title: The biophysical/biochemical test. A new marker of fetal lung maturity in borderline cases.
abstract: OBJECTIVE
  To assess the diagnostic accuracy of the combination of a biophysical (lamellar body count [LB]) with a biochemical test lecithin/sphingomyelin ratio (L/S) for the evaluation of fetal lung maturity (FLM) in cases of intermediate-borderline pulmonary maturity.
  
  
  METHODS
  We studied 105 cases with one or both intermediate (2.1-2.4:1 for L/S and/or 15,000-19,000/microL for LB) or borderline (2.5:1 for L/S and/or 20,000/microL for LB count) FLM indices and no phosphatidylglycerol who delivered within 72 hours of amniocentesis, excluding multiple gestation and contaminated amniotic fluid samples. The biophysical x biochemical marker (B x B) was calculated by multiplying L/S by the corresponding LB, then dividing by 10(3). By using the ROC curve, a cutoff of 50 was found.
  
  
  RESULTS
  B x B values were lower in respiratory distress syndrome (RDS) than in the non-RDS group (30 [23-41] vs. 52 [50-70], P < .001; median, 25-75%). All RDS cases had a B x B value < 50. Diagnostic accuracy for B x B was: sensitivity, 100%; specificity, 83%; positive predictive value, 61%; negative predictive value, 100%. Sensitivity and positive predictive values were higher for B x B than L/S.
  
  
  CONCLUSIONS
  B x B may be a useful tool for cases with borderline FLM.
authors.affiliation: Second Institute of Obstetrics and Gynecology, La Sapienza University, Rome, Italy.
authors.forename: J J
authors.initials: JJ
authors.lastname: Piazze
authors.forename: M M
authors.initials: MM
authors.lastname: Anceschi
authors.forename: L
authors.initials: L
authors.lastname: Maranghi
authors.forename: M G
authors.initials: MG
authors.lastname: Porpora
authors.forename: E V
authors.initials: EV
authors.lastname: Cosmi
mesh_terms: D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry / Q000166:cytology; D015415:Biomarkers; D005260:Female; D005325:Fetal Organ Maturity; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000196:embryology*; D010713:Phosphatidylcholines / Q000032:analysis; D011237:Predictive Value of Tests; D011247:Pregnancy; D012372:ROC Curve; D012127:Respiratory Distress Syndrome, Newborn / Q000175:diagnosis*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013109:Sphingomyelins / Q000032:analysis
chemical_list: D015415:Biomarkers; D010713:Phosphatidylcholines; D013109:Sphingomyelins