Community-based screening for Down's Syndrome in the first trimester using ultrasound and maternal serum biochemistry

Two years of community-based first trimester screening (FTS) were audited. All women with singleton pregnancy in a defined health region who completed FTS (ultrasound and biochemistry) were included (n= 10,436) and outcomes obtained for 98.4%. All scans were performed or supervised by experienced sonologists with Fetal Medicine Foundation (FMF) accreditation. FMF software generated all risk assessments based on nuchal translucency (NT), maternal serum-free beta human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein A (PAPP-A). The detection rate for Trisomy 21 was 90.6% with a screen-positive rate of 3.9%. These findings indicate that where FTS is accessible within routine antenatal care, a detection rate of 90% and low screen-positive rate can be achieved using the FMF programme.

Maternal Serum Invasive Trophoblast Antigen and First-Trimester Down Syndrome Screening

Background: In the United States, Down syndrome screening is still performed mainly in the second trimester, using 3 or 4 markers. Moving screening into the first trimester has the advantage of earlier diagnosis. Currently, first-trimester screening typically includes maternal serum pregnancy-associated plasma protein-A (PAPP-A), the free β-subunit of human chorionic gonadotropin (free β), and ultrasound measurement of nuchal translucency thickness (NT). The current report describes a case–control study of serum invasive trophoblast antigen (ITA) and its possible inclusion in first-trimester screening for Down syndrome.

Methods: As part of an earlier observational study, serum samples from 54 Down syndrome and 276 matched unaffected pregnancies were collected between 9 and 15 weeks of gestation. Samples had been aliquoted and stored at −20 °C for 8 years. ITA was measured and converted to weight-adjusted multiples of the median (MoM). The distributions of other first-trimester markers are from a single published study.

Results: Median ITA MoM in Down syndrome pregnancies increase as gestational age increases (2.02 MoM at 11 and 2.44 MoM at 13 completed weeks). At 75% detection, maternal age in combination with ITA and PAPP-A measurements have an 8.0% false-positive rate, slightly lower than the 8.8% found for the free β and PAPP-A combination; adding NT measurements reduces false positives for the 2 combinations to 2.0% and 1.8%, respectively.

Conclusion: Serum ITA appears to be a useful first-trimester Down syndrome marker that could replace free β measurements while maintaining performance.

Evidence-based obstetric ethics and informed decision-making by pregnant women about invasive diagnosis after first-trimester assessment of risk for trisomy 21

OBJECTIVE

The purpose of this study was to determine the ability of pregnant women to incorporate sophisticated screening information about risk assessment into their decisions about invasive testing in an appropriate way.

STUDY DESIGN

Assessment of risk for trisomy 21 was carried out by a combination of maternal age, fetal nuchal translucency (NT) thickness, and maternal serum free beta-human chorionic gonadotrophin (hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11 to 13+6 weeks. The patients were counseled with regards to their estimated risk, and were informed that the only way to know for sure whether or not the fetus has a chromosomal abnormality is by having an invasive test, but these tests carry a risk of miscarriage of about 1%. They were also informed that although a risk of 1 in 300 or more was generally considered to be high, it was up to them to decide in favor or against invasive testing.

RESULTS

Assessment of risk was carried out in 30,564 singleton pregnancies with live fetuses at 11 to 13+6. The median maternal age was 34 (range 15-49) years and, in 14,816 (48.5%), the age was 35 years or greater. The rate of invasive testing increased exponentially with increasing estimated risk (r = 0.917, P < .0001). The estimated risk for trisomy 21 was 1 in 300 or more in 2565 (8.4%) women, and 1991 (77.6%) of these had invasive testing. The risk was less than 1 in 300 in 27,999 (91.6%) women, and 1286 (4.6%) of these had invasive testing.

CONCLUSION

Pregnant women are able to use sophisticated screening information to make scientifically and ethically rational decisions about invasive testing for trisomy 21. These empiric data compliment the arguments of normative ethics to create evidence-based ethical standards for informed consent regarding invasive testing.

