A long, thin needle is inserted through the abdomen and into the uterus. You must sign a consent form. Your bladder must be full for the ultrasound . There are no food or fluid restrictions. When the needle enters into the amniotic sac, a sharp pain lasting a few seconds may be felt.
Some women have the sensation of pressure in the lower abdomen when the fluid is withdrawn.
After the procedure there may be some minor cramping. There is even a smaller chance of miscarriage . This test is typically performed when a problem is suspected, so the results outweigh the risk. Later on in a pregnancy , the test is used to identify suspected problems such as a blood group problem or infection. It is also used to determine whether a fetus in distress is mature enough to survive an early birth.