Search

There is a lack of standardized measurement tools globally to assess knowledge, attitudes, and perceptions of expecting women toward prenatal screening. The purpose of this systematic review was to identify reasons women pursue or decline prenatal screening and compare the strengths and limitations of available measurement tools used to assess pregnant women's perceptions, knowledge, and attitudes toward prenatal screening. This review followed the five-step York methodology by Arksey and O'Malley and incorporated recommendations from the Preferred Reporting Items for Systematic Reviews and Meta-Analysis checklist for the extraction, analysis, and presentation of results. The five steps consisted of: (1) identification of the research questions; (2) searching for relevant studies; (3) selection of studies relevant to the research questions; (4) data charting; and (5) collation, summarization, and reporting of results. Four online databases (PubMed, Embase, Web of Science, and Cochrane Library) were selected after the librarian's development of a detailed search strategy. The Rayyan platform was used between June 2023 and August 2023 to epitomize the articles produced from our search. A total of 68 eligible studies were included in the analysis. The top five major reasons for declining prenatal screening uptake included (1) being unsure of the risk of prenatal screening and harm to the baby or miscarriage (n = 15), (2) not considering action such as termination of pregnancy for prenatal screening to be considered as necessary (n = 14), (3) high cost (n = 12), (4) lack of knowledge about testing procedures and being anxious about the test (n = 10), and (5) being worried about probability of false negative or false positive results (n = 6). Only 32 studies utilized scientifically validated instruments. Difficulties in capturing representative, adequately sized samples inclusive of diverse ethnicities and demographics were pervasive. Findings highlight the need for rigorous validation of research measurement methodologies to ensure the accuracy and applicability of resulting data regarding the assessment of prenatal screening perceptions, knowledge, and attitudes across diverse female populations. Registration: N/A. Plain Language Summary: Measurement tools used to assess knowledge, attitudes, and perceptions of pregnant women toward prenatal screening The following systematic review provides a comprehensive summary and quality evaluation of measurement tools used globally to assess the role of knowledge, attitudes, and perceptions of pregnant women in seeking prenatal tests. [ABSTRACT FROM AUTHOR]

Objective: We present a case with prenatal diagnosis of submucous cleft palate (SMCP) which was described using 2- and 3-dimensional (3D) ultrasonography in utero. Case Report: A 25-year-old pregnant woman was referred to our department for fetal ultrasound screening. After the detection of cardiac and spinal malformations of fetal, further detailed examination detected SMCP, which showed a gap within the hard palate on axial transversal view with the soft palate visible on sagittal view. The imaging of a defective hard palate in prenatal 3D ultrasonography is similar to that in postmortem 3D computed tomography reconstruction. Conclusion: A gap within the hard palate and verification of the visibility of the soft palate should be key points in the prenatal diagnosis of SMCP. Three-dimensional ultrasonic imaging is helpful for displaying the shape and extent of the bony defect in SMCP. [ABSTRACT FROM AUTHOR]

Objective: To determine whether the improved precision of nuchal translucency (NT) measurement used in antenatal screening for Down's syndrome observed over time as evidenced by a decrease in the multiple of the median (MoM) standard deviation requires a modification to the NT MoM truncation limits to maintain accurate risk estimation. Methods: Probability plots were derived from the measurements of NT MoM values used in a 2018 audit of 22,362 unaffected pregnancies. The plots were used to determine whether the NT MoM upper truncation limit should be lowered. Validation plots were used to assess the screening accuracy of Down's syndrome risk estimates calculated from observed NT MoM values in the 22,362 unaffected pregnancies and 69 Down's syndrome pregnancies for original and revised NT MoM truncation limits. Results: Probability plots indicated that with improved precision of NT measurements, there was deviation from a Gaussian distribution at less high MoM values than with less precise measurements. Validation plots showed that using the current NT MoM upper truncation limit of 2.5 MoM with improved precision NT measurements overestimates the Down's syndrome risk (median risk in highest risk category expressed as an odds was 53.3:1 and observed prevalence was 1:1.1). The large discrepancy was corrected by changing the NTupper truncation limit to 2.0 MoM (median risk in highest risk category expressed as an odds was 1:1.78 and observed prevalence 1:2.7). Conclusion: The NT MoM upper truncation limit should be reduced from 2.5 to 2.0 MoM. [ABSTRACT FROM AUTHOR]