The value of a single combined measurement of VEGF, glycodelin, progesterone, PAPP-A, HPL and LIF for differentiating between ectopic and abnormal intrauterine pregnancy

BACKGROUND

To evaluate whether serum concentrations of the non-placental markers vascular endothelial growth factor (VEGF), glycodelin (GLY) and progesterone (P) and the novel placental markers pregnancy-associated plasmaprotein A (PAPP-A), human placental lactogen (HPL) and leukaemia inhibiting factor (LIF) differ in ectopic pregnancy (EP) when compared with abnormal intrauterine pregnancy (aIUP).

METHODS

A prospective clinical study was conducted at the University Hospital of Larissa, Greece. The study included 50 patients admitted with failed pregnancy and suspected ectopic pregnancy that were treated with curettage or laparoscopy and classified as histologically confirmed EPs (n = 27) or histologically confirmed aIUPs (n = 21) (mean gestational age of 7.15 and 7.3 weeks, respectively). Two suspected EPs proved to be normal IUPs and were excluded. VEGF, GLY, P, beta-HCG, PAPP-A, HPL and LIF were measured by enxyme-linked immunosorbent assay (ELISA) methods in a single pre-operative blood sample.

RESULTS

The median VEGF concentration was 227.2 pg/ml in the EP group versus 107.2 pg/ml in the aIUP group (P < 0.001), with a suggested threshold value of 174 pg/ml for their differential diagnosis. LIF, P, PAPP-A, HPL and GLY serum measurements did not differ significantly between EP and aIUP.

CONCLUSION

VEGF serum levels might be a useful marker in differentiating between EPs and aIUPs.

Relationship among pregnancy associated plasma protein-A levels, clinical characteristics, and coronary artery disease extent in patients with chronic stable angina pectoris

AIMS

To assess, in chronic stable angina (CSA) patients, the relationship among clinical characteristics and cardiovascular risk factors, extent of coronary artery disease (CAD), and pregnancy-associated plasma protein-A (PAPP-A) levels.

METHODS AND RESULTS

We studied 643 CSA patients (63+/-10 years, 482 men) undergoing diagnostic coronary angiography; 97 with angiographically normal coronary arteries or <50% stenosis, 127 with single vessel disease (VD), and 419 with multi-VD. Patients' age, gender, cardiovascular risk factors, body mass index, history of previous myocardial infarction, angina class, left ventricular ejection fraction (LVEF), and treatment were assessed at study entry. PAPP-A levels (mIU/L) were higher in men than in women (6.2+/-2.4 vs. 5.2+/-1.8; P<0.001) and in hypertensive vs. normotensive patients (6.4+/-2.8 vs. 5.8+/-2.1; P=0.01). PAPP-A correlated directly with age (r=0.19, P<0.001) and inversely with LVEF (r=-0.11, P=0.01). Patients with multivessel disease (VD) had higher PAPP-A levels (6.45+/-2.58) than those with single-VD (5.49+/-1.54, P<0.001) or normal coronaries (4.62+/-1.17, P<0.001). Male gender, age, history of a previous MI, hypercholesterolaemia, and PAPP-A levels were independent predictors for the presence of CAD.

CONCLUSION

In CSA patients PAPP-A levels correlate with age, male gender, hypertension, and CAD extent. In the present study, PAPP-A was an independent predictor for the presence and extent of CAD.

