Combination of elevated maternal serum alpha-fetoprotein (MSAFP) and low estriol is highly predictive of anencephaly

Increased levels of second trimester maternal serum alpha-fetoprotein (MSAFP) have long been established as a marker for neural tube defects (NTDs). In addition, decreased levels of maternal estriol in the third trimester have been reported in pregnancies with anencephalic fetuses. The purpose of this study was to evaluate whether early second trimester unconjugated serum estriol (uE3) is an independent predictor of NTDs. The study included 57,031 patients who underwent maternal serum screening with MSAFP at 14–22 weeks gestation. Of these, 23,415 also had uE3 measurements. There were 63 cases of NTD, an overall incidence of 1.1 per 1,000. Elevated MSAFP (≥2.5 MOM) was detected in 1,346 patients, 48 of which had NTDs. Decreased uE3 (≤0.5) was detected in 1,437 patients, 17 of which had NTDs. The incidence of NTDs was significantly higher in patients with low uE3, compared to patients with normal/high uE3 (1.15% vs. 0.09%, P < 001). Finally, 51 patients had both increased MSAFP and decreased uE3; 16 of these had NTDs, 14 of which were anencephalics. In conclusion, both elevated MSAFP and low maternal serum estriol are predictive of NTD but have a low sensitivity. The combination of abnormally elevated MSAFP and low estriol is highly predictive of NTD in particular anencephaly. Am. J. Med. Genet. 75:297–299, 1998. © 1998 Wiley-Liss, Inc.     

Predictive value of the triple screening test for the phenotype of Down syndrome.

Maternal serum alpha-fetoprotein (MSAFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) are routinely measured in the second trimester ("triple" test) and combined with maternal age to evaluate risk for fetal Down syndrome. Triple test results and clinical findings were retrospectively reviewed for 30 newborns with Down syndrome to determine whether analyte values or second trimester risks for Down syndrome were more extreme in affected pregnancies where cardiac or other severe congenital malformations were present compared to those cases where major anatomical abnormalities were absent. Mean MS-AFP, uE3, maternal age, and second trimester Down syndrome risk were all similar in the two groups of pregnancies. However, hCG concentrations did appear to be higher in the group of Down syndrome pregnancies with anatomical anomalies (mean 1.74 MoM versus 1.19 MoM) (P<0.05). Overall, there was no significant difference in the incidence of major anomalies in patients with screen-positive test results versus those cases that were not identified by the triple test. Prenatal counseling should therefore reflect the general expectations of the Down syndrome phenotype that have been established from live-born infants with this disorder.     

Human chorionic gonadotrophin and trisomy 18.

Estimation of maternal serum beta-hCG is used in conjunction with alpha-fetoprotein (AFP) and estriol (E3) for estimating the risk of Down syndrome (DS) affected fetuses. However, low hCG levels have not been regarded as having clinical significance. We report on 2 patients with trisomy 18 fetuses in whom antenatal screening showed extremely low hCG levels (0.05 and 0.15 MOM). Low hCG levels might indicate increased risk for trisomy 18 despite low estimated risk for DS.     

Human chorionic gonadotrophin and trisomy 18

Estimation of maternal serum β-CG is used in conjunction with α-fetoprotein (AFP) and estriol (E₃) for estimating the risk of Down syndrome (DS) affected fetuses. However, low hCG levels have not been regarded as having clinical significance. We report on 2 patients with trisomy 18 fetuses in whom antenatal screening showed extremely low hCG levels (0.05 and 0.15 MOM). Low hCG levels might indicate increased risk for trisomy 18 despite low estimated risk for DS.     