Background: Antenatal screening is vital to identifying couples at risk of having children with a clinically significant haemoglobinopathy. In Australia, immigration is increasing carrier incidence. Methods: A retrospective analysis was performed of full blood count, high-performance liquid chromatography and haemoglobin electrophoresis of women and their partners who underwent antenatal haemoglobinopathy screening over three years at a major NSW laboratory. Genetic testing results were included where available. Results: One thousand six hundred and twenty-eight women and 729 male partners were screened at a median gestation of 14 weeks. 8.2% of women had a clinically significant result, with a median 16-day interval to partner testing. In 35% of couples screened simultaneously, the partner did not require testing. Genetic confirmatory testing was performed in 65% of high risk couples. Conclusion: There was a significant delay to antenatal haemoglobinopathy screening for mothers, limiting time for genetic diagnosis, prenatal diagnosis and management of affected pregnancies. Screening should be performed earlier. Simultaneous couple testing is not cost-effective. [ABSTRACT FROM AUTHOR]

Objective To evaluate the repercussions of recent changes to the cut-offs used in the first screening step of the pre-marital screening programme for thalassaemia prevention in Iran. Methods The profiles of 984 subjects referred to a genetic laboratory, and the tests of 242 parents of children with thalassaemia major were assessed for red blood cell (RBC) indices, haemoglobin (Hb) A2 levels and results of Hb electrophoresis. Results Of 407 suspected thalassaemia minor (STM) cases, 18 proved positive for thalassaemia minor on molecular analysis (18/407, confidence interval 2.6–6.9%). If the revised screening cut-offs had been used to determine who would undergo molecular analysis, two of these cases would not have been identified. Only 4.4% of suspected cases with lower than normal RBC indices (mean corpuscular volume <80 fl and mean corpuscular Hb <27 pg) and HbA2 (<3.5%) were diagnosed with thalassaemia minor. Conclusion The thalassaemia major prevention programme is performed in two separate steps. One step involves the screening of subjects and identification of β-thalassaemia minor, suspected cases for thalassaemia minor (STM), and normal subject groups. The other step concerns the identification of thalassaemia minor in the STM group. Changing the cut-offs at the first screening step does not result in significant improvement from an economic view, and is associated with significant risk at the second screening step. [ABSTRACT FROM AUTHOR]

Ultrasound is widely used as a screening tool in obstetrics with the aim of reducing maternal and foetal morbidity. However, to be effective it is recommended that scanning services follow standard protocols based on national guidelines and that scanning practice is audited to ensure consistency. Bradford has a multi-ethnic population with one of the highest rates of birth defects in the UK and it requires an effective foetal anomaly screening service. We implemented a rolling programme of audits of dating scans, foetal anomaly scans and growth scans carried out by sonographers in Bradford. All three categories of scan were audited using measurable parameters based on national guidelines. Following feedback and re-training to address issues identified, re-audits of dating and foetal anomaly scans were carried out. In both cases, sonographers being re-audited had a marked improvement in their practice. Analysis of foetal abnormality detection rates showed that as a department, we were reaching the nationally agreed detection rates for the Fetal Anomaly Screening Programme auditable conditions. Audit has been shown to be a useful and essential process in achieving consistent scanning practices and high quality images and measurements. [ABSTRACT FROM AUTHOR]

Objectives A mixture model of crown-rump length (CRL)-dependent and CRL-independent nuchal translucency (NT) measurements has been proposed for antenatal screening for Down's syndrome. We here compare the efficacy of the mixture model method with the standard method, which uses NT multiple of the median (MoM) values in a single distribution. Settings A routine antenatal screening programme for Down's syndrome comprising 104 affected and 22,284 unaffected pregnancies. Methods The ability of NT to distinguish between affected and unaffected pregnancies was compared using the mixture model method and the standard MoM method by using published distribution parameters for the mixture model of NT and parameters derived from these for the standard MoM method. The accuracy of the two methods was compared for NT and maternal age by comparing the median estimated risk with the prevalence of Down's syndrome in different categories of estimated risk. Results Using NT alone observed estimates of discrimination using the two methods are similar; at a 70% detection rate the false-positive rates were 12% using the mixture model method and 10% using the MoM method. Risk estimation was marginally (but not statistically significantly) more accurate using the standard MoM method. Conclusions The mixture model method offers no advantage over the standard MoM method in antenatal screening for Down's syndrome, is more complicated and less generalizable to other data-sets. The standard MoM method remains the method of choice. [ABSTRACT FROM AUTHOR]