The IGF system in the neonatal ovine uterus

Postnatal development of the ovine uterus primarily involves uterine gland morphogenesis or adenogenesis. Adenogenesis involves the budding differentiation of the glandular epithelium (GE) from the luminal epithelium (LE) and then GE proliferation and coiling/branching morphogenetic development within the stroma between birth (postnatal day or PND 0) and PND 56. Insulin-like growth factor (IGF)-I and IGF-II mRNAs were previously found to be expressed only in the endometrial stroma, whereas the IGF receptor (IGF-1R) mRNA was most abundant in epithelia and in stroma, suggesting that an intrinsic IGF system regulates postnatal development of the uterus. Given that the biological activities of IGFs are modulated by a family of six IGF binding proteins (IGFBPs) and specific proteases, the objective was to determine the effects of age and estrogen disruption on expression of IGFs, IGFBPs and pregnancy-associated plasma protein A (PAPP-A or IGFBP-4 protease) in the ovine uterus. In Study One, circulating levels of IGF-I and IGF-II in the serum of neonatal ewes did not change between PND 0 and PND 56. Levels of immunoreactive IGF-I, IGF-II and IGF-1R protein were most abundant on the apical surface of the endometrial LE and GE. RT-PCR analyses detected expression of IGFBPs (3, 4, 5 and 6) as well as PAPP-A mRNAs in the uterus, but not IGFBP-1 and IGFBP-2 mRNAs. IGFBP-3 and IGFBP-4 mRNAs were expressed specifically in the endometrial stroma and myometrium and increased after birth. PAPP-A mRNA was expressed specifically in the endometrial stroma and increased after birth. In Study Two, ewes were treated from birth with estradiol-17beta valerate (EV), which reduces uterine growth and inhibits endometrial adenogenesis. On PNDs 14 and 56, IGFBP-3 mRNA was decreased in the uterus of EV-treated ewes, but IGF-1R and IGFBP-4 mRNAs were not affected. PAPP-A mRNA was increased by EV treatment on PND 14, but decreased on PND 56. These results support the hypothesis that an intrinsic IGF system in the uterus regulates epithelial-stromal interactions important for postnatal uterine growth and endometrial gland morphogenesis in the sheep.

First-trimester screening: an overview

An improvement in prenatal screening for chromosomal defects has been achieved by combining sonography and biochemical markers. Analyzing markers taken from maternal blood such as pregnancy-associated plasma protein A and free beta-human chorionic gonadotropin in combination with the ultrasound marker nuchal translucency provides detection rates of 90% for the most important chromosomal anomalies. In addition, nuchal translucency is a marker for severe heart defects. This report discusses the potential of new markers such as the nasal bone.

First-trimester screening for trisomy 21 combining biochemistry and ultrasound at individually optimal gestational ages. An interventional study

OBJECTIVE

To assess the effectiveness of the Combined Test in the prenatal detection of trisomy 21 in the general pregnant population using a new timing for the screening approach.

METHODS

First-trimester maternal serum biochemical markers (pregnancy-associated plasma protein-A and free-beta hCG) were determined in maternal serum at 7 to 12 weeks. Fetal nuchal translucency and gestational age were assessed at the 10- to 14-week ultrasound scan. A combined risk was estimated and delivered to the women the same day. When the risk was 1:250 or above, chorionic villus sampling was offered.

RESULTS

Mean gestational age at biochemistry was 9.4 weeks, being 12.3 at ultrasound. In the 2780 studied pregnancies with a complete follow-up, observed detection rates were 88% (7/8) for trisomy 21 and 75% (3/4) for trisomy 18, with a 3.3% (92/2765) false-positive rate.

CONCLUSION

The Combined Test, assessing biochemistry and ultrasound at individually optimal ages in the first trimester, showed an 88% detection rate for trisomy 21 with a remarkably reduced false-positive rate (3.3%).

Inhibin A is a maternal serum marker for Down's syndrome early in the first trimester

Inhibin A is a maternal serum marker for fetal Down's syndrome (DS) in the second trimester. We examined whether inhibin A could be used early in the first trimester. Maternal serum concentrations of inhibin A were determined in 81 controls and 27 cases of fetal trisomy 21 in gestational week 5-11. The log MoM (Multiple of the Median of normal pregnancies) inhibin A concentration in DS pregnancies increased with gestational age (p = 0.001) from a mean log MoM (standard deviation) of -0.1754 (0.3712) (n = 11) in week 7-8 to a mean log MoM (standard deviation) of 0.1842 (0.2145) (n = 12) in week 9-11. This corresponded to an increase in inhibin median MoM from 0.67 to 1.53. When inhibin A was used together with pregnancy-associated plasma protein-A, free beta-human chorionic gonadotrophin and nuchal translucency as DS markers, the estimated detection rates were 81.4 and 82.6% in weeks 7-8 and 9-11, respectively, for false-positive rates of 0.9 and 1.0%. The performance of the latter combination early in the first trimester is nearly as good as that of integrated first- and second-trimester screening, with the further advantage that the risk can be reported to the pregnant woman in first trimester.

