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Ronnie Falcao, LM MS, a homebirth midwife in Mountain View, CA

Anne Frye on VBAC and Uterine Rupture

For all those who are interested in knowing what a professional midwife has to say about scar type, thickness or thinness of the uterus, risk of rupture, etc., read on.  The info is from Anne Frye's book, "Holistic Midwifery," which is a primary text for those of us studying for the NARM exam to become a CPM.

(As an aside, I have changed the author's word, "yoni," and term, "YBAC," to the more commonly understood VBAC and words having "vagina" as their root.  It's a long story, having to do with the fact that "vagina" means "sheath for a sword," and the author prefers to avoid the use of such a disrespectful and chauvinistic word for a part of the female anatomy.  Otherwise, the information is directly quoted as it appears in the book, except that all typos are mine! <s>)

"RISKS OF VBAC:  While much has been made about VBAC risks among North American obstetricians, VBACs have been standard of care in Europe for many decades.  Some common myths are that the scar is highly likely to rupture, that multiple Cesareans increase this likelihood and that multiple gestations and breech presentations also increase these risks.  While the risk of disruption of uterine integrity certainly exists, it remains small, even for those who have had multiple Cesareans or Classical incisions.  Neither multiple gestation nor breech birth appears to increase the risk of scar separation. (Davies and Spencer, 1988)  In fact, rupture of the unscarred uterus occurs more often and does more harm than rupture of the scarred uterus.  (Martin, et al.., 1988)  In addition, the scar which has remained intact up to the threshold of labor is very likely to remain intact through the birth. (Macafee, 1958)  In her literature review, Henci Goer (1995, p.42) found reference to only 46 ruptures during 15,154 labors, a rate of 0.3% (benign scar separations [i.e. "windows" and dehiscences] are a more common occurrence).  The possibility of other unforeseen events occurring which may necessitate transport, such as intrapartum hemorrhage, fetal distress, or cord prolapse, is about 2.7%: roughly 10 times the rate of rupture during labor.  (Enkin, 1989) So, while a risk is present, it must be considered in context with the overall risks inherent in birth.  When viewed in this light and compared to the greater, multiple risks inherent in Cesarean surgery, vaginal birth after a Cesarean becomes the only sane standard of care. Therefore, as a midwife, the question is whether or not to attend a woman at home; in most cases, the advisability of vaginal birth is a given."

"THE CONSULTATION VISIT: ...It is important to address any questions she has about risks of birth with a scarred uterus in general, and her risk factors in particular.  Then, move on to the other topics relevant to the consultation interview; it is important that a woman feel that her whole situation is being addressed, not that she is a "walking scar," as so many medical model providers project."

"THE TYPE OF UTERINE SCAR, ANY COMPLICATIONS FROM SURGERY, ETC.: ...You want to know if there was any infection following the birth, how her scar healed (did it open and drain? were tubes put in to facilitate this?)?  What was her nutrition like after the surgery?  While having had an infection may make a woman more afraid about her scar's integrity, it can, in fact, make the site of infection that much stronger, as more scar tissue may build up in response to the disruption.  It could also cause one or more of the tissue layers to heal apart (a dehiscence) which is not, in itself, usually a problem. (Wainer-Cohen, 1994)  Endometritis may, however, leave the scarred area more susceptible to the development of placenta accreta.  Good nutrition and an easily assimilated multi vitamin and mineral supplement will help to optimize the situation as much as possible now.  Make sure her diet remains excellent!"

SCAR "TESTING":  "A few doctors may still be attempting to test the integrity of the scar.  Two tests may be suggested.  Hysterography uses radiopaque dye and x-ray to visualize the scar prior to conception. Amniography is done during pregnancy to detect dehiscence and involves amniocentesis and x-rays.  Neither of these tests are predictive of the strength or integrity of the scar, since dehiscence and or defects may be present in scars which maintain their integrity throughout pregnancy and birth.  THE THICKNESS OR THINNESS OF A SCAR DOES NOT PREDICT ITS LIKELIHOOD TO RUPTURE. [Emphasis mine and not the author's!] Fortunately, as VBAC has become more accepted, these dangerous and unnecessary tests have fallen by the wayside in most areas."

