Labor & Delivery: Complications of Cesarean Section Health Article

Most of the serious complications associated with cesarean section are not due to the operation itself. Instead, the complications arise from the indication for the cesarean section. For example, a woman whose placenta separates prematurely (placental abruption) may require an emergency cesarean section. Under these circumstances, complications arise primarily from the placental abruption itself. In other situations during labor and delivery, an emergency requiring cesarean section may arise and there may not be time to administer an epidural or spinal anesthetic (because administering these forms of anesthesia is more complicated); therefore, general anesthesia may be required. In these cases, complications may arise from the general anesthesia (complications of general anesthesia are considerably greater than those seen with spinal or epidural anesthesia).

Overall, cesarean section is an extremely safe operation-one report from the late-1990s described 10,000 women who underwent cesarean section without a single maternal death.

Fortunately, serious complications are rare. However, the following minor complications can occur in women having cesarean sections.

Infection

After the membranes have ruptured, the uterus is especially susceptible to infection-the bacteria that normally inhabit the vagina (which are generally harmless) can easily gain access to the uterus. If bacteria are present in the uterus, a cesarean section incision may result in endomyometritis (infection of the uterus).

Depending on the population studied, endomyometritis may occur in anywhere between 5 and 75% of women undergoing cesarean section. Fortunately, almost all cases of endomyometritis resolve with appropriate antibiotic treatment and future childbearing does not seem to be affected. In very rare cases, the infection may be more serious and require hysterectomy; in extremely rare cases, the infection may result in death. It is important to know that these complications are so rare that during their entire careers most obstetricians will not encounter a single case of hysterectomy or death due to infection. Serious infections rarely occur in women having planned cesarean sections before labor and before the membranes are ruptured; they are more common following long labors, where the membranes have been ruptured for a significant period of time.

Bleeding

The pregnant uterus has one of the greatest blood supplies of any organ in the body. The uterus must be surgically opened in order to perform a cesarean section. In every case, a number of large blood vessels are cut as the surgeon opens the wall of the uterus to gain access to the baby. While the average blood loss for a vaginal birth is about 500 cc (about two cups), the average blood loss with cesarean section is twice that much, about four cups or one quart. Most healthy pregnant women can tolerate this type of blood loss without any difficulty. Occasionally, however, blood loss can be greater than this. The following three conditions can potentially give rise to dangerous blood loss during cesarean section.

Atony

After the baby and the placenta are delivered, the uterus must contract to close the blood vessels that have supplied the placenta during pregnancy. Uterine atony is when the uterus remains relaxed, with lack of tone or tension. This can occur especially after a long labor or the birth of a big baby or twins. When the uterus has atony, bleeding may be quite rapid. Fortunately, a number of very effective medications were developed in the last decade of the twentieth century to treat uterine atony; most are variations of natural substances in the body called prostaglandins. With the use of prostaglandins, long-term complications from uterine atony are extremely rare.

Lacerations

Sometimes the cesarean section incision is not wide enough for the fetus to pass through, especially when the baby is very large. As the baby is delivered through the incision, the incision may tear into areas not intended by the surgeon. The areas just to the right and left of the uterus contain large arteries and veins that can be torn if the uterine incision tears accidentally. Often there is nothing the surgeon can do to avoid such tears; every obstetrician will encounter this problem many times during a career. If promptly recognized, these tears can be safely repaired, before too much blood loss occurs.

Placenta Accreta

When the tiny embryo travels from the fallopian tube to implant in the uterus, one of the first things that happens is the cells that will form the placenta begin to accumulate on the walls of the uterus. These cells are called trophoblasts. Trophoblasts generally grow together in long, finger-like projections (called villi) that penetrate the walls of the mother's uterus. The trophoblasts have one major purpose: to gain access to blood vessels of the mother. Through their access to the blood vessels, these cells play a vital role in transferring oxygen and nutrients from mother to fetus and waste products from fetus to mother. As the fetus and placenta grow, the trophoblasts continue to seek blood vessels to support the growing fetus. A fibrous layer (called Nitabuch's membrane) limits how deep the villi are able to reach into the uterine wall. After the baby delivers, the inner lining of the uterus is shed along with the trophoblastic tissue.

