Amniocentesis and chorionic villus sampling: Green-top Guideline No. 8

Absent or hypoplastic nasal bone: What to tell the prospective parents?

BACKGROUND

Absent or hypoplastic nasal bone (AHNB) on first or second-trimester ultrasonography (USG) is an important soft marker of Down syndrome. However, due to its varied incidence in euploid and aneuploid fetuses, there is always a dilemma of whether to go for invasive fetal testing for isolated AHNB. This study aims to assess outcomes specifically within the context of Indian ethnicity women.

MATERIALS AND METHODS

This was a prospective observational study. All patients who reported with AHNB in the first- or second-trimester USG were included. Genetic counseling was done, and noninvasive and invasive testing was offered. Chromosomal anomalies were meticulously recorded, and pregnancy was monitored.

RESULTS

The incidence of AHNB in our study was 1.16% (47/4051). Out of 47 women with AHNB, the isolated condition was seen in 32 (0.78%) cases, while AHNB with structural anomalies was seen in nine cases (0.22%). Thirty-nine women opted for invasive testing. Six out of 47 had aneuploidy (12.7%), while two euploid cases (4.25%) developed nonimmune hydrops. The prevalence of Down syndrome in fetuses with AHNB was 8.5% (4/47) and 0.42% (17/4004) in fetuses with nasal bone present. This difference was statistically significant (p = .001).

CONCLUSION

The results indicate that isolated AHNB cases should be followed by a comprehensive anomaly scan rather than immediately recommending invasive testing. However, invasive testing is required when AHNB is associated with other soft markers or abnormalities. As chromosomal microarray is more sensitive than standard karyotype in detecting chromosomal aberrations, it should be chosen over karyotype.

Challenges of prenatal diagnosis in obese pregnant women

Obesity rates are increasing world-wide with most of the increase in women of the reproductive age group. While recognised as an important contributor to non-communicable diseases, pregnant women with obesity are particularly at risk of not only maternal and pregnant complications but also have an increased risk of congenital malformations. Furthermore, pregnant obese women are more likely to be older and therefore at a greater risk of aneuploidy. Prenatal diagnosis in these women especially those who are morbidly obese is challenging due not only to their weight but the implications of the increase adiposity on biochemical markers of aneuploidy. In this review we discuss the current challenges in providing prenatal diagnosis for these women including those related to the ergonomics of ultrasound and those inherent in them because of their obesity. Appropriate counselling for these women should include the lower sensitivity of the tests, the difficulties in performing some of the procedures (imaging and invasive testing) as well as the increased risk of structural abnormalities related to their obesity.

An approach for state differentiation in nucleic acid circuits: Application to diagnostic DNA computing

BACKGROUND

Differentiating between different states in nucleic acid circuits is crucial for various biological applications. One approach, there is a requirement for complicated sequential summation, which can be excessive for practical purposes. By selectively labeling biologically significant states, this study tackles the issue and presents a more cost-effective and streamlined solution. The challenge is to efficiently distinguish between different states in a nucleic acid circuit.

RESULTS

An innovative method is introduced in this study to distinguish between states in a nucleic acid circuit, emphasizing the biologically relevant ones. The circuit comprises four DNA logic gates and two detection modules, one for determining fetal gender and the other for diagnosing X-linked genetic disorders. The primary module generates a G-quadruplex DNAzyme when activated by specific biomarkers, which leads to a distinct colorimetric signal. The secondary module responds to hemophilia and choroideremia biomarkers, generating one or two DNAzymes. The absence of female fetus indicators results in no DNAzyme or color change. The circuit can differentiate various fetal states by producing one to four active DNAzymes in response to male fetus biomarkers. A single-color solution for state differentiation is provided by this approach, which promises significant advancements in DNA computing and diagnostic applications.

SIGNIFICANCE

The innovative approach used in this study to distinguish states in nucleic acid circuits holds great significance. By selectively labeling biologically relevant states, circuit design is simplified and complexity is reduced. This advancement enables cost-effective and efficient diagnostic applications and contributes to DNA computing, providing a valuable solution to a fundamental problem.

A Low-Cost, High-Fidelity Simulator for Transabdominal Chorionic Villus Sampling

INTRODUCTION

Chorionic villus sampling (CVS) remains essential for first-trimester genetic diagnosis, yet clinical volume may be insufficient to train new clinicians in the technique. Available simulation models are expensive, require animal parts or specialized resins, and cannot be stored for repeated use.

METHODS

We present a model for trans-abdominal CVS (TA-CVS) which is constructed from readily available materials costing less than $10 and can be refrigerated and re-used to train maternal-fetal medicine fellows in CVS.

