Performance et indication du dépistage des trisomies 21, 18 et 13 en France par l’analyse de l’ADN fœtal dans le sang maternel

Megacystis in the first trimester of pregnancy: Prognostic factors and perinatal outcomes

OBJECTIVE

To determine whether bladder size is associated with an unfavorable neonatal outcome, in the case of first-trimester megacystis.

MATERIALS AND METHODS

This was a retrospective observational study between 2009 and 2019 in two prenatal diagnosis centers. The inclusion criterion was an enlarged bladder (> 7 mm) diagnosed at the first ultrasound exam between 11 and 13+6 weeks of gestation. The main study endpoint was neonatal outcome based on bladder size. An adverse outcome was defined by the completion of a medical termination of pregnancy, the occurrence of in utero fetal death, or a neonatal death. Neonatal survival was considered as a favorable outcome and was defined by a live birth, with or without normal renal function, and with a normal karyotype.

RESULTS

Among 75 cases of first-trimester megacystis referred to prenatal diagnosis centers and included, there were 63 (84%) adverse outcomes and 12 (16%) live births. Fetuses with a bladder diameter of less than 12.5 mm may have a favorable outcome, with or without urological problems, with a high sensitivity (83.3%) and specificity (87.3%), area under the ROC curve = 0.93, 95% CI (0.86-0.99), p< 0.001. Fetal autopsy was performed in 52 (82.5%) cases of adverse outcome. In the 12 cases of favorable outcome, pediatric follow-up was normal and non-pathological in 8 (66.7%).

CONCLUSION

Bladder diameter appears to be a predictive marker for neonatal outcome. Fetuses with smaller megacystis (7-10 mm) have a significantly higher chance of progressing to a favorable outcome. Urethral stenosis and atresia are the main diagnoses made when first-trimester megacystis is observed. Karyotyping is important regardless of bladder diameter.

Silica microbeads capture fetal nucleated red blood cells for noninvasive prenatal testing of fetal ABO genotype

ABO hemolytic disease of the newborn (ABO-HDN), which may cause neonatal jaundice and polycythemia, or even stillbirth or neonatal death, is widespread in China. Prenatal testing for the fetal ABO blood group can reduce unnecessary concerns or ensure prompt treatment. Herein, we presented a method to employ high-density silica microbeads (SiO₂ MBs) for capturing fetal nucleated red blood cells (fnRBCs) in maternal peripheral blood, and we detected the ABO genotype of the fetus using these captured cells. We evaluated 52 patients using the SiO₂ MBs. Among 26 pregnant women with type O blood, 8 (30.8%) of the fetuses had type A blood, 5 (19.2%) had type B blood, and 13 (50%) had type O blood. SRY genes were detected in all 27 male fetuses. This study represents a simple and effective method for noninvasive prenatal detection of the fetal ABO genotype. We believe that this method has great potential for noninvasive prenatal testing of the fetal Rh blood group and other fetal diseases as well.

High accuracy of quantitative fluorescence polymerase chain reaction combined with non-invasive pre-natal testing for mid-pregnancy diagnosis of common fetal aneuploidies: A single-center experience in China

Quantitative fluorescence polymerase chain reaction (QF-PCR) may be used as a mid-pregnancy test to confirm the diagnosis of common fetal aneuploidies, but its use is controversial. The present study aimed to determine the value of QF-PCR for diagnostic confirmation of karyotyping and the impact of parental origin and meiosis stage on the detected aneuploidy. The present prospective cohort study included pregnant women (age, 21-45 years; gestational age, 17-25 weeks) who consulted between May 2015 and December 2016. Women were screened and only consecutive high-risk individuals were included (n=428). QF-PCR analysis of amniocytes was performed. Karyotype analysis was considered the gold standard. Parental karyotyping was performed if the embryo exhibited any aneuploidy. GeneMapper 3.2 was used for data analysis. There were no false-negative or false-positive QF-PCR results, with 100% concordance with the karyotype. The aneuploidy distribution (n=105) was 68.6% for trisomy 21, 19.0% for trisomy 18, 7.6% for sex chromosome aneuploidy, 3.8% for trisomy 13 and 1.0% for 48,XXX,+18. Regarding trisomy 21, most cases (86.1%) were of maternal origin, 8.3% paternal and 6.5% undefined. Trisomy 18 was 88.2% maternal and 11.8% paternal. Maternal meiosis stage errors in trisomy 21 mainly occurred in meiosis I, while the origin of trisomy 18 exhibited similar proportions between meiosis I and II. The combination of non-invasive pre-natal testing and QF-PCR may become a rapid and effective method for fetal aneuploidy detection. QF-PCR may provide more genetic information for clinical diagnosis and treatment than karyotyping alone.

