delivery, particularly those with low transverse incisions can be counseled that a trial of labor and vaginal delivery is a strong option for them and well worth considering but their individual health and history must be considered.

What if the baby is big?
Large babies are often a reason for initial cesarean sections. However, more data about the infant's predicted birth weight should be taken into account when making decisions. Simply predicting a large baby, should not rule out consideration of labor.

What about babies who are late?
There is much information to be ascertained when a baby has gone past due dates, including the function of the placenta and the health of the mother but data shows that post-term status alone should not rule out trial of labor.

What if you don't know what type of incision was done of the previous section?
The concern is for the integrity of the uterus to sustain effective contractions without rupturing. The physician can try to determine the most likely location of the uterine scar, based on history and previous records and can discuss the risks with the patient.

What if the mother is carrying twins?
The College of Obstetrics and Gynecology states that women with one previous cesarean delivery with a low transverse incision, who are otherwise appropriate candidates for vaginal delivery, may be considered for a trial of labor even if they are carrying twins.

Among the other considerations the new guidelines address, along with other variations on maternal and fetal characteristics are:

  • What if labor needs to be augmented or induced?
  • What if the cervix hasn't opened properly?
  • What if the baby is in the breech position and the physician wants to try to change the position by providing external pressure on the uterus?
  • What about types of pain treatment? Can you have a trial of labor with an epidural?
  • What kind of monitoring should be done?
  • Do trials of labor after cesarean require more invasive monitoring then standard?

The American College of Obstetricians and Gynecologists has done women, their families, and medical providers a huge service by providing a set of guidelines that are documented with as many specific indicators as are available. This will provide a foundation as the continued experience of the medical community adds to the evidence and helps further elucidate the defining issues for considerations of trials of labor and vaginal delivery after cesarean.

The bottom line must remain preserving the optimum health of the mother and infant. Realizing that neither birth nor life are predictable, identification of potential vulnerabilities and having excellent back-up team for the unforeseen must be critical components of any decision-making.

Women and their families should begin talking with the providers who will be caring for them, very early on in the pregnancy. The type of delivery, location, emergency response availability, and identifiable risk factors should all be addressed. Above all, a set of guidelines is just that-guidelines based on the best interpretation of the available evidence. But in the end, it is the application of clinical evidence to individual patients that creates effective medical practice.