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Order Code LSPGD Lecithin/Sphingomyelin (L/S) Ratio, Phosphatidylglycerol (PG), and Disaturated Lecithin (DSL), Amniotic Fluid

Specimen Requirements

Specimen must arrive and be processed within 4 hours of collection. Notify Ridgeview Medical Center Laboratory at 952-442-2191, extension 5600 to let them know specimen is coming. Ridgeview Medical Center Laboratory will receive and process specimen per FUMC protocol. Notify FUMC Genetics Department that specimen is coming, and send by courier.


8 mL of unprocessed amniotic fluid. Send specimen refrigerated in a plastic, leakproof vial. 

Note: 1. Indicate “tap or pool,” “diabetic or nondiabetic,” and weeks gestation.

2. Label specimen with patient’s name, date of birth or hospital medical record number, specimen source, date and time of collection, and collector’s initials.

Day(s) Test Set Up

Monday through Friday

Reference Values

L/S ratio <2.0 indicates immature lungs; a ratio of 2.0-3.0 indicates borderline mature lungs; and a ratio >3.0 indicates mature lungs. Infants of diabetic mothers have an increased risk of developing respiratory distress syndrome when L/S ratio indicates borderline mature or mature lungs but PG is not present. In the presence of PG, the incidence of respiratory distress syndrome is very low (<0.5%) for all infants. DSL <750 µg/dL indicates immature lungs, between 750-1,500 µg/dL is borderline mature, and >1,500 µg/dL indicates mature lungs. As with the L/S ratio, the presence of PG further ensures the absence of respiratory distress syndrome when DSL is >1,500 µg/dL.

Performing Laboratory

Fairview University Medical Center (FUMC)


Thin-Layer Chromatography (TLC)/Densitometry

Test Classification and CPT Coding

82489 - chromatography, qualitative; thin layer, analyte not elsewhere specified

83361 - fetal lung maturity assessment; L/S ratio

84081 - PG