Objective To determine whether the standard deviation of nuchal translucency (NT) measurements has decreased over time and if so to revise the estimate and assess the effect of revising the estimate of the standard deviation on the performance of antenatal screening for Down's syndrome. Setting Data from a routine antenatal screening programme for Down's syndrome comprising 106 affected and 22,640 unaffected pregnancies. Methods NT measurements were converted into multiple of the median (MoM) values and standard deviations of log10 MoM values were calculated in affected and unaffected pregnancies. The screening performance of the Combined and Integrated tests (that include NT measurement) were compared using previous and revised estimates of the standard deviation. Results The standard deviation of NT in unaffected pregnancies has reduced over time (from 1998 to 2008) (e.g. from 0.1329 to 0.1105 [log10 MoM] at 12-13 completed weeks of pregnancy, reducing the variance by about 30%). This was not observed in affected pregnancies. Compared with results from the serum, urine and ultrasound screening study (SURUSS), use of the revised NT standard deviations in unaffected pregnancies resulted in an approximate 20% decrease in the false-positive rate for a given detection rate; for example, from 2.1% to 1.7% (a 19% reduction) at a 90% detection rate using the Integrated test with first trimester markers measured at 11 completed weeks' gestation and from 4.4% to 3.5% (a 20% reduction) at an 85% detection rate using the Combined test at 11 completed weeks. Conclusions The standard deviation of NT has declined over time and using the revised estimates improves the screening performance of tests that incorporate an NT measurement. [ABSTRACT FROM AUTHOR]

Objectives To assess the value of ductus venosus blood flow (expressed as pulsatility index, DVPI) in antenatal Down's syndrome screening when used with the Combined and Integrated tests. Methods DVPI measurements between 10 and 13 weeks' gestation in 66 Down's syndrome and 7184 unaffected pregnancies were collected from women attending the Hospital Clinic, Barcelona, for antenatal care from 1999 to 2007 and combined with the Serum Urine and Ultrasound Screening Study (SURUSS) data to model screening performance, safety and costeffectiveness of the screening tests with and without DVPI. Results The median DVPI multiple of the normal median in Down's syndrome pregnancies was 1.55 (95% CI 1.36-1.73). As a single screening marker without using maternal age, DVPI has a 62% detection rate for a 5% false-positive rate. At a 90% detection rate (first trimester measurements at 11 weeks' gestation) the addition of DVPI reduced the false-positive rate of the Combined test from 8.5% to 4.6% and the Integrated test from 2.0% to 1.1%, with a corresponding reduction in fetal losses from diagnostic procedures. There was no material loss of cost-effectiveness. Conclusion Addition of DVPI measurements to the Combined and Integrated tests substantially improves the efficacy and safety of antenatal Down's syndrome screening. [ABSTRACT FROM AUTHOR]

Objectives Antenatal screening for Down's syndrome relies on the use of multiple markers in combination. Markers that are highly correlated can cause statistical instability. We used the maximum variance inflation factor (VIFmax) to determine whether a screening test using multiple markers was robust to imprecision in the estimation of the marker distribution parameters. Methods The VIFmax for a specified screening test was calculated from the correlations between markers in Down's syndrome pregnancies for six tests: integrated and serum integrated tests without repeat measurements, both tests with repeat measurements across trimesters analysed in the standard way, and both tests with repeat measurements analysed as cross-trimester (CT) marker ratios. The screening performance of each test using published parameter values, in terms of the false-negative rates for a 3% false-positive rate (FN3), were calculated for simulated populations with medians 0.2 standard deviations (SD) higher or lower than the published values (to reflect imprecision in parameter estimation) for pregnancy-associated plasma protein A and unconjugated oestriol in affected pregnancies. For each test, the VIFmax value was compared with the coefficient of variation of the FN3 (FN3 CV). An independent set of 27 Down's syndrome pregnancies was used to determine how many had meaningless low risks (,1 in 10,000) with each test. Results Tests with VIFmax values greater than 5 had FN3CV values over 50%, but those with VIFmax values less than 5 had FN3 CV values less than 21%. The numbers of Down's syndrome pregnancies with meaningless low risk estimates in the independent set were 18 (64%) in tests with VIFmax values ≥5 and none for those with values >5. Conclusion VIFmax values of 5 or more suggest instability. The tests using CT marker ratios were stable (VIFmax < 3), but the tests using repeat measurements in the standard manner were not (VIFmax > 5). [ABSTRACT FROM AUTHOR]

