Follow-up on pregnant women with CMV

There are currently three tests that facilitate follow-up on a fetus whose mother was infected with the CMV virus.

One is amniocentesis, which very reliably diagnoses fetal infection up to the time of the test, but cannot diagnose if the fetus was injured as a result of the infection Other tests are targeted ultrasound scans and an fetal MRI test, the results of which, if normal, allow for the probable exclusion of serious newborn injury. See Articles tab.

1.Amniocentesis – enables the detection of the CMV virus in the urine excreted by the fetus, to know if he was infected.
Please keep in mind that the amniocentesis reflects the presence or absence of the virus at the time of the tests, providing that two conditions are met:

  1. The test was performed when the fetus already excretes urine (as of weeks 21-22).
  2. The test was 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 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.

Amniocentesis for the presence of CMV virus is performed by the same procedure of the regular genetic amniocentesis, with one difference – extraction of amniotic fluid in an additional test tube that is delivered to 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 must be done at a hospital with delivery rooms and in the presence of another physician in the room. This detailed protocol is intended to guarantee that even if something goes wrong during the test, the fetus will receive optimal care.

It is important to arrange for a Form 17 for both the amniocentesis and the virology lab. The result of the CMV virus infection test is received with a few days. List of hospitals where the test can be performed is available under the tab Important Telephone Numbers.

  1. CMV targeted scans – the targeted scans are performed starting from week 24 every three to four weeks until birth and concentrate mainly on the brain.The targeted scans are performed if the result of the CMV virus presence test is positive, or if the woman has chosen not to perform an amniocentesis, but there is a confirmed maternal infection with the virus during the pregnancy or close it.

The exact time for starting the targeted scans will be determined by the follow-up physician specializing in the CMV virus depending on the maternal week of viral infection.

Please note that the doctor performing the scan should be carefully selected, since this diagnosis relies on their experience in scanning  fetuses infected with the CMV virus in general, and in the brain of the fetus in particular.

  1. MRI (magnetic resonance imaging) of the fetus brain – a test conducted around gestational week 33 in cases of fetal CMV virus infection or if the mother has chosen not to perform an amniocentesis, but there is a confirmed maternal infection with the virus during the pregnancy or close it.

This test involves special performance and reading, and cannot be done at every hospital. List of hospitals where the test can be performed is available under the tab Important Telephone Numbers.

Some hospitals instruct women to take a Valium pill before the test, in order to reduce fetal movements and increase the accuracy level of the test.

Although the test is included in the follow-up protocol, in recent years there is a growing premise that the information it adds is inconsequential and it might even provide false positives that generate unnecessary stress.

At present, the approach of most leading experts in Israel in the field of the imaging of fetuses with CMV is that consistency in the findings of the targeted ultrasound scans and in the fetal brain MRI will support the diagnosis whether or not there were findings that raise suspicion for an injury following the infection.

Inconsistency regarding the presence of findings that raise the suspicion for an injury following the infection will bring about a discussion on the possibility of false results and of false positives, in particular.).

Follow-up protocol

The follow-up protocol for a patient who was infected with the CMV virus for the first time during pregnancy depends on the week of the infection.

Infection of more than six months before conception – currently considered safe, and so most experts will not recommend to perform special CMV tests, except for a newborn urine test.

Infection of about two months to six months before conception –  predominantly the recommendation will be one targeted scan around week 32, and a urine test for the newborn after the birth.

Infection between one month before conception and up to week 16-17 – predominantly, the woman will be offered to perform an amniocentesis in weeks 21-22 and further follow-up will be done depending on the result of the test:

A negative result in amniocentesis – means that the fetus was not infected up to the time of the test. Even if infected later in the pregnancy, in most cases, they will not suffer a serious injury.[3]  

In this light, some experts will recommend one targeted scan around week 32, and some experts will skip it. In any case, the recommendation will be to perform a urine test after the birth, in order to exclude late infection.

A positive result in amniocentesis – the full tests protocol will be engaged, which includes targeted scans for the virus as of week 24 until birth and fetal brain MRI around week 33. Despite the positive result in amniocentesis, hospitals still perform the urine test when the baby is born, but do not wait for the result and start the tests that will be detailed below under the tab Birth and time in the Neonatal Department.

Infection after weeks 16-17 – usually, the suggestion will be an amniocentesis in week 32, targeted scans every three-four weeks (not before week 24) until birth, and if the result of the amniocentesis is positive, a fetal brain MRI will be performed around week 33 and a urine test for the baby immediately after the birth.

It is herein stressed that no two cases are alike, and the attending doctor manages the follow-up of the pregnancy according to the level of risk, and according to the wishes and beliefs of each woman.


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