Biomaterial Database

Preanalytical factors that influence the Abbott TDx Fetal Lung Maturity II assay. 2003

David G Grenache, and Curtis A Parvin, and Ann M Gronowski

Washington University School of Medicine, Department of Pathology and Immunology, Division of Laboratory Medicine, Box 8118, 660 S. Euclid Ave., St. Louis, MO 63110, USA.

BACKGROUND The TDx Fetal Lung Maturity II (FLM II) assay uses amniotic fluid to assess lung maturity of the unborn infant. We investigated common preanalytical factors that influence FLM results, including centrifugation, sample storage, and contamination by whole blood. METHODS We tested 18 specimens after centrifugation and after resuspension by vortex-mixing. We also analyzed 23 specimens stored at -20 degrees C for up to 448 days and then thawed (duplicate measurements), 20 specimens stored at 4 degrees C, and 24 specimens stored at room temperature. In addition, we evaluated the effects of whole blood diluted into 19 different specimens. RESULTS Centrifugation significantly decreased FLM II results from baseline (P <0.0001), and resuspension returned results to baseline values (P = 0.286). Storage at -20 degrees C produced highly variable results that demonstrated a nonsignificant negative trend associated with storage time. Specimens were stable for 24 h when stored at 4 degrees C and 16 h at room temperature. Blood contamination produced significantly positive differences in results only in specimens with baseline values < or =39 mg/g with a 5.8 mg/g increase in FLM II for every 0.1 x 10(12)/L increase in the erythrocyte count (slope = 58.4). CONCLUSIONS Resuspension of centrifuged specimens produces clinically valid FLM II results. Results from specimens stored at -20 degrees C can be highly variable and decrease over time. Results from specimens stored at 4 degrees C and at room temperature are stable for 24 and 16 h, respectively. Blood contamination up to 0.03 x 10(12) erythrocytes/L is acceptable for FLM II analysis.

UI	MeSH Term	Description	Entries
D007231	Infant, Newborn	An infant during the first 28 days after birth.	Neonate,Newborns,Infants, Newborn,Neonates,Newborn,Newborn Infant,Newborn Infants
D008168	Lung	Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.	Lungs
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D011296	Prenatal Diagnosis	Determination of the nature of a pathological condition or disease in the postimplantation EMBRYO; FETUS; or pregnant female before birth.	Diagnosis, Prenatal,Fetal Diagnosis,Fetal Imaging,Fetal Screening,Intrauterine Diagnosis,Antenatal Diagnosis,Antenatal Screening,Diagnosis, Antenatal,Diagnosis, Intrauterine,Prenatal Screening,Antenatal Diagnoses,Antenatal Screenings,Diagnosis, Fetal,Fetal Diagnoses,Fetal Imagings,Fetal Screenings,Imaging, Fetal,Intrauterine Diagnoses,Prenatal Diagnoses,Prenatal Screenings,Screening, Antenatal,Screening, Fetal,Screening, Prenatal
D011663	Pulmonary Surfactants	Substances and drugs that lower the SURFACE TENSION of the mucoid layer lining the PULMONARY ALVEOLI.	Surfactants, Pulmonary,Pulmonary Surfactant,Surfactant, Pulmonary
D012127	Respiratory Distress Syndrome, Newborn	A condition of the newborn marked by DYSPNEA with CYANOSIS, heralded by such prodromal signs as dilatation of the alae nasi, expiratory grunt, and retraction of the suprasternal notch or costal margins, mostly frequently occurring in premature infants, children of diabetic mothers, and infants delivered by cesarean section, and sometimes with no apparent predisposing cause.	Infantile Respiratory Distress Syndrome,Neonatal Respiratory Distress Syndrome,Respiratory Distress Syndrome, Infant
D001769	Blood	The body fluid that circulates in the vascular system (BLOOD VESSELS). Whole blood includes PLASMA and BLOOD CELLS.
D002498	Centrifugation	Process of using a rotating machine to generate centrifugal force to separate substances of different densities, remove moisture, or simulate gravitational effects. It employs a large motor-driven apparatus with a long arm, at the end of which human and animal subjects, biological specimens, or equipment can be revolved and rotated at various speeds to study gravitational effects. (From Websters, 10th ed; McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
D005260	Female		Females
D005325	Fetal Organ Maturity	Functional competence of specific organs or body systems of the FETUS in utero.	Fetal Maturity, Functional,Functional Fetal Maturity,Maturity, Fetal Organ,Maturity, Functional Fetal,Organ Maturity, Fetal