Lamellar body counts

Alphabetical Test listing

Lamellar body counts-994

Lamellar body counts
Fetal Lung Maturity

Predicting fetal lung maturity and assessing the risk of developing neonatal respiratory distress syndrome, when performed from 32 to 39 weeks gestation

Amniotic Fluid
2.0 mL
0.75 mL

Amniotic specimens must be free of blood and meconium contamination


Do not centrifuge


Refrigerated (preferred) - 28 days

Ambient - 7 days

2 weeks
  • Gross hemolysis
  • Centrifuged specimen
  • Presence of blood or meconium
Mayo Clinic Laboratories (LBC): R-NX
Mo -Su
1 day



Immature: <15,000/mcL

Indeterminate: 15,000-50,000/mcL

Mature: >50,000/mcL


Fetal lung maturity testing is used to determine the risk for developing respiratory distress syndrome (RDS) in infants born prematurely (32-39 weeks). The risk for developing RDS is inversely related to gestational age and is the most common cause of respiratory failure in neonates. RDS is associated with preterm birth due to insufficient production of pulmonary surfactant. Pulmonary surfactant is synthesized by type II pneumocytes. Surfactant consists of 90% phospholipids (primarily phosphatidylcholine and phosphatidylglycerol) and 10% proteins (surfactant proteins [SP]-A, SP-B, SP-C). Surfactant is packaged into lamellar bodies and is excreted into the alveolar space where it unravels and forms a monolayer on alveolar surfaces. Lamellar bodies can also pass into the amniotic cavity and, hence, are found in amniotic fluid. The surfactant functions to reduce the surface tension in the alveoli, preventing atelectasis. When surfactant is deficient, the small alveoli collapse and the large alveoli become overinflated and stiff, which has been associated with increased risk of developing respiratory distress. The status of fetal lung maturity is reflected in the concentration of surfactant in the form of phospholipids and lamellar bodies present in amniotic fluid. Lamellar bodies are similar in size to platelets and can be quantified on a hematology analyzer utilizing the platelet channel and used to estimate fetal lung maturity.

Surfactant secretion into the amniotic fluid is minimal prior to 32 weeks gestation.
Fetal lung maturity testing is not indicated beyond week 39.
Specimens must not be frozen or centrifuged. Freezing and centrifuging the amniotic fluid falsely decreases the lamellar body count