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Zika Virus During Pregnancy

A Case Study on Fetal MRI

What is Zika?

Zika is a virus that is spread primarily through the bite of infected mosquitos. Adults who have been infected typically have mild symptoms such as fever, rash, joint pain, and red eyes. There is no vaccine or “cure” for those who become infected, and treatment is focused on relieving symptoms associated with the condition. This comes in the form of rest, rehydration, and acetaminophen for pain and fever. Symptoms usually resolve on their own after a week or so.

Zika is not endemic to the U.S. and is primarily brought back by infected travelers returning from affected areas such as the Caribbean, Central, and South America, the Pacific islands and Asia.

Zika During Pregnancy

A pregnant woman who becomes infected with the Zika virus can pass it to the fetus. Infection during pregnancy can cause underdevelopment of the fetal brain resulting in an abnormally small brain, a condition termed micrencephaly. When the brain stops growing, the head’s growth stops as well creating a smaller than expected head size, or microcephaly.

Not every pregnant woman who is infected with Zika will have a baby with a birth defect; however, the chances of these problems occurring are increased due to the Zika infection.

If a woman who is not pregnant is infected with the virus, the CDC believes that there is no risk for birth defects in future pregnancies once the virus has cleared from her blood.

20 Tips to Help You Have A Healthy Pregnancy

Babies Born with Zika

Conditions associated with Zika infection during pregnancy are collectively known as congenital Zika syndrome. Such conditions may include:

  • Abnormally small brain and head
  • Brain underdevelopment
  • Feeding problems (e.g. difficulty swallowing)
  • Hearing loss
  • Seizures
  • Vision problems
  • Contractures – problems with joint movement
  • Lack of muscle flexibility soon after birth

These conditions may lead to developmental delays with moving, learning, speaking and playing. Not all babies born with congenital Zika syndrome will have all of these problems and each case is different. It is difficult to predict the effects of congenital Zika syndrome on each baby’s outcome. Regardless, babies affected by Zika virus require specialized care from many types of healthcare providers and caregivers as they age.

Diagnosing Zika in an Unborn Baby

If a pregnant woman has tested positive for Zika virus, her physician will want to monitor the developing fetus throughout the term to track its development.

Ultrasound is a common method for tracking fetal growth. While it is a safe procedure for the mother and baby, ultrasound has limited sensitivity for detecting developmental abnormalities associated with Zika infection secondary to the timing of screening, gestational age, equipment used, certain patient factors like obesity, the degree of micrencephaly, and the expertise of the technologist performing the procedure.

An amniocentesis may also be considered between 15-18 weeks gestational age; however, the accuracy of the tests on amniotic fluid for congenital Zika virus is not known.

The use of fetal MRI in conjunction with ultrasound is an effective method for detecting abnormalities and providing additional information that can impact pregnancy management. According to the CDC, “Interpretation of fetal MRI requires specialized expertise and has limited availability in the United States.” Diversified Radiology’s neuroradiologists and pediatric radiologists are highly trained and experienced in the interpretation of fetal MRI and perform more of these studies than any other private practice in the region.

Case Study:

A pregnant 16-year-old from Honduras with confirmed Zika virus infection presented for MRI following an abnormal ultrasound. Fetal MRI confirms micrencephaly and ventriculomegaly, a condition in which the fluid-filled structures in the brain are too large.

Micrencephaly – Underdevelopment of the brain. Notice also the overlapping sutures of the skull, indicating a smaller than normal head.
Ventriculomegaly – Notice the large fluid-filled structures indicated by the white color.


The images below indicate the appearance of convexity polymicrogyria, a condition in which the brain develops too many folds that are unusually small.

Suspected Polymicrogyria
Suspected Polymicrogyria


Imaging in this case of the abnormal development of the fetal brain are characteristic of congenital Zika infection.


Zika infection during pregnancy can cause severe brain abnormalities resulting in developmental delay. Fetal MRI in conjunction with ultrasound provides conclusive identification of micrencephaly and/or other developmental abnormalities related to Zika infection during pregnancy. This advanced knowledge provides parents the opportunity to properly manage the pregnancy and to prepare for life with a child having special needs.

To assist parents with what can be a very anxious, confusing, and difficult time, the CDC has compiled several helpful resources and outlined them here.


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