Serum Alpha-fetoprotein Screening Research Articles

What participants understand about a maternal serum alpha-fetoprotein screening program.

We investigated the knowledge of pregnant women participating in a maternal serum alphafetoprotein (MSAFP) screening program for the detection of neural tube defects (NTDs) in the fetus. Women participating in the screening program scored higher on two knowledge tests than a comparison group of pregnant women who were not offered screening. However, there were substantial gaps in the knowledge base of women in the program, as measured by one of the tests. Women did not misinterpret a negative test result to mean that the test had identified a potential problem with the fetus; instead, there is a suggestion that they tended to interpret a negative result too positively, as an assurance that the baby was healthy in all respects.

Effect of Chorionic Villus Sampling on Serum Alpha Fetoprotein Levels

Chorionic villus sampling (CVS) is a recent advance in prenatal diagnosis in the first trimester. maternal serum alpha fetoprotein (AFP) screening for neural tube defects is done from 14-17 weeks gestation. Previous studies have shown an elevation of AFP levels following amniocentesis. The aim of this study was to determine the effect of CVS on AFP levels immediately following this procedure. CVS was performed under sonographic guidance on 22 patients between 6 and 12 weeks gestation undergoing elective termination of pregnancy. A Portex catheter was used for obtaining villi. Maternal serum AFP levels were ascertained before and after CVS by radioimmunoassay. In the group of patients 8 weeks or less, no change in AFP levels was seen; in patients greater than 8 weeks gestation, a significant rise in post-biopsy AFP level was noted in 7 of 14 patients. Further studies are planned to clarify the effect of CVS on AFP levels in patients with ongoing pregnancies. Clarification of this issue is important to the role of CVS in prenatal screening.

Pentamidine and Renal Toxicity

Pentamidine and Renal Toxicity

Results and benefits of a maternal serum alpha-fetoprotein screening program

Results and benefits of a maternal serum alpha-fetoprotein screening program

MATERNAL‐SERUM‐ALPHAFETOPROTEIN SCREENING FOR FETAL MALFORMATIONS IN 28062 PREGNANCIES

From 1st March, 1980 and up to 29th February 1984 a multicenter serum alpha-fetoprotein (S-AFP) screening project was carried out for the detection of severe fetal malformations. S-AFP was determined by a radio-immunoassay in 28 062 pregnant women between the 16th and 20th week of gestation. Patients with elevated S-AFP values, e.g. above 95 percentile, were examined further with a second S-AFP and by ultrasound scan. 244 amniocenteses (0.9%) were carried out to detect 62 malformations (21 anencephalies, 14 spina bifidas, 2 encephaloceles, 7 omphaloceles, 5 gastroschises, 4 chromosome abnormalities and 9 other malformations). Fifteen of the 16 cases of spina bifida could not be verified by ultrasound scan, whereas all other malformations except chromosome abnormalities were confirmed by ultrasonography. Two cases of spina bifida and one case of skin-covered encephalocele had normal S-AFP concentrations and were therefore not detected. There were no definitive false-positives, e.g. therapeutic abortion of a normal fetus. Our conclusion is that a nationwide S-AFP screening should be recommended.

The impact of maternal serum alpha fetoprotein screening on open neural tube defect births in North‐East Scotland

Over the three years period 1980-1982, 18 256 pregnancies in the Grampian Region of N-E Scotland including the islands of Orkney and Shetland were screened for raised levels of maternal serum alpha fetoprotein (MSAFP) in the second trimester. Thirty six cases of fetal open neural tube defect in singletons were detected (18 anencephaly and 18 spina bifida). Four additional cases of open spina bifida were associated with normal MSAFP levels although two of these were detected by amniotic fluid AFP measurement when amniocentesis was carried out because of previous NTD history. A further three cases of open spina bifida and two of anencephaly occurred in unscreened pregnancies. The MSAFP screening programme alone was thus instrumental in reducing the birth incidence of open neural tube defects by 36 out of 45 cases (80 per cent) in singletons.

Some aspects of late abortion for congenital abnormality.

