Lecithin/Sphingomyelin Ratio, Amniotic Fluid

CERNER / EPIC MNEMONIC: L/S
POE DESCRIPTION: L/S RATIO W PG; L/S
CPT CODE:

83661-90, 83516-90

TURNAROUND TIME: 4-6 hours
SPECIAL INSTRUCTIONS: State gestational age on requisition.
CONTAINER TYPE: Brown plastic tubes for amnios
SPECIMEN REQUIREMENTS: Amniotic fluid, 10 mL
MINIMUM VOLUME: Amniotic fluid, 5 mL
HANDLING INSTRUCTIONS: Protect from light. Send sample on ice to the laboratory immediately after collection. Do not process specimen in any manner.
REFERENCE RANGE:

See Quest Diagnostics - Search Test Code 35057

 

Interpretation of the Lecithin/Sphingomyelin (L/S) Ratio is made as follows:

 

Immature <1.0

PG = Not Detected

Weeks Gestation 26 - 30

 

Premature 1.0 - 1.5

PG = Not Detected

Weeks Gestation 30 - 34

 

Transitional 1.5 - 1.9

PG = Not Detected

Weeks Gestation 35 - 36

 

Mature (Caution) 2.0 - 2.5

PG = Not Detected

Weeks Gestation 36 - 37

 

Mature >2.5

PG = Detected

Weeks Gestation 37 - 40

 

A Lecithin/Sphingomyelin Ratio of greater than 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 SYNONYM(S):Amniotic Fluid Phospholipids; L/S Ratio, Lung Maturity Profiles