Clinical proceduress in prenatal diagnosis

Trophoblast retrieval and isolation from the cervix: origins of cervical trophoblasts and their potential value for risk assessment of ongoing pregnancies

BACKGROUND

Early during human development, the trophoblast lineage differentiates to commence placentation. Where the placenta contacts the uterine decidua, extravillous trophoblast (EVT) cells differentiate and invade maternal tissues. EVT cells, identified by expression of HLA-G, invade into uterine blood vessels (endovascular EVT), as well as glands (endoglandular EVT), and open such luminal structures towards the intervillous space of the placenta. Endoglandular invasion diverts the contents of uterine glands to the intervillous space, while glands near the margin of the placenta that also contain endoglandular EVT cells open into the reproductive tract. Cells of the trophoblast lineage have thus been recovered from the uterine cavity and endocervical canal. An emerging non-invasive technology [trophoblast retrieval and isolation from the cervix (TRIC)] isolates and examines EVT cells residing in the cervix to explore their origin, biology and relationship to pregnancy and fetal status.

OBJECTIVE AND RATIONALE

This review explores the origins and possible uses of trophoblast cells obtained during ongoing pregnancies (weeks 5-20) by TRIC. We hypothesize that endoglandular EVT cells at the margins of the expanding placenta enter the uterine cavity and are carried together with uterine secretion products to the cervix where they can be retrieved from a Papanicolaou (Pap) smear. The advantages of TRIC for investigation of human placentation and prenatal testing will be considered. Evidence from the literature, and from archived in utero placental histological sections, is presented to support these hypotheses.

SEARCH METHODS

We used 52 out of 80 publications that appeared between 1966 and 2017 and were found by searching the PubMed and Google Scholar databases. The studies described trophoblast invasion of uterine vessels and glands, as well as trophoblast cells residing in the reproductive tract. This was supplemented with literature on human placental health and disease.

OUTCOMES

The literature describes a variety of invasive routes taken by EVT cells at the fetal-maternal interface that could displace them into the reproductive tract. Since the 1970s, investigators have attempted to recover trophoblast cells from the uterus or cervix for prenatal diagnostics. Trophoblast cells from Pap smears obtained at 5-20 weeks of gestation have been purified (>95% β-hCG positive) by immunomagnetic isolation with nanoparticles linked to anti-HLA-G (TRIC). The isolated cells contain the fetal genome, and have an EVT-like expression profile. Similar EVT-like cells appear in the lumen of uterine glands and can be observed entering the uterine cavity along the margins of the placenta, suggesting that they are the primary source of cervical trophoblast cells. Cells isolated by TRIC can be used to accurately genotype the embryo/fetus by targeted next-generation sequencing. Biomarker protein expression quantified in cervical trophoblast cells after TRIC correlates with subsequent pregnancy loss, pre-eclampsia and fetal growth restriction. A key remaining question is the degree to which EVT cells in the cervix might differ from those in the basal plate and placental bed.

WIDER IMPLICATIONS

TRIC could one day provide a method of risk assessment for maternal and fetal disease, and reveal molecular pathways disrupted during the first trimester in EVT cells associated with placental maldevelopment. As perinatal interventions emerge for pregnancy disorders and inherited congenital disorders, TRIC could provide a key diagnostic tool for personalized precision medicine in obstetrics.

Chorionic villous sampling through transvaginal ultrasound approach: A retrospective analysis of 1138 cases

AIM

The aim of this study was to evaluate the effectiveness and safety of a transvaginal approach for chorionic villous sampling (CVS).

METHODS

We carried out a retrospective data analysis of all the transvaginal CVS procedures performed for the purpose of prenatal diagnosis in a university-level referral center between January 2000 and December 2014. Women underwent the prenatal testing between 10 and 17 weeks of gestation mainly for hematological disorders involving single gene defects. The main outcomes were successful sampling rate, maternal contamination rate, post-procedure complications rates, and immediate fetal loss rate (<14 days post-procedure).

