Prenatal diagnostics deals with examinations of the unborn child in the womb (prenatal = before birth).
It is offered primarily to women after the age of 35, since the risk of malformations of the child due to chromosomal changes then increases significantly. Furthermore, prenatal diagnostics can also be used to examine various infections, metabolic and hereditary diseases (monogenic diseases) of the child.
Indications (areas of application)
- Maternal age; as maternal age increases (>35 years of age), the likelihood of chromosomal abnormalities in the child increases
- Result of a noninvasive screening procedure (e.g., sonography/nude translucency measurement; triple test).
- A sonographic finding that makes it possible to suspect a chromosomal disorder.
- A chromosomal abnormality such as translocation, insertion, or inversion in one parent (in such cases, the likelihood of an unbalanced chromosomal abnormality in the child is increased above the maternal age-related risk).
- Familial genetic predisposition to severe disease.
Methods of prenatal diagnostics
| Method | Time |
| Preimplantation genetic diagnosis (PGD)* . | In vitro fertilization |
| NIPT (noninvasive prenatal test): molecular genetic blood test to detect cell-free DNA. | 10+0 SSW |
| Chorionic villus sampling* * (tissue sampling from the fetal (child) portion of the placenta* (placenta)). | 11-14TH SSW |
| Amniocentesis* * (amniotic fluid collection by puncture of the amniotic cavity). | 15-17 SSW |
| Placental puncture* (puncture of the placenta). | from 15. SSW |
| Cordocentesis* * * (puncture of the umbilical cord, preferably at the placental attachment site). | From 16-20 SSW |
| Fetal biopsy (fetal tissue sampling) for diagnosis of certain genodermatoses | From 20th SSW |
| Fetal blood collection (ultrasound-guided collection of fetal blood from the umbilical vein or fetal heart) | Earliest time: 20 SSW |
| Fetoscopy (endoscopic observation of the unborn child; nowadays performed only in exceptional cases). | Optimal time: 18th-24th SSW. |
SSW = week of gestation* Screening for chromosomal abnormalities using cell biology and molecular genetic testing; detection of specific genetic defects (gene mutations) including. Aneuploidy screening (screening for the presence of supernumerary or missing chromosomes) * * Examination for chromosomal changes with the aid of chromosome analysis; furthermore, genetic diagnostics and biochemical diagnostics; in the case of amniocentesis, furthermore, diagnostics of open neural tube defects * * * Examination for chromosomal changes with the aid of chromosome analysis; furthermore, hematological and biochemical diagnostics
Other future procedures
- Prenatal diagnosis is possible from the fifth week of pregnancy from fetal cells (fetal cells) in a cervical smear (smear from the cervix). Approximately every 2,000th cell in the smear is a trophoblast (outer cell layer of a blastocyst (developmental stage of embryogenesis) that connects it to the uterine wall) from the placenta and thus originates from the fetus. The procedure is still under development.
- The next step in prenatal diagnostics is whole-exome sequencing (WES; potentially coding segments of DNA). In cases of fetal structural anomalies, fetal DNA has been analyzed from chorionic villi, amniotic fluid, and blood. WES thus allowed detection of additional diagnostic genetic variants at rates ranging from approximately 3% to 15%.
