amnioinfusion

Amnioinfusion is a medical procedure in which sterile fluid is infused into the amniotic sac through the cervix during labor or, less commonly, pregnancy. It is performed to augment amniotic fluid volume or to address fetal heart rate abnormalities thought to be caused by umbilical cord compression. The infused fluid is usually warmed isotonic saline or lactated Ringer's solution and is delivered via a sterile transcervical catheter, sometimes through an intrauterine pressure catheter.

Indications include relief of variable fetal heart rate decelerations associated with cord compression during labor, management of oligohydramnios in labor to improve cushion around the umbilical cord, and dilution of meconium-stained amniotic fluid to reduce the risk of meconium aspiration. It is generally considered during labor rather than as a routine procedure in uncomplicated pregnancies.

Technique and monitoring: after membranes have ruptured, sterile technique is used. A transcervical cannula or intrauterine catheter is placed into the amniotic cavity and warmed crystalloid is infused slowly. Typical total volumes range from several hundred to about 1000 mL, infused over 15–30 minutes and then adjusted based on fetal status and amniotic fluid volume. Continuous fetal monitoring is maintained, and the infusion is stopped if there are signs of tachysystole, fetal distress, or infection.

Risks and considerations: potential complications include maternal fever or chorioamnionitis, uterine tachysystole, placental abruption, and rarely uterine rupture. Amnioinfusion is not a substitute for delivery when ongoing fetal compromise or obstetric indications for delivery exist. Contraindications include active intra-amniotic infection and other conditions where infusion could worsen maternal or fetal risk. The evidence for routine use is mixed, and guidelines emphasize individualized decision-making.