The prediction of adverse pregnancy outcome using low unconjugated estriol in the second trimester of pregnancy without risk of Down's syndrome

To investigate the relationship between low unconjugated estriol (uE3) levels in the second trimester and adverse perinatal outcomes in pregnancies without increased risk for Down's syndrome, 1,096 women under 35 years of age underwent a mid-trimester AFP-hCG-uE3 screening test between January 1995 and June 1998. Multiple pregnancies, maternal diabetes, smoking and elevation of AFP and hCG levels more than 2.0 multiple of median (MoM) were excluded from our study population. The results were divided into a low-uE3 group with uE3 levels at or below 0.75 MoM and a normal uE3 group with uE3 levels above 0.75 MoM. The risk for adverse pregnancy outcome was compared between the two groups and the role of low uE3 as a predictor of adverse pregnancy outcome was determined. The data were assessed using chi 2 or Fisher exact test and then logistic regression was used for the final analysis. The odds ratio (OR) and corresponding 95% confidence intervals (CI) were also calculated. Unconjugated E3 levels at or below 0.75 MoM was significantly associated with fetal growth restriction after adjustment for maternal age, weight, sampling weeks, AFP and hCG levels (OR 0.413, 95% CI 0.174-0.900; P = 0.035). Low uE3 levels in the second-trimester could help in the detection of fetal growth restriction by a low risk group in Down's syndrome. Careful gestational dating and serial clinical and sonographic assessment of fetal growth may be required for the clinician to manage these parturients.     

Effect of adjustment of maternal serum α-fetoprotein levels in insulin-dependent diabetes mellitus

Our objective was to determine the effect of the 20% upward adjustment of maternal serum alphafetoprotein (MSAFP) in patients with insulin-dependent diabetes mellitus (IDDM) on the number of patients that would be classified at increased risk for pregnancy complicated by either Down syndrome (DS) or neural tube defect (NTD). We retrospectively evaluated a database containing 63,110 patients who underwent multiple serum marker screening between 14 and 22 weeks gestation; 620 patients with IDDM had measurements of MSAFP of which 479 also had measurements of β-HCG, allowing calculation of DS risk. Increased NTD risk was defined as MSAFP >2.5 MOM while increased DS risk was defined as a calculated risk ≥1/270. One IDDM patient delivered an infant with a NTD; it was not detected on serum screening. No infants were born with DS. Of the 620 patients with MSAFP determinations, 9 had values >2.5 MOM before adjustment. After upward adjustment, 7 additional patients were identified. Sixteen patients were identified at increased risk for DS before and after adjustment. Our data suggest that the 20% upward adjustment of MSAFP increases by 78%, the number of patients who would require further evaluation for NTD's. Although we were able to identify 620 women with IDDM who underwent serum screening for NTD, the low prevalence of NTD's did not allow us to demonstrate an increased detection rate. The effect of upward adjustment of MSAFP on the number of patients categorized at increased DS risk appears to be minimal. Am. J. Med. Genet. 75:176–178, 1998. © 1998 Wiley-Liss, Inc.     

兰州地区孕妇孕中期产前筛查结果回顾性分析

目的通过检测孕妇血清中AFP,Free-βhOG和uE3的浓度,对孕中期胎儿患DS、ES和NTD的风险进行评估。方法运用时间分辨荧光法定量测定孕妇血清中AFP,Free-βhC6和uE,的浓度,采用“Life cycle 3．2”软件计算风险。结果9430例孕妇中高龄共289例,占总筛查人数的3．06％,其中DS、BS和NTD的阳性筛查率分别为5．4％（1／19）、0．21％（1／476）和O．32％（1／313）。确诊阳性病例19例,其中高龄lO例。结论孕中期母血清三联产前筛查是检测胎儿染色体异常的有效途径,对降低出生缺陷,提高人口素质有重要意义。     

Maternal serum alpha-fetoprotein and fetal trisomy-21 in women 35 years and older: implications for alpha-fetoprotein screening programs

A retrospective study of 3,411 women who underwent midtrimester amniocentesis for fetal chromosome analysis between June 1979 and August 1984 was performed to evaluate an association between low maternal serum alpha-fetoprotein (AFP) concentrations and Down syndrome (DS) pregnancies. A total of 71 pregnancies was found with abnormal fetal chromosomes; of these, 26 cases were trisomy-21 and 10 cases were trisomy-18. The maternal serum AFP in women with DS fetuses was relatively lower than levels in women with fetuses that had normal chromosomes. In addition, the AFP concentrations in amniotic fluid were decreased in cases involving DS fetuses. We have estimated the risks for DS pregnancy at all maternal ages and most serum AFP concentrations. Using these calculations, genetic counselors will be able to provide more accurate risk estimates for trisomy-21 following maternal serum AFP testing.     