[Overview of feelings and practices of gynecologists and obstetricians for the noninvasive prenatal testing in France]

OBJECTIVES

To evaluate the feelings and practices of French obstetrician-gynecologists in prescribing the noninvasive prenatal testing (NIPT) before the release of the French High Authority of Health recommendations.

METHODS

Descriptive, declarative and transversal study, analyzing the feelings and practices of obstetrician-gynecologists, members of the French College of Gynecologists and Obstetricians (CNGOF) between February and May 2017 using an online questionnaire. Practitioners' feedback was self-assessed for several clinical situations using a numerical scale ranging from 1 to 10. This experience was rated as "good" (grades 6 to 10) or "bad" (grades 1-5).

RESULTS

Overall, 529 practitioners (29.2%) of 1812 CNGOF members, answered the online questionnaire. A "good" feeling was found for more than 65% of the practitioners audited. Feelings were significantly better for obstetricians, sonographers (P<0.05) and CPDPN members (P=0.003) compared to other practitioners. Situations where the DPNI was proposed "systematically" were risks greater than 1/250 (70.9%), between 1/250 and 1/500 (59.4%), greater than 1/250 associated with history of spontaneous miscarriages and/or fetal death in utero (66%), greater than 1/250 associated with pregnancy resulting from PMA (68.3%), history of fetal aneuploidy (54%) and a parent carrying a Robertsonian translocation (51.6%).

CONCLUSION

This study highlights a good overall feeling of the practitioners with the NIPT.

Genomics-based non-invasive prenatal testing for detection of fetal chromosomal aneuploidy in pregnant women

BACKGROUND

Common fetal aneuploidies include Down syndrome (trisomy 21 or T21), Edward syndrome (trisomy 18 or T18), Patau syndrome (trisomy 13 or T13), Turner syndrome (45,X), Klinefelter syndrome (47,XXY), Triple X syndrome (47,XXX) and 47,XYY syndrome (47,XYY). Prenatal screening for fetal aneuploidies is standard care in many countries, but current biochemical and ultrasound tests have high false negative and false positive rates. The discovery of fetal circulating cell-free DNA (ccfDNA) in maternal blood offers the potential for genomics-based non-invasive prenatal testing (gNIPT) as a more accurate screening method. Two approaches used for gNIPT are massively parallel shotgun sequencing (MPSS) and targeted massively parallel sequencing (TMPS).

OBJECTIVES

To evaluate and compare the diagnostic accuracy of MPSS and TMPS for gNIPT as a first-tier test in unselected populations of pregnant women undergoing aneuploidy screening or as a second-tier test in pregnant women considered to be high risk after first-tier screening for common fetal aneuploidies. The gNIPT results were confirmed by a reference standard such as fetal karyotype or neonatal clinical examination.

SEARCH METHODS

We searched 13 databases (including MEDLINE, Embase and Web of Science) from 1 January 2007 to 12 July 2016 without any language, search filter or publication type restrictions. We also screened reference lists of relevant full-text articles, websites of private prenatal diagnosis companies and conference abstracts.

SELECTION CRITERIA

Studies could include pregnant women of any age, ethnicity and gestational age with singleton or multifetal pregnancy. The women must have had a screening test for fetal aneuploidy by MPSS or TMPS and a reference standard such as fetal karyotype or medical records from birth.

DATA COLLECTION AND ANALYSIS

Two review authors independently carried out study selection, data extraction and quality assessment (using the QUADAS-2 tool). Where possible, hierarchical models or simpler alternatives were used for meta-analysis.