RESULTS

A total of 1138 transvaginal CVS were performed during the study period and were available for analysis. The sampling success rate after the first attempt was 98.5% (1121/1138) and the overall success rate was 99.6% (1133/1138). The maternal contamination rate was 0.4% (5/1138). While two patients had vaginal bleeding (0.2%), fresh retroplacental collection was noted in four patients (0.4%) post-procedure. None of the patients developed ascending uterine infection following CVS. The immediate fetal loss rate was 0.2% (2/1138).

CONCLUSION

Transvaginal approach is associated with high sampling success, along with low rates of maternal contamination and post-procedure complications; hence, it can be offered as an effective alternative method of CVS.

About one-half of early spontaneous preterm deliveries can be identified by a rapid matrix metalloproteinase-8 (MMP-8) bedside test at the time of mid-trimester genetic amniocentesis

OBJECTIVE

Mid-trimester amniocentesis continues to be used for the prenatal diagnosis of chromosomal anomalies and other genetic disorders. Analysis of amniotic fluid obtained at the time of mid-trimester genetic amniocentesis identifies those patients who are at risk for early spontaneous preterm delivery. This is based on a solid body of evidence that found subclinical intra-amniotic inflammation/infection to be causally linked to early spontaneous preterm birth. Although several biomarkers have been proposed to identify intra-amniotic inflammation, the accumulated data suggest that the determination of amniotic fluid matrix metalloproteinase-8 (MMP-8), or neutrophil collagenase, is a powerful predictor of spontaneous preterm delivery. MMP-8 is released by inflammatory cells in response to microbial products or "danger signals". A rapid point-of-care test has been developed to determine MMP-8 at the bedside within 20 min, and without the requirement of laboratory equipment. The objective of this study was to determine whether an elevation of MMP-8 in the amniotic fluid, measured by a rapid point-of-care test, can identify those patients at risk for spontaneous preterm delivery after a mid-trimester genetic amniocentesis.

STUDY DESIGN

A case-control study was designed to obtain amniotic fluid from asymptomatic singleton pregnant women who underwent mid-trimester genetic amniocentesis. An MMP-8 bedside test was performed to analyze the amniotic fluid of 64 patients with early spontaneous preterm delivery (<30 weeks) and 128 matched controls with normal pregnancy outcomes.

RESULTS

(1) The MMP-8 bedside test (Yoon's MMP-8 Check™) was positive in 42.2% (27/64) of patients with spontaneous preterm delivery but in none (0/128) of the control cases (p < 0.001); (2) the MMP-8 bedside test had a sensitivity of 42.2%, and a specificity of 100% in the prediction of spontaneous preterm delivery (<30 weeks) following a mid-trimester genetic amniocentesis; and (3) among the patients with spontaneous preterm delivery, those with a positive MMP-8 bedside test had a significantly higher rate of spontaneous delivery within 2 weeks and 4 weeks of an amniocentesis [40.7% (11/27) versus 5.4% (2/37); 63.0% (17/27) versus 24.3% (9/37)] and a shorter interval-to-delivery period than those with a negative test [interval-to-delivery: median (range), 16 d (0-95 d) versus 42 d (2-91 d); p < 0.05 for each].

CONCLUSION

We conclude that 42% of patients with an early spontaneous preterm delivery (< 30 weeks) could be identified by a rapid MMP-8 bedside test at the time of their mid-trimester genetic amniocentesis. The MMP-8 bedside test is a powerful predictor of early spontaneous preterm birth in asymptomatic pregnant women.

A Proof-of-Concept Case Study for Personalized Noninvasive Prenatal Diagnosis: Can We Put It to Work?

This commentary highlights the article by van den Oever et al that describes a new method of prenatal diagnosis of single-mutation disorders.

The human sex ratio from conception to birth

We describe the trajectory of the human sex ratio from conception to birth by analyzing data from (i) 3- to 6-d-old embryos, (ii) induced abortions, (iii) chorionic villus sampling, (iv) amniocentesis, and (v) fetal deaths and live births. Our dataset is the most comprehensive and largest ever assembled to estimate the sex ratio at conception and the sex ratio trajectory and is the first, to our knowledge, to include all of these types of data. Our estimate of the sex ratio at conception is 0.5 (proportion male), which contradicts the common claim that the sex ratio at conception is male-biased. The sex ratio among abnormal embryos is male-biased, and the sex ratio among normal embryos is female-biased. These biases are associated with the abnormal/normal state of the sex chromosomes and of chromosomes 15 and 17. The sex ratio may decrease in the first week or so after conception (due to excess male mortality); it then increases for at least 10-15 wk (due to excess female mortality), levels off after ∼20 wk, and declines slowly from 28 to 35 wk (due to excess male mortality). Total female mortality during pregnancy exceeds total male mortality. The unbiased sex ratio at conception, the increase in the sex ratio during the first trimester, and total mortality during pregnancy being greater for females are fundamental insights into early human development.

