Amniotic Fluid Alpha-fetoprotein Levels Research Articles

Sonography as a procedure complementary to alpha-fetoprotein testing for neural tube defects.

Forty-four fetuses were studied sonographically because of an elevated amniotic fluid alpha-fetoprotein level noted during routine amniocentesis, questionable findings during an ultrasound examination at another institution, or a history of a neural tube defect in prior pregnancy. Eleven neural tube defects, 16 non-neural tube defect anomalies, and 17 normal fetuses were all correctly identified by sonography. Ultrasound answers the need for a second diagnostic tool to complement the alpha-fetoprotein measurement.

Stage II ultrasound examination for the diagnosis of fetal abnormalities with an elevated amniotic fluid alpha- fetoprotein concentration

Previous studies have indicated that patients with elevated levels of amniotic fluid alpha-fetoprotein (AFAFP) are at very high risk for fetal neural tube defects. Twenty-eight patients whose levels of AFAFP were >3 standard deviations above the mean were evaluated wifh a Stage It ultrasound examination for detailed assessment of fetal anatomy. In 16 patients with AFAFP levels >5 SD above the mean, six fetuses with open spins bifida were identified (37.5%). Moreover, in four fetuses in this group, the diagnosis was ventral wall defects (two with gastroschisis and two with omphalocele), and one fetus had multiple lethal anomalies. The other 5 patients had normal scans, and, with the exception of one patient who was delivered of a nondysmorphic stillborn infant at 28 weeks, all had normal infants at birth. Among the other 12 patients with AFAFP levels between 3 and 5 SD above the mean, there were only two adverse findings—an intrauterine death and an omphalocele. A Stage II ultrasound examination performed when AFAFP levels are elevated enables one to distinguish between conditions which are lethal or associated with significant impairment and those which are amenable to surgical procedures. Morphologically normal fetuses can also be identified. Since this diagnostic technique will allow salvage of many pregnancies that otherwise would be aborted, it should be an integral part of any alpha-fetoprotein screening program.

Affinity chromatography of amniotic fluid alphafetoprotein using concanavalin A-sepharose.

We measured Concanavalin A (Con A) non-binding alphafetoprotein in amniotic fluid from 21 normal pregnancies and 20 abnormal pregnancies (complicated by anencephaly, spina bifida, or exomphalos) using small Con A-sepharose chromatography columns. There was a highly significant difference between percentage non-binding alphafetoprotein levels for pregnancies with a normal outcome (mean result 32%; range 18-47%) and pregnancies complicated by a neural tube defect or exomphalos (mean 14%; range 7-20%). The test is therefore of potential value in cases where there is uncertainty over the interpretation of total amniotic fluid alphafetoprotein levels.

Congenital malformation syndromes and elevation of amniotic fluid alpha-fetoprotein.

Fetal malformations may introduce complications of maternal pregnancy. A polyhydramnios represents one such complication during pregnancy. We want to report five abnormal pregnancies which were marked by acute polyhydramnios and/or premature labor due to an amniotic band syndrome associated with cerebral herniation in two cases, malignant oral teratoma in one case, bilateral cystic hygromas associated with generalized fetal hydrops in one case, and multiple internal malformations in one case alpha-fetoprotein (AFP) values between the 25th and 34th week of gestation were elevated 3.5 to 44 times the normal median value. Since all fetuses showed severe malformations incompatible with life our observations indicate the necessity to determine AFP in cases of acute polyhydramnios independent of the week of gestation. Conversely, elevated AFP levels in amniotic fluid obtained during prenatal diagnosis in the 16th week of gestation may also suggest rare fetal malformations outlined above.

Prenatal Diagnosis of Congenital Nephrosis in 23 High-Risk Families

AULA, PERTTI; RAPOLA, JUHANI; KARJALAINEN, OLAVI; LINDGREN, JAN; HARTIKAINEN, ANNA L. and; SEPPÄLÄ, MARKKU Author Information

Prenatal diagnosis of congenital nephrosis in 23 high-risk families.