Triple marker screening for fetal chromosomal abnormalities in Korean women of advanced maternal age

The purpose of this article is to assess the value of maternal serum triple marker screening of alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) for the prenatal diagnosis of fetal chromosomal abnormalities in Korean women of advanced maternal age. Maternal sera were collected from 458 pregnant Korean women aged 35 between 15 and 20 weeks gestation before amniocentesis. A patient- specific second trimester risk for fetal Down's syndrome was calculated using the median values for AFP, hCG, uE3 and maternal age. Twelve fetal chromosomal abnormalities were identified. These included six cases of trisomy 21, one case of 46,XY/47,XY,+21, two cases of trisomy 18, one case of trisomy 13, and two cases of 45, X. A cutoff level of 1:200 detected 85.7% (6/7) of the cases of Down's syndrome and 20% (1/5) of the other aneuploidies, with a 27.3% false positive rate. However, a cutoff level of 1:270 did not result in any gains in detecting Down's syndrome or other aneuploidies at the expense of a false positive rate of 34.3%. Second trimester triple marker testing is an effective screening tool for detecting fetal Down's syndrome in Korean women > or = 35 years old. However, it is not an effective screening tool for non-Down's chromosomal abnormalities.     

Maternal serum alpha-fetoprotein screening for Down syndrome: economic considerations

The economic consequences of using an index of maternal age and maternal serum alpha-fetoprotein (MSAFP) screening to indicate risk of Down syndrome (DS) are examined. If DS screening indicated solely by a given maternal age is economically justifiable, then amniocentesis indicated by a DS risk equivalent to that maternal age cutoff, but based on an index of maternal age (for ages below the cutoff) and low MSAFP results, is also economically justifiable. It is concluded that the extant use of MSAFP screening for DS is a move toward the cost-effective use of scarce resources that can be made available with coordinated planning. However, increased professional and public awareness may result in significant increases in aggregate demand for these services. While MSAFP screening for DS is economically justifiable, there exists some potential for bottlenecks at the aggregate level, and these should be considered in conjunction with recommendations that the technology be adopted on a widespread basis.     

Familial risk of congenital heart defect

The economic consequences of using an index of maternal age and maternal serum alpha-fetoprotein (MSAFP) screening to indicate risk of Down syndrome (DS) are examined. If DS screening indicated solely by a given maternal age is economically justifiable, then amniocentesis indicated by a DS risk equivalent to that maternal age cutoff, but based on an index of maternal age (for ages below the cutoff) and low MSAFP results, is also economically justifiable. It is concluded that the extant use of MSAFP screening for DS is a move toward the cost-effective use of scarce resources that can be made available with coordinated planning. However, increased professional and public awareness may result in significant increases in aggregate demand for these services. While MSAFP screening for DS is economically justifiable, there exists some potential for bottlenecks at the aggregate level, and these should be considered in conjunction with recommendations that the technology be adopted on a widespread basis.     

游离雌三醇在孕中期唐氏综合征筛查中的临床意义

目的探讨游离雌三醇（unconjugated estriol,uE3）在孕中期唐氏综合征筛查中的应用价值。方法采用时间荧光分辨免疫法测定孕中期母血清中甲胎蛋白（AFP）、游离人绒毛促性腺激素β亚单位（Free-β-hCG）和游离雌三醇水平,再采用随机配套的Wallac 2T专用风险评估软件进行教据分析,比较二联（AFP、Free-β-hCG）和三联（AFP、Free-β-hCG和uE3）唐氏综合征（Down＇s Syndrome,DS）筛查的检出率和假阳性率以评价uE3在Ds筛查中的应用价值。结果通过对绍兴妇保院2010年1月～2012年12月50188例孕中期孕妇进行产前筛查,筛查阳性检出DS 19例,漏诊7例,DS发病率1／1930;以1／270为阳性截断值,Ds三联和二联筛查方案的检出率分别为73.08％、61.54%,检出率没有明显提高,统计学上无显著差异（X2=O.79,P〉0.05）：DS三联和二联的筛查假阳性率分别为2.53％和4.15％,三联假阳性率明显低于二联（X2=204.18,P〈0.01）。结论孕中期在DS二联筛查的基础上增加uE3指标,能一定程度上提高DS检出率,能明显降低假阳性率,具有广泛的应用价值。     

