Vaginal Birth After Cesarean

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VBAC Basics - Green Lights & Red Flags

VBAC: Vaginal Birth After Cesarean. TOLAC: Trial Of Labor After Cesarean.

  • Suitable Candidates (Green Lights):
    • One prior Low Transverse Cesarean Section (LTCS).
    • Clinically adequate pelvis; no history of Cephalopelvic Disproportion (CPD).
    • No other uterine scars (e.g., from myomectomy) or previous uterine rupture.
    • Immediate access to emergency Cesarean delivery & anesthesia.
    • Recommended interval from previous CS: >18 months.
    • Singleton pregnancy, cephalic presentation.
    • Informed consent obtained.

Cesarean Incisions and Uterine Scars

Contraindication TypeExamples
AbsolutePrevious classical/T-shaped incision, prior uterine rupture, extensive transfundal uterine surgery
Relative≥2 previous LTCS, unknown uterine scar type, twin gestation, breech presentation, suspected macrosomia (>4kg)

VBAC Risks - Rupture Roulette

Uterine rupture: most critical risk.

  • Incidence: LTCS 0.5-0.9%; Classical/Vertical 4-9%.
  • Prior rupture: Absolute contraindication.

Risk Factors for Uterine Rupture:

FactorRisk Impact
Prior classical scar↑↑↑
<18-24 months since CS
Induction (Prostaglandins)
Macrosomia
Multiple prior CS (≥2)
  • Fetal bradycardia (most common)
  • Sudden, severe abdominal pain/scar tenderness
  • Loss of fetal station
  • Vaginal bleeding (variable)
  • Maternal tachycardia/hypotension

Illustration of uterine rupture

⭐ Fetal bradycardia is the most common and often earliest sign of uterine rupture during TOLAC.

Other Risks: Maternal (hysterectomy, hemorrhage); Neonatal (HIE, death).

Management: Suspected Rupture

TOLAC Tactics - Labor Game Plan

  • Intrapartum Care:
    • Delivery in a facility equipped for emergency Cesarean Section (CS).
    • Continuous Electronic Fetal Monitoring (EFM) mandatory.
  • Induction & Augmentation:
    • Mechanical methods (e.g., Foley catheter) preferred for cervical ripening.
    • Oxytocin: Cautious, low-dose protocol (e.g., start 0.5-2 mU/min, titrate slowly, max 20 mU/min).
    • Avoid prostaglandins.

    ⭐ Prostaglandin E1 (Misoprostol) is generally contraindicated for cervical ripening or induction in TOLAC due to increased risk of uterine rupture.

  • Pain Relief: Epidural analgesia is not contraindicated; can be used.
  • Abandon TOLAC & Proceed to CS if:
    • Arrest of labor (dilation/descent).
    • Non-reassuring fetal status.
    • Signs of uterine rupture (e.g., fetal bradycardia, maternal tachycardia/hypotension, scar tenderness, loss of station).

VBAC Success - Victory Predictors

Overall VBAC success rate: 60-80%.

Favorable Factors (↑ Success)Unfavorable Factors (↓ Success)
* Prior vaginal birth (especially prior VBAC)* Recurrent indication for previous CS (e.g., CPD)
* Spontaneous labor* Need for induction/augmentation of labor
* Non-recurrent indication for previous CS* Increased maternal age (>40 years)
* Favorable cervix (e.g., Bishop score >6)* Obesity (BMI >30)
* Inter-delivery interval >18 months* Macrosomia (>4-4.5 kg)
* Single layer uterine closure (controversial)* Gestational age >41 weeks

High-Yield Points - ⚡ Biggest Takeaways

  • One prior low transverse CS (LTCS) is the ideal prerequisite for VBAC.
  • Risk of uterine rupture with one LTCS is ~0.5-0.9%.
  • Absolute contraindications include classical/T-shaped incision or prior uterine rupture.
  • Continuous electronic fetal monitoring is mandatory during TOLAC.
  • Prostaglandins for induction are contraindicated; Oxytocin may be used cautiously.
  • Fetal bradycardia is the most common and earliest sign of uterine rupture.
  • Successful TOLAC rates are 60-80%.

Practice Questions: Vaginal Birth After Cesarean

Test your understanding with these related questions

In pregnancies complicated by intrauterine growth restriction (IUGR) with otherwise reassuring fetal surveillance, what is the recommended gestational age for planned delivery to optimize neonatal outcomes?

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Flashcards: Vaginal Birth After Cesarean

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Perimortem cesarean delivery should be considered if there is no return of spontaneous circulation in _____ minutes

TAP TO REVEAL ANSWER

Perimortem cesarean delivery should be considered if there is no return of spontaneous circulation in _____ minutes

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