In vivo effects of pregnancy-associated plasma protein-A, activin-A and vascular endothelial growth factor on other follicular-fluid factors during follicle deviation in mares

During a follicular wave in mares, the two largest follicles (F1 and F2) begin to deviate in diameter when F1 is a mean of 22.5 mm. The intrafollicular effects of pregnancy-associated plasma protein-A (PAPP-A), IGF-I, activin-A and vascular endothelial growth factor (VEGF) on other follicular-fluid factors during deviation were studied. In four treated groups (n= 7/group), a single dose of one of the four factors was injected into F2 when F1 was ≥20.0 mm (expected beginning of deviation). In a control group (n= 7), F2 was injected with vehicle. One day after treatment, a sample of follicular fluid was taken from F1 and F2 of the control group and from F2 of the treated groups and was assayed for free IGF-I, oestradiol, androstenedione, activin-A, inhibin-A, follistatin and VEGF. In the control group, the means for all end points were significantly greater in F1 than in F2, except that concentrations of androstenedione were lower in F1 than in F2. The treatment effects for F2 were significant as follows: PAPP-A increased the concentrations of free IGF-I, inhibin-A, follistatin and VEGF and decreased the concentrations of androstenedione; IGF-I increased the concentration of inhibin-A and decreased the concentration of androstenedione; activin-A decreased the concentrations of follistatin and androstenedione and increased the diameter of F2; and VEGF increased the concentration of IGF-I and decreased the concentration of androstenedione. These results support the hypotheses that during deviation in mares PAPP-A increases the follicular-fluid concentrations of free IGF-I, follistatin responds to changes in follicular-fluid concentrations of activin-A, and VEGF affects the concentrations of other follicular-fluid factors.

First trimester increased nuchal translucency associated with fetal achondroplasia

A 30-year-old woman, gravida 2, para 1, was referred for nuchal translucency, free beta-human chorionic gonadotropin (beta-hCG), and pregnancy-associated plasma protein A (PAPP-A) screening at 12 weeks gestation. The nuchal translucency was increased to 3.8 mm, resulting in a post-test result of 1:15 risk for Down syndrome by a combination of maternal age plus nuchal translucency, and 1:5 by a combination of maternal age plus nuchal translucency plus free beta-hCG plus PAPP-A. The patient underwent uncomplicated chorionic villus sampling that demonstrated a normal 46,XY fetus. The patient was then followed-up weekly by ultrasound. At 18 weeks gestation, generalized features of rhizomelic micromelia together with macrocrania and narrow thorax were seen. All fetal long bones were less than 2 standard deviations from the mean value. At that time, DNA analysis was performed on stored villi and a G380R mutation in the locus gene encoding for the fibroblast growth factor receptor 3 on chromosome 4p16.3 was found, leading to a prenatal diagnosis of achondroplasia. The couple opted for termination of pregnancy after counseling. Postmortem X-ray was done and confirmed the ultrasound diagnosis of achondroplasia. This is the second known case of increased nuchal translucency in the first trimester associated with prenatal confirmed diagnosis of fetal osteochondrodysplasia.

Future biomarkers for detection of ischemia and risk stratification in acute coronary syndrome

BACKGROUND

Evaluation of patients who present to the hospital with a complaint of chest pain or other signs or symptoms suggestive of acute coronary syndrome (ACS) is time-consuming, expensive, and problematic. Recent investigations have indicated that increases in biomarkers upstream from biomarkers of necrosis (cardiac troponins I and T), such as inflammatory cytokines, cellular adhesion molecules, acute-phase reactants, plaque destabilization and rupture biomarkers, biomarkers of ischemia, and biomarkers of myocardial stretch may provide earlier assessment of overall patient risk and aid in identifying patients with higher risk of an adverse event.