Present methods of prenatal diagnosis are not applicable until at least 16 weeks of gestation. Most abortions for suspected congenital abnormality are therefore usually done in the second trimester of pregnancy. Abortions at over 20 weeks of gestation account for about 0.8% of all abortions for residents of England and Wales, but the operations are unpleasant and carry a significant morbidity. Screening the population for neural tube defects has led to a marked reduction in the recorded incidence of infants born with the condition. A survey in the Northern Region of England, with official statistics from Scotland, shows that in spite of the contribution made by selective abortion, there appears to be a genuine reduction in the population incidence of neural tube defect in Scotland. The diagnosis of chromosomal abnormalities, and to a lesser extent of neural tube defects, depends on amniocentesis and there is evidence of more delay in initiating amniocentesis for neural tube defect than for chromosomal tests, probably because of administrative delay associated with the use of serum alphafetoprotein screening. The possible impact of proposals to change the law concerning the limit of viability of the fetus on the practice of late abortion for congenital abnormality is examined. Abortion for congenital abnormality should be permitted after 22 weeks' gestation.

Maternal serum alpha-fetoprotein screening for neural tube defects. Report of a combined study in Germany and short overview on screening in populations with low birth prevalence of neural tube defects.

The basis of maternal serum alpha-fetoprotein (AFP)-screening for neural tube defects is discussed. A report is given of a large scale screening study in the Federal Republic of Germany combining the experiences in Giessen and Hannover on over 50,000 pregnant women, about evenly distributed among both centers. Published and known forthcoming data from other low incidence populations, particularly of European countries, are reviewed briefly. The conclusion is reached that general screening could effectively be instituted and in the final result should also be cost-beneficial.

Results and Benefits of a Maternal Serum α-Fetoprotein Screening Program

Maternal serum alpha-fetoprotein (MSAFP) screening was offered in a private suburban practice to 21,000 nondiabetic and 442 diabetic women with apparently normal pregnancies. Using 2.5 or greater multiples of the median as the normal upper limit, 249 (1.2%) had a raised MSAFP level. There were 25 neural tube defects (NTDs) (1.2/1,000 births); 18 were detected by screening and two by ultrasound scanning. Three had closed spina bifida lesions. Two had anencephaly with normal MSAFP levels, but were studied at more than 24 weeks' gestation. An additional 13 with raised MSAFP levels had other congenital defects. One in 400 women screened had a recommended amniocentesis; 26.4% of them had a fetus with an NTD or major malformation. Our detection efficiency before 24 weeks' gestation for anencephaly was 85.7% (12/14), 62.5% (5/8) for open and closed spina bifida, and 1/1 for encephalocele. A raised MSAFP level occurred in ten (2.3%) of the 442 diabetic women, four (0.9%) of whom had a fetus with an open NTS. A screening program should be established only where there is linked excellent interdisciplinary support among obstetrician, laboratory, clinical geneticist, ultrasonographer, and an identified program coordinator.

Results and benefits of a maternal serum alpha-fetoprotein screening program

Results and benefits of a maternal serum alpha-fetoprotein screening program

Ultrasound screening for structural defects in early pregnancy.

Since 1975, the primary method of antenatal diagnosis of structural defects has been by ultrasound visualisation. Improvements in equipment and operator experience have progressively increased the confidence and reliability of this technique which in 1982 provided a 100% detection rate. (Alternative methods are relatively costly and in our opinion, unsatisfactory). Total population screening for structural defects is entirely feasible by ultrasound and acceptable to the patient. Serum alpha feto-protein screening techniques are less reliable- generate unnecessary anxieties, and have given no supplementary assistance to detection rates in our experience. Ultrasound is considered to be the best screening technique available to the obstetrician for the detection of structural defects in early pregnancy and obviates the use of amniocentesis as a confirmatory procedure.

Elevated maternal serum alpha-fetoprotein, second-trimester oligohydramnios, and pregnancy outcome.

