About 3 percent to 5 percent of women who have the screening test will have an abnormal reading, but only about 10 percent of those women will have a child with a genetic problem. During the procedure, a device is moved across the abdomen that transmits sound waves to create an image of the uterus and fetus on a computer monitor. This test measures your blood-sugar level an hour after you've had a glass of soda. If the reading is high, which happens about 20 percent of the time, you'll take a more sensitive glucose-tolerance test, in which you drink a glucose solution on an empty stomach and have your blood drawn once every hour for three hours. The procedure is done by inserting a needle through the abdomen into the amniotic sac and withdrawing fluid that contains fetal cells.
Analysis can detect neural tube defects and genetic disorders.
The miscarriage rate varies depending on the experience of the physician, averaging about 0.2 percent to 0.5 percent at 15 weeks and 2.2 percent at 11 to 14 weeks, but the test can detect 99 percent of neural-tube defects and almost 100 percent of certain genetic abnormalities. All rights reserved. All rights reserved.