APPROACH AND CONTENT

The purpose of this review is to provide an overview of the pathophysiology and clinical and analytical characteristics of several biomarkers that may have potential clinical utility to identify ACS patients. These biomarkers (myeloperoxidase, metalloproteinase-9, soluble CD40 ligand, pregnancy-associated plasma protein A, choline, ischemia-modified albumin, unbound free fatty acids, glycogen phosphorylase isoenzyme BB, and placental growth factor) have demonstrated promise and need to be more thoroughly evaluated for commercial development for implementation into routine clinical and laboratory practice.

SUMMARY

Specifications that have been addressed for cardiac troponins and natriuretic peptides will need to be addressed with the same scrutiny for the biomarkers discussed in this review. They include validating analytical imprecision and detection limits, calibrator characterization, assay specificity and standardization, pre-analytical issues, and appropriate reference interval studies. Crossing boundaries from research to clinical application will require replication in multiple settings and experimental evidence supporting a pathophysiologic role and, ideally, interventional trials demonstrating that monitoring single or multiple biomarkers improves outcomes.

Multicenter study of first-trimester screening for trisomy 21 in 75 821 pregnancies: results and estimation of the potential impact of individual risk-orientated two-stage first-trimester screening

OBJECTIVES

To evaluate the performance of first-trimester screening for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A). In addition, the potential impact of a new individual risk-orientated two-stage approach to first-trimester screening was examined.

METHODS

First-trimester combined screening for trisomy 21 was carried out in 75 821 singleton pregnancies with live fetuses at 11 + 0 to 13 + 6 gestational weeks. The detection and false-positive rates for different risk cut-offs were calculated. To examine the potential impact of an individual risk-orientated two-stage approach to first-trimester screening it was assumed that, after first-trimester combined screening, chorionic villus sampling (CVS) would be performed in all patients with a risk estimate of 1 in 100 or more and in none of those with a risk estimate of less than 1 in 1000. Those in the intermediate-risk category, with a risk estimate of between 1 in 101 and 1 in 1000, would have further assessment of risk by first-trimester ultrasound examination to determine presence/absence of the nasal bone, presence/absence of tricuspid regurgitation or normal/abnormal Doppler velocity waveform in the ductus venosus, and CVS would be performed if their adjusted risk became 1 in 100 or more.

RESULTS

Fetal NT and maternal serum free beta-hCG and PAPP-A were successfully measured in all cases. The median maternal age was 31 (range, 13-49) years, the median gestation at screening was 12 (range, 11 + 0 to 13 + 6) weeks and the median fetal crown-rump length was 62 (range, 45-84) mm. Chromosomal abnormalities were identified in 544 pregnancies, including 325 cases of trisomy 21. The estimated risk for trisomy 21 was 1 in 300 or greater in 5.2% of normal pregnancies, in 92.6% of those with trisomy 21, in 88.5% of those with trisomy 18 or 13 and in 85.6% of those with other chromosomal defects. The detection rates for trisomy 21 were about 75% and 80% for respective false-positive rates of 1% and 2%. In the proposed individual risk-orientated two-stage screening for a risk cut-off of 1 in 100 the total false-positive rate would vary with the method used for the second stage of screening from 2.1% for absence of the nasal bone to 2.7% for increased impedance in the ductus venosus and 2.7% for tricuspid regurgitation and the respective detection rates would be 92.0%, 94.2% and 91.7%.

CONCLUSIONS

First-trimester combined screening for trisomy 21 is associated with a detection rate of about 90% for a false-positive rate of 5%. Individual risk-orientated two-stage screening for trisomy 21 can potentially identify, in the first trimester of pregnancy, more than 90% of affected fetuses for a false-positive rate of 2-3%.