Objective: To investigate the relationship between maternal serum screening markers and pregnancy outcome in fetuses with cystic hygroma at 15–18 weeks of gestation. Study design: We retrospectively reviewed case-notes of 34 consecutive singleton fetuses with cystic hygroma referred at 15–18 weeks of gestation. All cases had maternal blood sampled for triple screening at the time of the ultrasound scan. Results In total, 62% of fetuses with cystic hygroma had abnormal chromosome complements and 80% had a poor outcome. Six fetuses presenting normal values of human chorionic gonadotropin (0.5–2.5 MoM [multiples of the median]), serum alpha-fetoprotein (0.5–2.5 MoM) and unconjugated estriol (>0.5 MoM), normal karyotype and absence of associated structural anomalies had an uneventful outcome. Conclusions Our data demonstrated that cystic hygroma at 15–18 weeks has a strong association with chromosomal abnormalities. In euploid fetuses, maternal serum screening results may have a role in the diagnostic work-up of the pregnancy. [ABSTRACT FROM AUTHOR]

Objectives: It is widely thought that correlations between screening markers will tend to degrade screening performance. We performed a computer simulation study to investigate the quantitative effect of correlations between two markers on screening performance, using prenatal screening for Down's syndrome as an example, although the results apply generally. Methods: Monte Carlo simulation was used to generate values of two hypothetical markers, A and B, in 1000 affected and 1000 unaffected pregnancies. The means, standard deviations and correlations of A and B were varied in five different examples. Results: If markers A and B are, on average, higher in affected than unaffected pregnancies and each marker, individually, has the same detection rate for a given false-positive rate (i.e. the same screening performance), then the screening performance of A and B together tends to decrease as A and B become more positively correlated with each other (within affected or unaffected categories) and tends to increase as A and B become more negatively correlated. If A is, on average, higher in affected pregnancies and B is, on average, lower in affected pregnancies (but again each marker has the same screening performance), the opposite pattern is observed; screening performance increases as A and B become more positively correlated and screening performance decreases as they become more negatively correlated. If A and B have unequal screening performances, modest correlations between A and B have little effect on the screening performance of A and B together, but when the correlations are strong whether positive or negative (with r values greater than about 0.45 or less than -0.45) screening performance progressively increases. Conclusion: Correlations between screening markers considered separately in affected and unaffected pregnancies can either decrease or increase screening performance. In practice, these effects are usually modest, because most screening markers are not highly correlated with each other and the effects become important only with strong correlations, whether positive or negative. [ABSTRACT FROM AUTHOR]

Objectives: To determine the prevalence of pregnancies with a neural tube defect (NTD) in England and Wales between 1964 and 2004 and to estimate the relative impact of antenatal screening and a change in the incidence of these defects on the prevalence of births with NTDs. Settings: Use of data published by the Office for National Statistics (ONS) on terminations of pregnancies with an NTD and births with an NTD from 1964 to 2004. Methods: Estimates were made of the total number of terminations of pregnancies and births with an NTD by taking account of the under-reporting of these terminations and births using a previously described method. In 1995 ONS started to report the number of terminations with an NTD rather than the total numbers of terminations with a central nervous system (CNS) malformation that had previously been used to estimate the number of NTD terminations. Adjustment was made for this and new estimates of the total number of NTD pregnancies were produced to 2004. Results: There were an estimated 969 pregnancies with NTDs (168 (17%) births and 801(83%) terminations) in England and Wales in 2004. An estimated 44% of NTD terminations and 32% of births were not reported as such. The birth prevalence per 1000 decreased fallen 93% from 3.6 in 1964 to 0.3 in 2004, 59% due to an underlying decrease in the prevalence of NTDs and 34% due to screening diagnosis and subsequent termination of affected pregnancies. Conclusion: The prevalence of NTD pregnancies decreased by around two per 1000 from 1964 to 1990 and thereafter remained fairly constant. The prevalence of NTD pregnancies is substantially underestimated if it is based only on reported NTD births (by 88%) and also if it is based on reported NTD births and terminations (by 52%), because most NTD pregnancies in England and Wales are terminated following antenatal screening and most of these terminations are not reported. [ABSTRACT FROM AUTHOR]

