A fetal tissue biopsy is done by using ultrasound guidance to insert a needle through the mother's abdomen and into the uterus to obtain a sample of the fetal tissue.
Another device may also be used for the fetal tissue biopsy and the exact method of a fetal tissue biopsy can vary depending on the type of issue that is being sampled, which can be the skin, liver or muscle tissue and the gestational age of the fetus.
Often though the fetal tissue biopsy is done with the needle being guided by a real time ultrasound to ensure that the needle or device is accurately positioned in the uterus and near the desired fetal tissue.
The needle or a sheath or trocar is inserted through the abdominal wall of the mother and into the uterus.
Then a small sample of skin is taken using forceps or a biopsy gun.
For liver or muscle tissue samples a thin needle is used to obtain samples from the fetal liver or muscle.
Most fetal tissue biopsies are done between 17 weeks to 20 weeks of gestation.
And local anesthesia is used to numb the mother's skin and intravenous sedation can be used as needed.
An alternative to the normal fetal tissue biopsy through the needle is by Chorionic Villus Sampling which is a method of obtaining fetal tissue by sampling placental tissue, which is genetically identical to the fetus and can be performed transabdominal or transcervically.
Another option is amniocentesis which involves collecting of amniotic fluid, that contains fetal cells and chemicals for testing.