Subtelomeric multiplex ligation-dependent probe amplification as a supplement for rapid prenatal detection of fetal chromosomal aberrations

Background

Pregnant women with high-risk indications are highly suspected of fetal chromosomal aberrations. To determine whether Multiplex Ligation-dependent Probe Amplification (MLPA) using subtelomeric probe mixes (P036-E2 and P070-B2) is a reliable method for rapid detection of fetal chromosomal aberrations. The subtelomeric MLPA probe mixes were used to evaluate 50 blood samples from healthy individuals. 168 amniocytes and 182 umbilical cord blood samples from high-risk fetuses were analyzed using the same subtelomeric MLPA probe sets. Karyotyping was also performed in all cases of high-risk pregnancies, and single nucleotide polymorphism array analysis was used to confirm submicroscopic and ambiguous results from MLPA/karyotyping.

Results

Subtelomeric MLPA analysis of normal samples showed normal result in all cases by use of P036-E2 probe mix, while P070-B2 probe mix gave normal results for all but one case. In one normal control case P070-B2 produced a duplicated signal of probe for 13q34. In the high-risk group, totally 44 chromosomal abnormalities were found by karyotyping and MLPA, including 23 aneuploidies and 21 rearrangements or mosaics. MLPA detected all 23 aneuploidies, 12 rearrangements and 1 mosaic. Importantly, MLPA revealed 4 chromosomal translocations, 2 small supernumerary marker chromosomes (sSMCs), and 3 subtelomeric imbalances that were not well characterized or not detectable by karyotyping. However, MLPA showed negetive results for the remaining 8 rearrangements or mosaics, including 3 low mosaic aneuploidies, 1 inherited sSMC, and 4 paracentric inversions.

Conclusions

Results suggest that combined use of subtelomeric MLPA and karyotyping may be an alternative method for using karyotype analyses alone in rapid detection of aneuploidies, rearrangements, and sSMCs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13039-014-0096-1) contains supplementary material, which is available to authorized users.

Noninvasive prenatal detection of aneuploidy

Noninvasive prenatal testing (NIPT) uses cell-free fetal DNA from the plasma of pregnant women to provide valuable information about the potential risks for fetal aneuploidy. This article provides a historical overview of both invasive diagnostic testing and serum screening approaches, both biochemical and the newer molecular noninvasive prenatal testing assays, used to identify patients who would be best served by invasive testing.

Investigation of the frequencies of prenatally diagnosed fetal chromosomal abnormalities at a single institution

The objective of this study was to investigate, retrospectively, the frequencies of fetal chromosomal abnormalities identified in 4176 prenatal cytogenetic examinations at the Xiamen Maternity and Child Health Care Hospital over the 5-year period from October 2005 to September 2010. The frequency of abnormal fetal karyotypes was 4.6%. Numerical chromosome abnormalities were identified in 150 cases. The frequency of trisomy 21 was by far the highest, followed by trisomy 18. Structural aberrations of chromosomes were identified in 43 cases, including 21 cases with balanced and 22 cases with unbalanced chromosomal aberrations. In addition, 16 cases of apparently de novo chromosomal aberrations and 27 cases of familial inheritances were observed. Increased awareness of the frequencies of fetal chromosome abnormalities is important for the improvement of prenatal care and providing the options of termination or continuation of the pregnancy. Data obtained in this study provide the basis of a database for genetic counseling.

