AMNIOINFUSION


I. Indications

  1. Severe variable FHR decelerations
    1. Pts randomized to amnioinfusion vs. usual care had greater resolution of variable decels and, in nulliparous pts, was ass'd with decreased incidence of c/s (Am. J. Obs. Gyn 153:301, 1985; cited in AFP rvw)
  2. Thick meconium
    1. Might help either by diluting the mec, preventing variables that might lead to fetal gasping, or both
    2. Meta-analyses have reported decreased incidence of meconium aspiration syndrome and neonatal ventilation
    3. Some controversy exists as to its utility

II. Risks

  1. Generally safe; few case reports, e.g. of uterine scar disruption, elevated intrauterine pressure leading to fetal bradycardia, amniotic fluid embolism (though all reports ass'd w/other risk factors for that),
  2. Contraindications
  1. Amnionitis
  2. Polyhydramnios
  3. Uterine hypertonicity
  4. Multiple gestation
  5. Known fetal anomaly
  6. Known uterine anomaly
  7. Severe fetal distress
  8. Nonvertex presentation
  9. Fetal scalp pH < 7.20
  10. Placenta previa
  11. Abruptio placentae

III. Protocol

  1. FHR monitoring with fetal scalp electrode is recc'd
  2. Warming of infusion is not necessary
  3. Place intrauterine pressure catheter (IUPC) and document resting tone (should be < 15mm Hg)
  4. Practice varies
    1. One protocol for variables is for 250ml bolus over 20-30min then 10-20ml/min up to total infusion of 600ml or resolution of decelerations, then additional 250ml, then stop unless decels resume. Recc'd max total of 1 liter
    2. For thick mec, infuse 250-500ml over 30min then constant infusion at 60-180ml/h
  5. Use NS If intrauterine pressure is consistently elevated (> 30mm Hg or > 15mm Hg above baseline resting tone, d/c in fusion and recheck at 5min intervals

(Source: AFP 57:504, 1998)