Neonatal diagnostic

Question

Hello,
I would like to know to what extent a choriocentesis conducted for screening for cystic fibrosis can be reliable. Can not the sample be contaminated by the blood of the mother?
Is it mandatory to wait at least for the 10th week of pregnancy to perform choriocentesis?
Without counting the delay to have the results, an interrupted pregnancy, will necessarily be done by curetage?
Thank you in advance.

Answer

Hello,

Choriocentesis consists in collecting chorion cells (the fetal part of the future placenta) by puncture-aspiration, which therefore have the genetic characteristics of the fetus. This sampling used to carry out a prenatal diagnosis of a serious fetal disease must be carried out between the 10th and the 14th week of pregnancy in order not to delay too much the possible medical interruption of pregnancy in case the diagnosis is positive.
The test is reliable because genetic tests differentiate between cells from the mother and those from the fetus.

The medical interruption of pregnancy before the 22nd week is performed after preparation by taking anti-progesterone and then 48 hours after the onset of labour by oral or vaginal use of prostaglandins, drugs causing cervical dilation and uterine contractions with expulsion of the fetus. An infusion of analgesics on demand is instituted (morphine). In the rare circumstances when the lower course is impossible (placenta in front of the cervix, for example), a mini cesarean section is possible.

Hope this answer can help.
Best wishes
Gilles RAULT, MD, Roscoff CF Center

14.02.2017