However, when the uterus has been damaged (for instance, due to previous cesarean section) the fibrous layer (Nitabuch's membrane) may not prevent the trophoblasts from penetrating deep within the mother's uterus and even into other organs such as the bladder. This condition is called placenta accreta. Placenta accreta is especially common in women who have had one or more cesarean section and whose embryo, during a subsequent pregnancy, implants in the area of the previous cesarean section scar. Although this complication is rare, doctors are now seeing it with increasing frequency because of the large number of cesarean sections that have been performed in the last 10 years.

The good news is that doctors are now able to recognize women at risk for this condition and, in most cases, are prepared to deal with it. The bad news is that virtually all cases require hysterectomy to save the life of the mother. Since the chances of this complication occurring tend to increase with each cesarean section a woman has, the potential for avoiding placenta accreta is another reason that some women may wish to consider vaginal birth after a previous cesarean section.

Blood Clots

Probably the most feared complication of cesarean section today is the formation of blood clots in the mother's legs or pelvis. These blood clots can break off and travel to the lungs (called pulmonary embolism). This complication is the leading cause of death among pregnant women in most developed countries. Fortunately, in most cases, the clots cause swelling and pain in the legs and most women will bring this to their doctor's attention before the clots travel to the lung. If this condition is detected early, it may be treated with use of a blood thinner (e.g., Coumadin or Warfarin). Occasionally, there are no warning signs until after the clots have broken off and reached the lungs. Most women recover with appropriate treatment, but occasionally the clot can be so large that the mother dies. Unfortunately, there does not appear to be a reliable way of preventing or detecting this condition. It is more common in women who have had a long operation, who are relatively overweight, or who have had a long period of bedrest following their operation. This complication was much more common in the past when women were commonly advised to remain in bed for weeks after giving birth. Fortunately, it is less common today.

Blood clots are more common when a woman is pregnant (than when she is not) for two reasons. First, the hormone estrogen is produced in large amounts by the placenta and increases the body's production of clotting proteins. It is important that blood clots rapidly after delivery to avoid the bleeding complications we have discussed above. Second, as the baby grows, the expanding uterus places pressure on the veins that bring blood back from the mother's legs. Thus, blood flow is slower during pregnancy. The combination of slower blood flow and increased ability to clot leads to increased risks for clotting conditions during pregnancy.

Cesarean Hysterectomy

Certain complications of cesarean section (usually those associated with severe bleeding) may require the doctor to remove the uterus to save the mother's life. Cesarean hysterectomy is removal of the uterus directly after performance of a cesarean section. While the potential for a hysterectomy is probably greater following a cesarean section, bleeding requiring hysterectomy may occur even after a seemingly normal vaginal delivery. As with all of the complications listed above, this complication is extremely uncommon. Most obstetricians will encounter a situation requiring an emergency hysterectomy probably only a few times in their careers.

While women who have had a hysterectomy cannot have further children, generally there are no additional side effects associated with this operation. Obviously, this is not a desirable situation and physicians try their best to avoid it; however, there is no question that cesarean hysterectomies save lives, especially in the case of bleeding that cannot be controlled by simpler measures.

Although hysterectomy following cesarean section is probably easier than performing one later, blood loss is greater. For this reason, most surgeons do not plan cesarean hysterectomies-even when a woman has other conditions that might require hysterectomy. Under certain circumstances, however, a planned cesarean hysterectomy may be appropriate. This is the case only when there is a pressing need to perform the hysterectomy for reasons unrelated to pregnancy and when the mother's medical condition is good and her blood count is high. Otherwise, cesarean hysterectomies are performed only in the case of emergency, as in those situations described above.

For more information on cesarean section, go to Why Are Cesareans Performed? and History of the Cesarean Section.

For information on other types of delivery, go to Spontaneous Vaginal Delivery and Assisted Vaginal Delivery.