"IS ANOTHER SURGICAL BIRTH NECESSARY AND IS HOMEBIRTH ADVISABLE?: Regardless of the reason for the previous surgery, in almost every case a woman can give birth naturally with a subsequent baby.  Vaginal birth is ill-advised only in those cases where a physical deformity prevented birth or in which so much scarring is present on the uterus that carrying a pregnancy to term would put the mother at great risk of uterine rupture.  ...As far as the type of incision goes, the mother who has a low transverse uterine incision is at the lowest risk for scar-related problems such as dehiscence and rupture.  Those with classical or T-shaped incisions are at more risk for rupture, which tends to be more traumatic than the usually benign scar disruptions which occur in women with low transverse incisions.  While some types of incisions pose more risk, the highest risk is still probably around 5% (some scars are more rare and limited data is available. From looking at the existing data, 5% seems to me a generous estimate of risk for all types of Cesarean scars, with the order of risk as follows: low transverse [0.5% Haq, 1988; to 2% Clark, 1988], low vertical [1.3% Enkin, 1989], classical and inverted T [probably about the same for both: 2.2% to 4%, depending on the study], upright T and J-incision [probably somewhat higher, but no specific data is available].).  Women with an upright T, J-shaped, or classical incision or those who have experienced previous uterine rupture may want to birth in the hospital, although finding a practitioner that will assist them to have a VBAC will be more difficult.  However, in these cases scar disruption is **most likely** [emphasis the author's] to occur during pregnancy with accompanying fetal distress and possible death, or not at all.  The mother must weigh the risk of rupture with a VBAC, with the risks of major surgery and multiple Cesareans.  As a midwife, you must assess whether you are up to dealing with the increased risk at home, especially since rupture of these incisions tends to be more traumatic than scar disruption in a low transverse incision.  Studies indicate that a history of multiple surgical births does not increase the risk of rupture. (Farmakides, 1987; Porreco & Meier, 1983; Roberts, 1991)"

"DETECTING A SPLIT IN BELIEFS DURING PREGNANCY:  Sometimes women who have had difficult births in the past are split within themselves about who or what to trust.  Part of them wants to trust their intuitive sense that birth works and that they are okay.  The part that is afraid gives an open ear to the voices of doctors, tests, and technology which assert that birth is dangerous and needs highly skilled assistance just in case something goes wrong.  ...point it out to the parents by discussing their feelings of trust in birth versus technology."

"NUTRITION AND THE VBAC MOTHER:  When a woman has had the disappointment of experiencing a surgical birth for a previous baby, good nutrition can help her feel empowered as well as significantly increase the chances she will have a vaginal birth this time around. Many problems which lead to surgical solutions for childbirth are essentially preventable with the adequate intake of a whole foods diet... A few of these problems include abruption, toxemia, prematurity, and some complications of multiple birth.  Many other problems, such as unexplained stillbirth, infections, poor healing, anemia, coagulation problems, weak contractions, poor hormonal response and others may be related to nutrition as well.  Their recurrence can be minimized with a good diet."

"PREVIOUS UTERINE SURGERIES:  ...Preterm Cesareans are usually done with low vertical or classical incisions because the lower uterine segment IS NOT THIN ENOUGH [emphasis mine] to allow a low transverse incision, AS WOULD BE THE CASE IF THE SURGERY WAS DONE AFTER LABOR HAD BEEN ONGOING FOR A WHILE."

"RISK FACTORS:  The primary risk factor involves separation of the scar with or without associated complications such as fetal distress, maternal hemorrhage or fetal death.  Generally speaking, the higher up a vertical uterine incision extends, the greater the risk of subsequent, relatively benign scar separation (dehiscence) or scar rupture (traumatic tearing open of the scar, which may cause pain or bleeding, but most consistently causes fetal distress).  Classical and T- or J-shaped incisions pose significantly more risk of rupture than does a low transverse incision... These incisions are more likely to give way during pregnancy.  However, when you consider that the overall maternal mortality for Cesarean section has been reported to be at least four times higher (Petitti, 1982) to as much as 26 times higher (Evrard and Gold, 1977) than for vaginal birth, the relatively small risk of uterine scar separation is put into perspective."

"SCAR DEHISCENCE AND UTERINE RUPTURE IN THE THIRD TRIMESTER:  ...The rather ominous term "rupture" is often used to describe all types of uterine disruption.  Many scar problems which do occur are relatively benign and may go completely undetected, even though (when they are,) they may get lumped in with statistics of more traumatic rupture events.  When rupture occurs during labor, it usually happens in women who have had previous (uterine) surgery, many babies or when a woman is unusually sensitive to the effects of oxytocic drugs. ...Any scar that has made it to the threshold of labor intact is likely to stay that way throughout the birth, unless the injudicious use of oxytocin or intrauterine manipulations provide sufficient stress to cause a rupture."

In a section on types/degrees of scar disruptions and how to diagnose them, she notes that even the so-called "silent rupture" eventually shows symptoms that would alert a mother and her care provider.  This type of rupture generally has a much different outcome than the "violent rupture" OBs threaten moms with.  Violent rupture is generally much more severe in terms of bad outcomes for mother and baby.

I know this was long but it covered so many of the recent questions people had posted that I thought it might help!