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Fetal Lung Maturity Panel (Lamellar Body Count & Phosphatidyl glycerol)
|Test group||Fetal Lung Maturity|
|Performed by||Parnassus Hematology (LBC) and Chemistry (PG)|
|In House Availability||
|Method||Particle counting by impedance utilizing platelet channel of an automated hematology analyzer (LBC)
Immunoagglutination assay (PG)
|Collection Instructions||Specify if the specimen has been collected from drainage through the vagina by writing "vaginal pool" on the requisition.
Transport sample immediately to laboratory for testing. If delivery must be delayed or if sending from a remote site refrigerate sample and transport refrigerated.
|Container type||Red top (preferred) or Plastic tube|
|Amount to Collect||2 mL Amniotic fluid|
|Sample type||Amniotic fluid|
|Preferred volume||2 mL Amniotic fluid|
|Min. Volume||1 mL Amniotic fluid (mat not be sufficient for both assays)|
|UCSF Rejection Criteria||Sample received at room temperature > 1 hour after collection.|
|Processing notes||Do not centrifuge. Deliver immediately to Hematology|
|Normal range|| LBC:
|Stability||Refrigerated 5 days|
|Turn around times||Stat: 2 hours, Routine: 4 hours|
|Additional information||Test begins with lamellar body count and if needed based on those results a Phosphatidyl glycerol analysis.
Lamellar body count (LBC) testing employs enumeration of lamellar bodies in amniotic fluid as an index of fetal lung maturity and replaces the surfactant/albumin ratio (S/A ratio), which is no longer commercially available. Numerous studies have demonstrated the clinical performance of the LBC as equal to or better than the S/A ratio.
LBC results are reported as >50 x10e9/L (mature), 15-50 x10e9/L (transitional), and <15 x10e9/L (immature). With mature results, there is a very low risk of respiratory distress syndrome (RDS) of the newborn with delivery. With transitional results, the fetal lungs are probably mature, but the possibility of RDS cannot be excluded. With immature results, the fetal lungs may not be mature and the risk of RDS is significant.
Phosphatidylglycerol (PG) testing will only be performed in cases of transitional LBC results. In samples that are either 'immature' or 'mature' by the LBC assay the PG will be credited.
Note that PG is usually not detectable in significant amounts before 35 weeks gestation. The presence of PG is indicative of fetal lung maturity, however, absence of PG does not necessarily predict development of RDS. Most amniotic fluid samples with LBCs in the transitional range will be negative for PG.
As blood, meconium, and mucous contamination adversely affect the LBC assay, such samples will automatically be submitted to the UCSF Chemistry division for phosphatidylglycerol (PG) testing and the LBC assay will be credited
|LDT or Mod FDA?||Yes|
|Last Updated||8/22/2013 4:12:33 PM|