The basic invasive prenatal diagnostic tests consist of puncture of the uterus to obtain amniotic fluid (amniocentesis), the removal of placentary tissue (chorion biopsy) or obtaining blood from the umbilical cord (umbilical blood sampling).
Chorion biopsy is an invasive diagnostic method that is mainly employed during early pregnancy (embryonic period). Normally, chorial tissue is removed trans-vaginally using a biopsy needle and examined in the direct preparation or after short-term in-vitro cultivation.
Amniocentesis represents an additional invasive prenatal diagnostic possibility. Here in the 13th – 15th WoP (15 - 17 weeks after the LMP) 10 - 20 ml of amniotic fluid is obtained via a puncture. This examination is performed with ultrasound supervision in order to reduce the danger of hitting the fetus or placenta and thereby harming the gestation.
Umbilical blood sampling
After the 20th WoP, the umbilical cord can be punctured. Umbilical blood sampling is performed when hemoglobin pathology, coagulation pathology or viral embryopathy is suspected.