• Nathan Riley, MD

Obgyno Wino Podcast Episode 7 - Vaginal Birth After Cesarean Delivery

"Humankind has not woven the web of life. We are but one thread within it. Whatever we do to the web, we do to ourselves. All things are bound together. All things connect.” ― Chief Seattle

2016 Apothic Crush Smooth Red Blend

PB#205 - Published January 2019

Epidemiology and history

- CS rates are on the rise: in the US, 5 → 32% between 1970 and 2016


- Reason is unclear, but clearly multi-factorial: sicker patients, older patients, more inductions, transition after from vaginal breech, rise of elective primary, and previously poor support for TOLAC

- to the point of this PB: VBAC rates on the rise (5-> 28% from 1985 to 1996)

- As TOLAC support improved, reports of rupture also increased with a decrease in VBACs over the subsequent decade and a reflective increase in CS rates

- Many hospitals don’t offer TOLAC today

- In 2010, the NIH convened a consensus to evaluate the safety and outcome data for TOLAC; they concluded that we should be offering TOLAC

We worry a lot, but keep this in mind about the data...

- keep in mind that no RCTs have been completed comparing maternal and neonatal outcomes between TOLAC and elective repeat CS; the data is all observational or retrospective

- “Before considering the results of any analysis, it is important to note that the appropriate clinical and statistical comparison is by intention to deliver. Comparing outcomes from VBAC or repeat cesarean delivery after TOLAC with those from a planned repeat cesarean delivery is inappropriate because no one patient can be guaranteed VBAC, and the risks and benefits may be disproportionately associated with failed TOLAC.”

What IS the big worry?

- benefits seen in successful VBAC: avoid risks of abdominal surgery so short recovery time, avoid the delay in maternal-newborn bonding generally seen in CS, lower rates of hemorrhage, VTE, and infection

- and let’s not forget the risks of repeat CS (higher rates of hysterectomy, abnormal placentation, bowel or bladder injury, transfusion)

- however, both approaches (TOLAC versus elective repeat cesarean) carry risks

- Most maternal morbidity related to TOLAC occurs when repeat cesarean delivery becomes necessary

- Thus VBAC is safer than elective repeat cesarean delivery, but failed TOLAC is less safe than elective repeat cesarean delivery

- Considering the additional risks, VBAC success calculators may be helpful

- important to remember that calculators like this one haven’t been shown to improve outcomes

The dreaded uterine rupture

- rupture associated with greatest risk of maternal and neonatal morbidity

- many studies have lumped together asymptomatic scar dehiscence with catastrophic rupture

- hysterotomy types: after one CS, low transverse carries lowest risk (0.5-0.9%)

- after 2x CS, risk of rupture up to 3.7%, though very little data

- few data for low vertical incision, but the data we do have suggests there is not an increased risk of rupture compared to low transverse hysterotomy

**In counseling a patient on the risks of rupture, it’s important to also provide the risks to future pregnancies associated with history of c-section

Higher risk of placenta previa (1.5-5-fold increased risk over a baseline risk of 0.3-0.5%)

Furthermore, if placenta previa is diagnosed in setting of 1 prior c-section, risk of abnormal placentation (accreta, increta, percreta) is 3%

After 2: 10%

After 3: 40%

After 4: 60%

Likelihood of VBAC success

- all-comers? VBAC success rate is 60-80%, but success is highly individualized (refer to the calculator)

- factors I look at: parity, previously successful VBAC, spontaneous labor, and reason for previous arrest

- one point I found interesting was short interdelivery interval (<19 mos) or presence of preeclampsia in prior delivery both related to decreased likelihood of VBAC success


- one prior c-section w/ LTCS

- still...must be individualized...what if a patient presents in labor at 2 or 3+ station and reports a history of 2x prior CS? Are you going to rush to the OR to perform a repeat CS?

- other factors that might dissuade your decision: suspect macrosomia or history of macrosomia, gestation >40 wks, obesity

- none of these factors alone preclude TOLAC

- remember: risks versus benefits

- The more CS, the greater the risk of abnormal placentation and the more dangerous the subsequent surgeries

- As I mentioned, for patients with 2 or more CS, risk of rupture generally considered higher, but the data is inconclusive

- if VBAC calculator gives a success likelihood of >70%, might be reasonable to consider

- ECV is safe if history of prior CS

What about TOLAC with induction?

- massive study found a higher risk of rupture with prostaglandins (up to 2.25%)

- however, data unable to distinguish if prostaglandin use itself was the culprit versus the use of multiple ripening agents

- most studies comparing outcomes in IOL to spontaneous labor are misleading because “the alternative to labor induction is not spontaneous labor (which may or may not occur) but expectant management”

- the data that we do have suggest higher likelihood of rupture:

- with IOL compared with expectant management (however, a large retrospective observational study also found lower rates of CS in pts with prior CS induced at 39 and 41 wga compared with expectant management and a separate cohort study showed higher VBAC success rate (73% vs 61%) with IOL at 39 wga again compared to expectant management)

- with augmentation or induction (secondary analysis found the association with IOL may only be increased for women who have no prior vaginal delivery

- with higher doses of oxytocin augmentation (though threshold unclear)

- use of prostaglandin E1 (misoprostol)

Diagnosis of uterine rupture

- first sign of rupture? Changes to fetal heart rate tracing (70% of cases) → continuous FHR monitoring important

- other signs: increased uterine contractions, vaginal bleeding, loss of station, or new onset intense uterine pain

- pain is non-specific, thus regional anesthesia still OK (unlikely to mask rupture)

Delivery considerations

- nothing special here

- previously a common practice was to manually explore the uterine scar even if asymptomatic, but this has not panned out to show better outcomes in the long run

- no need to repair asymptomatic scar dehiscence

Risk of repeat rupture

- if rupture occurs in lower segment, 6%

- if rupture occurs in upper segment, 15-32%

- therefore, recommend delivery by repeat CS in patients with h/o rupture before onset of labor

- timing individualized between 36.0 and 37.0 wga (same for h/o classical incision)

Management of 2nd tri delivery or IUFD in women w/ prior CS

- induction with prostaglandins equal in safety compared to their use in unscarred uterus

- if >28 wks, ripening balloon has been to be safe

- TOLAC may be appropriate even in presence of other typical contraindications like classical incision

Final considerations (aka soap box moment)

- My feelings: If my wife desired TOLAC, I would recommend she labor in a hospital, where an operating room and anesthesia staff are readily available

- having said that, here is are some important quotes to consider in counseling your patients:

“The decision to offer and pursue TOLAC in a setting in which the option of emergency cesarean delivery is limited should be carefully considered by patients and their obstetricians or other obstetric care providers. In such situations, the best alternative may be to refer patients to a facility with available resources. Another alternative is to create regional centers where patients interested in TOLAC can be readily referred and needed resources can be more efficiently and economically organized. Obstetricians and other obstetric care providers and insurance carriers should do all they can to facilitate transfer of care or co-management in support of a desired TOLAC, and these procedures should be initiated early in the course of antenatal care…[Conversations around risks and benefits] should be documented and should include reference to anticipated risks and site-specific resources...Because of unpredictability of complications requiring emergency medical care, home birth is contraindicated for women undergoing TOLAC. However, none of the principles, options, or processes outlined here should be used by centers, obstetricians or other obstetric care providers, or insurers to avoid appropriate efforts to provide the recommended resources to make TOLAC available and as safe as possible...Respect for patient autonomy also dictates that even if a center does not offer TOLAC, such a policy cannot be used to force women to have cesarean delivery or to deny care to women in labor who decline to have a repeat cesarean delivery.”

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