Pregnancy

The trophoblast biopsy


To look for trisomy 21, the trophoblast biopsy is used more and more in place of amniocentesis. What is it exactly? How is the trophoblast biopsy?

What is the trophoblast biopsy?

  • The biopsy of the trophoblast consists of taking a fragment of the tissue of the future placenta, called chorionic villi.
  • Achieved as early as 9 weeks of amenorrhea, this puncture is proposed to study the chromosomes of the embryo (in particular trisomy 21) or to look for certain genetic anomalies. It is more and more used in place of amniocentesis.

How's it going ?

  • Before the sampling, an ultrasound makes it possible to verify if the conditions of realization of the examination are met. It is not uncommon for the doctor to postpone the examination for a week or so. Ultrasound also determines the appropriate technique. The obstetrician chooses either the transabdominal (through the belly) or the vaginal route.
  • He punctures the chorionic villi with a thin needle or a microscopic forceps. The sampling is fast, but the preparation takes time to limit any risk of infection. Thanks to local anesthesia, the pain sensation is usually close to a simple blood test.

What precautions after the biopsy?

  • After the biopsy, it is advisable to rest at least one day. The risk of miscarriage, estimated at 1%, is maximum within ten days.
  • Pains, bleeding or amniotic fluid flow require prompt consultation.

Good to know

With the generalization of trisomy 21 screening in the first trimester of pregnancy, 5% of pregnant women are in a risk zone (greater than 1/250) after the analysis of maternal serum markers and the measurement of This early research significantly increases the number of trophoblast biopsies.

Christine Cointe

Biopsy of the trophoblast, the video.