Maternal serum hCG and SP1 in pregnancies with fetal aneuploidy

In a retrospective study, maternal serum levels of chorionic gonadotropin (hCG) and pregnancy specific beta 1-glycoprotein (SP1) from 63 pregnancies with aneuploid fetuses were compared to the levels observed in pregnancies with a chromosomally normal fetus. Thirty-eight percent of the abnormal pregnancies had elevated levels (greater than 2.0 multiples of the normal median [MoM]) of hCG and 14% had depressed levels (less than 0.25 MoM). With a false-positive rate of 5%, 44% of the 42 fetuses with trisomy 21 would have been detected by elevated hCG levels. With the same false-positive rate, only 21% had elevated SP1 levels. hCG was significantly depressed in 12 pregnancies affected by fetal trisomy 18.     

怀化市孕中期唐氏综合征的血清筛查和产前诊断分析

目的探讨孕中期采用甲胎蛋白(AFP)、游离β-绒毛膜促性腺激素(Free-β-HCG)、游离E3(uE3)联合筛查法在孕中期筛查唐氏综合征(DS)、神经管缺陷(NTD)及其他胎儿异常的可行性。方法应用时间分辨免疫荧光法检测孕妇血清中AFP、Free-β-HCG、uE3浓度,结合母龄、体重、孕周等个体参数,经过软件计算风险率;对高风险孕妇在知情的情况下,自愿选择进行染色体核型分析。结果 12 559例样本共筛查出高危孕妇862例,其中457例进行羊水染色体核型诊断;检出唐氏综合征儿16例,染色体结构异常27例,染色体多态11例。结论孕中期应用母血清三联法筛查,结合产前诊断是减少出生缺陷发生的有效手段之一。     

Low maternal serum alpha-fetoprotein levels and congenital diaphragmatic defects

We report on 2 cases of fetal congenital diaphragmatic defects with normal chromosomes among 105 patients referred for evaluation for low maternal serum alpha-fetoprotein (MSAFP) levels. The mechanism for this striking association is not clear. The association of low MSAFP levels and congenital diaphragmatic defects may have importance for MSAFP screening programs.     

Differential increases in AFP,hCG, and uE3 in twin pregnancies: Impact on attempts to quantify Down syndrome screening calculations

Since the advent of multiple marker screening (MMS) for Down syndrome (DS) risk calculations, limitations for twins have been apparent. Recent attempts have been made to extrapolate mathematically singleton risks to twins. Here we investigate the pattern of levels among AFP, hCG, and uE3 in twins. MMS screening data from 4,443 twin pregnancies were compared to those from 258,885 singletons from 14–21 weeks of gestational age during a 3-year period (1992–1994) in our laboratory. Medians were determined for singletons and twins, and the ratios of twins to singletons were derived. Median AFP levels for twins are approximately double those of singletons, but median increases for hCG and uE3 are less than double. The data were divided further by ethnic groups (white, African American, Asian, and Hispanic), among which there were significant variations in medians, but not in the ratios of twins to singletons. The increased serum levels of different markers in twins are not consistent across analytes, possibly reflecting independent development of different compartments. Such differences mean that a mere mathematical conversion of singleton DS risks would be imbalanced among the analytes and cannot be applied reasonably to twins. Ethnic-specific databases are as important in twins as they are in singletons. Am. J. Med. Genet. 73:109–112, 1997. © 1997 Wiley-Liss, Inc.     

