Induction and Augmentation of Labor

IOL Foundations - Go or No-Go?

• Indications for IOL: Post-term (≥41 wks), PPROM/PROM, GDM, preeclampsia/eclampsia, IUGR, chorioamnionitis, fetal demise, certain maternal conditions.
• Contraindications: Cephalopelvic disproportion (CPD), placenta/vasa previa, active genital herpes, prior classical uterine incision or myomectomy entering cavity, transverse lie, cord prolapse.
• Cervical Assessment: Bishop Score predicts IOL success.
  • Components: Dilation, Effacement, Station, Consistency, Position (📌 Mnemonic: Call PEDS For Parturition - Cervix, Position, Effacement, Dilation, Station).
  • Score <6: Unfavorable cervix; ripening usually needed.

⭐ A Bishop score of ≥8 (or ≥6 by some sources) generally predicts a successful induction similar to spontaneous labor.

• Proceed if benefits outweigh risks & cervix favorable or ripened.

Cervical Ripening - Prepping the Path

• Goal: Soften, efface, and dilate cervix if Bishop score <6. Prepares for oxytocin.
• Pharmacological Agents:
  • Prostaglandin E1 (Misoprostol): 25 mcg intravaginally/orally, Q4-6h.
  • Prostaglandin E2 (Dinoprostone): Gel or vaginal insert/pessary.
• Mechanical Methods:
  • Transcervical Foley catheter: Balloon provides direct pressure.
  • Hygroscopic dilators (e.g., Laminaria): Absorb fluid, expand.

⭐ Misoprostol (PGE1) 25 mcg intravaginally every 4-6 hours is a common cervical ripening agent, but contraindicated in previous uterine scar (e.g., CS).

Induction Methods - Labor Launch!

Key methods to initiate contractions once cervix is favorable (Bishop Score >6-8).

• Amniotomy (ARM)
  • Artificial rupture of membranes.
  • Releases prostaglandins; allows head application.
  • Requires engaged head. ⚠️ Risk: Cord prolapse.
• Oxytocin Infusion
  • IV, titrated for 3-5 contractions/10 min.
  • Continuous FHR & uterine monitoring.
  • ⚠️ Risk: Tachysystole.

⭐ Oxytocin is typically started at 0.5-2 mU/min and increased every 30-60 minutes until adequate contraction pattern is achieved (e.g., 3-5 contractions in 10 min).

Augmentation - Boosting Progress

• Goal: Accelerate slow labor (dystocia) in active phase.
• Prerequisites: No Cephalopelvic Disproportion (CPD), confirmed fetal well-being.
• Methods:

• Caution: Titrate oxytocin; watch for uterine tachysystole.

⭐ Augmentation is indicated for labor dystocia in the active phase, often defined as <1 cm/hr cervical dilation for ≥4 hours with adequate uterine activity or ≥6 hours with inadequate activity despite oxytocin.

Monitoring & Mayhem - Vigilant Watch

• Maternal: Vitals. Uterine activity (freq, duration, strength, tone). Tachysystole: >5 ctx/10min (avg over 30min) - see flow. Partogram.
• Fetal: Continuous EFM (Baseline, variability, accels, decels).
• ⚠️ Mayhem:
  • Uterine Rupture: Scar, pain, FHR Δ, shock.
  • Non-reassuring FHR: Resuscitate (O2, IVF, lateral, stop oxytocin 📌 LIONS).
  • Oxytocin SE: Hypotension, water intoxication.

⭐ Uterine tachysystole (>5 contractions in 10 min) with fetal heart rate changes requires immediate oxytocin discontinuation and potential tocolysis.

High‑Yield Points - ⚡ Biggest Takeaways

• Bishop score >8 favorable for induction; <6 often needs cervical ripening.
• Misoprostol (PGE1) & Dinoprostone (PGE2) are key for cervical ripening.
• Oxytocin is primary for inducing or augmenting labor contractions.
• Amniotomy (ARM) augments labor; risk of cord prolapse if head not engaged.
• Foley catheter is a common mechanical method for cervical ripening.
• Uterine tachysystole (>5 contractions in 10 minutes) is a major risk of uterotonics.
• Failed induction: no progress after 12-24h oxytocin with ruptured membranes.