SYTO9 and SYBR GREEN1 with a high-resolution melting analysis for prenatal diagnosis of β⁰-thalassemia/hemoglobin-E

The β⁰-thalassemia/Hb-E causes a wide range of severe conditions. A high medical cost is incurred in severe cases. Thus, the prevention of new cases of β⁰-thalassemia/Hb-E is required. The aim of this study is to use the SYTO9 and SYBR GREEN1 high-resolution melting (HRM) analysis for prenatal diagnosis of β⁰-thalassemia/Hb-E. DNA samples were extracted from amniotic fluid or cord blood of 11 pregnancies whose fetuses were at risk for β-thalassemia/Hb-E. PCR products from multiplex amplification refractory mutation system PCR for the detection of β⁰-thalassemia mutations at codons 17(A>T), 41/42(-TCTT), and 71/72(+A) and from amplification refractory mutation system PCR for the detection of Hb-E were characterized by SYTO9 HRM analysis. Moreover, β⁰-thalassemia 3.5- kb deletion was detected using real-time PCR with SYBR GREEN1 HRM analysis. Seven of 11 fetuses (64%) were diagnosed as β⁰-thalassemia/Hb-E (4 fetuses with mutation at codon 17, 2 with mutation at codon 41/42, and 1 with 3.5- kb deletion). Results from HRM analysis were completely consistent with those from fetal blood samplings analyzed at the time of delivery or pregnancy termination using HPLC. Therefore, the HRM analysis is easy to use. It is simple, flexible, non-destructive and has superb sensitivity and specificity. This approach might facilitate the laboratory diagnosis and genetic counseling for regions with a high prevalence of β⁰-thalassemia/Hb-E.

Clinical consequences of an increasing trend of preferential use of cultured villi for molecular diagnosis by CVS

OBJECTIVE

To compare the use of uncultured versus cultured villus cells for DNA-based prenatal diagnosis.

METHODS

A retrospective review of molecular testing of chorionic villus sampling (CVS) cases from 1988-2007. Method of analysis, gestational age (GA) at CVS and at diagnosis, time from procedure to results, results of maternal contamination studies, and the laboratory employed were abstracted from patient charts. Trends in laboratory practices over time were analyzed.

RESULTS

Time from CVS to diagnosis was longer when cultured cells were used. Average GA at diagnosis was 14-6/7 weeks with cultured cells vs 13-0/7 weeks with uncultured villi (p < 0.001). Recently, laboratories are more frequently requiring cultured cells, resulting in significantly greater delays in time to diagnosis and GA at results.

CONCLUSIONS

'Direct' DNA extraction saves 2 weeks from CVS to results. More women are afforded the option of an earlier, safer pregnancy termination if uncultured villi are used for molecular diagnosis. Implementation of standardized DNA extraction protocols and sample-size requirements can optimize the use of uncultured villi for molecular prenatal diagnosis. Increased awareness of the importance of rapid results and the advantages of 'direct' DNA extraction from uncultured villi can lead to improvements that are of clinical significance for patients undergoing early prenatal diagnosis.

Prenatal screening and diagnosis of congenital toxoplasmosis: a review of safety issues and psychological consequences for women who undergo screening

As part of the EUROTOXO initiative, this review focuses on the potential risks associated with prenatal testing for congenital toxoplasmosis. We first review the evidence on the risks of adverse events associated with amniocentesis, which is required for definitive diagnosis of toxoplasmosis infection in the fetus, and for which the most important risk is fetal loss. To date, there has been only one randomized trial to document risks associated with amniocentesis. This trial, which was conducted in 1986, reported a procedure-related rate of fetal loss of 1.0% (95% CI, 0.3-1.5). However, evidence from available controlled studies suggests that the pregnancy loss associated with mid-trimester amniocentesis may be lower. Potential psychological consequences of prenatal testing for congenital toxoplasmosis include parental anxiety due to false positive results and uncertainties related to prognosis of children with a prenatal diagnosis of congenital toxoplasmosis. Parental anxiety may be particularly important in screening strategies that include more frequent screenings, which may in turn entail substantial, and at times unnecessary, anxiety or other negative consequences for women and their families. These negative psychological outcomes should be balanced against the benefits of testing, which can allow women to make an informed choice regarding the pregnancy.

