Fetal Lung Maturity (FLM)—Lamellar Body Counts (LBC)


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Subject: Fetal Lung Maturity (FLM)—Lamellar Body Counts (LBC)

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  • Most common test currently use in the United States. LBCs are concentrically layered “packages” of phospholipids produced by type II pneumocytes. LBCs represent the storage form of surfactant. They are present in amniotic fluid in increasing quantities as gestation advances. They are similar in size as platelets and can be counted in most hematology analyzers.

  • Normal range:

    • Mature fetal lungs: ≥50,000/μL

    • Borderline: 15,000–50,000/μL

    • Immature fetal lungs: ≤15,000/μL


  • Predicting FLM and assessing the risk of developing neonatal respiratory distress syndrome, when performed during 32–39 weeks of gestation


  • Increased in mature fetal lungs

  • Decreased in immature fetal lungs


  • It is as accurate as TDM/FLEXII FPIA method (no longer available) surfactant/albumin ratio.

  • LBCs not indicated >39 weeks of gestation.

  • Amniotic fluid samples should be free of blood or meconium contamination.