RESULTS

All three attending physicians performing TA-CVS at our institution described the model as an accurate visual and tactile simulation, prompting its integration into our fellowship curriculum. To date, two senior fellows have achieved competency on the simulator and begun to perform clinical CVS under supervision, one of whom is an author on this paper. Both fellows and attendings indicated that the simulator provided a valuable tool for repeated practice prior to clinical CVS. Simulators are now maintained on the unit and have been re-used for 3 months and dozens of simulated procedures each without any apparent qualitative degradation in performance.

DISCUSSION/CONCLUSION

We describe a low-cost easily constructed, durable, high-fidelity simulator for TA-CVS.

Experience in prenatal genetic testing and reproductive decision-making for monogenic disorders from a single tertiary care genetics clinic in a low-middle income country

OBJECTIVES

Explore health-care seeking behaviour among couples with pregnancies at-risk of monogenic disorders and compare time duration for obtaining Prenatal Genetic Test (PGT) results based on (i) amniocentesis and Chorionic Villus Sampling (CVS) (ii) in-house testing and out-sourced testing. Report the spectrum of monogenic disorders in our cohort.

METHODS

Medical records of women consulting prenatal genetic counselling clinic at Aga Khan University Hospital, Karachi from December-2015 to March-2021 with history of miscarriage or a monogenic disorder in previous children were reviewed.

RESULTS

Forty-three pregnancies in 40 couples were evaluated, 37(93%) were consanguineous. Twenty-five (63%) couples consulted before and 15(37%) after conception. Thirty-one (71%) pregnancies underwent CVS at the mean gestational age of 13-weeks and 6-days ± 1-week and 3-days and amniocentesis at 16-weeks and 2-days ± 1-week and 4-days. PGT for 30 (70%) pregnancies was outsourced. The mean number of days for in-house PGT was 16.92 ± 7.80 days whereas for outsourced was 25.45 ± 7.7 days. Mean duration from procedure to PGT result was 20.55 days after CVS compared to 28.75 days after amniocentesis. Eight (18%) fetuses were homozygous for disease-causing variant for whom couples opted for termination of pregnancy (TOP). Twenty-six monogenetic disorders were identified in 40 families.

CONCLUSION

Proactive health-care seeking behaviour and TOP acceptance is present amongst couples who have experienced a genetic disorder.

The association of prenatal amniotic sex hormones and digit ratio (2D:4D) in children aged 5 to 70 months: A longitudinal study

The sex difference of the 2D:4D digit ratio (female > male)-a proposed marker for prenatal testosterone exposure-is well established. Studies suggest it already exists in utero and is of moderate effect size in adulthood. However, evidence for the claim that 2D:4D reflects prenatal androgen action is limited, and the sex difference may exhibit lability during childhood. In the present study, 244 mothers were recruited in the course of an amniocentesis examination (performed between gestational weeks 14 and 18). Prenatal testosterone (T) and estradiol (E) levels were determined from amniotic fluid for boys and girls. The majority (97.4%, n = 114) of available female T levels (n = 117) were found below the level of quantification. Therefore, only male amniotic fluid data (n = 117) could be included for the analysis of associations between amniotic sex hormones (T levels and T to E ratio (T/E)) and 2D:4D. The families were then invited to each of the five consecutive follow-ups (ages: 5, 9, 20, 40, and 70 months) where children's 2D:4D was measured for both hands. The alternative marker D[r-l] reflects the directional asymmetry of 2D:4D (right subtracted by left 2D:4D) and was subsequently calculated as an additional measure for prenatal T exposure. No significant correlations between amniotic T or the T/E ratio (measured between week 14 and 18 of gestation) with 2D:4D respectively D[r-l] were observed for any time point. There was a significant sex difference (females > males) and a significant age effect with moderate correlations of 2D:4D between time points. 2D:4D increased between 20 and 40 months and between 40 and 70 months of age. The findings raise questions regarding the applicability of 2D:4D as a marker for prenatal androgen action and are discussed in terms of the reliability of obtained digit ratio data as well as in terms of the developmental timing of amniocentesis.

Do online decision aids reflect new prenatal screening and testing options? An environmental scan and content analysis

Objective

Decision aids have been developed to help prospective parents make informed, shared decisions about medical tests, but these options are rapidly changing. This study aimed to identify and evaluate publicly available decision aids written in English for prospective parents seeking prenatal test information.

Methods

A systematic review process was followed using 3 sources: known decision aid repositories, fetal medicine organisations and Google. The search, screening process, quality assessment, and data extraction was performed by two independent researchers. The quality assessment of the decision aids was based on the International Patient Decision Aids Standards (IPDAS v.4.0).

Results

We identified 13 decision aids, which varied in the screening and diagnostic tests that they discussed. No decision aid met all the IPDAS v.4.0. criteria and no decision aid reported updated risk of miscarriage for amniocentesis and chorionic villus sampling (CVS). There was a lack of decision aids for some common decisions in the prenatal context.

