Reliability of amniotic fluid surfactant measurements

A proficiency study designed to assess interlaboratory precision of amniotic fluid surfactant measurements is presented. A total of 31 laboratories participated in the study. The assays includes lecithin/sphingomyelin (L/S) ratio test, the measurement of phosphatidyl glycerol (PG), and the Lumadex-FSI test. L/S ratio values varied from "1.3" to over "5.0" on aliquots derived from the same pool. With only three exceptions, all PG values read as "positive." The interlaboratory agreement for the Lumadex-FSI assay was excellent. With the exception of two values of "46," all the other values were with "47" or "48."