Role of ultrasound for Down syndrome screening in advanced maternal age

Cost-effectiveness of ultrasound before non-invasive prenatal screening for fetal aneuploidy

OBJECTIVE

To determine the cost-effectiveness of first-trimester ultrasound before fetal aneuploidy screening with cell-free DNA (cfDNA) compared with screening by cfDNA alone.

METHODS

A decision analytic model was constructed for 400 000 pregnant individuals with advanced maternal age who desired first-trimester aneuploidy screening with cfDNA in the USA, to compare two screening strategies: (1) cfDNA only and (2) ultrasound performed within 4 weeks before cfDNA. Input parameters included probability of fetal aneuploidy, cfDNA performance, desire for diagnostic testing, pregnancy outcomes, and pregnancy and lifetime costs and utilities. The primary outcome measure was the incremental cost-effectiveness ratio (ICER), in terms of cost in 2020 US dollars (USD) per quality-adjusted life year (QALY) gained. Secondary outcomes included procedure-related loss, pregnancy termination, live birth with aneuploidy, live birth with structural anomaly and stillbirth. Discounting was performed at 3% per year with an estimated maternal lifespan of 81 years starting at the age of 35 years. One-way, multiway and Monte Carlo probabilistic sensitivity analyses were performed. All base-case estimates and ranges of uncertainty were derived from the literature. The willingness-to-pay threshold was set at 100 000 USD per QALY.

RESULTS

In the base-case analysis, ultrasound before cfDNA screening was more cost-effective than cfDNA screening without pretest ultrasound, with an ICER of 12 588 USD and higher net monetary benefit (24 241 vs 20 466). The strategy involving ultrasound before cfDNA was more costly by 544 USD but also more effective (by 0.04 QALY) compared with cfDNA alone. Base-case results were robust in sensitivity analyses with the strategy involving ultrasound before cfDNA always remaining the most cost-effective approach with the highest net monetary benefit.

CONCLUSION

First-trimester ultrasound before cfDNA is a more cost-effective strategy for non-invasive prenatal aneuploidy screening compared with cfDNA alone. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Optimizing use of existing prenatal genetic tests: Screening and diagnostic testing for aneuploidy

Screening and diagnostic testing for detection of fetal aneuploidy has been an integral part of prenatal care for over three decades. The recent introduction of new technologies, such as cell free DNA (cfDNA) screening and preimplantation genetic screening, has created increased complexity for obstetrical care providers. Inconsistencies among the professional society recommendations have caused confusion and disparities in practice. As we work to responsibly incorporate new technologies, clear guidelines with consensus among relevant professional societies are needed. In January of 2017, a workshop was convened during the Society for Maternal-Fetal Medicine Pregnancy Meeting. Representatives from many stakeholder groups were present with the goal to develop a framework for introduction of new genetic tests into clinical practice. This paper provides consensus recommendations from this workshop on the use of existing prenatal screening and diagnostic testing for aneuploidy.

Prenatal decision-making in the second and third trimester in trisomy 21-affected pregnancies

Down syndrome (DS) is the most common chromosome abnormality among live-born infants and the most frequent genetic cause of intellectual disability. The majority of pregnancies affected by DS are terminated. The decision concerning whether or not to continue a pregnancy following the prenatal diagnosis of DS is complex and amongst others, motivated by attitudes towards termination, socioeconomic factors, and ultrasound findings. In Germany, termination of pregnancy (TOP) is a legal option, even during the later stages of gestation. The aim of the present study was to evaluate the pregnancy outcomes as well as possible factors that influence the decisions made by women with trisomy 21-affected pregnancies. In our study 112 pregnancies affected by trisomy 21 were included. Our data confirm that most patients are more likely to terminate a trisomy 21-affected pregnancy [76 (67.9%) vs. 36 (32.1%) continued pregnancies]. Beyond that we found that women who continued their pregnancy tended to be at an advanced stage in their pregnancy at the time of karyotyping. With regards to factors from their medical history as well as sonographic findings there was no identifiable single factor that could distinguish between women that opted to continue or terminate their pregnancy.

Trends in state/population-based Down syndrome screening and invasive prenatal testing with the introduction of first-trimester combined Down syndrome screening, South Australia, 1995-2005

OBJECTIVE

The purpose of this study was to review trends in the us of maternal serum Down syndrome screening and invasive prenatal testing before and after the introduction of a state-based first-trimester combined Down syndrome screening program.

STUDY DESIGN

A retrospective population-based study was performed on first- and second-trimester Down syndrome screening, invasive prenatal testing, and prenatal detection of Down syndrome from 1995 to 2005 in South Australia with data from state-based registers. Chi-square tests were used to evaluate trends.

