ATLANTA -- The CDC no longer recommends serial ultrasounds to check for fetal abnormalities in asymptomatic Zika virus patients with a negative IgM test, according to the president of the Society of Maternal Fetal Medicine (SMFM). At its meeting here, SMFM held a special session to discuss how the interim CDC guidelines for Zika virus may impact their clinical practices, covering such topics as asymptomatic travelers, symptomatic travelers, and women from endemic areas.
The panel was led by Laura Riley, MD, SMFM president. In an interview with MedPage Today, Riley said that the CDC was no longer recommending serial ultrasounds to check for fetal abnormalities in asymptomatic patients with a negative IgM test. The latter detects the first antibodies produced in response to a viral infection.
"The guidance is more on serology, but we're still using ultrasound to see if the baby is affected," she explained. "The main difference is that instead of going straight to ultrasound, there is still that patient who might be able to avoid multiple ultrasounds if, in fact, she is asymptomatic, has been exposed, has a negative IgM and a negative ultrasound; she might be able to just be done because the likelihood that she has infection is incredibly low."
Despite the guidance from the CDC to begin with an IgM test, a meeting attendee from Houston said that, in her area, the plan is to go to straight to polymerase chain reaction (PCR) testing, which can detect the virus within 7 days of exposure.
"We admit we don't have perfect testing right now, and there's an argument in either direction," the attendee stated.
But panelist R. Phillips Heine, MD, of the Duke University School of Medicine in Durham, N.C., cautioned that after 7 days -- 11 at most -- the virus will no longer be in the patient's system, which is why the CDC had recommended testing for antibodies with serology testing versus testing for the virus.
"If you traveled and it's a week later, you've already cleared organisms," he said. "In an asymptomatic population, serology is [the] way to go."