Meconium concentration and amniotic fluid index influence the outcome of amnioinfusion

Abstract

Background: To determine the usefulness of amnioinfusion as a function of meconium concentration and amniotic fluid index.

Methods: This was a prospective study of 206 pregnant women in whom amniotic fluid was moderately or heavily stained with meconium, according to subjective evaluation. The women were assigned randomly to receive amnioinfusion (n=103) or no amnioinfusion (control group, n=103). The results were compared in women with =/<15 % or >15 % meconium in the amniotic fluid (measured by centrifugation), and in women in whom the amniotic fluid index calculated 60 min after insertion of the amnioinfusion catheter was <10 or =/>10.

Results: In women with >15% meconium, amnioinfusion decreased the rate of cesarian sections motivated by fetal distress (2.5% vs 22.2%), and in women with =/<15% meconium, amnioinfusion decreased the presence of meconium below the vocal cords (6.4% vs 25.9%). Greater benefits after amnioinfusion were seen in women with an amniotic fluid index =/>10: the rate of cesarian sections was lower (1.3% vs 13.3%), as was the frequency of meconium below the vocal cords (10.1% vs 33.3%).

Conclusions: Beneficial effects of amnioinfusion were seen in women with high and low concentrations of meconium, and with high and low amniotic fluid indexes. These criteria should therefore not be used to decide whether amnioinfusion is indicated when the amniotic fluid is moderately or heavily stained with meconium.