Invasive Diagnostics

Occasionally a pregnancy may be complicated by an abnormal ultrasound finding, an increased risk of a genetic abnormality on a screening tests or the mother has been exposed to a virus that is affecting her baby’s health. In such cases, there may be a need for a more invasive procedure or test to get further information to help the baby prior to delivery or to help the family and pediatricians prepare for delivery. The Maternal Fetal Medicine team here at Woman’s has vast experience in providing these options here at our facility.

Chorionic Villus Sampling

Chorionic Villus Sampling (CVS) test is carried out around the 9th or 10th week of pregnancy, and again it is an outpatient procedure. This test takes a very small amount of material from the developing placenta.

How the Test is Performed

Typically this test is performed by placing a thin tube through the cervix (neck of the womb) to obtain the sample. Most women say that this is only slightly uncomfortable.


The external appearance of a newborn baby can provide important clues for genetic syndromes or to confirm the likelihood of normal outcome. However, sometimes the quality of these images can be affected by fetal size, position, and movement.

How the Test is Performed

Fetoscopy involves placement of a thin, flexible instrument into the uterus through a small abdominal incision on the mother. The endoscope can also be used through the maternal cervix. This procedure is typically performed at approximately 18 weeks when many of the external fetal structures are more easily visualized.

Fetal Blood Sampling

Fetal blood sampling (FBS) is the collecting of fetal blood directly from the umbilical cord or fetus. The fetal blood is tested for signs of anemia and other blood problems. FBS is also known as cordocentesis or percutaneous umbilical cord blood sampling. FBS is usually used when a Doppler ultrasound and/or a series of amniocentesis tests have first shown moderate to severe anemia.

How the Test is Performed

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 abdomen is numbed with an injection of local anesthetic.

• Ultrasound is used to guide a needle through your abdomen into an umbilical vein in the umbilical cord.

• A small amount of blood is withdrawn into the needle and collected.

Fetal Tissue Biopsy

This procedure is used to detect hereditary conditions of the fetus that cannot be identified through more conventional methods such as amniocentesis or chorionic villus sampling of the placenta. The biopsy is typically performed between 17-20 weeks gestation

How the Test is Performed

Anesthetic is used to numb the mother’s skin. Using ultrasonic guidance, the physician inserts a small hollow tube into the mother’s abdomen and through the gestational sac to reach the fetus. The tube permits passage of biopsy forceps that is used to obtain a fetal skin sample. A small amount of intravenous sedation is used for the mother as needed.

Genetic Amniocentesis

Genetic amniocentesis can provide information about your baby's genetic makeup. Generally, genetic amniocentesis is offered when the test results might have a significant impact on the management of the pregnancy or your desire to continue the pregnancy.

How the Test is Performed

The test involves placing a needle in to the womb through the woman’s abdomen and obtaining a small sample of the fluid in which the baby floats (the amniotic fluid). Most women say that the test is not painful.

The amniocentesis test is usually carried out between 16 and 18 weeks of the pregnancy and can be done in an outpatient clinic.