Cell-free DNA testing: An aid to prenatal sonographic diagnosis

Fetal Surgery for Gastroschisis—A Review with Emphasis on Minimally Invasive Procedures

(1) Background: The morbidity of gastroschisis is defined by exposure of unprotected intestines to the amniotic fluid leading to inflammatory damage and consecutive intestinal dysmotility, the viscero-abdominal disproportion which results in an abdomen too small to incorporate the herniated and often swollen intestine, and by associated pathologies, such as in complex gastroschisis. To prevent intestinal damage and to provide for growth of the abdominal cavity, fetal interventions such as amnio exchange, gastroschisis repair or covering have been evaluated in several animal models and human trials. This review aims to evaluate the reported techniques for the fetal treatment of gastroschisis by focusing on minimally invasive procedures. (2) Methods: We conducted a systematic database search, quality assessment and analyzed relevant articles which evaluate or describe surgical techniques for the prenatal surgical management of gastroschisis in animal models or human application. (3) Results: Of 96 identified reports, 42 eligible studies were included. Fetal interventions for gastroschisis in humans are only reported for EXIT procedures and amnio exchange. In animal models, particularly in the fetal sheep model, several techniques of open or minimally invasive repair of gastroschisis or covering the intestine have been described, with fetoscopic covering being the most encouraging. (4) Discussion: Although some promising minimally invasive techniques have been demonstrated in human application and animal models, most of them are still associated with relevant fetal morbidity and mortality and barely appear to be currently applicable in humans. Further research on specific procedures, instruments and materials is needed before any human application.

Discordant fetal sex on NIPT and ultrasound

Prenatal diagnosis of sex discordance is a relatively new phenomenon. Prior to cell-free DNA testing, the diagnosis of a disorder of sexual differentiation was serendipitous, either through identification of ambiguous genitalia at the midtrimester morphology ultrasound or discovery of genotype-phenotype discordance in cases where preimplantation genetic diagnosis or invasive prenatal testing had occurred. The widespread integration of cfDNA testing into modern antenatal screening has made sex chromosome assessment possible from 10 weeks of gestation, and discordant fetal sex is now more commonly diagnosed prenatally, with a prevalence of approximately 1 in 1500-2000 pregnancies. Early detection of phenotype-genotype sex discordance is important as it may indicate an underlying genetic, chromosomal or biochemical condition and it also allows for time-critical postnatal treatment. The aim of this article is to review cfDNA and ultrasound diagnosis of fetal sex, identify possible causes of phenotype-genotype discordance and provide a systematic approach for clinicians when counseling and managing couples in this circumstance.

Fetal Tachycardia Is an Independent Risk Factor for Chromosomal Anomalies in First-Trimester Genetic Screening

OBJECTIVES

The association of an abnormal fetal heart rate (FHR) and chromosomal anomalies in the first trimester of pregnancy remains unclear, probably because of the lack of control for known confounding factors. This study was designed to determine whether an increased FHR is an independent risk factor for chromosomal anomalies between 11 and 14 weeks' gestation.

METHODS

This cohort study included women who underwent first-trimester genetic screening between 2011 and 2014 at a single institution. A multivariable logistic regression analysis was performed to determine whether an FHR of 170 beats per minute (bpm) or higher, derived from a receiver operating characteristic curve, is an independent risk factor for all chromosomal anomalies while controlling for known confounding factors. P < .05 was considered significant.

RESULTS

An FHR of 170 bpm or higher was observed in 7% (228 of 3254), and chromosomal anomalies were present in 1.0% (31 of 3254) of the population. A higher proportion of fetuses with an FHR of 170 bpm or higher had chromosomal anomalies compared to those with an FHR lower than 170 bpm. An FHR of 170 bpm or higher was an independent risk factor for chromosomal anomalies after controlling for known confounding factors. Of note, in the group of fetuses with a nuchal translucency above the 95th percentile, the frequency of chromosomal anomalies was significantly higher among fetuses with an FHR of 170 bpm or higher compared to those with an FHR lower than 170 bpm.

CONCLUSIONS

Fetal tachycardia is a risk factor for chromosomal anomalies during first-trimester genetic screening, independent of increased nuchal translucency, nuchal septations, and maternal age.

Clinical utility of exome sequencing in the prenatal diagnosis of congenital anomalies: A Review

Advances in prenatal genomics have enabled the assessment of not only the sub-microscopic structure of chromosomes using chromosomal microarray analysis, but also the detection of "pathogenic variants" to the resolution of a single base pair with the use of next generation sequencing. Research is emerging on the additional prenatal diagnostic yield that exome sequencing offers when structural fetal anomalies are detected on ultrasound examination, in particular the identification of monogenic abnormalities defining prognosis and recurrence of anomalies. Primarily assessed using fetal DNA obtained by invasive techniques (amniocytes or chorionic villi), this technology is progressing into a non-invasive approach using maternal plasma. There are several challenges, to be addressed before this technology can be introduced into routine clinical practice. These are primarily technical and interpretational but also relate to service provision; cost-effectiveness; turn-around time; patient acceptability and ethical dilemmas. With adequate pre- and post-test counselling many of these challenges may be overcome and such counselling has to be multi-disciplinary, involving clinical geneticists, genetic scientists, paediatricians, perinatal pathologists and fetal medicine subspecialists. There is therefore a need for obstetricians to have an understanding of the clinical utility, application, advantages and challenges of such technologies before introduction into routine clinical practice.