Improved first-trimester Down syndrome screening performance by lowering the false-positive rate: a prospective study of 9941 low-risk women

OBJECTIVE

To determine the performance of screening for Down syndrome (DS) and other major chromosomal abnormalities using nuchal translucency (NT), free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A) in a prospective study of a non-selected population.

METHODS

Of 9941 women with an early ultrasound examination, NT was measured in 8622 singleton pregnancies with a gestational age between 10 + 3 and 13 + 6 weeks. beta-hCG and PAPP-A were analyzed in 6441 cases. Detection rates (DR) and false-positive rates (FPR) for the NT screening, the double test (beta-hCG and PAPP-A) and the combined test (NT and the double test) were calculated using a 1 : 250 cut-off.

RESULTS

NT could be measured in 97.5% of cases. The DR for DS with NT screening alone was 75% with a FPR of only 1.8%. The double test detected 73% and the combined test 91%, for FPRs of 8.8% and 2.1%, respectively. We detected 80% of fetuses with other major chromosomal abnormalities with a combination of NT screening and other ultrasound findings. Low beta-hCG and PAPP-A values (below 0.4 MoM) were observed in 0.5% of the women including all cases of triploidy and trisomy 18 and 13.

CONCLUSIONS

The performance of a screening strategy for DS using a combination of NT and the double test was superior to that using either NT or the double test alone due to a very low FPR and a higher DR.

Circulating pregnancy-associated plasma protein A is not an early marker of acute myocardial infarction

OBJECTIVE

The purpose of this study was to assess whether serum levels of pregnancy-associated plasma protein A (PAPP-A) are elevated early in patients with acute myocardial infarction (AMI).

DESIGN AND METHODS

We measured serum levels of PAPP-A in 80 patients with AMI and in 80 age-matched healthy control subjects. The mean (+/-SEM) time from onset of symptoms to blood sampling was 6.3 +/- 2.8 h in the group with AMI.

RESULTS

The PAPP-A levels did not differ between the control group and the AMI group (1.24 +/- 0.07 vs. 1.29 +/- 0.02 mIU/l; P = 0.54).

CONCLUSIONS

Measurement of serum PAPP-A does not seem to be a useful early marker for AMI.

Molecular Distinction of Circulating Pregnancy-Associated Plasma Protein A in Myocardial Infarction and Pregnancy

Background: In the blood of pregnant women, pregnancy-associated plasma protein A (PAPP-A) is present as a covalent complex with the proform of eosinophil major basic protein (proMBP). Recently, increased serum concentrations of PAPP-A have been found in acute coronary syndromes (ACS). The aim of this study was to investigate whether the circulating PAPP-A in ACS is the same as that in pregnancy.

Methods: We developed two time-resolved immunofluorometric assays based on a relative epitope map constructed by the use of 17 monoclonal antibodies. One assay, which measured total PAPP-A, used two PAPP-A subunit-specific antibodies. The other assay, which measured PAPP-A/proMBP complex, used one proMBP subunit-specific antibody and one PAPP-A subunit-specific antibody. Serum samples from four patients with myocardial infarction (MI), three pregnant women in their first trimester, and one in her third trimester were fractionated by gel filtration on a Superose™ 6 precision column. The two assays were used to analyze fractions obtained by gel filtration as well as serum samples serially collected from four other MI patients.

Results: Pregnancy-related PAPP-A was eluted as a single peak with a molecular mass of ∼700 kDa, whereas ACS-related PAPP-A was also eluted as a single peak but with a molecular mass of ∼530 kDa. Pregnancy-related PAPP-A was detected equally by the two assays, whereas increased ACS-related PAPP-A was detected only by the assay for total PAPP-A.

Conclusions: Our results provide the first evidence that circulating ACS-related PAPP-A is different from circulating pregnancy-related PAPP-A in that it is not complexed with proMBP. These findings provide a solid foundation for the design of immunoassays to accurately measure atherosclerosis-associated plasma protein A in the circulation.

