Amniotic fluid surfactant-albumin ratio as a screening test for fetal lung maturity. Two years of clinical experience.
An automated amniotic fluid surfactant-albumin ratio (SAR) test was performed as a screening test for pregnancies requiring fetal pulmonary maturity testing. Of the 178 neonates delivered within 3 days of the testing, respiratory distress syndrome (RDS) developed in 21 (11.8%) and transient tachypnea of the newborn infant (TTN) in 11 (6.1%). A positive test was defined as one which predicted RDS or TTN. Sensitivity was interpreted as the proportion of neonates with RDS or TTN detected by SAR less than 70 mg/gm. Sensitivity was 90.7% with a specificity of 76.1%. The positive predictive value was 45.3%; the negative predictive value 97.4%. The interassay coefficient of variability was 3.5%. The SAR test has proven to be a rapid, precise laboratory tool. Our combined testing protocol uses the SAR as an initial screening test with the lecithin/sphingomyelin ratio used as backup if the SAR did not predict maturity (SAR < 70 mg/gm). This protocol has markedly lowered the use of lecithin/sphingomyelin ratios while maintaining necessary clinical accuracy.
Bayer-Zwirello
L A
LA
Department of Obstetrics and Gynecology, Tufts University School of Medicine, Baystate Medical Center, Springfield, Mass 01199.
Jertson
J
J
Rosenbaum
J
J
Moccio
R
R
O'Grady
J P
JP
Kanaan
C M
CM
Gimovsky
M L
ML
D000418:Albumins / Q000032:analysis*; D000653:Amniotic Fluid / Q000737:chemistry*; D005325:Fetal Organ Maturity; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000196:embryology*; D011237:Predictive Value of Tests; D011663:Pulmonary Surfactants / Q000032:analysis*; D012372:ROC Curve; D012120:Respiration Disorders / Q000175:diagnosis; D012127:Respiratory Distress Syndrome, Newborn / Q000175:diagnosis; D012680:Sensitivity and Specificity
D000418:Albumins; D011663:Pulmonary Surfactants