Genetic counseling issues in urea cycle disorders

The goal of counseling families that have a urea cycle disorder (UCD) is to facilitate the process of scientific understanding, emotional acceptance, and decision-making in a nondirective way. A proper understanding of the genes involved, inheritance patterns, available testing, and complicating factors is critical to serving the families' needs. This article summarizes the needed information, in particular describing the complexities of prenatal testing and counseling issues for each UCD. Included case histories illustrate the genetic counseling process and the decision-making scenarios for two families.

Use of prenatal diagnostic procedures in pregnancies affected with birth defects, Hawaii, 1986–2002

BACKGROUND

Information on the utilization of prenatal ultrasound (US), amniocentesis (AC), and chorionic villus sampling (CVS) in pregnancies affected by birth defects in the United States is limited. The intent of this study was to report on the utilization of these procedures in Hawaii.

METHODS

Cases were all infants and fetuses of any pregnancy outcome with birth defects, included in a Hawaii birth defects registry, and delivered during 1986-2002. The rates of prenatal US, AC/CVS, and prenatal diagnosis were calculated.

RESULTS

Prenatal US was performed in 76% of the cases and AC/CVS in 14% of the cases. Prenatal diagnosis of a birth defect was made in 16% of the cases. The prenatal US, AC/CVS, and prenatal diagnosis rates in 1998-2002 were 1.5, 1.5, and 1.7 times the rates in 1986-1991, respectively. Among all birth defects, the AC/CVS rate for women aged <35 years was 7% and for women aged > or =35 years was 48%. Among chromosomal abnormalities, the AC/CVS rate for women aged <35 years was 36% and for women aged > or =35 years was 66%.

CONCLUSIONS

Only a fraction of the Hawaii birth defects cases was prenatally diagnosed. The rates for prenatal US, AC/CVS, and prenatal diagnosis among pregnancies affected by birth defects were higher in 1998-2002 than in 1986-1991. AC/CVS rates were lower for maternal age <35 years.

Invasive prenatal diagnostic procedures 2005

Amniocentesis and Chorionic Villus Sampling have been the two most common prenatal diagnostic procedures for decades. There are wide variations in utilization, operator skills, quoted procedure risks, actual observed risks, and patient choices that come from highly variable counseling as to those risks. The compilation of published data suggests procedure risks of amniocentesis to be about 1/200 and in very skilled hands to be slightly lower. The risks of CVS in very experienced hands may also be about 1/200. Most studies comparing CVS to amniocentesis in skilled hands have found equivalency of risks. No well controlled studies support claims of amniocentesis risk at 1/1000 or lower. There is no increased risks of limb reduction defects following CVS at 10 weeks or greater, but there is an increase in Talipes from "Early Amniocentesis." In the first trimester CVS is the safer procedure.

46,XY,18q+/46,XY,18q− mosaicism in a fragile X prenatal diagnosis

OBJECTIVES

We describe a fetus with confined placental mosaicism for 46,XY,dup(18)(q21q23)/46,XY, del(18)(q21) in which finally the 18q- cell line formed the embryo. This prenatal diagnosis was performed on a pregnant woman carrying a premutation in the FMR1 gene. The purpose of the current study was to characterise the final fetus genotype and to discuss how this chromosomal abnormality was originated.

METHODS

Conventional cytogenetic analyses were performed from chorionic villi, amniocytes, and fetal blood samples in order to establish the fetal chromosome constitution. Molecular studies with microsatellite markers and CGH were carried out to this end. PCR and Southern blot were used to analyse the CGG-repeat region of the FMR1 gene.

RESULTS

An initial chorionic villi sample analysis showed a normal allele for the fragile X syndrome, but an abnormal 46,XY,dup(18)(q21q23) karyotype. Amniocentesis was subsequently performed, and a different 46,XY,del(18)(q21) cell line was detected. Re-examination of original chorionic villi sample evidenced a mosaicism for 46,XY,dup(18)(q21q23)/46,XY,del(18)(q21). Molecular findings allowed us to determine that the deletion expands at least 20 Mb and that it is paternally inherited.

CONCLUSION

Two different cell lines with structural abnormalities on chromosome 18 were formed as a consequence of an unequal sister chromatid exchange during the first post-zygotic division. This case reinforces the necessity of performing a karyotype in all prenatal diagnosis even when the indication is for a monogenic disease.