First-trimester screening for Down syndrome with ductus venosus Doppler studies in addition to nuchal translucency and serum markers

OBJECTIVE

To estimate the improvement in screening efficiency when fetal ductus venosus Doppler studies are added to existing first-trimester Down syndrome screening protocols.

METHODS

Statistical modelling was used with parameters derived from prospective ductus venosus studies and from the published literature. The pulsatility index for veins (PIV), was determined in the fetal ductus venosus for 3706 unaffected and 25 Down syndrome pregnancies at 10-14 weeks' gestation. Concurrent nuchal translucency measurement and maternal serum pregnancy associated plasma protein A and free-beta human chorionic gonadotrophin were also measured.

RESULTS

The median PIV in Down syndrome was 1.70 times higher than in unaffected pregnancies (95% confidence interval 1.36-2.12). PIV levels followed an approximately log Gaussian distribution with log(10) standard deviations of 0.193 and 0.076 in Down syndrome and unaffected pregnancies. There were no statistically significant correlations between PIV and the other markers. Modelling predicts that for a fixed 5% false-positive rate, the addition of PIV to nuchal translucency alone will increase the detection rate from 76 to 85%, and combined with serum markers, from 88 to 92%. For a fixed 85% detection rate, the false-positive rate reduced from 15 to 4.8% and from 3.2 to 1.2% respectively.

CONCLUSION

Ductus venosus Doppler studies can substantially improve Down syndrome screening efficiency.

Down syndrome screening marker levels in women with a previous aneuploidy pregnancy

BACKGROUND

In Down syndrome screening programmes, women with a previous affected pregnancy are assumed to have the same marker distribution as those without a family history. This assumption needs to be tested.

METHODS

Information on previous aneuploidy pregnancies was routinely sought on the test request forms in three centres, Leeds, Romford and the Fetal Medicine Centre, London. For each woman with a previous aneuploidy (case), five unaffected pregnancies to women without a history were selected as controls. The markers tested included maternal serum free beta-human chorionic gonadotrophin (hCG), pregnancy-associated plasma protein A (PAPP-A), alpha-fetoprotein, unconjugated estriol and ultrasound nuchal translucency thickness.

RESULTS

There were 375 cases: 303 with previous Down syndrome, 63 with Edwards syndrome and 9 with Patau's syndrome. There was a statistically significant difference between cases and controls, in the distribution of free beta-hCG and PAPP-A levels, adjusted for gestation. On average, free beta-hCG was increased by 10% in a subsequent pregnancy after aneuploidy (p < 0.005, Wilcoxon rank sum test) and for PAPP-A the increase was 15% (p < 0.0001). No other marker was significantly different.

CONCLUSION

Risk calculation algorithms need to be modified to take account of the increased marker levels. Until data from sufficient affected pregnancies are available for study, it would be prudent to assume that the same increase as in unaffected pregnancies applies.

[The characteristics of combined genetic screening of the first trimester of pregnancy after use of assisted reproductive technology programs]

Results of comparison of nuchal translucency measurments (NT) and parameters of the biochemical analysis of blood serum of pregnant women in the first trimester and after use of assisted reproductive technologies (in vitro fertilization and cytoplasmic sperm injection (ICSI)) are submitted. It was shown that NT does not differ from those of women with spontaneous pregnancy, and parameters of biochemical markers tend only to change. After ICSI use concentration of free beta-HCG authentically increases.

Population screening for fetal trisomy 21: easy access to screening should be balanced against a uniform ultrasound protocol

OBJECTIVES

To evaluate the performance of a first-trimester fetal aneuploidy screening program, with a documented underestimation of nuchal translucency thickness measurements (NT) compared to the Fetal Medicine Foundation (FMF) reference range.

METHODS

We analysed the data of Algemeen Medisch Laboratorium (AML) in Antwerp, Belgium, on combined screening with pregnancy-associated plasma protein-A (PAPP-A), free beta-human chorionic gonadotropin (FB-hCG) and NT. NT-multiples of the median (MoM), relative to the FMF reference range, were used for risk calculations.

