FBS is performed in a hospital's outpatient surgery department. You will probably be given a sedative to reduce your and the fetus's movement during the FBS procedure.

• The fetus may be given an injection of medicine that temporarily stops movement.
• A small area of your belly is numbed with an injection of local anesthetic.
• Ultrasound is used to guide a needle through your belly into an umbilical vein in the umbilical cord.
• A small amount of blood is withdrawn into the needle and collected.

You may be given more medicine during FBS. These may include antibiotics to prevent infection or medicine to prevent preterm labour (tocolytic drugs).

Fetal blood tests show the oxygen level, red blood cell condition, and red blood cell count. This helps your doctor plan the best treatment for you during your pregnancy.

If the effects of Rh sensitization are severe and the fetus has severe anemia, a fetal blood transfusion may be done right away. Future transfusions may be scheduled to keep the fetus healthy until it can be delivered safely.