Comprehensive Clinical and Exam Notes: Induction of Labour
Patient Assessment and Cervical Evaluation
The first critical step is assessing cervical favourability using the Bishop score to determine the appropriate induction method. 1
Bishop Score Assessment
- Favourable cervix (Bishop score ≥5 in nulliparous, ≥4 in multiparous): Proceed directly to oxytocin with artificial rupture of membranes 1, 2
- Unfavourable cervix (Bishop score <5): Requires cervical ripening before oxytocin 1
Key Physical Examination Findings to Document
- Cervical dilation (0-3 cm = 0-3 points) 1
- Cervical effacement (0-80% = 0-3 points) 1
- Station of presenting part (-3 to +2 = 0-3 points) 1
- Cervical consistency (firm/medium/soft = 0-2 points) 1
- Cervical position (posterior/mid/anterior = 0-2 points) 1
Induction Methods Based on Cervical Status
For Favourable Cervix (Bishop ≥5)
Use oxytocin infusion with artificial rupture of membranes as the standard approach. 1, 3
Oxytocin Protocol
- Starting dose: 1-2 mU/min intravenously 2
- Titration: Increase by 1-2 mU/min every 40-60 minutes until adequate contraction pattern established 2
- Goal: 3-5 contractions per 10 minutes with adequate intensity 4
- Maximum duration: Consider failed induction if no progress after 12-18 hours in latent phase 5
FDA-Approved Indications for Oxytocin
- Induction of labour with medical indication (Rh problems, maternal diabetes, pre-eclampsia at/near term, premature rupture of membranes) 3
- Stimulation or reinforcement of labour in selected cases of uterine inertia 3
- Control of postpartum bleeding or hemorrhage 3
For Unfavourable Cervix (Bishop <5)
Oral misoprostol solution 20-25 µg every 2-6 hours is the preferred pharmacological method for cervical ripening. 1, 6
Misoprostol Protocol (Oral Route Preferred)
- Dose: 20-25 µg orally every 2-6 hours 1, 6
- Advantages over vaginal route:
- Monitoring: Continuous fetal heart rate and uterine activity monitoring from 30 minutes to 2 hours after each dose 6
Alternative: Mechanical Methods (Foley Catheter)
- Single-balloon Foley catheter: No reported risk of uterine rupture 2
- Preferred in specific populations:
Dinoprostone (Prostaglandin E2)
- FDA indication: Ripening unfavourable cervix in pregnant women at or near term with medical/obstetrical need for labour induction 7
- Contraindications: Active cardiovascular disease due to profound blood pressure effects 1, 2
- Risk: Theoretical coronary vasospasm and low risk of arrhythmias 1
Critical Contraindications and Safety Considerations
Absolute Contraindications to Misoprostol
Never use misoprostol in women with prior cesarean delivery—the uterine rupture risk is 13%, which is unacceptably high. 1, 2, 6
Uterine Rupture Risk Stratification
- Misoprostol with prior cesarean: 13% rupture risk 1, 2
- Prostaglandin E2 with prior cesarean: 2% rupture risk 1, 2
- Oxytocin with prior cesarean: 1.1% rupture risk (acceptable when indicated) 1, 2
- Mechanical methods with prior cesarean: 0% rupture risk 2
Other Critical Contraindications
- Dinoprostone: Contraindicated in active cardiovascular disease 1, 2
- Oxytocin: Never use when cephalopelvic disproportion is suspected or confirmed (40-50% of arrested active phase cases involve CPD) 2
- Nifedipine + Magnesium sulfate: Avoid combination during induction—causes uncontrolled hypotension and fetal compromise 2
Special Population Considerations
Women with Prior Cesarean Delivery
Mechanical methods (Foley catheter) are strongly preferred for cervical ripening due to absence of rupture risk. 2
- If pharmacological induction required: Oxytocin only (1.1% rupture risk) 2
- Absolutely avoid misoprostol in third trimester 2, 6
- Prostaglandin E2 carries 2% rupture risk—use with extreme caution 2
Cardiac Patients or Cyanotic Conditions
Use mechanical methods over prostaglandins to avoid systemic vascular resistance drops. 1
- Prostaglandins contraindicated in active cardiovascular disease 2
- Oxytocin acceptable but monitor for fluid overload 5
Advanced Liver Failure
