Relationship between amylase concentration, L/S ratio and lecithin concentrations in amniotic fluid

Area of Science:

• Obstetrics and Gynecology
• Clinical Chemistry
• Neonatal Medicine

Background:

• Assessing fetal lung maturity is crucial for optimizing delivery timing.
• Traditional methods like the lecithin/sphingomyelin (L/S) ratio and lecithin concentration can be complex and time-consuming.

Purpose of the Study:

• To evaluate the utility of amniotic fluid amylase concentration as a predictor of fetal maturity.
• To compare amylase levels with established fetal maturity markers such as L/S ratio and lecithin concentration.

Main Methods:

• Amniotic fluid samples (n=110) from 106 uneventful pregnancies were analyzed.
• Amylase concentration, L/S ratio, and lecithin concentration were measured in each sample.
• Statistical analysis was performed to correlate amylase levels with gestational age and phospholipid concentrations.

Main Results:

• Amylase concentrations < 200 U/l significantly correlated with gestational age < 37 weeks, L/S ratio < 2, and lecithin < 3.5 mg% (p<0.001).
• Amylase concentrations > 300 U/l significantly correlated with gestational age > 37 weeks, L/S ratio > 2, and lecithin > 3.5 mg% (p<0.001).
• Amylase levels between 200-300 U/l showed no significant correlation with gestational age or phospholipid levels.

Conclusions:

• Amniotic fluid amylase concentration is a simple, rapid, and cost-effective screening method for predicting fetal maturity.
• Amylase levels < 200 U/l suggest prematurity, while levels > 300 U/l indicate maturity.
• Intermediate amylase values (200-300 U/l) necessitate confirmatory testing using specific fetal maturity assessments.