RESULTS

There was a significant decrease in the use of second-trimester Down syndrome maternal serum screening (from 75% in 1995 to 25% in 2005; P < .001) and a corresponding significant increase in first-trimester combined screening (from 0.8% in 2000 to 49% in 2005; P < .001). The proportion of all confinements that involved invasive prenatal testing fell (from 9.3% in 1995 to 7.6% in 2005; P < .001). There was a significant decrease in the number of invasive prenatal tests that were needed to detect 1 Down syndrome fetus (from 86 tests in 1995 to 40 tests in 2005; P < .001), with no significant change in the proportion of Down syndrome cases that were detected prenatally.

CONCLUSION

The introduction and increased use of first-trimester combined Down syndrome screening has been associated with more efficient use of invasive prenatal testing in South Australia and has maintained a high level of overall prenatal detection.

Dépistage de la trisomie 21 par le test combiné du premier trimestre suivi par l'échographie du second trimestre en population générale

BACKGROUND

Recent studies have reported the efficacy of first trimester combined screening for Down Syndrome based on maternal age, serum markers (human chorionic gonadotropin, pregnancy-associated plasma protein A), and ultrasound measurement of fetal nuchal translucency. However, those do not incorporate the value of the widely accepted routine 20-22 week anomaly scan.

STUDY DESIGN

We carried out a multi-centre, interventional study in the unselected population of a single health authority in order to assess the performance of first trimester combined screening, followed by routine second trimester ultrasound examination and/or screening by maternal serum markers (free beta-hCG and alpha-fetoprotein measurement or total hCG, alpha-fetoprotein and unconjugated estriol measurement) when incidentally performed. Detection and screen positive rates were estimated using a correction method for non verified issues. A cost analysis was also performed.

RESULTS

During the study period, 14,934 women were included. Fifty-one cases of Down Syndrome were observed, giving a prevalence of 3.4 per 1000 pregnancies. Of these, 46 were diagnosed through first (N=41) or second (N=5) trimester screening. Among the 5 screen-negative Down syndrome cases, all were diagnosed postnatally after an uneventful pregnancy. Detection and screen positive rates of first trimester combined screening were 79.6% and 2.7%, respectively. These features reached 89.7 and 4.2%, respectively when combined with second trimester ultrasound screening. The average cost of the full screening procedure was 108 euro (120 $) per woman and the cost per diagnosed Down syndrome pregnancy was 7,118 euro (7,909 $).

CONCLUSION

Our findings suggest that one pragmatic interventional two-step approach using first-trimester combined screening followed by second trimester detailed ultrasound examination is a suitable and acceptable option for Down syndrome screening in pregnancy.

Screening for Down syndrome using first-trimester combined screening followed by second-trimester ultrasound examination in an unselected population

OBJECTIVE

Recent studies have reported the efficacy of first-trimester combined screening for Down syndrome based on maternal age, serum markers (human chorionic gonadotropin, pregnancy-associated plasma protein A), and ultrasound measurement of fetal nuchal translucency. However, those do not incorporate the value of the widely accepted routine 20-22 weeks' anomaly scan.

STUDY DESIGN

We carried out a multicenter, interventional study in the unselected population of a single health authority in order to assess the performance of first-trimester combined screening, followed by routine second trimester ultrasound examination and/or screening by maternal serum markers (free beta-hCG and alpha-fetoprotein measurement or total hCG, alpha-fetoprotein, and unconjugated estriol measurement) when incidentally performed. Detection and screen positive rates were estimated using a correction method for nonverified issues. A cost analysis was also performed.

RESULTS

During the study period, 14,934 women were included. Fifty-one cases of Down syndrome were observed, giving a prevalence of 3.4 per 1000 pregnancies. Of these, 46 were diagnosed through first (n = 41) or second (n = 5) trimester screening. Among the 5 screen-negative Down syndrome cases, all were diagnosed postnatally after an uneventful pregnancy. Detection and screen positive rates of first-trimester combined screening were 79.6% and 2.7%, respectively. These features reached 89.7%, and 4.2%, respectively, when combined with second-trimester ultrasound screening. The average cost of the full screening procedure was 108 euros (120 dollars) per woman and the cost per diagnosed Down syndrome pregnancy was 7,118 euros (7909 dollars).

CONCLUSION

Our findings suggest that 1 pragmatic interventional 2-step approach using first-trimester combined screening followed by second-trimester detailed ultrasound examination is a suitable and acceptable option for Down syndrome screening in pregnancy.

Re-evaluation of risk for Down syndrome by means of the combined test in pregnant women of 35 years or more

OBJECTIVE

Evaluation of combined test in pregnant women 35 years of age and over to detect fetal Down syndrome.