RESULTS

The proportion of first-trimester screening tests in the total of serum screening tests increased from 1.3% (125/9424) in 2000 to 53.1% (6577/12 377) in 2003. Only 11.4% (1514/13 267) of NT measurements were performed according to FMF criteria. The 80.8% (21/26) trisomy 21 (T21) detection rate (DR) at cut off 1:300 resulted from maternal serum screening. NT measurements did not add to this DR, but reduced the false-positive rate from 16.8% (2212/13181) to 8.6% (1130/13181). Only 23.8% (5/21) of T21 detections were by FMF trainees.

CONCLUSION

Easy access to screening and maternal serum parameters accounted for the majority of T21 detections in our first-trimester combined screening program.

First-trimester screening for trisomy 21 in twin pregnancy: does the addition of biochemistry make an improvement?

OBJECTIVE

To evaluate the effectiveness of the addition of first-trimester biochemistry to fetal nuchal translucency (NT) measurement in the Combined Test when screening for trisomy 21 in twin pregnancies.

METHODS

Maternal serum free beta-hCG and PAPP-A were determined at 8 to 12 weeks and fetal NT was measured at 11 to 14 weeks. The individual risks were estimated for each of the fetuses using both NT screening alone and the Combined Test. An invasive diagnostic procedure was offered when the risk was 1:250 or over in either one of the fetuses. In the first period, only the results of NT screening were clinically applied. After previous analysis, the Combined Test was introduced into clinical practice.

RESULTS

In the two-and-a-half-year study period, a complete follow-up was obtained in 100 twin pregnancies. Three fetuses (two pregnancies) with trisomy 21 were detected by both methods. The false-positive rate achieved by NT screening (14.3% of pregnancies and 8.6% of fetuses) was substantially reduced when first-trimester biochemistry was added in the Combined Test (5.1% of pregnancies and 3.6% of fetuses).

CONCLUSION

The Combined Test appears to maintain the detection rate achieved by NT screening for trisomy 21 in twin pregnancies, but false-positive rates and invasive diagnostic procedures are reduced.

The influence of maternal insulin-dependent diabetes on fetal nuchal translucency thickness and first-trimester maternal serum biochemical markers of aneuploidy

OBJECTIVE

To evaluate the influence of maternal insulin dependent diabetes mellitus (IDDM) on maternal serum free beta-hCG, PAPP-A and fetal nuchal translucency (NT), thickness at 11 to 13(+6) weeks of gestation in a large cohort of women screened prospectively for chromosomal anomalies.

METHODS

Information on maternal IDDM status, maternal serum biochemical marker levels and fetal NT were collected from the prenatal screening computer records in two first-trimester screening centres. In total the control group included 33 301 pregnancies of which 16 366 had NT and maternal serum biochemistry results and 16 305 with NT only. The IDDM group included 195 pregnancies of which 79 had NT and maternal serum biochemistry results and 127 with NT only. The median maternal weight corrected free beta-hCG and PAPP-A, expressed as multiple of the median (MoM), and fetal NT, expressed as delta values, in the IDDM and non-IDDM groups were compared.

RESULTS

There were no significant differences between the IDDM and non-IDDM groups in median maternal weight corrected free beta-hCG (IDDM 0.87 MoM, 95% Confidence Interval 0.75 to 1.16 MoM, non-IDDM 1.00 MoM), median maternal weight corrected PAPP-A (IDDM 1.02 MoM, 95% Confidence Interval 0.83 to 1.05 MoM, non-IDDM 1.01 MoM), or mean delta NT (IDDM 0.0358 mm, non-IDDM 0.0002 mm).

CONCLUSIONS

In pregnancies with maternal IDDM, first-trimester screening for chromosomal defects does not require adjustments for the measured fetal NT. However, more data are required before the possible reduction in maternal serum free beta-hCG and the reduction of PAPP-A suggested by the published world series can be considered sufficiently important to take into account in the calculation of risks for chromosomal defects.