Misoprostol may be less suitable as it requires hepatic metabolism to convert from E1 to active E2 prostaglandin; consider alternative methods. 1, 6
Low-Risk Nulliparous Women at 39 Weeks
- Elective induction at 39 weeks reduces cesarean delivery rate (18.6% vs 22.2%; RR 0.84) 5
- Reduces hypertensive disorders (9.1% vs 14.1%; RR 0.64) 5
- Number needed to treat: 28 women to prevent 1 cesarean delivery 5
Labour Management During Induction
Positioning and Monitoring
- Position: Lateral decubitus position to attenuate haemodynamic impact of uterine contractions 5
- Monitoring: Continuous electronic fetal heart rate monitoring mandatory 5, 1
- Avoid: Maternal pushing until fetal head at perineum to avoid Valsalva manoeuvre effects 5
Analgesia Options
- Preferred: Lumbar epidural analgesia with local anaesthetics or opioids 5
- Benefits: Reduces pain-related sympathetic activity, reduces urge to push, provides anaesthesia for emergency surgery 5
- Caution: Can cause systemic hypotension—use carefully in obstructive valve lesions 5
Assisted Delivery
- Delivery may be assisted by low forceps or vacuum extraction 5
- Routine antibiotic prophylaxis not recommended 5
Post-Partum Management
Third Stage Management
Administer slow intravenous oxytocin infusion (<2 U/min) after placental delivery to prevent maternal haemorrhage. 5
- Oxytocin avoids systemic hypotension when given slowly 5
- Avoid methylergonovine: >10% risk of vasoconstriction and hypertension 5
- Prostaglandin F analogues useful for post-partum haemorrhage unless increased pulmonary artery pressure undesirable 5
Post-Delivery Monitoring
- Continue haemodynamic monitoring for at least 24 hours after delivery 5
- Important fluid shifts occur in first 12-24 hours that may precipitate heart failure in women with structural heart disease 5
- Meticulous leg care, elastic support stockings, and early ambulation to reduce thrombo-embolism risk 5
Common Pitfalls to Avoid
Failed Induction Recognition
Do not prolong induction indefinitely with unfavourable cervix—consider mechanical methods or cesarean delivery if cervical ripening fails. 1
- Allow at least 12 hours after cervical ripening completion before declaring failed induction 5
- Failed induction occurs occasionally and is an important risk 8
Medication Errors
- Never use misoprostol in prior cesarean—rupture risk unacceptably high 1, 2, 6
- Never combine nifedipine with magnesium sulfate—causes uncontrolled hypotension 2
- Avoid dinoprostone in cardiovascular disease—profound blood pressure effects 1, 2
Monitoring Failures
- Hyperstimulation is frequent but usually brief and well-tolerated 8
- Fetal heart rate changes herald uterine rupture more reliably than pain 8
- Intrauterine pressure catheters with oxytocin usage usually well worth their minor risks 8
Cephalopelvic Disproportion
Perform thorough cephalopelvimetry before oxytocin use in arrested labour—40-50% of arrested active phase cases involve CPD. 2
Anticoagulation Management (If Applicable)
Timing of Anticoagulation Cessation
- Switch oral anticoagulants to LMWH or UFH from 36th week 5
- Switch LMWH to intravenous UFH at least 36 hours before induction or cesarean delivery 5
- Discontinue UFH 4-6 hours before planned delivery 5
- Restart 4-6 hours after delivery if no bleeding complications 5
Neuraxial Analgesia Considerations
- At least 24-hour interval required between last dose of therapeutic LMWH and epidural catheter placement 5
- Multidisciplinary approach required for delivery plans and anesthetic options 5
Documentation Requirements
Pre-Induction Documentation
- Bishop score with all components 1
- Indication for induction (medical vs elective) 3
- Prior cesarean delivery status 2
- Cardiovascular disease status 1, 2
- Anticoagulation status if applicable 5
Intrapartum Documentation
- Method of induction and doses administered 1, 6
- Continuous fetal heart rate monitoring findings 5
- Uterine activity pattern 1
- Time intervals: induction start, active labour, delivery 5
- Any hyperstimulation episodes and management 6