VBAC Position Statement: Part 2 ~ Cesarean rates & risks; availability of VBAC

Part 2:

Risk of Primary and Repeat Cesareans and the Unintended Consequences of VBAC bans by hospitals and obstetrical groups

As discussed in part 1, hospitals and obstetricians attribute policies banning VBAC to their concerns over possible lawsuits. Viewed from this perspective, there may be a legitimate economic reasons for hospitals and obstetrical practices to ban VBACs.

But what people generally do not understand is that a hospital VBAC ban translates into mandatory repeat cesareans. Our national VBAC rate is only 10%, which means 90% of previous Cesarean mothers are being forced into unwanted and medical unnecessary repeat cesareans, along with all the attendant risks of a second or subsequent surgical delivery.

It must be remembered that both NIH and ACOG describe VBAC as a safe, reasonable, and appropriate option for most women.

According NIH, ACOG, American Academy of Family Practice Physicians and other national healthcare organizations, hospital and practice-wide VBAC bans do not have any scientific justification. At best, they represent the defensive practice of medicine.

Defensive medicine is by definition a doctor- or hospital-centered decision that may be ‘safer’ choice for the institution or individual physician, but does not provide any additional benefit to the patient or family.

The high Cesarean rate and associated risks in subsequent pregnancies

It is a happenstance of biology that the first Cesarean is much simpler surgery to perform and has significantly less risks for mother and baby than repeat Cesareans. {ref} This is not say that all primary Cesareans are simple or without complications, as confirmed by a 13-fold increase in emergency hysterectomy during or after a Cesarean delivery when compared to vaginal birth. {Obstet Gynecol. 2003 Jul;102(1):141-5}

But unfortunately for surgeons performing a second or subsequent Cesarean, this repeat operation is far more complicated due to abdominal adhesions from the previous C-seciton. The intra-operative bleeding during the first C-section, which is a normal accompaniment of all surgery, causes tough bands of tissue or ‘adhesions’ to form in the mother’s abdominal cavity, so that her uterus and/or other abdominal organs (particularly the bladder) adhere to each other in an abnormal manner. In subsequent Cesareans, the surgeon must carefully dissect this tangle of connective tissue — a time-consuming and tedious process — before the Cesarean delivery can precede.

Unfortunately, freeing the uterus from its entanglements is associated with excessive intra-operative bleeding that sometimes requires blood transfusions. Also, the tangle of adhesions in a previous-Cesarean mother can delay delivery of the baby if an emergency C-section is required in a subsequent pregnancy. {refs}

Abnormal placenta implantation & increased risk of mortality for both mother and baby in post-Cesarean pregnancies

Another post-Cesarean complication in subsequent pregnancies is a statistically-significant increased rate of placental abruption and abnormal placental implantation compared to pregnancies in women who have never had a Cesarean.

The first post-Cesarean placental issue is placental abruption during pregnancy, a situation which is usually (not not always) very painful for the mother-to-be and accompanied by bright red vaginal bleeding. In these cases, bleeding from the maternal side of the placenta lifts it off the uterine wall, which prevents that part of the placenta from exchanging oxygen and nutrients between the mother’s body and the unborn baby via the umbilical cord. If the dysfunctional area is greater than 50% of the placenta’s surface, it the fetus usually dies during pregnancy or may be stillborn.

There is increased rate of fetal demise or stillbirth of approximately 1 per 1,000 associated with placental abruption in post-Cesarean pregnancies.

However, a bigger and more frequent problem in post-Cesarean pregnancies is an abnormal implantation of the placenta, which is a potentially-fatal complication for both mother and baby.

The first type of placental problem is a called a ‘previa‘, which describes a placenta implanted at the bottom of the uterus. In this case the placenta grows over top of the cervix, blocking the baby’s access to the birth canal. Should such a woman go into labor, any dilatation of the cervix would predictably trigger a torrential hemorrhage that would be life-threatening to both mother and baby. Women with a placenta previa must always be delivered by Cesarean surgery to insure the health of both.

When classifying cases of placenta previa by whether or not the mother had a previous Cesarean, studies find that only 5% occur in women with no previous Cesarean or other invasive uterine surgery, while 50% occur to post-cesarean pregnancies.

But the down-stream complications of Cesarean don’t stop there. In addition to the higher rate of placenta previa in post-Cesarean mothers, there is also an order-of-magnitude increase in another potentially-lethal type of abnormal implantation called placenta accreta, increta, or percreta, depending on how invasively the tissue of the placenta grows into, or through the uterine wall. {ref}.