Conclusion

We identified outdated content in current prenatal decision aids. The findings will inform healthcare professionals of the quality of current prenatal decision aids, which may facilitate their patients' informed decision-making about prenatal tests.

Innovation

Considerations for improving future decision aids are outlined.

Invasive Prenatal Diagnostic Testing for Aneuploidies in Singleton Pregnancies: A Comparative Review of Major Guidelines

Sophisticated screening protocols for genetic abnormalities constitute an important component of current prenatal care, aiming to identify high-risk pregnancies and offer appropriate counseling to parents regarding their options. Definite prenatal diagnosis is only possible by invasive prenatal diagnostic testing (IPDT), mainly including amniocentesis and chorionic villous sampling (CVS). The aim of this comparative review was to summarize and compare the existing recommendations on IPDT from the most influential guidelines. All the reviewed guidelines highlight that IPDT is indicated based on a positive screening test rather than maternal age alone. Other indications arise from medical history and sonography, with significant variations identified between the guidelines. The earlier time for amniocentesis is unequivocally set at ≥15 gestational weeks, whereas for CVS, the earlier limit varies from ≥10 to ≥11 weeks. Certain technical aspects and the overall approach demonstrate significant differences. Periprocedural management regarding Rhesus alloimmunization, virologic status and use of anesthesia or antibiotics are either inconsistent or insufficiently addressed. The synthesis of an evidence-based algorithm for IPDT is of crucial importance to healthcare professionals implicated in prenatal care to avoid unnecessary interventions without compromising optimal prenatal care.

Clinical Assessment of Fetal Well-Being and Fetal Safety Indicators

Delivering safe clinical trials of novel therapeutics is central to enable pregnant women and their babies to access medicines for better outcomes. This review describes clinical monitoring of fetal well‐being and safety. Current pregnancy surveillance includes regular antenatal checks of blood pressure and urine for signs of gestational hypertension. Fetal and placental development is assessed routinely using the first‐trimester “dating” and mid‐trimester “anomaly” ultrasound scans, but the detection of fetal anomalies can continue throughout pregnancy using targeted sonography or magnetic resonance imaging (MRI). Serial sonography can be used to assess fetal size, well‐being, and placental function. Carefully defined reproducible imaging parameters, such as the head circumference (HC), abdominal circumference (AC), and femur length (FL), are combined to calculate an estimate of the fetal weight. Doppler analysis of maternal uterine blood flow predicts placental insufficiency, which is associated with poor fetal growth. Fetal doppler analysis can indicate circulatory decompensation and fetal hypoxia, requiring delivery to be expedited. Novel ways to assess fetal well‐being and placental function using MRI, computerized cardiotocography (CTG), serum circulating fetoplacental proteins, and mRNA may improve the assessment of the safety and efficacy of maternal and fetal interventions. Progress has been made in how to define and grade clinical trial safety in pregnant women, the fetus, and neonate. A new system for improved safety monitoring for clinical trials in pregnancy, Maternal and Fetal Adverse Event Terminology (MFAET), describes 12 maternal and 18 fetal adverse event (AE) definitions and severity grading criteria developed through an international modified Delphi consensus process. This fills a vital gap in maternal and fetal translational medicine research.

Uptake of prenatal genetic diagnosis and termination of pregnancy by Omani Muslim families at risk of genetic disorders: experience over a 9-year period

Studies on the acceptance of prenatal diagnosis and termination of pregnancy for single gene disorders within Islamic societies in the Middle East are limited. A few have examined the attitudes toward pregnancy termination for fetal indications, but a dearth of published data exists on actual behavior and uptake. This study reports on all prenatal diagnosis requests for single gene disorders, from the Sultanate of Oman, over 9 years. A retrospective study was conducted during which the medical records of all women who performed prenatal diagnoses for single gene disorders were reviewed. A total of 148 invasive procedures were performed for 114 families. The total number of yearly requests for prenatal diagnosis increased exponentially from three in 2012 to 21 in 2020. Sixty-four different diagnoses were tested for with the majority being autosomal recessive in nature. Seventy-one percent (28/39) of cases where an affected pregnancy was identified were terminated. Fifty-two of the 114 women (45.6%) repeated prenatal diagnosis in a future pregnancy. Seventy-two couples (63%) were consanguineous parents related as second cousins or closer. The majority of tests performed were for couples from Muscat (27%), Albatinah (27%), and Alsharqiya (20.3%) governorates in Oman. The findings of this study provide evidence that prenatal diagnosis is an acceptable reproductive option to prevent the occurrence of genetic disorders that meet termination eligibility criteria as outlined by the Islamic Jurisprudence (Fiqh) Council Fatwa, among Omani Muslim couples.