Echogenicity of fetal lung: relation to fetal age and maturity

Reports of echogenicity of the fetal lung as it relates to maturity of that organ are scant and at variance. A study was undertaken to determine if any correlation between fetal age and/or lung maturity and echogenicity could be determined in a clinical setting. Studies were performed with either linear array or mechanical sector real-time devices. Echogenicity of the fetal lung was compared with that of the fetal liver in the same longitudinal (parasagittal or coronal) sonogram. Lung echogenicity was judged to be hypodense, isodense, slightly hyperdense, or markedly hyperdense as compared with the liver texture. One hundred eighty-five studies were evaluated; of these, some 37 patients also underwent amniocentesis for determination of lecithin/sphingomyelin ratios (L/S) and presence of phosphatidyl glycerol (PG). Linear regression analyses were performed to determine if lung echogenicity would serve as an indicator of fetal maturity. No clinically applicable relation was established between fetal lung echogenicity and gestational age, L/S, or presence of PG in amniotic fluid with current methodology. The possibility persists that tissue characterization techniques may find application in such an investigation.