Vaginal Birth after C-sectionDr M.Rashidi

History of C-section in U.S.

1916: Once a cesarean, always a cesarean

History of VBAC1980: NIH panel begins to encourage trial of labor (TOL) for women with h/o C-section 1981 VBAC rate: 3%1990: US Public Health Service propose goal of C-section rate of 15% (and VBAC rate of 35%)

Early data: Pro-Trial of labor (TOL)Rosen (1991): No significant difference in maternal mortality rate found for ERCS vs. TOL. Failed TOL results in no major risk.

Flamm (1994): TOL pts shown to have shorter hospitalizations, fewer postpartum transfusions, and fewer postpartum fevers.

Hook (1997): Infants born after TOL developed fewer neonatal respiratory problems (ie: TTN) compared to those born by elective repeat C-section (ERCS)

More recent concerns about VBAC1999: NEJM editorial pointed out increasing rates of uterine rupture as VBAC rates have increased

1999: Use of Misoprostol for cervical ripening/labor induction (vs spontaneous labor) found to bring almost 30-fold increase in uterine rupture rate

2001: Use of prostaglandins for cervical ripening/labor induction (vs spontaneous labor) found to carry 5-fold increased risk of uterine rupture

Paradigm shift on C-sectionsSome OB/Gyns and patients are now questioning whether vaginal births should always be the goal - Some advocate elective C-section as better in long run, with decreased rates of pelvic dysfunction and urinary & fecal incontinence

New attitudes toward C-sectionExtreme example: Brazil - where the C-section rate is currently around 25% in public hospitals and around 98% for women who have access to private medicine- Sign of status (Middle class & up)- More convenient for MDs (quicker)- MDs receive little training in difficult vaginal delivery

Advantages of VBACLower rates of maternal morbidityPostpartum feverWound infectionBlood transfusionHysterectomyMaternal discomfortLength of stayFewer cases of neonatal respiratory distress

Disadvantages of attempting VBACIncreased rates of uterine rupture - 0.2% for ERCS vs 0.4% for TOLIncreased rates of perinatal death- 0.3% for ERCS vs 0.6% for TOLInduction with prostaglandins or misoprostol contraindicated

Uterine rupture Nonsurgical complete disruption of all uterine layers which usually leads to bleeding and extrusion of all or part of the fetal-placental unit.

Risk factors for uterine rupture during TOL

Maternal age > 30Fetal weight > 4000 gramsInduction of laborNo previous h/o vaginal delivery

Risk factors for uterine rupture during TOL

Previous C-section due to dystociaType of C-sectionClassical incision (4 - 9%)T-shaped incision (4 - 9%)Low vertical incision (1 - 7%)Low transverse incision (0.2 - 1.5%)

Clinical manifestations of uterine ruptureFetal bradycardiaVariable or late decelerationsMaternal hypotension/shockVaginal bleedingCessation of contractionsLoss of station/fetal presenting partAbdominal pain

Complications of uterine ruptureMaternal mortality very rareFetal morbidity/mortality more common- Fetal asphyxia occurs in 5%- Perinatal morbidity/mortality highest when fetus extruded into abdomen or when interval between bradycardia & delivery exceeded 18 minutes

ACOG-approved VBAC candidates

Maximum of 2 previous LTCSVertex fetal presentationNo other uterine scarsNo history of previous uterine ruptureClinically adequate pelvisAbility to perform emergency C-section

Absolute contraindications to VBAC

Prior transfundal myomectomy Prior classical or T-shaped uterine incisionInability to perform emergency C-section

Relative contraindications to VBAC (more research needed)

Unknown uterine scar (most will be LTCS)Low-vertical uterine incisionBreech presentationTwin gestationPostterm pregnancySuspected macrosomia

Success rates for attempted VBAC50-70% of attempted VBACs result in successful vaginal birthFactors making VBAC success more likely:- Previous vaginal delivery- Favorable cervix/Bishop score- Spontaneous onset of labor- Breech presentation as reason for previous C-section (85% success)

Induction of labor in attempted VBACSpontaneous labor is most successful & has lowest rate of uterine ruptureMisoprostol should never be used Rates of rupture shown in U.W. study (2001 NEJM) differed by method of induction:Spontaneous labor - 0.52%Induction without prostaglandins - 0.72%Induction with prostaglandins 2.45%

Other issues in attempted VBACAmnioinfusion considered safeEpidural anesthesia is considered safeContinuous EFM recommended throughout laborUltrasound or MR imaging of lower uterine segment may prove helpful in predicting risk of uterine rupture

ConclusionsAt least 50% of attempted VBACs are successfulAbsolute risk from TOL is smallUterine rupture 0.2 1.5%Hysterectomy 0.1 0.2%Perinatal death 0.2%

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