Predictive value of the triple screening test for the phenotype of Down syndrome

Maternal serum alpha-fetoprotein (MS-AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) are routinely measured in the second trimester (“triple” test) and combined with maternal age to evaluate risk for fetal Down syndrome. Triple test results and clinical findings were retrospectively reviewed for 30 newborns with Down syndrome to determine whether analyte values or second trimester risks for Down syndrome were more extreme in affected pregnancies where cardiac or other severe congenital malformations were present compared to those cases where major anatomical abnormalities were absent. Mean MS-AFP, uE3, maternal age, and second trimester Down syndrome risk were all similar in the two groups of pregnancies. However, hCG concentrations did appear to be higher in the group of Down syndrome pregnancies with anatomical anomalies (mean 1.74 MoM versus 1.19 MoM) (P < 0.05). Overall, there was no significant difference in the incidence of major anomalies in patients with screen-positive test results versus those cases that were not identified by the triple test. Prenatal counseling should therefore reflect the general expectations of the Down syndrome phenotype that have been established from live-born infants with this disorder. Am. J. Med. Genet. 85:123–126, 1999. © 1999 Wiley-Liss, Inc.     

Low material serum alpha-fetoprotein levels and congenital diaphragmatic defects

We report on 2 cases of fetal congenital diaphragmatic defects with normal chromosomes among 105 patients referred for evaluation for low maternal serum alpha-fetoprotein (MSAFP) levels. The mechanism for this striking association is not clear. The association of low MSAFP levels and congenital diaphragmatic defects may have importance for MSAFP screening programs.     

Maternal serum alpha-fetoprotein screening and fetal chromosome anomalies: is lowering maternal age for amniocentesis preferable?

We have compared the cytogenetic abnormalities diagnosed prenatally in 1,098 patients referred for amniocentesis because of low maternal serum alpha-fetoprotein (MSAFP) to those of 445 patients whose indication was elevated MSAFP and those of 361 patients who had amniocentesis for "maternal anxiety." Autosomal trisomies, sex chromosome aberrations, and various structural rearrangements were detected in all 3 groups and actually exceeded the age-related incidence estimates. The frequency of chromosome anomalies in cases studied because of "maternal anxiety" with no prior screening was similar to that in the group referred for low MSAFP (1.38 and 1.27%, respectively). A relatively higher frequency (2.02%) was detected in the group whose indication was elevated MSAFP. Maternal serum screening is designed primarily to recalculate risk figures for Down syndrome, but not for other major chromosome abnormalities. The concept of prenatal screening for chromosome aberrations must therefore be reevaluated. We think that efforts should be directed at making amniocenteses more accessible to patients who request it. "Lowering" maternal age limits to 30 would encompass a greater proportion of pregnancies at risk and would be a step toward more effective prenatal diagnosis for chromosome abnormalities.     

Maternal serum α-fetoprotein screening and fetal chromosome anomalies: Is lowering maternal age for amniocentesis preferable?

We have compared the cytogenetic abnormalities diagnosed prenatally in 1,098 patients referred for amniocentesis because of low maternal serum α-fetoprotein (MSAFP) to those of 445 patients whose indication was elevated MSAFP and those of 361 patients who had amniocentesis for “maternal anxiety.” Autosomal trisomies, sex chromosome aberrations, and various structural rearrangements were detected in all 3 groups and actually exceeded the age-related incidence estimates. The frequency of chromosome anomalies in cases studied because of “maternal anxiety” with no prior screening was similar to that in the group referred for low MSAFP (1.38 and 1.27%, respectively). A relatively higher frequency (2.02%) was detected in the group whose indication was elevated MSAFP. Maternal serum screening is designed primarily to recalculate risk figures for Down syndrome, but not for other major chromosome abnormalities. The concept of prenatal screening for chromosome aberrations must therefore be reevaluated. We think that efforts should be directed at making amniocenteses more accessible to patients who request it. “Lowering” maternal age limits to 30 would encompass a greater proportion of pregnancies at risk and would be a step toward more effective prenatal diagnosis for chromosome abnormalities.