Objective: To validate empirically the accuracy of antenatal Down's syndrome screening using the Integrated test, to compare this with other screening tests (including the Integrated test with the addition of cross trimester [CT] marker ratios) and to suggest how such validation analyses should be presented and interpreted. Methods: Using data from 7809 unaffected and 27 Down's syndrome pregnancies that had had an Integrated test, risk estimates for various screening tests (maternal age, Double, Triple, Quadruple, Combined, Integrated and serum Integrated tests) that use Integrated test markers were categorized according to quintile categories of risk estimates of the 27 affected pregnancies. For each screening test, the median risk estimate for each category was plotted against the observed prevalence within each category. Such validation plots were also produced for the Integrated test with CT marker ratios by measuring the level of the serum markers in the trimester of pregnancy not already measured in stored samples of all affected and a one-in-five sample of unaffected pregnancies. The robustness of the method was assessed by repeating the analysis for the Integrated test after re-classifying affected pregnancies with low risk estimates as unaffected, simulating the underascertainment of cases. Results: The validation plots (i) confirmed the accuracy of risk estimation for the different tests (by how close the points lay to the line of identity between predicted risk and observed prevalence), (ii) demonstrated the differences in screening performance of the different tests (by the range of risk spanned by the points and, in particular, the separation between the points representing the lowest risk and the next point), and (iii) are robust to underascertainment of affected pregnancies (by having little influence on the closeness of the points to the line of identity). Conclusion: The validation plot is a useful, simple and robust way to assess the validity of new screening methods, to assess the accuracy of risk estimation and to audit the performance of screening programmes. [ABSTRACT FROM AUTHOR]

The author reflects on the importance of medical screening of cystic fibrosis on newborn infants. She said that neonatal screenings were done for affected families but ignored the importance of antenatal screening which is more effective in avoiding the birth of an affected child. However, she added that newborn screening poses scientific uncertainty to whether it can improve the survival of cystic fibrosis patients.

Objectives To assess the impact of current serum α fetoprotein (AFP) assays on the performance of screening for open neural tube defects and Down's syndrome. Methods Maternal serum samples, collected between weeks 15 and 22 from 470 singleton pregnancies without neural tube defects or Down's syndrome, were assayed for AFP using an automated fluorometric immunoassay. The samples had been assayed for AFP using an in house radioimmunoassay with a lower precision ten years before. The variance of AFP using the radioimmunoassay was compared with that using the current fluorometric assay and then used to estimate the detection rates and false positive rates for neural tube defect and Down's syndrome screening. Results Current serum AFP assays are more precise. Using a cut off level of 2.5 multiples of the median, the false positive rate in screening for anencephaly and open spina bifida was 0.8% with the new assay compared with 2% using the previous assay. When screening for Down's syndrome, the false positive rate is reduced by about one percentage point without loss of detection. Conclusion Improvements in the precision of maternal serum AFP measurement have led to small but useful improvements in screening for open neural tube defects and Down's syndrome. Published estimates of screening performance using such modern assays can be revised accordingly. [ABSTRACT FROM AUTHOR]

A systematic review of recent economic evaluations of antenatal screening was conducted. Relevant studies were identified from a number of sources including computerised databases, bibliographies of economic evaluations, and searches of unpublished manuscripts. Each study identified by the literature searches was categorised on the basis of its title and abstract. Studies considered relevant to the systematic review were obtained from libraries. The methodology, results, and policy implications of studies categorised as economic evaluations upon full review were documented.A total of 566 studies were identified by the literature searches, 41 of which were categorised as economic evaluations upon full review. The economic evaluations covered a range of antenatal screening practices, aimed mainly at the prevention of infectious diseases and fetal anomalies. The review highlighted the poor methodological quality of the bulk of economic evaluations of antenatal screening. The study design, data collection methods, and analysis and interpretation of results frequently violated methodological guidelines adopted by health economists. The review also highlighted the narrow definition of benefits adopted by this body of literature, with most studies reporting outcomes in terms of cases detected, cases of particular disorders prevented or, most often, costs averted.The conclusions arrived at differed by area of antenatal screening. There appeared to be clear economic arguments in favour of some forms of antenatal screening, for example, triple test screening for Down's syndrome. Other economic evaluations pertained to specific locations, which suggests that the results may not necessarily be generalisable to different settings. For all areas of antenatal screening, an updating of published economic evaluations may be required to account for evolving economic, epidemiological, and clinical effectiveness evidence. [ABSTRACT FROM AUTHOR]