The efficacy of maternal serum and amniotic fluid alpha-fetoprotein (AFP) estimation for the prenatal detection of congenital nephrosis was assessed in 23 pregnancies of couples with a previously affected child. At 15 to 18 weeks' gestation, amniotic fluid AFP concentration was elevated in seven of 23 cases, and maternal serum AFP level in five of these. Legal abortion was carried out at 18 to 19 weeks in all those cases where he amniotic fluid AFP concentration was abnormally high, and in all cases the fetus was found to be affected. The diagnosis of intrauterine congenital nephrosis was obvious by electron microscopic examination of the fetal kidney, but not by light microscopy. The child was born without congenital nephrosis in all 16 cases where amniotic fluid AFP level was normal, and in 16 of 18 cases (89%) where maternal serum AFP concentration was normal. Thus, the amniotic fluid AFP assay is more reliable and is recommended whenever congenital nephrosis is suspected on the basis of family history.

Raised alpha-fetoprotein levels in amniotic fluid and maternal serum associated with distension of the fetal bladder caused by absence of urethra.

Raised alpha-fetoprotein concentrations were found at 29 and 30 weeks' gestation in the amniotic fluid and maternal serum of a woman who presented in her seventh pregnancy with apparent polyhydramnios. The fetus had multiple abnormalities including gross distension of the bladder resulting from absence of the urethra, intestinal artresia, and a congenital heart defect.

False positive amniotic fluid alpha fetoprotein levels resulting from contamination with fetal blood: Results of an experiment

The finding of an elevated level of alpha fetoprotein (AFP) in amniotic fluid is of value in the prenatal diagnosis of open neural tube defects. The present study was done to determine the amount of fetal blood required in amniotic fluid to produce a significant and misleading increase in AFP. Fetal blood was obtained at hysterotomy, and measured volumes were added to amniotic fluid samples. Betke-Kleihauer tests, red cell counts, and AFP determinations were done. On the average, at 16 weeks' gestation, contamination of 5 ml. of amniotic fluid with 22 μl of fetal blood will result in an increase in AFP of 1.6 mg. per deciliter. Fetal cells in a much lower concentration can readily be detected by the Betke-Kleihauer technique. A Betke-Kleihauer test and red cell count should be done on all blood-stained amniotic fluid samples to determine the amount of fetal blood present. The contribution of the fetal blood AFP can then be estimated and must be considered in the interpretation of the total amniotic fluid AFP result.

Alpha-fetoprotein (AFP) levels in maternal serum and amniotic fluid in singleton pregnant women in their 10th-25th week post last menstrual period.

A rapid paper disk radioimmunoassay of the sandwich type was used to determine the levels of alpha fetoprotein (AFP) in 826 maternal serum samples derived from an equal number of singleton pregnant women prospectively investigated during their 10th-25th week past last menstrual period (LMP). In addition 396 amniotic fluid (AF) samples from the 14th-20th week post LMP were analyzed. Theoretical ranges of normal AFP variation are presented. The extreme range of AFP in serum samples from 236 nonpregnant blood donors varied fron .2-18.3 mcg/liter. Variability of AFP in maternal serum samples increased considerably with gestational progress. A specific low cut-off could not be defined until Week 15 post LMP because of the overlap between distribution of AFP levels in the pregnant and nonpregnant populations studied. However from Week 15 post LMP a feasibly low and decreasing frequency of maternal serum samples from normal pregnancies still had an AFP value below 10 mcg/liter; this value also represented the upper limit for 98.5% of the nonpregnant population. Thus 10 mcg/liter was found to be a useful cut-off from the 15th post LMP week below which pregnancy complications or severe gestation age miscalculations could be deduced. For AF AFP values a strong negative correlation between gestational age and AFP levels was found at least up to Week 20 post LMP.

Antepartum evaluation of the high-risk fetus: problems and prospects.

