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Lamellar Body Count

Item Value
Approval req'd? No
Available Stat? Yes
Test code LBC
Test group Fetal Lung Maturity
Performed by Parnassus Hematology
In House Availability Test available 24 hours per day 7 days per week
Method Particle counting by impedance utilizing platelet channel of an automated hematology analyzer
Collection Instructions Specify if the specimen has been collected from drainage through the vagina by writing "vaginal pool" on the requisition.
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 (volumes is sufficient for PG assay as well)
Min. Volume 1 mL Amniotic fluid
Processing notes Do not centrifuge. Deliver immediately to Hematology
Units x109/L
Normal range
> 50 x 10e9/L Mature
15 - 50 x 10e9/L Transitional
< 15 x 10e9/L Immature
Synonyms Fetal Lung maturity;
Stability Refrigerated 5 days
Turn around times Stat: 2 hours, Routine: 4 hours
Additional information 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 may be also ordered but will only be performed in cases of transitional LBC results. 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.
CPT coding 83664
LDT or Mod FDA? Yes
Last Updated 5/22/2013 1:21:51 PM
Entry Number 1425
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