lecithin-sphingomyelin ratio

lecithin-sphingomyelin ratio

n.

The ratio of lecithin to sphingomyelin present in amniotic fluid, used to determine fetal pulmonary maturity.

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ratio

[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. It differs from a proportion in that the numerator is not included in the denominator. Thus x/(x + y) is a proportion, x:y is a ratio.

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A-G ratio

albumin-globulin ratio.

area-incidence ratio

the number of new cases of a specific disease in a population during a specified time period, divided by the geographic area size in which the observations are made, multiplied by the time elapsed, e.g. cases per hectare per month.

arm ratio

a figure expressing the relation of the length of the longer arm of a mitotic chromosome to that of the shorter arm.

A/S ratio

the diameter of the ascending aorta divided by the diameter of the aorta at the sinus of Valsalva; less than 1 in a normal dog. In subaortic stenosis it becomes greater than 1.

cardiothoracic ratio

the ratio of the transverse diameter of the heart to the internal diameter of the chest at its widest point just anterior to the dome of the diaphragm.

cross ratio

see odds ratio.

fetal death ratio

the number of fetal deaths divided by the number of live births.

gain ratio

individual animal's gain/average gain in group × 100.

lecithin-sphingomyelin ratio

the ratio of lecithin to sphingomyelin in amniotic fluid. See also lecithin, sphingomyelin.

odds ratio

see odds ratio.

rates ratio

the ratio between two rates. See odds ratio and relative risk ratio (below).

relative risk ratio

the ratio between the rate (of mortality or some such parameter) in one group of animals and the rate in another group, used as a standard and the comparison expressed as a ratio. See also relative risk.

sex ratio

the number of males in a population per number of females, usually stated as the number of males per 100 females.

S/P ratio

secondary-to-primary ratio. An indicator of fleece type in sheep, the greater the ratio the finer the fleece. Coarse-wool sheep have ratios of 3:1 to 4:1; merinos have a ratio of 20:1.

stillbirth ratio

the ratio of stillbirths to total births in the population.

urea excretion ratio

the ratio of the amount of urea in the urine excreted in one hour to the amount in 100 ml of blood. The normal ratio is 50.