Amniocentesis

The Procedure Itself

An amniocentesis is a procedure that is only carried out under circumstances that determine the absolute need to do so. Due to the small risk of miscarriage, amniocentesis is not a decision that is taken lightly by the obstetricians or the expectant parents. The procedure is generally carried out between the 15th and 20th week of the pregnancy.

Women are recommended to have the procedure if:

• They have had an abnormal ultrasound
• There is a family history of genetic defects
• They already have a child with a certain defect
• If they will be 35 at the time of delivery – however not all obstetricians follow this benchmark.

The procedure involves a long slim needle being passed through the abdomen of the pregnant woman to the uterus where amniotic fluid is carefully drawn from the amniotic sac. The cells contain fluid that contains genetic information about the fetus. The test also enables parents to discover the precise sex of the baby should they wish to do so before the birth.

Although an invasive one, the procedure is relatively straightforward and is performed with the aid of abdominal ultrasound technology to enable the physician to see the exact location of the needle as it passes through the abdomen. Some women experience abdominal cramping, like period pain, during the procedure, however this soon passes. There also can be slight leakage of amniotic fluid or minimal blood loss, but providing that the woman rests for a few hours afterwards and avoids strenuous activity for 24 hours afterwards, this can be kept to a minimum.

Results of Amniocentesis

For those who are required to undergo the procedure, waiting for the results afterwards can be a worrying time. On average, results can take around two weeks, which parents are fully informed of at the time of the procedure. Amniocentesis is believed to be around 99.4 percent accurate, so results can offer relatively good peace of mind to parents. The information provided by the amnio enables parents to make a decision regarding the need to terminate the pregnancy if it is believed that significant deformity is likely.

There are rare occasions when there may be problems performing the test and these situations usually involve an inability to obtain the necessary amniotic fluid. There can also be laboratory issues where the cells that are collected fail to grow when they are cultured.

Genetic Counseling

All couples required to undergo amniocentesis are offered genetic counselling to ensure that they are fully aware of the reasons for the test as well as the physical risks involved in relation to miscarriage and infection following the procedure. Of course, couples do have the choice whether or not to go ahead with the procedure. If they decide not to have the procedure, this at least is a decision made when the couple are fully armed with the facts.

Some couples prefer to take a calculated risk and choose not to have the procedure. In these cases, it is often due to a fear that they may risk losing the baby as a result of the procedure itself. Research is ongoing in a hope that there will one day be a blood test that will be able to identify fetal cells to determine the presence of genetic abnormality without the need for an invasive procedure that carries undesirable risk.