Change in Fetal Lung Maturity Testing

Effective Monday October 25, 2010, the University of Iowa Hospitals and Clinics Core Laboratory will change the main method used to assess fetal lung maturity by analysis of amniotic fluid. The current test is an Abbott Diagnostics assay that measures the surfactant/albumin ratio ("FETAL LUNG MATURITY – MG SURF, G ALB", Epic #LAB606). Abbott is discontinuing marketing this assay. The new assay is "LAMELLAR BODY COUNT" (Epic #LAB7446), which measures 1-5 micron diameter particles of surfactant (lamellar bodies) that increase throughout gestational age and correlate with lung maturity. The analysis of lamellar bodies will be done in the Hematology laboratory.

For a reference range, each result will have appended a table relating percent risk of respiratory distress syndrome based on lamellar body count and gestational age (in weeks). This table is based on a published study (Karcher R et al. Gestational age-specific predicted risk of neonatal respiratory distress syndrome using lamellar body count and surfactant-to-albumin ratio on amniotic fluid. Am J Obstet Gynecol 193(5):1680-1684, 2005). View a screenshot of results on a test patient.

Like the surfactant/albumin ratio test, the lamellar body count cannot be performed with amniotic fluid contaminated with blood or meconium. The core Chemistry laboratory will continue to offer the Phosphatidylglycerol (PG) assay on amniotic fluid (Epic LAB#657), which can be used if the sample is contaminated with meconium or blood.

Questions should be directed to Matthew Krasowski, MD, PhD, Medical Director of the Clinical Chemistry Laboratory (384-9380,