Although the primary purpose of maternal serum alpha-fetoprotein (AFP) screening is to detect open neural tube defects, the technique is of value in the diagnosis of other fetal abnormalities. Six patients from the Alpha-Fetoprotein Screening Program, Perinatal Region IV, were found to have twice elevated maternal serum AFP levels associated with severe early second-trimester oligohydramnios. Five of the fetuses were found to have urinary tract abnormalities. The source of the elevated maternal serum AFP is not clear. Pregnancy prognosis appears poor. These cases should be thoroughly studied so that patients may be accurately informed of the recurrence risk.

Anxiety concerning fetal malformations in women who accept or refuse alpha-fetoprotein screening in pregnancy

Degrees of anxiety concerning fetal malformations were assessed by self-rating on Visual Analogue Scales in early, mid, and late pregnancy in 263 women who agreed to take part in a serum alpha-fetoprotein (AFP) screening program. Women who refused to undergo the test were found to have similar distributions of degrees of anxiety throughout pregnancy. Women with normal AFP-test results showed a significant decrease of anxiety between the assessments in early and mid pregnancy. The distributions in mid and late pregnancy were similar. In early pregnancy the women who refused the test displayed less anxiety than women who accepted the test. In mid-pregnancy the refusing women and the women with normal test results showed similar degrees of anxiety, but on this occasion women with initially abnormal test results displayed even less anxiety than other women. Increased attention to the women with abnormal test results during the period of the investigation together with an altered frame of reference with respec...

The reduction of anencephalic and spina bifida births by maternal serum alphafetoprotein screening.

The reduction of anencephalic and spina bifida births by maternal serum alphafetoprotein screening.

Effect of estimating gestational age by ultrasound cephalometry on the specificity of alpha-fetoprotein screening for open neural-tube defects.

A total of 1268 women had a maternal serum alpha-fetoprotein (AFP) screening test for open neural-tube defects between 15 and 22 weeks gestation and a routine ultrasound examination at their first antenatal visit. All had a singleton infant without a neural-tube defect. AFP values were expressed as multiples of the normal median at the relevant gestational age (MoM). The percentage of women with raised maternal serum AFP levels was less when gestation was estimated by the fetal biparietal diameter (BPD) than when the time since the first day of the last menstrual period (LMP) was used; 1.8% compared with 2.3% at a serum AFP cut-off level of 2.5 MoM. Different ultrasound policies were compared for their effect on AFP screening and the best was found to be routine BPD measurement used together with a higher cut-off level than usual. For example, using a cut-off level of 3.0 MoM the detection rate for open spina bifida at 16-18 weeks gestation would be about 88% and the proportion of unaffected singleton pregnancies with raised levels only 0.9%. These results are materially better than those achieved by a policy of scanning only those women with a raised AFP level (79% and 1.4% respectively with a more conventional cut-off level of 2.5 MoM) or, in addition, scanning those with doubtful gestational ages (82% and 1.7% respectively with a cut-off level of 2.5 MoM).

Prenatal diagnosis of neural tube defects: VIII. The importance of serum alpha-fetoprotein screening in diabetic pregnant women

Maternal serum alpha-fetoprotein (AFP) screening of routine pregnancy is a valuable tool for the prenatal detection of neural tube defects (NTDs). Against our background experience with >24,000 screened pregnancies, we have studied 411 pregnant insulin-dependent diabetic women. More than a tenfold increase (19.5/1,000) in the frequency of NTDs was observed m the offspring of these diabetic patients (p < 0.000001). Serum AFP values were tower in diabetic than in nondlabetic women. Our data indicate that the normal standard of care for diabetic pregnancy should include serum AFP screening.

AMNIOTIC FLUID CHOLINESTERASE MEASUREMENT AS A RAPID METHOD FOR THE EXCLUSION OF FETAL NEURAL-TUBE DEFECTS

Amniotic fluid total cholinesterase (ChE) and acetylcholinesterase (AChE) activities have been measured in 404 pregnancies without fetal malformation and 79 pregnancies associated with open neural-tube defects (NTDs). Neither measurement, either alone or in combination, gave complete separation of the two groups. However, measurement of ChE can be used to assess the probability that a woman is carrying a fetus with an open NTD. Since ChE can be measured within 15 minutes and shows at least 70% of women selected for amniocentesis by serum alpha-fetoprotein screening to have a less than 1 in 1000 chance of carrying a fetus with an open NTD, we suggest that this test may be used in an amniocentesis clinic both to reassure women with normal pregnancies and to select probable abnormalities for immediate further investigation.