MAIN RESULTS

Sixty-five studies of 86,139 pregnant women (3141 aneuploids and 82,998 euploids) were included. No study was judged to be at low risk of bias across the four domains of the QUADAS-2 tool but applicability concerns were generally low. Of the 65 studies, 42 enrolled pregnant women at high risk, five recruited an unselected population and 18 recruited cohorts with a mix of prior risk of fetal aneuploidy. Among the 65 studies, 44 evaluated MPSS and 21 evaluated TMPS; of these, five studies also compared gNIPT with a traditional screening test (biochemical, ultrasound or both). Forty-six out of 65 studies (71%) reported gNIPT assay failure rate, which ranged between 0% and 25% for MPSS, and between 0.8% and 7.5% for TMPS.In the population of unselected pregnant women, MPSS was evaluated by only one study; the study assessed T21, T18 and T13. TMPS was assessed for T21 in four studies involving unselected cohorts; three of the studies also assessed T18 and 13. In pooled analyses (88 T21 cases, 22 T18 cases, eight T13 cases and 20,649 unaffected pregnancies (non T21, T18 and T13)), the clinical sensitivity (95% confidence interval (CI)) of TMPS was 99.2% (78.2% to 100%), 90.9% (70.0% to 97.7%) and 65.1% (9.16% to 97.2%) for T21, T18 and T13, respectively. The corresponding clinical specificity was above 99.9% for T21, T18 and T13.In high-risk populations, MPSS was assessed for T21, T18, T13 and 45,X in 30, 28, 20 and 12 studies, respectively. In pooled analyses (1048 T21 cases, 332 T18 cases, 128 T13 cases and 15,797 unaffected pregnancies), the clinical sensitivity (95% confidence interval (CI)) of MPSS was 99.7% (98.0% to 100%), 97.8% (92.5% to 99.4%), 95.8% (86.1% to 98.9%) and 91.7% (78.3% to 97.1%) for T21, T18, T13 and 45,X, respectively. The corresponding clinical specificities (95% CI) were 99.9% (99.8% to 100%), 99.9% (99.8% to 100%), 99.8% (99.8% to 99.9%) and 99.6% (98.9% to 99.8%). In this risk group, TMPS was assessed for T21, T18, T13 and 45,X in six, five, two and four studies. In pooled analyses (246 T21 cases, 112 T18 cases, 20 T13 cases and 4282 unaffected pregnancies), the clinical sensitivity (95% CI) of TMPS was 99.2% (96.8% to 99.8%), 98.2% (93.1% to 99.6%), 100% (83.9% to 100%) and 92.4% (84.1% to 96.5%) for T21, T18, T13 and 45,X respectively. The clinical specificities were above 100% for T21, T18 and T13 and 99.8% (98.3% to 100%) for 45,X. Indirect comparisons of MPSS and TMPS for T21, T18 and 45,X showed no statistical difference in clinical sensitivity, clinical specificity or both. Due to limited data, comparative meta-analysis of MPSS and TMPS was not possible for T13.We were unable to perform meta-analyses of gNIPT for 47,XXX, 47,XXY and 47,XYY because there were very few or no studies in one or more risk groups.

AUTHORS' CONCLUSIONS

These results show that MPSS and TMPS perform similarly in terms of clinical sensitivity and specificity for the detection of fetal T31, T18, T13 and sex chromosome aneuploidy (SCA). However, no study compared the two approaches head-to-head in the same cohort of patients. The accuracy of gNIPT as a prenatal screening test has been mainly evaluated as a second-tier screening test to identify pregnancies at very low risk of fetal aneuploidies (T21, T18 and T13), thus avoiding invasive procedures. Genomics-based non-invasive prenatal testing methods appear to be sensitive and highly specific for detection of fetal trisomies 21, 18 and 13 in high-risk populations. There is paucity of data on the accuracy of gNIPT as a first-tier aneuploidy screening test in a population of unselected pregnant women. With respect to the replacement of invasive tests, the performance of gNIPT observed in this review is not sufficient to replace current invasive diagnostic tests.We conclude that given the current data on the performance of gNIPT, invasive fetal karyotyping is still the required diagnostic approach to confirm the presence of a chromosomal abnormality prior to making irreversible decisions relative to the pregnancy outcome. However, most of the gNIPT studies were prone to bias, especially in terms of the selection of participants.

[Training of residents in amniocentesis: Effectiveness of a craft simulator]

OBJECTIVE

This prospective study aims to assess a low fidelity simulation device for learning amniocentesis to gynecology-obstetrics residents.

METHODS

From 2013 to 2016, gynecology-obstetrics residents of all levels, from the maternity of Nancy hospital, which have already performed amniocentesis or not, participated in amniocentesis training on an artisanal simulator. Residents were evaluated on the amniocentesis simulator according to seven quality criteria. Three scores were assigned: the first (S1) at the beginning of the first training session, the second (S2) at the end of the first session after individualized personal training and the third (S3) two months after the first simulation.

RESULTS

A total of 40 residents were included. The scores obtained by the residents were 3.2±1.8 points for S1 versus 6.2±0.9 points for S2 (P<0.001). Two months after, the residents' performances remained significantly improved compared to the initial assessment with a score (S3) of 5.8±1.3 points at S3 (P<0.001).

CONCLUSION

Amniocentesis craft simulator is effective for performance improvement and allows a persistence of acquired skills two months after the training. At the time of "never the first time on the patient", it should be part of the curriculum of gynecology-obstetrics residents in order to guarantee patients quality care and optimum safety.