Sonographic identification of lung maturation in the fetal lamb

Ultrasound evaluation of fetal lung development in utero could be a noninvasive method for frequent monitoring of the state of pulmonary maturity and predicting when parturition could occur with minimum or no risk of respiratory distress syndrome of the newborn. In cases of high-risk obstetric management in premature labor, this ability may be a particularly useful tool. To pursue this possibility, the lungs and livers of 13 living fetal lambs were successfully imaged with a modified clinical B-scanner under carefully controlled conditions; physiologic function tests on the excised lungs determined the state of pulmonary maturity. In eight cases, maturity or immaturity was correctly identified by sonographic criteria. The results wer ambiguous in four cases. One case of immature lung was incorrectly identified as mature. The trends established in these animal studies appear promising and with refinement may form the basis for sonographic assessment of fetal lung maturity in a clinical setting.