Uterotonic Pregnancy: Indicated in pregnancy — risk/benefit

Oxytocin

Brand names: Syntocinon

Adult dose

Dose: Labour induction: 1–2 milliunits/min IV infusion, increasing by 1–2 milliunits/min every 30 min to max 20–40 milliunits/min. Third stage: 10 units IM or 5 units slow IV

Route: IV infusion or IM

Frequency: Continuous infusion (induction) or single dose (third stage)

Standard infusion: 30 units in 500mL normal saline or Hartmann's. PPH: 40 units in 500mL over 4h after initial dose.

Clinical pearls

NEVER bolus IV oxytocin in obstetric emergencies (except carefully) — profound hypotension
Tachyphylaxis occurs — receptor downregulation with prolonged use
Water intoxication risk: oxytocin has ADH activity — restrict IV fluids and monitor sodium in prolonged labours
Syntocinon + ergometrine = Syntometrine: used IM for active management of third stage
Fetal monitoring mandatory throughout oxytocin labour induction/augmentation

Contraindications

Cephalopelvic disproportion
Fetal distress
Uterine scar with high risk of rupture
Vasa praevia
Hypertonic uterine contractions

Side effects

Uterine hyperstimulation
Fetal distress (secondary to hyperstimulation)
Maternal hyponatraemia (water intoxication — ADH-like effect)
Hypotension (IV bolus)

Interactions

Prostaglandins — additive uterotonic effect (monitor closely)
Inhalational anaesthetics — reduced uterotonic response

Monitoring

CTG monitoring (continuous)
Uterine contraction frequency/duration
Maternal BP and HR
Fluid balance (water intoxication risk)
Serum sodium (prolonged use)

Reference: RCOG Induction of Labour Guideline; WHO PPH Prevention Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Pathways