Maternal serum alpha-fetoprotein screening: A report of the Forsyth County Project

A pilot screening program for the prenatal detection of neural tube defects has been conducted in Forsyth County, North Carolina. During the first 2 years of the program, 3,476 women were screened by quantitating levels of maternal serum alpha fetoprotein. Three neural tube defects and one case of multiple congenital anomalies with severe gastroschisis were detected as a result of the screening program. Outcome of pregnancy has been monitored in this group of women and no false negatives have been reported. No false positive amniotic fluid alpha-fetoprotein values were observed and no normal fetuses were aborted. Data gathered from this screening program again document the validity of maternal serum screening. The method of implementing a program for the prenatal detection of neural tube defects in urban areas is discussed.

Pregnancy-specific β1-glycoprotein as a screening test for at-risk pregnancies

A serum assay was performed on 605 women for pregnancy-specific β1-glycopcotein (SP-1) between 31 and 34 weeks’ gestation. SP-1 was also estimated for 255 of these women between 15 and 20 weeks’ gestation, coincidental with maternal serum alpha-fetoprotein (AfP) screening. A clinical classification of pregnancy outcome was constructed for each group. SP-1 values at 31 to 34 weeks’ gestation in pregnancies that resulted in the birth of a small-for-dates (SFD) infant were statistically different from those in normal pregnancies (p < 0.001). value of 100 mg per liter was chosen as suitable discriminatory level 31 to 34 weeks, below which SP-1 had a sensitivity of 64% a predictive value of 24% and defined a relative risk of 5.3 for SFD infants.These parameters compare favorably with published data on the use of human palcental lactogen as a screening test. No statistical relationship was found between SP-1 va1ues at 31 to 34 weeks weight, and birth weight placental weight, parity, or other abnormal pregnancy outcomes. SP-1 screening at 15 to 20 weeks’ gestation showed no correlation with serum AFP or with other parameters studled. (Am. J. Obstet. Gynecol. 141:499, 1981.)

Maternal serum alphafetoprotein in pregnancy and the prevention of birth defect.

Screening by measurement of the maternal serum alphafeto protein is the first genetic tool that could be applied to the entire pregnant population, so the recent report from a working group on maternal serum alphafetoprotein screening2 prompts us to attempt to put into perspective, firstly, an assess ment of the benefits and risks of maternal serum alphafeto protein screening programmes in averting the birth of affected babies; secondly, the value that such programmes may coincidentally have in identifying high-risk but salvageable fetuses; and, thirdly, the possibility of true prevention of neural tube defect by supplementing the mother's diet. Alphafetoprotein and the fetus?Alphafetoprotein is a normal fetal protein that passes into the amniotic fluid, rising to a peak at the end of the first trimester and then declining rapidly. The alphafetoprotein derived from the fetus can be detected in the maternal serum in concentrations about 100-fold less than in the amniotic fluid. The serum concentrations continue to rise until the third trimester and then fall to normal non-pregnant concentrations at delivery.3 Brock and Sutcliffe4 first reported high concentrations of amniotic alphafetoprotein in association with open neural tube defect and this has been repeatedly confirmed.5-7 The concentration of the protein in the mother's serum also rises with a fetal neural tube defect; but there are several other causes for such a rise, including other fetal malformations, multiple pregnancy, threatened abortion, intrauterine death, and (frequently) incorrect assessment of gestational age. When a raised value is found during pregnancy further investigations are carried out, including a repeat estimation and an ultrasound scan to verify the gestational age. In the absence of any other cause for a raised concentration, amniocentesis is performed. A raised amniotic alphafetoprotein concentration is found in about 10% of these cases and usually means that a fetal defect is present, most often an open neural tube defect. In the remaining 90% of