Induction of Labour and Elective Caesarean Section - Theory

PART 1: INDUCTION OF LABOUR

Definition and Overview

• Elective - performed for the convenience of the patient or professional staff
• Indicated - performed for medical, obstetric, or fetal complications of pregnancy

Cervical Assessment: The Bishop Score

• Bishop score ≥ 9: Favorable cervix - induction likely to succeed (similar success rate to spontaneous labor)
• Bishop score < 6: Unfavorable cervix - cervical ripening should be attempted first
• Bishop score 6-8: Intermediate

A. ELECTIVE INDUCTION

1. To assure the patient that the physician she has good rapport with will be present at delivery
2. To avoid unattended delivery (history of rapid labours)
3. To reduce anxiety during final weeks of pregnancy
4. Social or geographic convenience
5. Logistical planning (e.g., distance from hospital)

• Gestational age ≥ 39 weeks confirmed (to reduce risk of iatrogenic prematurity)
• Favorable cervix (Bishop score ≥ 9) OR Bishop score ≥ 6 with no contraindication
• No contraindication to labor or vaginal delivery
• Vertex presentation
• No evidence of feto-pelvic disproportion

Important note: Nicholson and Caughey challenged the conventional belief that induction increases cesarean risk. Their cohort analysis showed that when comparing induced women to the entire cohort awaiting spontaneous labor (the true comparison group), induction reduces the risk of cesarean delivery compared to expectant management. A randomized trial of 619 women aged ≥ 35 years confirmed that induction at 39 weeks had no adverse impact on cesarean rate or maternal/fetal outcomes.

B. INDICATED INDUCTION

• Gestational hypertension / Pre-eclampsia / Eclampsia
• Chronic hypertension with complications
• Diabetes mellitus (poorly controlled)
• Renal disease (deteriorating)
• Antiphospholipid syndrome
• Chorioamnionitis
• Prelabour rupture of membranes (PROM) at or near term

• Post-term pregnancy (≥ 42 weeks)
• Intrauterine growth restriction (IUGR) with abnormal Doppler/biophysical profile
• Fetal macrosomia in a diabetic mother
• Oligohydramnios
• Isoimmunization (Rh incompatibility)
• Intrauterine fetal death

• Placenta or vasa previa
• Transverse lie
• Umbilical cord prolapse
• Prior classical (vertical) uterine incision
• Active genital herpes
• Invasive cervical carcinoma
• Severe feto-pelvic disproportion

Methods of Cervical Ripening and Labour Induction

1. Mechanical Methods

• Balloon catheters (e.g., Foley catheter, Cook catheter): Placed intracervically, mechanical distension stimulates prostaglandin release and causes cervical ripening
• Membrane stripping/sweeping: Separation of membranes from the lower uterine segment; stimulates prostaglandin release
• Amniotomy (AROM - Artificial Rupture of Membranes): Releases prostaglandins, enhances uterine contractions; used to augment or initiate labor when cervix is favorable

2. Pharmacological Methods

• Dinoprostone (PGE₂): Available as vaginal gel (Prepidil) or vaginal insert (Cervidil/Propess). Ripens cervix by softening cervical collagen and stimulating uterine contractions. Dose: 0.5 mg intracervically every 6 hours (gel) or 10 mg controlled-release insert for 12 hours
• Misoprostol (PGE₁): Highly effective, inexpensive. Given vaginally (25 mcg every 3-6 hours) or orally. Can cause uterine tachysystole; caution in women with prior uterine scar

• The most commonly used agent for augmentation and induction
• Given as IV infusion - typically started at 0.5-2 mU/min, increased every 15-40 minutes
• Acts on oxytocin receptors in the myometrium to stimulate coordinated uterine contractions
• Requires continuous fetal heart rate monitoring
• Complications include: uterine hyperstimulation/tachysystole, water intoxication (antidiuretic effect), fetal distress

3. Non-pharmacological Methods

• Sexual intercourse (natural prostaglandins in semen)
• Nipple stimulation (causes endogenous oxytocin release)
• Castor oil (largely historical, not recommended)

Monitoring During Induction

• Continuous cardiotocography (CTG) for fetal heart rate monitoring
• Regular uterine contraction assessment (frequency, duration, strength)
• Maternal vital signs
• Progress of labor assessed by cervical examination
• Awareness for complications: uterine tachysystole (> 5 contractions in 10 minutes), uterine hyperstimulation, fetal bradycardia

PART 2: ELECTIVE CAESAREAN SECTION

Historical Background

1. Aseptic technique
2. Reliable anaesthesia
3. Introduction of the low-segment (lower uterine segment) incision - the uterine wound could be excluded from the peritoneal cavity, dramatically reducing postoperative peritonitis risk
4. Blood transfusion and antibiotic therapy

