lecithin/sphingomyelin ratio

ratio /ra·tio/ (ra´she-o) [L.] an expression of the quantity of one substance or entity in relation to that of another; the relationship between two quantities expressed as the quotient of one divided by the other.

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A-G ratio , albumin-globulin ratio the ratio of albumin to globulin in blood serum, plasma, or urine in various renal diseases.

cardiothoracic ratio  on a radiograph, the ratio of the transverse diameter of the heart to the internal diameter of the chest at its widest point just above the dome of the diaphragm.

lecithin/sphingomyelin ratio , L/S ratio the ratio of lecithin to sphingomyelin concentration in the amniotic fluid, used to predict the degree of pulmonary maturity of the fetus and thus the risk of respiratory distress syndrome (RDS) if the fetus is delivered prematurely.

sex ratio  the proportion of one sex to another, traditionally the number of males in a population per number of females.

ventilation-perfusion ratio  the ratio of oxygen received in the pulmonary alveoli to the flow of blood through the alveolar capillaries.

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lecithin/sphingomyelin ratio

L/S ratio Obstetrics The ratio of lecithin–phosphatidyl choline to sphingomyelin, a 'bench' parameter used to determine lung maturity and predict an infant's ability to survive without developing respiratory distress. See Biophysical profile, Lung profile, Respiratory distress syndrome.