MATERIALS AND METHODS

The study population included 408 pregnant women of 35 years and over, who requested the combined test (nuchal translucency, PAPP-A, free beta hCG, maternal age, cut-off 1:250) before deciding whether to undergo amniocentesis.

RESULTS

The test was positive in 66 women who then requested amniocentesis for fetal karyotype determination; the other women had a negative test and declined amniocentesis. False-positives increased with maternal age from 6.6% at 35 years to about 50% at 40 to 41 and 100% in women over 41. Six cases of Down syndrome and two cases of trisomy 18 were detected. Not a single case of Down syndrome or trisomy 18 was missed, and other chromosome abnormalities were detected as well.

CONCLUSIONS

The application of the combined test reduced the need for invasive testing to only 14% of the studied pregnant population, without missing any of the fetuses with trisomy 21 or 18.

Changes in the Utilization of Prenatal Diagnosis

OBJECTIVE

The impact of prenatal screening for Down syndrome has largely been assessed under the assumption that screening protocols and policies are fully used. To measure the overall effectiveness in actual clinical practice, we analyzed the tests performed by a single cytogenetics laboratory.

METHODS

We reviewed all amniotic fluid and chorionic villus samples (CVS) processed by the University of Connecticut Health Center's cytogenetics laboratory for the years 1991 to 2002. We evaluated trends in the use of prenatal testing, referral indications, and the numbers of cytogenetic abnormalities identified.

RESULTS

The number of women receiving amniocentesis or CVS declined more than 50% from 1,988 in 1991 to 933 in 2002 (P <.001), despite an increase in the number of women of advanced maternal age in the population served. There was a 68% decline in the number of women who underwent invasive prenatal testing solely on the basis of their age (1,314 in 1991 to 423 in 2002, P <.001). The number of Down syndrome fetuses detected prenatally increased from 20 to 31 (P =.08), representing approximately one half of the affected pregnancies present in the population served. Between 1991 and 2002, the proportion of antenatal cytogenetic tests with a significant chromosomal abnormality increased from 1 in 43 (2.3%) to 1 in 14 (7.0%; P <.001).

CONCLUSION

Advances in maternal serum screening and second-trimester ultrasonography have resulted in more judicious use of amniocentesis and chorionic villus sampling.

LEVEL OF EVIDENCE

II-2

Different preferences for prenatal diagnosis in pregnancies following assisted reproduction versus spontaneous conception

The uptake of prenatal diagnosis in 436 singleton and 146 twin pregnancies following assisted reproduction was compared with a matched group of spontaneous conceptions. The first and second trimester ultrasound examination included target fetal anatomic evaluation and screening by specific markers described for fetal aneuploidy. Women with assisted conception attended significantly more often for first trimester prenatal diagnosis (57.9 versus 34.9%, P < 0.01), but had fewer examinations in the early second trimester at 15-18 weeks (37.8 versus 48.8%, P < 0.01) than those with spontaneous conception. Screen positive results of 6.5 and 6.9% for first trimester examination and 6.0 and 7.3% for second trimester examination were found in assisted conceptions and controls respectively. A significantly higher rate of invasive prenatal diagnosis was observed in the second trimester for spontaneous conceptions, 20.0 versus 11.8% (P < 0.01) compared with assisted conceptions. This was attributed to the higher rate of invasive procedures in advanced maternal age >/=35 years of 40.7 versus 28.6% (P = 0.01) in spontaneous and assisted conceptions respectively. With the purpose of avoiding invasive testing, women with assisted conception were more likely to use the results of the ultrasound examination to guide their final decision about invasive testing, rather than undergo genetic amniocentesis as a first option.

Down syndrome screening using race-specific femur length

OBJECTIVE

The study was undertaken to evaluate the influence of maternal race on fetal femur length when screening for Down syndrome.

STUDY DESIGN

We reviewed our patient databases to obtain fetal biometry from 15 to 22 weeks' gestation, maternal race, and cases of Down syndrome. Institution and race-specific regression lines for femur length (FL) to biparietal diameter (BPD) were created. The efficiency of using published expected FL was compared with our institution and race-specific regression in screening for Down syndrome.

RESULTS

There were 4350 African American, 4271 white, 2315 Hispanic, and 654 Asian subjects and 42 cases of Down syndrome (1:276) included in the study. Our institutionally derived regression for FL by BPD had an R(2) of 0.82. Regression lines for FL by BPD generated by race had an R(2) of 0.86, 0.84, 0.83, and 0.80 for African American, Hispanic, Asian, and white subjects, respectively. The race-specific regression was no better than institution-specific data.

CONCLUSION

Using institution-specific FL was more efficient in screening for Down syndrome than published expected FL; race-specific analysis did not improve efficiency.

