The lecithin/sphingomyelin (L/S) ratio is measured for assessing maturity of:
High-Yield Explanation
The lecithin/sphingomyelin (L/S) ratio for assessment of fetal pulmonary maturity. The test depends on outward flow of pulmonary secretions from the lungs into the amniotic fluid, thereby changing the phospholipid composition of the latter and permitting measurement of the L/S ratio in a sample of amniotic fluid. In the absence of complications, the ratio of these 2 components reaches 2.0 at approximately 35 weeks. The presence of blood or meconium may interfere with test interpretation. Ref: Mehta S.H., Sokol R.J. (2013). Chapter 12. Assessment of At-Risk Pregnancy. In A.H. DeCherney, L. Nathan, N. Laufer, A.S. Roman (Eds), CURRENT Diagnosis & Treatment: Obstetrics & Gynecology, 11e.