Objective Antenatal screening for syphilis is well established in the United Kingdom. The prevalence of syphilis is now very low, prompting the question as to whether this screening programme is still necessary. This paper aims at identifying possible screening strategy options for the programme and comparing their effectiveness and cost effectiveness. Methods The cost of the screening programme in the United Kingdom was estimated. This was based on the cost of screening tests, treatment, and follow up of infected women and their infants. This information was obtained from laboratories, antenatal clinics, and genitourinary medicine clinics. Epidemiological data from a survey of women treated for syphilis in pregnancy were analysed to identify groups at increased risk of syphilis. Strategic options for the screening programme were then identified. The effectiveness, number needed to treat, and cost effectiveness of these options were compared. Results Antenatal screening in the United Kingdom detected at least 40 pregnant women who need treatment for syphilis every year. This means that 18 602 women are screened for every woman detected who needs treatment for syphilis. The marginal annual cost of this screening programme in the United Kingdom is £672 366. This is equivalent to 90p per woman screened, or £16 670 to detect one woman who needs treatment for syphilis. The screening programme could be targeted geographically at pregnant women in the Thames regions. This option has the potential to save £482 185. Other strategic options are to target pregnant women in non-white ethnic groups, or those born outside the United Kingdom. These targeted options would each detect between 70% and 77% of women needing treatment for syphilis. These options could potentially save £592 938 and £562 691 respectively. Conclusions Targeting or stopping the screening programme would save relatively little money. Although selectively screening groups by country of birth or by ethnic group could detect at least 70% of cases, this would be politically and practically difficult. Targeting by region would also be effective, but would pose similar ethical and medicolegal problems. These facts and the changing international epidemiology of syphilis lead us to recommend that the current universal antenatal screening for syphilis should continue. [ABSTRACT FROM AUTHOR]

Objective To evaluate universal antenatal screening for haemoglobinopathies. Setting District general hospital serving a London borough with 45% ethnic minorities. Methods Retrospective cohort study of 1444 women referred in 1688 pregnancies and 95 tertiary referrals during 101 pregnancies. Results Unselected women at risk for sickle cell disease booked 2.7 weeks (95% confidence interval (CI) 0.14 to 5.1) later in gestation than those at risk for β thalassaemia were less likely to attend counselling (83% v93%, relative risk (RR) 0.89; 95% CI 0.85 to 0.94), their partners were less likely to be tested (77% v 95%, RR 0.81; 0.77 to 0.83), and they were less likely to accept prenatal diagnosis (22% v 90%, RR 0.37; 0.24 to 0.57). Over 99% of tertiary referrals attended counselling and had their partners tested. There were no significant differences in acceptance of prenatal diagnosis between those at risk of sickle cell disease and β thalassaemia (55% v 67%). Unselected women at risk of sickle cell disease were significantly less likely to have their partner tested or to accept prenatal diagnosis than tertiary referrals, but not those at risk of β thalassaemia. 80% of β thalassaemia and 16% of SS births were prevented. Conclusions Uptake of prenatal diagnosis among unselected women at risk of β thalassaemia is similar to that reported by tertiary centres. It is considerably lower for sickle cell disease but could increase considerably if screening occurred earlier in gestation. Acceptance of counselling is universally high, suggesting that informed choices are made, and indicating a need to measure these outcomes for cost effectiveness studies. [ABSTRACT FROM AUTHOR]

