Lecithin/Sphingomyelin Ratio, Phosphatidylglycerol and Disaturated Lecithin

Sunquest Code:LSPGDL  
Epic Code:LAB3595Epic Name:L/S RATIO WITH PG AND DSL
Synonyms:DSL, Amniotic Fluid; LS/Ratio; PG
Methodology:Thin layer chromatography; densitometry
CPT Code:83661, 82489, 84081
Test Includes:Lecithin/sphingomyelin (L/S) ratio; phosphatidylglycerol (PG); and disaturated lecithin (DSL)
Turnaround Time:Performed Mon-Fri, 0800-1600; results are reported the same day. After 1600 weekdays, on weekends or holidays, stat sample analysis must be approved by laboratory.
Special Instructions:

Contact laboratory when sending a sample. Specimens must be processed within 4 hours of collection. Provide estimated gestational age. Blood and meconium will interfere with the L/S determination but not the Disaturated Lecithin. L/S ratio is a reliable indicator of fetal lung maturity in non-diabetic pregnancies. PG detection confirms fetal lung maturity and is particularly important in diabetic pregnancies.


Collection Instructions

Specimen:Amniotic Fluid
Optimal Volume:8 mL
Minimum Volume:2 mL; dependent on the quality (contamination) of the sample collected
Container:Plastic leakproof container, sterile.
Collection Instructions:Place specimen on ice and deliver to laboratory immediately.
Contraindications:Improper centrifugation may significantly reduce the DSL and may unpredictably affect the L/S. Freezing specimen before processing will affect the accuracy of the results.

Processing and Shipping

Specimen Processing:Process specimen within 4 h. Centrifuge for exactly 5 m at 1000-1100xg. Contact lab for assistance calculating centrifuge parameters. Do not centrifuge more than once. Separate supernatant (8 mL, 2 mL min) from pellet and label both. Store in freezer.
Shipping Instructions:Ship unprocessed amniotic fluid on wet ice to arrive within 4 h of collection. Alternately, process and ship supernatant and pellet on dry ice. Notify the laboratory when a specimen is sent.
Test Performed at or Referral Lab Biochemical Genetics  (UMMC-East Bank)


Reference Range:L/S ratio less than 2.0 indicates immature lungs, a ratio of 2.0-3.0 indicates borderline mature lungs, and a ratio greater than 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 phosphatidylglycerol is not present. In the presence of phosphatidylglycerol, the incidence of respiratory distress syndrome is very low (less than 0.5%) for all infants. Disaturated lecithin less than 750 ug/dL indicates immature lungs, between 750-1500 ug/dL is borderline mature, and greater than 1500 ug/dL indicates mature lungs. As with L/S ratio, the presence of phosphatidylglycerol further ensures the absence of respiratory distress syndrome when disaturated lecithin is greater than1500 ug/dL.
Use:Assessment of fetal lung maturity in high risk or problem pregnancies, diabetics, C-section, fetal distress, Rh sensitization and premature labor. Insufficient surfactant produced by the perinatal lung can lead to respiratory distress and/or hyaline membrane disease. The primary surface-active phospholipid is dipalmitoyl phosphatidylcholine (disaturated lecithin - DSL). Phosphatidylglycerol (PG) is another important phospholipid that helps to stabilize the surfactant complex. Use of disaturated lecithin in conjunction with L/S ratio and phosphatidylglycerol is recommended.

Stats- call the Biochemical Genetics Laboratory at 612-273-5059 or refer to paging schedule in Acute Care.  BGEN Lab will pick up stat samples.  Any specimens received after lab hours must be processed. Note: A sample can be accepted if it has been centrifuged, separated, and refrigerated for up to 12 hours or frozen.


CPT Multiplier Notes Epic Proc
Billing# Chg/EaTotal Chg
Date modified:1/17/2012 7:21:23 AM -->

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