There is no conclusive answer. There are different approaches on the subject and each couple should follow their beliefs.
The approach that supports amniocentesis will give significant weight to the following parameters:
Even though a negative result in amniocentesis does not guarantee that the fetus will not become infected later, the studies of Bilavsky, Pardo and otherssuggest that even if there is an infection, the fetus is not expected to suffer serious injury. Therefore, in the event of a negative amniocentesis result, some experts will recommend to stop monitoring until the delivery, and some will recommend one targeted scan to be on the safe side, around week 32. On the other hand, a woman who does not undergo amniocentesis is regarded as having an infected fetus, and therefore she will undergo the full protocol of tests until the end of the pregnancy.
In cases where an amniocentesis was performed, the experts on targeted scans report that it is easier for them to read the findings and diagnose injuries as related to the virus, if such are found. For example, an injury identified in the digestive system can be inconsequential if it is known that the fetus was infected with CMV, but can be of great significance if he was not infected.
On the other hand, there is also the opposite approach that contends that the amniocentesis is not necessary, since the test is invasive and poses a risk, and only provides information on whether the fetus was infected, and not on whether they were injured as a result of being infected with the virus.
If a woman chooses not to have the amniocentesis, she will undergo the full protocol of tests, and if any finding is discovered, the doctors will consider recommending the amniocentesis at a later date.
How important is the choice of the doctor performing the amniocentesis?
The choice of the doctor performing the amniocentesis in the case of CMV is as important as in the case of an amniocentesis without a CMV infection.
Some hospitals will do the test in their own lab; some hospitals do not have a lab, but they will arrange for the test tube to be delivered for you to an appropriate lab; and in some hospitals, the woman’s escort will have to independently deliver the test tube to a virology lab; independent delivery is also required if the amniocentesis is done in the private setting. For a list of virology labs that test amniotic fluid.
What are the differences between the genetic amniocentesis and the CMV amniocentesis?
CMV amniocentesis is a test to detect the virus in the urine excreted by the fetus, and therefore, unlike the genetic amniocentesis that is performed in gestational weeks 16-20, the CMV amniocentesis is performed in weeks 21-22, in which the fetus already excretes urine.
It is important that the test be done at least 6-7 weeks after the estimated date of infection.
In Israel, the standard is not to perform the test between weeks 24-32, due to the risk of premature birth as result of the puncture and the birth of a premature infant at an early week, with all of the risks that this entails, regardless of the CMV virus.
A woman undergoing CMV amniocentesis will have genetic counselling prior to the amniocentesis, and at the time of the test, separate test tubes will be collected for the genetic tests and for CMV virus detection.
Contrary to the results of the genetic test, which take weeks to arrive, the results of the CMV test are received within a few days.
In addition to Form 17 for the amniocentesis, it is also important to arrange for a Form 17 for the virology lab.
Women who perform the test in week 32 will be asked to receive two injections to mature the fetus’ lungs a few days prior to the amniocentesis. After the test, the woman will remain for observation and will be connected to a monitor for about half an hour. In addition, the test has to be performed at a hospital with delivery rooms and another doctor must be present in the room. This procedure is in place for the event that premature birth develops due to the test.
What is the difference between amniocentesis in weeks 21-22 and amniocentesis in week 32?
In most hospitals, the standard is not to perform the test between weeks 24-32, due to the risk of premature birth due to the puncture and the birth of a premature infant at an early week, with all of the risks that this entails, regardless of the CMV virus.
Women who undergo the test in week 32 will be asked to have genetic counselling even if they had genetic amniocentesis in an earlier week of the pregnancy.
The women will be asked to receive two injection to mature the fetus’ lungs a few days prior to the amniocentesis.
The test has to be performed at a hospital with delivery rooms and another doctor, in addition to the doctor performing the amniocentesis, must be present in the room.
After the test, the woman will remain for observation and will be connected to a monitor for about half an hour.
This procedure is in place for the event that premature birth develops due to the test.
Does a negative amniocentesis definitively exclude fetal infection and should further tests be done?
moment the test was done. The fetus can become infected at a later stage of the pregnancy, but a recent study  has found thatAfter receiving a negative result in amniocentesis, even if the fetus becomes infected, they are not expected to suffer a serious injury due to contracting the virus.
In this case, some experts will recommend to have one targeted scan around week 32, to be on the safe side, and some experts will skip it. In any case, doctors specializing in CMV will recommend a postnatal urine test even after a negative amniocentesis result, in order to exclude a later infection.
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