Risk of serious complications increase with each cesarean surgery

Yesterday I shared a Canadian article, and last year a letter from two OBs opposing a hospital VBAC ban, which discuss the risks of cesarean sections including placenta accreta and hysterectomy.

Today I want to share a study that measured the increasing risks that come with multiple cesareans, but before I do so, lets do a quick review of definitions.

Placenta accreta (March of Dimes 2005):

In a normal pregnancy, the placenta attaches itself to the uterine wall, away from the cervix.

• Placenta accreta is a placenta that attaches itself too deeply and too firmly into the wall of the uterus.
• Placenta increta is a placenta that attaches itself even more deeply into the uterine wall.
• Placenta percreta is a placenta that attaches itself through the uterus, sometimes extending to nearby organs, such as the bladder.

Hysterectomy (Women’s Health 2009):

A hysterectomy (his-tur-EK-tuh-mee) is a surgery to remove a woman’s uterus or womb. The uterus is where a baby grows when a woman is pregnant. The whole uterus or just part of it may be removed. After a hysterectomy, you no longer have menstrual periods and cannot become pregnant.

Placenta previa (PubMedHealth 2011):

Placenta previa is a complication of pregnancy in which the placenta grows in the lowest part of the womb (uterus) and covers all or part of the opening to the cervix.

There are different forms of placenta previa:

• Marginal: The placenta is next to cervix but does not cover the opening.
• Partial: The placenta covers part of the cervical opening.
• Complete: The placenta covers all of the cervical opening.

The risks of placenta accreta, cystotomy [surgical incision of the urinary bladder], bowel injury, ureteral [ureters are muscular ducts that propel urine from the kidneys to the urinary bladder] injury, and ileus [disruption of the normal propulsive gastrointestinal motor activity], the need for postoperative ventilation, intensive care unit admission, hysterectomy, and blood transfusion requiring 4 or more units, and the duration of operative time and hospital stay significantly increased with increasing number of cesarean deliveries.

Accreta was defined as the “placenta being adherent to the uterine wall without easy separation [and] included placenta accreta, increta, and percreta.”

For women who had placenta accreta, they also experienced the following complications:

• surgical injury to bladder:  15.4% (1 in 6.5 women with accreta)
• surgical injury to the ureters which are the tubes that connect the kidneys to the bladder and is the “most serious complication of gynecologic surgery:”  2.1%  (1 in 48 women with accreta)
• blockage of an artery in the lungs (pulmonary embolism):  2.1%  (1 in 48 women with accreta)
• couldn’t breathe effectively, so mom was put on a mechanical ventilator:  14% (1 in 7 women with accreta)
• mom requires advanced monitoring and care so she is admitted to the intensive care unit:  26.6% (1 in 3.8 women with accreta)
• mom requires another operation:  5.6% (1 in 17.8 women with accreta)
• Endometritis, “an inflammation or irritation of the lining of the uterus:”  3.5% (1 in 28.6 women with accreta)

Because the risks of cesarean are so great, Silver (2006) concluded with the following statement,

Because serious maternal morbidity increases progressively with increasing number of cesarean deliveries, the number of intended pregnancies should be considered during counseling regarding elective repeat cesarean operation versus a trial of labor and when debating the merits of elective primary cesarean delivery.

Many women do not think these complications are applicable to them as they don’t plan on more children after their two cesareans.  But I know many women, and I’m sure you do too, who were not planning on more children, but got pregnant nonetheless.  Unless you or your partner get sterilized or practice abstinence (what fun!), the chance of you getting pregnant is there.

I was especially interested to see the relationship between previa and accreta.  Silver (2006) found that if you have previa, you are very likely to have accreta and that risk increases with each cesarean.  For example, if a woman has one cesarean and is diagnosed with previa in her next pregnancy, her risk of having accreta is 11%.  That risk jumps to 40% in the third pregnancy, 61% in the fourth pregnancy and 67% for the fifth and sixth pregnancy.

And accreta is nothing to mess around with as it has a very high rate of maternal mortality (up to 7%) and morbidity including hemorrhage and hysterectomy.  Fang (2006) asserted, “abnormal adherent placentation [is] the primary indication leading to emergent peripartum hysterectomy…. As the number of prior cesarean deliveries rises, the risk of cesarean hysterectomy increases dramatically.”   In other words, all these primary cesareans and repeat cesareans are causing placentas to abnormally implant in subsequent pregnancies.  As a result, many women who have placenta accreta end up having hysterectomies as that is the best way to control the hemorrhaging that results from accreta.

Alternatives to a cesarean hysterectomy were discussed in a February 2006 Healthline article by Alison Stuebe, Department of Maternal-Fetal Medicine, Brigham and Women’s Hospital, Boston, MA:

In the majority of cases, hysterectomy is the most effective way to manage the potentially fatal consequences of placenta accreta. Unfortunately, however, most cases of placenta accreta are not discovered until the last minute. And, because a hysterectomy results in infertility, some women may want to consider more conservative options.