Objective To summarise a conference convened to examine how cystic fibrosis screening might appropriately be introduced into routine prenatal practice. Methods Participants included experts from various relevant disciplines. Systematic reviews and data from individual trials were presented; issues were identified and discussed. Results Judged by published criteria, prenatal cystic fibrosis screening is suitable for introduction. Screening can be performed cost effectively by identifying racial/ethnic groups at sufficient risk and then using either of two models for delivering laboratory services. Validated educational materials exist. Ethical issues are not unique. Conclusions Once adequate facilities for patient and provider education, testing, counselling, quality control, and monitoring are in place, individual programmes can begin prenatal screening for cystic fibrosis. [ABSTRACT FROM AUTHOR]

The article discusses the clinical and genetic aspects of retinoblastoma, a malignant ocular tumor involving the retinal cells. Most cases of retinoblastoma are apparently sporadic, but a significant proportion are familial and inheritance follows an autosomal dominant mode with high penetrance. The hereditary nature of many cases of retinoblastoma means that all siblings and children of patients with retinoblastoma are screened regularly during the first 5 years of life.

An editorial is presented which explores the comparison of different screening methods to keep the specific test performance, both the detection rate and false-positive rate, distinct from the uptake of further testing.

Upper and lower truncation limits are commonly applied to quantitative markers used in medical screening tests. We here examine data on 375 trisomy 18 and 522,081 unaffected singleton pregnancies, to determine if the lower truncation limit should be set below the previously specified 0.2 multiples of the median. A lower truncation limit of 0.15 would reduce the underestimation of the risk of having a trisomy 18 pregnancy in about 50% of affected pregnancies and would lead to an estimated 10 percentage point increase in the detection rate, with only a very small increase in the false-positive rate. [ABSTRACT FROM AUTHOR]

An editorial is presented on the presentations submitted on the webpage by the members and the non-members of the Medical Screening Society which discusses preventive medicine.

Antenatal sickle and thalassaemia screening programmes are now established in most high prevalence areas in England. Although screening reliably detects β-thalassaemia trait, in many cases, results state that α-thalassaemia trait cannot be excluded. The detection of couples at risk of a child with hydrops fetalis is one of the aims of the national programme. We, therefore, performed polymerase chain reaction (PCR) for the common α-thalassaemia gene deletions to assess the usefulness of this technique in routine screening practice. Between August 2001 and August 2002, of the 5092 women booked at the antenatal clinic, 425 were found to have a mean corpuscular haemoglobin (MCH) <27 pg in the absence of β-thalassaemia trait; 189 (44.5%) had an MCH <25 pg. All 425 patients underwent PCR analysis for the common deletions: –SEA (South-East Asian), –MED (Mediterranean), -α20.5, –FIL (Filipino), -α 3.7 and -α 4.2 genotypes. In total, 130 (31%) women were positive for α-thalassaemia deletion; 86 (24.7%) were heterozygous for -α 3.7, 19 (4.4%) were homozygous for -α 3.7, 12 (2.8%) were heterozygous for -α 4.2, 1 (0.2%) was homozygous for -α 4.2, 11 (2.6%) were heterozygous for –SEA and one (0.2%) was heterozygous for the –MED genotype. Although the detection rate for α+-thalassaemia was high, a strategy of selective screening using MCH <25 pg and ethnic group (SEA, Middle East or Eastern MED) would have identified all individuals heterozygous for α0-thalassaemia. Routine molecular screening for all forms of α-thalassaemia trait is unjustified in antenatal screening. [ABSTRACT FROM AUTHOR]

The article comments on issues concerning the lack of medical screening in Great Britain. It is estimated that 40% of the decline in the prevalence rate of neural tube defects (NTD) in Britain was due to antenatal screening. However, despite the availability of a highly effective and simple method of prevention, women continue to have pregnancies with NTD, because screening is not enough. With this regard, immediate implementation of national fortification programs is recommended.

The article comments on the prenatal screening for congenital disease. It discusses the importance of prenatal screening and how it causes miscarriage and anxiety, and medicalizes pregnancy. The authors suggest using the price signals of the market, or vouchers, to let parents perform realistic cost/benefit analyses.

The article presents the summary of prenatal screening for sickle cell disease. It states that a group of autosomal inherited disorders results from production of abnormal globin in the ß chain of hemoglobin. In medical screening, the pregnant woman was asked whether she or the father of the child have any origins where the malaria disease is common. However, screening is worthwhile by offering hemoglobin eletrophoresis to pregnant women in communities where sickle disease occurs.