Test Code LS Lecithin/Sphingomyelin (L/S) Ratio, Phosphatidylglcerol(PG), Amniotic Fluid
Performing Laboratory
Quest Teterboro
Methodology
Thin-Layer Chromatography (TLC), Latex Agglutinatin
Reference Values
Interpretation of the lecithin/sphingomyelin (L/S) Ratio is made as follows:
Interpretation L/S
Ratio Phosphatidyl
Glycerol
Weeks Gestation
Immature
<1.0
Not
detected
26-30
Premature
1.0-1.5
Not
detected
30-34
Transitional
1.5-1.9
Not
detected
35-36
Mature (Caution)
2.0-2.5
Not
detected
36-37
Mature >2.5 Detected
37-40
A lecithin/sphingomyelin ratio of >2.0 together with the
presence of phosphatidylglycerol may suggest mature fetal lung
development.
The designation "Mature (Caution)" refers to patients other than
those with diabetes. Phospholipid data in diabetic pregnancies do
not necessarily follow the above classification.
Test Classification and CPT Coding
83661
83516
Physician Office Specimen Requirements
Obtain 10 mL of amniotic fluid. Freeze immediately, and send specimen frozen in a screw-capped, sterile container. Protect specimen from light.