Ethical dimensions of genetic counseling

Genetics is one of the most exciting and most dynamically developing fields of medicine. Genetic counseling has reached the limelight of public attention. Given the fact that the subject of counseling is of momentous consequences and has important effects for the short and long-term, its ethical aspect is paramount. It is crucial that the relevant regulation be designed. The center of the ethical questions is occupied by the treatment of important personal information and the method of its being made public. The way the problems are dealt with is always changing just as society is in a constant process of change. It is important, however, that we always be ready to offer proper help to those in need when they need it.

Cost analysis of Down syndrome screening in advanced maternal age

OBJECTIVE

To analyze the potential cost and efficacy of Down syndrome screening in the population with advanced maternal age.

METHODS

Three screening methods defining Down syndrome risk for women with advanced maternal age were analyzed: advanced maternal age; advanced maternal age and maternal serum triple screen; and advanced maternal age, maternal serum triple screen and genetic sonogram. Costs for all tests and procedures were estimated. Procedure-related loss for amniocentesis was assumed to be 1:200. Efficacy was defined as: number of amniocenteses performed, number of Down syndrome cases detected, procedure-related losses, Down syndrome cases detected per fetal loss, cost per Down syndrome case detected and total cost of screening.

RESULTS

In 1999 in the USA, there were 530,610 women with advanced maternal age at 16 weeks' gestation carrying an estimated 4,043 fetuses with Down syndrome. Screening by maternal age alone would result in the 100% detection of Down syndrome cases, but would require over 530,000 amniocenteses and result in 2,653 procedure-related losses. Combining age with serum screen and genetic sonogram would detect 97.6% of Down syndrome cases, but would require only 119,791 amniocenteses and result in 599 procedure-related losses. The projected cost per Down syndrome case detected using age screening is 219,109 dollars versus 155,992 dollars using serum screen and genetic sonogram.

CONCLUSIONS

The combination of advanced maternal age, maternal serum screen and genetic sonogram would result in the fewest procedure-related losses and lowest cost per Down syndrome case detected.

Antenatal Down syndrome screening in the United States in 2001: a survey of maternal-fetal medicine specialists

OBJECTIVE

Our objectives were to determine patterns of antenatal Down syndrome screening and risk adjustment by maternal-fetal medicine specialists in the United States in 2001.

STUDY DESIGN

A survey to investigate Down syndrome screening practice patterns was mailed to the 1,638 members of the Society of Maternal-Fetal Medicine in the United States. Practice demographics, screening patterns, and the numeric risks quoted in counseling were analyzed.

RESULTS

Five hundred forty-three specialists (33.2%) responded; 530 of these specialists (97.6%) performed antenatal Down syndrome screening; all of them offered second-trimester screening, and 247 of them (45.5%) offered first-trimester screening. With the use of second-trimester ultrasonography, risk was increased by 69.4% of respondents and decreased by 33.1%. Amniocentesis was the most frequently used diagnostic test (83.2%), with loss rates quoted at 1:100 to 1:1,000.

CONCLUSION

Maternal-fetal medicine specialists show a wide in variation practices used for Down syndrome screening, modification of risk, and quoted procedure-related loss rates. This information calls for a consensus regarding risks that are quoted in Down syndrome counseling.

Advances in prenatal screening for Down syndrome: I. general principles and second trimester testing

BACKGROUND

Down syndrome is one of the most important causes of mental retardation in the population. In the absence of prenatal screening and diagnosis, prevalence at birth in the United States would currently exceed 1:600. The purpose of prenatal screening is to identify those women at the increased risk for an affected pregnancy and to maximize the options available to these women.

TESTS AVAILABLE

Second trimester serum screening involves combining the maternal age-specific risk for an affected pregnancy with the risks associated with the concentrations of maternal serum alpha-fetoprotein (MSAFP), unconjugated estriol (uE3), and human chorionic gonadotropin (hCG) (triple testing). A forth analyte, inhibin-A (INH-A), is increasingly being utilized (quadruple testing). Optimal second trimester screening requires the integration of a number of clinical variables, the most important of which is an accurate assessment of gestational age. In addition to Down syndrome, the triple and quadruple tests preferentially identify fetal trisomy 18, Turner syndrome, triploidy, trisomy 16 mosaicism, fetal death, Smith-Lemli-Opitz syndrome, and steroid sulfatase deficiency. Some programs modify the Down syndrome risks generated through maternal serum screening tests with fetal biometric data obtained by ultrasound. Other second trimester tests have shown promise, including the analysis of maternal urine and fetal cells in the maternal circulation, but none are in routine clinical use.

CONCLUSION

The second trimester triple and quadruple tests provide benchmarks for evaluating new screening protocols. The combination of fetal biometry, new test development as well as clarification of the role of co-factors that affect the concentrations of analytes in existing tests should lead to greater efficacy in second trimester screening for Down syndrome.