Total and unconjugated plasma estriol. A comparison.

Total and unconjugated plasma estriol levels from the 24th to the 40th gestational week in 161 normal and 44 pathological pregnancies were studied. A lack of correlation between the two fractions was observed at the different gestational ages, probably due to the different rates of the several metabolic steps which condition the levels of the hormone fractions also in quite physiological conditions. The onset of pregnancy complications further modifies the ratio between the two fractions, as they differently affect the single metabolic processes which are essential for estriol to be produced, conjugated, recovered and excreted. E.P.H. gestosis and poor intrauterine fetal growth can be better diagnosed by the assay of total than unconjugated estriol: the total fraction proved to have the higher sensitivity, predictive value and relative risk and should therefore be preferred for pregnancy monitoring, as it better corresponds to the clinical situation.

What are the most suitable fetoplacental tests in the monitoring of the third trimester of pregnancy?

The case-series of the Institute of Obstetrics and Gynaecology were examined to evaluate the suitability of urinary estriol, total plasma estriol, unconjugated plasma estriol, unconjugated plasma estetrol, plasma placental lactogen, plasma S.P.-1 glycoprotein, plasma alphafetoprotein and biparietal diameter in correctly forecasting the perinatal risk, when performed after the 25th week of pregnancy. In high-risk pregnancies, according to our results, S.P.-1 glycoprotein and urinary estriol are the most sensitive tests, while S.P.-1 glycoprotein, placental lactogen and biparietal diameter are found to have the highest predictive value. The repetition of the considered tests increases their sensitivity, but not their predictive value. In pregnancy mass screening the most suitable tests, on the basis of the "relative risk" are S.P.-1 glycoprotein (or even placental lactogen), estriol and biparietal diameter. For the last one a single measurement seems to be enough during the third trimester.