Amniotic Fluid Alpha-fetoprotein Concentration Research Articles

Alpha-fetoprotein and albumin in experimentally-induced exencephaly in the rat.

Alpha-fetoprotein and albumin were quantified in the sera and amniotic fluids from control, Vitamin A-treated non-exencephalic and Vitamin A-treated exencephalic rat fetuses. Exencephaly was associated with amniotic fluid alpha-fetoprotein concentrations which were significantly elevated over those of Vitamin A-treated non-exencephalic and of untreated fetuses. Amniotic fluid albumin concentrations also were higher in the exencephalic fetuses than in the non-exencephalic fetuses. Serum alpha-fetoprotein and albumin concentrations were lower in the exencephalic than in the non-exencephalic fetuses. The results are cosistent with simple diffusion across a defective barrier as the cause of elevated amniotic fluid alpha-fetoprotein concentrations in the presence of open neural tube defects. This experimental model of neural tube defects result in changes in amniotic fluid alpha-fetoprotein similar to those changes found in human amniotic fluid alpha-fetoprotein concentrations in the presence of neural tube defects.

Alpha-fetoprotein concentration in amniotic fluid during the last trimester in normal pregnancies and in pregnancies with severe fetal abnormalities.

The concentration of alpha-fetoprotein (AFP) in the amniotic fluid was studied during the last trimester of pregnancy. 129 samples of amniotic fluid were collected by transabdominal amniocentesis in 94 pregnant women. Only women with uncomplicated pregnancies giving birth to normal infants at term were included. The 90% reference interval was calculated and a distinct decrease in the amniotic fluid AFP concentration was found during the last trimester. An AFP concentration above the 90% reference interval was found in 8 out of 10 cases of anencephaly. Normal AFP concentration was found in a case of congenital heart disease with severe oedema, and a low concentration was found in a case of Down's syndrome (Trisomy 21).

THE VALUE OF ALPHA-FETOPROTEIN IN THE PRENATAL DIAGNOSIS OF NEURAL TUBE DEFECTS

The normal range of alpha-fetoprotein (AFP) concentrations in amniotic fluid during the second trimester of gestation is documented from a study of 482 normal pregnancies. Additional specimens of amniotic fluid were examined from (1) 43 mothers who were at risk for having offspring with one of the neural tube defects, (2) 24 women whose pregnancies were monitored by routine prenatal genetic studies and who had fetuses with hereditary or congenital abnormalities, (3) eight pregnancies in which fetal death had occurred, (4) nine pregnancies with significant obstetric complications, and (5) 11 pregnancies with fetuses affected by neural tube defects. Although the specificity, validity, and applicability of AFP concentrations in amniotic fluid require further study, it is apparent that AFP estimations thus far represent the most significant advance in the early detection of these defects.

The value of alpha-fetoprotein in the prenatal diagnosis of neural tube defects

The normal range of alpha-fetoprotein (AFP) concentrations in amniotic fluid during the second trimester of gestation is documented from a study of 482 normal pregnancies. Additional specimens of amniotic fluid were examined from (1) 43 mothers who were at risk for having offspring with one of the neural tube defects, (2) 24 women whose pregnancies were monitored by routine prenatal genetic studies and who had fetuses with hereditary or congenital abnormalities, (3) eight pregnancies in which fetal death had occurred, (4) nine pregnancies with significant obstetric complications, and (5) 11 pregnancies with fetuses affected by neural tube defects. Although the specificity, validity, and applicability of AFP concentrations in amniotic fluid require further study, it is apparent that AFP estimations thus far represent the most significant advance in the early detection of these defects.

Elevated amniotic fluid alpha fetoprotein in fetal hydrocephaly

This report associates fetal hydrocephaly with high-for-dates alpha fetoprotein (AFP) values in amniotic fluid (AF) in 4 cases. All 4 hydrocephalic pregnancies showed abnormally high AF AFP concentrations (440 1800 7300 and 4750 vs. normal range of 15-340 ng/ml). Cerebrospinal fluid (CSF) was obtained from 3 fetuses. 2 contained a high AFP concentration (6400 and 148000 ng/ml); in both cases AF AFP was greatly elevated (7300 and 1800 ng/ml). In the 3rd case the moderately elevated AF AFP (440) was associated with a similar level (345 ng/ml) in fetal CSF. The total protein concentration was abnormally high in all CSF samples but no correlation existed between the total protein and AFP in either CSF or AF. AFP in maternal and fetal sera were within normal pregnancy range. The AFP level of newborn urine (23 ng/ml) was similar to previously measured normal infant urine values. The significance of high AFP on the prognosis of these infants cannot be indicated by these results because all infants died at or shortly after delivery. Prospective studies aimed at early antenatal detection of hydrocephaly by AF AFP are warranted.