VAGINAL BIRTH AFTER PREVIOUS CAESAREAN SECTION

(TRIAL OF SCAR)

Definition

• Planned VBAC (vaginal birth after caesarean) refers to any woman who has experienced a prior caesarean birth who plans to deliver vaginally rather than by ERCS (elective repeat caesarean section).

• The most frequent indications for Caesarean section are – previous Caesarean section– Maternal request– Failure to progress– malpresentation– non-reassuring fetal status

Recommendation

• Vaginal birth after caesarean section (VBAC) should be considered as an option for all women who present for antenatal care with a history of previous caesarean birth.

• Where contraindications exist, a repeat caesarean section should be advised, but in the majority of cases successful vaginal birth can be achieved safely for both mother and baby.

• The success rate is up to 72-76% for birth after a single previous caesarean section

• All women who have experienced a prior caesarean birth should be counselled about the maternal and perinatal risks and benefits of planned VBAC and ERCS when deciding the mode of birth.

• Where possible, there should be review of the operative notes of the previous caesarean to identify the indication, type of uterine incision and any perioperative complications.

Factors that increase likelihood of success of TOS

• Prior vaginal delivery• Prior vaginal birth after caesarean section - 90%

success rate

• Enter the labor spontaneously• Favourable cervix• Previous caesarean section for non-recurring

indication

Risk factors for unsuccessful VBAC are:

• no previous vaginal birth• body mass index greater than 30• previous caesarean section for dystocia• VBAC at or after 41 weeks of gestation• birth weight greater than 4000 g• previous preterm caesarean birth• cervical dilatation at admission less than 4 cm• less than 2 years from previous caesarean birth• advanced maternal age• short stature

Contraindication of TOS

• Previous classical or T-inverted uterine scar– increased risk of uterine rupture

• Previous hysterotomy or myomectomy entering the uterine cavity

• Previous uterine rupture• Previous perforated uterus• Previous cornual pregnancy• two or more previous caesarean deliveries

– the rates of hysterectomy and transfusion were increased

• Presence of contraindication for vaginal delivery– Eg; placenta praevia or malpresentation

• Patient decline for TOS and request ERCS

Risk of VBACAll women who have experienced a prior caesarean birth should be

counselled about the maternal and perinatal risks and benefits of planned VBAC and ERCS when deciding the mode of birth.

• Uterine rupture– Planned VBAC carries a risk of uterine rupture of 22–74/10,000. There is

virtually no risk of uterine rupture in women undergoing ERCS.• Blood transfusion and endometritis

– planned VBAC compared with ERCS carries around 1% additional risk of either blood transfusion or endometritis.

• Birth related perinatal death– planned VBAC carries a 2–3/10,000 additional risk of birth-related

perinatal death when compared with ERCS. • The risk of respiratory problems in the newborn is increased in ERCS

(6% vs. 3%), compared with women who have a successful VBAC

ERCS may increase the risk of serious complications in future pregnancies

The following risks significantly increase with increasing number of repeated caesarean deliveries:

• injury to bladder, bowel or ureter• need for postoperative ventilation• intensive care unit admission• blood transfusion requiring four or more units • placenta accreta• hysterectomy

– knowledge of the woman’s intended number of future pregnancies may be an important factor to consider during the decision-making process for either planned VBAC or ERCS

• Trial of scar can only be contemplated when appropriate personnel and facilities are available:– Obstetrician– Anaesthetist– Paediatrician– Operation theatre– Blood transfusion

Induction of labor in women undergoing trial of scar

• increased risk of uterine rupture in induced and/or augmented labours compared with spontaneous labours.

• When the fetal head is 3/5th or above, induction of labor with prostaglandin E2 or oxytocin is contraindicated.– Repeat caesarean section is indicated

• When fetal head is 2/5th and lower, induction of labor may be considered with extra caution.

Management of trial of scar

• Spontaneous onset of labour is desirable• The fetal head should be 2/5th or less• Group and cross match 2 units of packed cells• Insert iv infusion line• Perform early ARM• Continuous FHR monitoring throughout labour• If labour dysfunctional, proceed with caesarean section.

Oxytocin should only be used with extra caution• Manage 2nd stage of labour as usual.

Uterine rupture

• complete separation of the myometrium with or without extrusion of the fetal parts into the maternal peritoneal cavity and requires emergency Caesarean section or postpartum laparotomy.

• It is an uncommon complication of VBAC but is associated with significant maternal and perinatal morbidity and mortality

• Planned VBAC carries a risk of uterine rupture of 22–74/10,000

• Induction and augmentation carry 2-3 times risk of uterine rupture compared to spontaneous labor in VBAC

There is no single pathognomic clinical feature that is indicative of uterine rupture but the presence of any of the following peripartum should raise the concern of the possibility of this event:

• severe abdominal pain, especially if persisting between contractions• chest pain or shoulder tip pain, sudden onset of shortness of breath• acute onset scar tenderness• abnormal vaginal bleeding • haematuria• cessation of previously efficient uterine activity• maternal tachycardia, hypotension or shock• Palpable scar defect or fetal part• loss of station of the presenting part. • abnormal CTG

– Fetal tachycardia or absent fetal heart activity– Fetal distress

How to manage ruptured scar?

• Established a minimum of 2 large bore iv access• Urgent cross match- a minimum of 6 unit of whole blood• Call for help- summon anaesthetist, obstetrician and

paediatric oncall• Perform standard ABC resuscitation if required• Emergency caesarean section• Operative treatment – immediate laparotomy for repair of the

uterus or hysterectomy

• DIVC treatment if required– 4 units FFP1– 6 units cryoprecipitate– 2 units platelet concentrate

End