When the placenta attaches abnormally to the inner surface of the uterus it is called a ‘placenta accreta’, which is the least serious of the three types. If it invades the uterine muscle it is an ‘increta’. When it grows completely through the uterine wall it is a percreta and the most serious of the three. In cases of percreta, placental tissue that has grown through all the layers of uterus then attaches itself (and its very large blood vessels) to other abdominal organs such as the mother’s bladder.

Maternal consequences of placental accreta, increta and percreta

After delivery of the baby, an improperly implanted placenta cannot detach itself easily like a normal placenta does, and sometimes causes bleeding that can’t easily be stopped. In these cases, obstetricians must either surgically remove the placenta, or perform an emergency cesarean hysterectomy.

Post-cesarean mothers are at risk of having either or both of these placental abnormalities — placenta previa and accreta or percreta. It is a potentially deadly complication when both occur at the same time.

The really bad news is that any woman who has had prior surgery on her uterus is at a substantially increased risk of abnormal placenta implantation. Cesarean section is the most common form of uterine surgery in the United States{Guise, 2010}.

Potentially-fatal placental abnormalities and Cesarean surgery

Potentially-fatal placental abnormalities are the most well-known complication of Cesarean that the public has NEVER heard of – that is, until a childbearing woman with a history of previous Cesarean is diagnosed with this true frightening condition.

In the last 50 years, there has been 10-fold rise in abnormal placentation. During same period of time, researchers have statistically identified a direct correlation between the nearly 7-fold increase in the Cesarean section rate since 1975 and the dramatically increased frequency of placenta previa, abruption and invasive implantation of the placenta. As noted earlier, 50% of childbirth-related emergency hysterectomies are associated with the downstream complications of Cesarean surgery. {Ob.Gyn.News Dec 5, 2002, Vol 37, No 24}

Placenta percreta is the most extreme form of these three conditions. It is always a life-threatening situation, and requires a hysterectomy to be performed after a Cesarean delivery of the baby. Even in the very best of hospitals, with an experienced team of surgeons, interventional radiologist and hematologist all present in the OR, the mortality rate for women with a placenta percreta is seven percent. {ACOG, 2012 & Ob.Gyn.News Mar 1 01, Vol 36}

Maternal morbidity associated with percreta includes multiple blood transfusions, admission to the ICU, iatrogenic complications, drug reactions and hospital-acquired antibiotic-resistant infection such as MERSA. Drug-resistant hospital infections are associated with the most dreaded complication of all — necrotizing fasciitis. This flesh-eating bacteria destroys vital organs such as kidneys and intestines, and shuts off blood circulation to arms and legs; this quickly spreading type of gangrene frequently requires amputated of all four limbs.

One prominent expert in the field, in discussing his recent experience with a placenta precreta patient, stated:

“Even when physicians are prepared and well equipped, (percreta) can be extremely dangerous. … the patient ended up going into cardiac arrest during the procedure and had post-operative complications that kept her in the hospital for 20 days.” {Ob.Gyn.News Mar 1 01, Vol 36}

Perinatal Consequences of Placental Abnormalities

These serious placental problems are not just a risk for the childbearing woman. A large retrospective study of post-Cesarean pregnancies found an increased risk for fetal demise and stillbirth due to placenta abruption.  A growing body of evidence suggests that abnormal implantation of the placenta is due to uterine scarring after cesarean section. This can cause problems for the fetus in the next pregnancy and has been linked to unexplained stillbirth. {Ob.Gyn.News May 15, 2003, Vol 38, No.10}

Neonatal deaths from abnormal placental implantation also occur as a result of prematurity, which is associated with this placental problem. As many as 43% of these babies who were delivered early weighed less than 5 ½ pounds at birth {Eshkoli, Weintraub, Sergienko, & Sheiner, 2013}.

The rising rate of placental implantation problems parallels the rising rate of cesarean surgery in the US: from 1 in 4,027 pregnancies in the 1970s, to 1 in 2,510 pregnancies in the 1980s, to 1 in 533 from 1982-2002 {American College of Obstetricians and Gynecologists {ACOG}; 2012}.

But what is most disturbing is that the risk for all 5 of these placental abnormalities rises with each additional cesarean surgery (Silver, Landon, Rouse, & Leveno, 2006).

Continue to Part 3: Ethical, Economic, personal and societal cost of a high-Cesarean/low-VBAC rate