Conservative or alternate techniques for treating placenta accreta include:

• curettage (scraping) of the uterus;
• surgical repair of the part of the uterus where the placenta was attached;
• clamping the blood vessels that nourish the pelvis (to control the bleeding); and
• using x-ray guidance to inject gelatin sponge particles or spring coils into the blood vessels that nourish the uterus (this procedure usually is not feasible in emergency situations.) This procedure requires help from interventional radiologists, doctors who specialize in advanced treatments for bleeding.

Reported success rates of these procedures vary widely. In one recent study, 31 cases of placenta accreta were managed without hysterectomy; there were no reports of infertility or maternal death.

Keep in mind that those maternal mortality statistics are from hospital based studies where women have access to operating rooms, surgeons, and blood products available.  I suspect that the likelihood of a mother dying from hemorrhage due to placenta accreta is significantly higher in a out-of-hospital birth.

While the risk of accreta after one cesarean is only 0.31%, that small statistic does represent real moms.   Even though the risk is small, it is still relevant because many women are confronted with VBAC bans and many feel like they have two options: an unnecessary cesarean which will make future pregnancies more risky or a home VBAC where the results could be horrific if the mom has accreta and doesn’t know it.  This is especially true for women who live in rural areas or are far from a hospital as rural hospitals are more likely to have VBAC bans.  (Read VBAC Rationale is Irrational and Mom encounters VBAC ban and requests advice for more information.)

Because of this high rate of maternal mortality and morbidity, some doctors suggest if accreta is diagnosed via ultrasound and/or magnetic resonance imaging (MRI) during pregnancy, a cesarean hysterectomy should to performed as early as 34 – 35 weeks.  (Read Does Antenatal Diagnosis of Placenta Accreta Improve Maternal Outcomes?, The maternal outcome in placenta accreta: the significance of antenatal diagnosis and non-separation of placenta at delivery and Placenta accreta: A dreaded and increasing complication for more information on early delivery via cesarean section.)

There appears to be some controversy about the ability to accurately diagnose accreta during pregnancy.  According to a 2011 Medscape article byDr. Robert Resnik, “the diagnosis [of placenta accreta] can be made with accuracy, by very specific ultrasound findings, about 80% of the time, and can be confirmed with MRI findings.”

However, in a 2010 article published in the Journal Watch Women’s Health, Andrew M. Kaunitz, MD states, “If ultrasound findings [while looking for accreta] are not definitive, MRI evaluation is appropriate.  Unfortunately, the diagnostic precision of these two imaging modalities for placenta accreta can be suboptimal.”

Below are some slides from the VBAC Class I developed and teach illustrating the  rates of placenta accreta, previa, previa with accreta, and hysterectomy by number of cesareans (Silver 2006).   The number below the cesarean number indicate how many women were included in that category.

Remember as you look these over, the risk of uterine rupture in a spontaneous labor after one prior low horizontal (“bikini-cut”) cesarean is 0.4% (Landon 2004).  Risk of uterine rupture during one’s second cesarean is 0.9%. (Landon 2006)

Here is the study abstract:

OBJECTIVE: Although repeat cesarean deliveries often are associated with serious morbidity, they account for only a portion of abdominal deliveries and are overlooked when evaluating morbidity. Our objective was to estimate the magnitude of increased maternal morbidity associated with increasing number of cesarean deliveries.

METHODS: Prospective observational cohort of 30,132 women who had cesarean delivery without labor in 19 academic centers over 4 years (1999-2002).

RESULTS: There were 6,201 first (primary), 15,808 second, 6,324 third, 1,452 fourth, 258 fifth, and 89 sixth or more cesarean deliveries. The risks of placenta accreta, cystotomy, bowel injury, ureteral injury, and ileus, the need for postoperative ventilation, intensive care unit admission, hysterectomy, and blood transfusion requiring 4 or more units, and the duration of operative time and hospital stay significantly increased with increasing number of cesarean deliveries. Placenta accreta was present in 15 (0.24%), 49 (0.31%), 36 (0.57%), 31 (2.13%), 6 (2.33%), and 6 (6.74%) women undergoing their first, second, third, fourth, fifth, and sixth or more cesarean deliveries, respectively. Hysterectomy was required in 40 (0.65%) first, 67 (0.42%) second, 57 (0.90%) third, 35 (2.41%) fourth, 9 (3.49%) fifth, and 8 (8.99%) sixth or more cesarean deliveries. In the 723 women with previa, the risk for placenta accreta was 3%, 11%, 40%, 61%, and 67% for first, second, third, fourth, and fifth or more repeat cesarean deliveries, respectively.

CONCLUSION: Because serious maternal morbidity increases progressively with increasing number of cesarean deliveries, the number of intended pregnancies should be considered during counseling regarding elective repeat cesarean operation versus a trial of labor and when debating the merits of elective primary cesarean delivery.

LEVEL OF EVIDENCE: II-2.

Last updated 3/25/12.

Be Sociable, Share!

•