VBAC Flashcards
What are the contraindications for VBAC? (3)
- Previous uterine rupture
- History of classical CS
- Contraindication to vaginal birth regardless of history of CS (e.g. placenta praevia)
- caution if complicated uterine scars (e.g.g inverted T or J incisisons)
When should you raise mode of birth (i.e. VBAC) and when should a plan be finalised?
Raise mode of birth following 20wk morph scan and decide by 36 weeks.
What factors favour successfull VBAC?
Previous vaginal birth - strongest predictor of VBAC (VBAC rates reported to be 85-91% in this cohort).
Spontaneous onset of labour.
Higher Bishop score
Malpresentation as indication for previous CS
Uncomplicated, low risk pregnancy.
What are signs and symptoms of uterine rupture?
Typically non-specific and dx is difficult.
Most reliable sign is prolonged, persistent and profound fetal bradycardia.
Abnormal CTG.
Abdominal pain, acute onset of scar tenderness
Abnormal progress in labour.
Vaginal bleeding.
Cessation of previously efficient uterine activity.
Loss of station of the presenting part.
Chest/shoulder tip pain.
Maternal tachycardia, hypotension or shock.
In counselling a woman re onset of labour (ie. spontaneous vs induced) what would you include?
Increased risk of uterine rupture with IOL. If induction required, mechanical methods of induction preferred due to increased risk of rupture with prostaglandins.
What are the maternal and fetal/neonatal benefits of planned VBAC?
Maternal benefits:
- 72-75% chance of vaginal birth.
- If vaginal birth:
- shorter hospital stay.
- Faster recovery
- Avoidance of major surgery and multiple CS in future.
- Increased likelihood of future VB.
- Sense of satisfaction/empowerment in having VB if desired.
- Increased likelihood of breastfeeding compared with ERCS.
- (increased likelihood remains even if planned VBAC results in emergency CS).
Fetal and neonatal benefits:
- Increased likelihood of BFing at birth, hospital discharge and 6-8 weeks postpartum
What are the maternal and fetal/neonatal risks of planned VBAC?
Maternal:
-25-28% chance of emergency CS (and emCS is a/w increased morbidity compared to ERCS).
-Around 0.5% (1:200) risk of uterine rupture and if rupture occurs, it may be a/w significant meternal and perinature morbidity. Risk of rupture increases with induction and augmentation o flabour .
-If vaginal birth, potential trauma to perineum and pelvic floor.
Increased risk of anal sphincter injury for women ahving second birth following one previous CS compared with nulliparous women (BW is strongest predictor; rate of instrumental birth also increased).
Fetal and neonatal risks:
- Increased risks of perinatal mortality compared with ERCS (0.13% vs 0.05%)
- Increased risk of hypoxic ischameic encephalopathy and associated long term sequelae compared with ERCS. (0.08% vs less htan 0.01% -> majority of cases a/w uterine rupture.
What are the maternal and fetal/neonatal benefits of planned ERCS?
Maternal:
- Extremely low risk of uterine rutpure. (<0.03%)
- can plan the date.
- Increased likelihood of avoiding an emCS
- Prevalence of urinary incontinence and pelvic organ prolapse is lower in women who have only given birth by CS than in those who have given birth vaginally.
Fetal and neonatal benefits:
- Reduced risk of HIE compared with planned VBAC (< 0.01% c.f. 0.08%). -> related to reduced risk of uterine rupture.
- Lower rate of perinatal mortalitiy compared to planned VBAC (0.05% VS 0.13%)
What are the maternal and neonatal/fetal risks of planned ERCS?
Maternal:
- Potential difficulties conceiving further pregnancies.
- More likely to require CS for future births. (increasing risks of maternal morbidity with increasing number of CS).
- Increased risk of maternal mortality compared with planned VBAC.
- Decreased rates of breastfeeding.
Fetal/neonatal:
- Decreased likelihood of breastfeeding at birth, hospital discharge and 6-8 weeks postpartum
What risks are increased with recurrent CSs?
- Hysterectomy
- Haemorrhage and blood transfusion
- Adhesions
- Surgical injuries
- Placenta praevia and accreta.
Nb: No change has been fond in rates of infection or abruption with increasing number of CS.
Neonatal respiratory morbidity and mode of delivery
Neonatal respiratory morbidity can occur regardless of mode of birth, making conclusions about the relationship to method of labour and birth unclear.
Studies are conflicting re whether VBAC OR ERCS results in more transient tachypnoea of newborn.
CS is known to be a/w resp morbidity, esp prior to 39+0 weeks gestation.
Factors reducing likelihood of VBAC? (10)
No previous vaginal birth.
Previous CS for:
- Dystocia or failure to progress
- Failed induction
- Cephalopelvic disproportion
- IOL
Hypertensive disorders complicating pregnancy
- Obesity
- Advanced maternal age.
- Current fetal macrosomia of 4kg or more
- Diabetes (both gestational and pre-existing)
Timing of elective repeat CS?
Book ERCS after 39+0
-> risk of resp morbidity decreases after 39+0
VBAC and suspected fetal macrosomia?
Studies consistenlty report lower VBAC rates in women with neonatal BW >4kg
BW of 4kg or more and a history of previous CS is a/w an increased risk of:
- Uterine rupture
- Caesarean birth
- Shoulder dystocia
- 3rd and 4th degree perineal tears.
If suspected fetal macrosomia, consider US at 36weeks.
