Ultrasound recommendations: Zika Virus

If a pregnant patient has returned from an high risk area  and is concerned about microcephaly.  

The Royal College of Obstetricians and Gynaecologists advises that women who’ve had no symptoms or whose symptoms have resolved should be referred for ultrasonography, which can be repeated every four weeks.

Women with symptoms indicating Zika virus infection should have samples sent to the Rare and Imported Pathogens Laboratory (clotted blood, an EDTA “purple top” blood, and a small volume of urine without preservative). 

• Women who test negative should be referred for ultrasonography, which can be repeated every four weeks. 
• Women who test positive should be referred for ultrasonography and to fetal medicine for follow-up.

Reference : BMJ 2016;352:i649

Microcephaly: On antenatal ultrasound it is usually defined as fetal head measurements  falling under two standard deviations expected for gestation or falling under the 3rd percentile. But some authors advocate the use of three standard deviations which increases specificity. 

Image courtesy:  
Wikipedia: https://upload.wikimedia.org/wikipedia/commons/8/80/Microcephaly.png