The Society for Maternal-Fetal Medicine (SMFM) has issued a recommendation statement on ultrasound screening for fetal microcephaly following Zika virus exposure. The statement outlines the prenatal ultrasound diagnostic criteria for microcephaly and what is currently known about the predictive value for microcephaly at birth. The current CDC, ACOG, and SMFM guidance recommends serial ultrasounds, every 3 to 4 weeks, with evidence of maternal infection. These recommendations further suggest that serial ultrasounds can be considered for women who have traveled to endemic areas but have no evidence of infection, as Zika infection can be asymptomatic. At present, there are very limited data with respect to the natural history and outcomes of fetal microcephaly in the setting of Zika infection or exposure. As new data emerge, these recommendations may change. In addition, diagnostic testing, surveillance, and management of suspected prenatal Zika exposure and infection is evolving and will continue to change as new data become available. Recommendations included in the statement are:

• If the head circumference (HC) by prenatal ultrasound is >2 standard deviations (SD) below the mean, a careful evaluation of the fetal intracranial anatomy is indicated. If the intracranial anatomy is normal, SMFM recommends follow-up ultrasound in 3-4 weeks.

• SMFM recommends that isolated fetal microcephaly should be defined as fetal HC >3 SD or more below the mean for gestational age. The diagnosis of pathologic microcephaly is considered certain when the fetal HC is >5 SD. A detailed neurosonographic examination should be performed and follow-up ultrasound done in 3-4 weeks.

Citation: SMFM Publications Committee. SMFM statement: Ultrasound screening for fetal microcephaly following Zika virus exposure. [Published online ahead of print February 18, 2016]. Am J Obstet Gynecol. doi: http://dx.doi.org/10.1016/j.ajog.2016.02.043.