A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
L/S Ratio
Test CodeCPT Codes
83661
Preferred Specimen
Amniotic Fluid
Minimum Volume
Other Acceptable Specimens
Instructions
PROTECT FROM LIGHT
Transport Container
SPECIAL/1
Transport Temperature
Specimen Stability
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Methodology
TLC
Setup Schedule
Monday - Friday, 8:00 - 14:00, Report available: Upon Completion of Analysis
Report Available
Limitations
Reference Range
Ratio of 1.5 or less indicates immaturity
Ratio of 1.5 - 1.9 is borderline
Ratio of 2.0 or greater indicates maturity(PI is present after 30 weeks and peaks at 36-37 weeks. PG appears after 35 weeks and increases beyond term.
Clinical Significance
The determination of lectithin levels in amniotic fluid is the most sensitive method for estimating fetal lung maturity. A deficiency of surfactant in the lungs is considered the primary etiological defect in RDS. In the mature lung 90-95% of the lipids are phosphlipids, the major surface active component is dipalmitoyl lecithin. The second major component is phosphatidyglycerol(PG), and other minor components including sphingomyelin. As the pregnancy progresses, the sphingomyelin level remains fairly constant while the lecithin level continues to increase, showing a very sharp increase after the 35th week.