The chief obstetrical problems encountered today in the prenatal evaluation of the high-risk fetus are presented. Advantages and pitfalls or recent techniques utilized in the management of the high-risk pregnancy are discussed. They include: a prenatal scoring system for identifying the high-risk population; examination of the karyotype of cells in amniotic fluid, and quantitation of alpha-fetoprotein levels in maternal plasma and amniotic fluid for the early prenatal detection of birth defects; ultrasonography for the intrauterine diagnosis of fetal growth retardation and assessment of fetal maturity; the use of maternal urinary estriol excretion, maternal plasma human placental lactogen levels and the oxytocin stress test for the early detection of fetal distress; estimation of fetal maturity by amniotic fluid analysis of lecithin or lecithin-sphingomyelin ratios, creatinine and Blue Nile fetal cell staining. Newer, still experimental, techniques (e.g., fatal breathing movements, fetoscopy, and dehydroepiandrosterone plasma clearance) are viewed in light of further possible decreases in maternal and perinatal mortality.

Alphafetoprotein by Radioimmunoassay in Maternal Serum and Amniotic Fluid

Summary: The use of a competitive inhibition radioimmunoassay allows the measurement of alphafetoprotein (AFP), a specific a‐globulin produced by fetal and malignant liver cells, in serum and amniotic fluid at low concentrations of ng/ml. In normal pregnancy, mean AFP levels in maternal serum showed a slow rise, from undetectable levels (less than 20 ng/ml) before 12 weeks of gestation, to a maximum at 30 weeks. After that, there was a comparable decline in levels for the remainder of pregnancy, up to 42 weeks. From 14 weeks there was a wide variation in individual AFP values at all stages of gestation, but most of them fell within 2 standard deviations above the mean.A correlation was found between AFP levels in samples of maternal serum and amniotic fluid taken simultaneously, with levels in amniotic fluid reading at least 50% higher. AFP levels in amniotic fluid in late pregnancy corresponded to the lecithin/sphingomyelin ratio in an inverse relationship.

Sounding board: Antenatal diagnosis, alpha fetoprotein and the FDA.

Elevated amniotic fluid alpha fetoprotein (AFP) levels have been associated with neural tube defects and may be associated with fetal death, omphalocele, and congenital nephrosis. AFP levels determined in 2694 cases where amniotic fluid samples were obtained for routine antenatal genetic studies resulted in the detection of 9 cases (1 in 300) of open neural tube defects. Thus AFP determination is important in every second trimester amniotic fluid sample obtained. However, the U.S. Food and Drug Administration (FDA) banned the commercial distribution of serologic reagents for AFP testing in 1973, thereby limiting availability of AFP assays to a few large centers. The FDA should establish criteria to license AFP reagents immediately so that they may be available for routine use.

Alpha-fetoprotein levels in maternal plasma and amniotic fluid during prostaglandin-induced mid-trimester abortions: the relation to fetal distress and death.

Alpha-fetoprotein (AFP) levels were measured in both plasma and amniotic fluid during 43 abortions induced with prostaglandin F2alpha (PGF2alpha) and their relationship to the induction-abortion interval and signs of fetal distress or intrauterine death examined. The mean plasma AFP levels showed a progressive rise after PGF2alpha administration but abnormally high levels were found infrequently until the time of delivery. Feto-maternal bleeding could explain the abnormally high plasma AFP levels which occurred early in a few cases. A shorter induction-abortion interval was found in patients with normal plasma AFP levels. Neither fetal distress nor intrauterine death were associated with abnormally high plasma AFP levels. No change in AFP levels in amniotic fluid was found.

Alpha-fetoprotein levels in amniotic fluid in pregnancies complicated by rhesus isoimmunization.

SummaryAlpha‐fetoprotein (AFP) has been estimated in 249 samples of amniotic fluid from 71 patients, 60 of whom had rhesus isoimmunization. No difference was found between the AFP levels in unaffected pregnancies, pregnancies complicated by mild or moderate disease or in severe rhesus isoimmunization when the baby survived. However, in the severe group with an unfavourable fetal outcome, 42 per cent of the cases had amniotic fluid levels of AFP which were above 5.5 mg. /ml. on one or more occasions. In the most severely affected cases a correlation existed between the amniotic fluid AFP levels and both the optical density difference (Δ) at 450 mμ and protein concentration in the liquor amnii. Erroneously elevated amniotic fluid levels of AFP may be found when the fluid has been contaminated by ascitic fluid or fetal blood. It is suggested that the level of AFP in amniotic fluid taken in conjunction with the Δ 450 mμ, peak might be a valuable guide in identifying the severely affected pregnancy in which the fetal prognosis is grave.