Types of Caesarean Section

Indications for Elective Caesarean Section

• Placenta previa (major/complete)
• Vasa previa
• Transverse or oblique lie
• Prior classical uterine incision (vertical incision through uterine body)
• Obstructive pelvic mass (e.g., large fibroids blocking birth canal)
• Severe feto-pelvic disproportion

• Previous caesarean section (1 or more lower segment scars)
• Breech presentation at term (if external cephalic version fails or is contraindicated)
• Twin pregnancy with non-vertex first twin
• Maternal request (caesarean on maternal request - CDMR)
• Certain fetal anomalies (gastroschisis, myelomeningocoele)
• Active genital herpes at term
• Prevention of mother-to-child transmission (HIV, some viruses)
• Severe pre-eclampsia with unfavorable cervix
• Severe IUGR with abnormal Doppler studies
• Maternal cardiac/neurological conditions where pushing is contraindicated

Maternal Request Caesarean (CDMR - Caesarean Delivery on Maternal Request)

• Avoidance of pelvic floor injury (urinary incontinence is twofold greater after spontaneous vaginal delivery vs. caesarean delivery at 6 months postpartum)
• Avoidance of birth trauma to infant
• Patient autonomy

• Risks of surgical procedure (haemorrhage, bladder injury, adhesions)
• Increased morbidity in future pregnancies (placenta accreta spectrum)
• Longer recovery time
• Risks to neonate (respiratory morbidity, especially if < 39 weeks)

Pre-operative Assessment and Preparation for Elective CS

• Elective CS should not be performed before 39 completed weeks unless there is a documented medical/obstetric indication, to minimize neonatal respiratory morbidity (transient tachypnoea of the newborn, respiratory distress)

• Full history and examination
• Blood group and cross-match (at minimum group and save)
• Full blood count, coagulation profile
• Anaesthetic assessment (choice of regional vs. general anaesthesia)
• Consent - must include risks: haemorrhage, wound infection, DVT/PE, bladder/ureter injury, anaesthetic complications, future pregnancy complications (uterine rupture, placenta praevia/accreta)
• Fasting (minimum 6 hours for solids, 2 hours for clear fluids)
• Antacid prophylaxis (sodium citrate/ranitidine/omeprazole) to reduce aspiration risk
• Antibiotic prophylaxis (cefazolin 1-2 g IV, given before skin incision to reduce wound infection and endometritis)
• Thromboprophylaxis: LMWH +/- compression stockings

Surgical Technique

1. Skin incision: Pfannenstiel (Joel-Cohen) transverse incision preferred over midline vertical for elective cases
2. Opening of rectus sheath and separation of rectus muscles
3. Entry into peritoneum
4. Formation of bladder flap: Peritoneum over lower uterine segment reflected downward to protect bladder
5. Uterine incision: Transverse lower uterine segment incision (Kerr incision) - lower risk of rupture in future pregnancies compared to classical vertical incision
6. Delivery of the fetus: Head delivered first; oxytocin 5 IU IV given after delivery to contract uterus
7. Delivery of placenta: Controlled cord traction
8. Uterine closure: 2-layer closure of uterine incision
9. Peritoneal closure: Opinion varies - some units do not close visceral peritoneum
10. Fascial and skin closure

Anaesthesia for Elective CS

Complications of Caesarean Delivery

• Haemorrhage (uterine atony, uterine artery injury, placental bed bleeding)
• Bladder injury (especially with adhesions from prior CS)
• Ureteric injury
• Bowel injury
• Anaesthetic complications

• Wound infection / dehiscence
• Endometritis
• Urinary tract infection
• Deep vein thrombosis / pulmonary embolism
• Paralytic ileus
• Anaemia

• Uterine scar rupture in subsequent labour (risk ~0.5% for LSCS scar, up to 9% for classical incision)
• Placenta praevia
• Placenta accreta spectrum (especially with multiple prior CS)
• Adhesion formation (bowel obstruction, infertility)

• Transient tachypnoea of the newborn (TTN) - more common with elective CS before labour onset (no catecholamine surge to clear fetal lung fluid)
• Iatrogenic prematurity if timing is wrong
• Scalpel lacerations (uncommon)

Comparison: Elective CS vs. Vaginal Delivery

Key Points Summary

• Elective IOL is appropriate at ≥ 39 weeks with a favorable cervix
• Bishop score guides management: ≥ 9 = favorable; < 6 = ripen first
• Methods: PGE₂ (dinoprostone), misoprostol, mechanical (balloon), oxytocin infusion, amniotomy
• Indicated IOL: post-dates, pre-eclampsia, IUGR, PROM, diabetes, etc.
• Continuous CTG monitoring required during induction

• Should not be performed before 39 completed weeks
• Requires full pre-op workup, antibiotic prophylaxis, thromboprophylaxis
• Spinal anaesthesia is first choice
• Pfannenstiel incision + transverse lower uterine segment incision (Kerr) is standard
• Major long-term risk is placenta accreta spectrum with repeat CS
• Neonatal respiratory morbidity is higher without exposure to labour