You must sign a consent form. Your bladder must be full for the ultrasound . There are no food or fluid restrictions. How the Test will Feel If an anesthetic is used, there may be a sharp, stinging sensation for a few seconds. 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Some women have the sensation of pressure in the lower abdomen when the fluid is withdrawn.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. Later on in a pregnancy , the test is used to identify suspected problems such as Rh incompatibility or infection. It is also used to determine whether a fetus in distress is mature enough to survive an early birth. Late in the pregnancy, lung maturity can be determined using this test. Please read this Important notice .