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Vaginal Birth after C-section. Andrea Chymiy, R3 MD. History of C-section in U.S. 1916: “Once a cesarean, always a cesarean” 1970 C-section rate: 5.5% 1970’s: Advent of EFM, new medico-legal pressures, increase in diagnosis of dystocia 1988 C-section rate: 24.7%. History of VBAC.
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Vaginal Birth after C-section Andrea Chymiy, R3 MD
History of C-section in U.S. • 1916: “Once a cesarean, always a cesarean” • 1970 C-section rate: 5.5% • 1970’s: Advent of EFM, new medico-legal pressures, increase in diagnosis of dystocia • 1988 C-section rate: 24.7%
History of VBAC • 1980: 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)
Swing of the pendulum In the 1990’some insurance companies & managed care organizations mandated that (almost) all women with previous cesarean deliveries must undergo a trial of labor (TOL).
Total C-section, primary C-section & VBAC delivery rates: United States, 1989–2000 Year Total Primary VBAC 2000 . . . . . . . . . . . . . . . . . . . . . 22.9 16.0 20.7 1999 . . . . . . . . . . . . . . . . . . . . . 22.0 15.5 23.4 1998 . . . . . . . . . . . . . . . . . . . . . 21.2 14.9 26.3 1997 . . . . . . . . . . . . . . . . . . . . . 20.8 14.6 27.4 1996 . . . . . . . . . . . . . . . . . . . 20.7 14.6 28.3 1995 . . . . . . . . . . . . . . . . . . . . . 20.8 14.7 27.5 1994 . . . . . . . . . . . . . . . . . . . . . 21.2 14.9 26.3 1993 . . . . . . . . . . . . . . . . . . . . . 21.8 15.3 24.3 1992 . . . . . . . . . . . . . . . . . . . . . 22.3 15.6 22.6 1991 . . . . . . . . . . . . . . . . . . . . . 22.6 15.9 21.3 1990 . . . . . . . . . . . . . . . . . . . . . 22.7 16.0 19.9 1989 . . . . . . . . . . . . . . . . . . . . . 22.8 16.1 18.9
More recent concerns about VBAC • 1999: 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-sections • Some 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-section • Extreme example: Brazil - where the C-section rate is currently around 25% in publichospitals and around 98% for women who have access to privatemedicine - Sign of status (Middle class & up) - More convenient for MDs (quicker) - MDs receive little training in difficult vaginal delivery
Healthy People 2010 1. For nulliparous women at 37 weeks of gestation or greater with singleton fetuses with vertex presentation, the target c-section rate is 15.5% (In 1996 the national rate was 17.%). 2. For multiparous women with one prior LTCS delivery at 37 weeks of gestation or greater with singleton fetuses with vertex presentations, the target VBAC rate is 37% (In 1996 the national rate was 30%).
Advantages of VBAC • Lower rates of maternal morbidity • Postpartum fever • Wound infection • Blood transfusion • Hysterectomy • Maternal discomfort • Length of stay • Fewer cases of neonatal respiratory distress
Disadvantages of attempting VBAC • Increased rates of uterine rupture - 0.2% for ERCS vs 0.4% for TOL • Increased rates of perinatal death - 0.3% for ERCS vs 0.6% for TOL • Induction 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 > 30 • Fetal weight > 4000 grams • Induction of labor • No previous h/o vaginal delivery
Risk factors for uterine rupture during TOL • Previous C-section due to dystocia • Type of C-section • Classical incision (4 - 9%) • T-shaped incision (4 - 9%) • Low vertical incision (1 - 7%) • Low transverse incision (0.2 - 1.5%)
Clinical manifestations of uterine rupture • Fetal bradycardia • Variable or late decelerations • Maternal hypotension/shock • Vaginal bleeding • Cessation of contractions • Loss of station/fetal presenting part • Abdominal pain
Complications of uterine rupture • Maternal mortality very rare • Fetal 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 LTCS • Vertex fetal presentation • No other uterine scars • No history of previous uterine rupture • Clinically adequate pelvis • Ability to perform emergency C-section
Absolute contraindications to VBAC • Prior transfundal myomectomy • Prior classical or T-shaped uterine incision • Inability to perform emergency C-section
Relative contraindications to VBAC (more research needed) • Unknown uterine scar (most will be LTCS) • Low-vertical uterine incision • Breech presentation • Twin gestation • Postterm pregnancy • Suspected macrosomia
Success rates for attempted VBAC • 50-70% of attempted VBACs result in successful vaginal birth • Factors 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 VBAC • Spontaneous labor is most successful & has lowest rate of uterine rupture • Misoprostol 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 VBAC • External cephalic version probably safe • Amnioinfusion considered safe • Epidural anesthesia is considered safe • Continuous EFM recommended throughout labor • Ultrasound or MR imaging of lower uterine segment may prove helpful in predicting risk of uterine rupture
Conclusions • At least 50% of attempted VBACs are successful • Absolute risk from TOL is small • Uterine rupture 0.2 – 1.5% • Hysterectomy 0.1 – 0.2% • Perinatal death 0.2%