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21: Acute parvovirus infection in pregnancy: are we underestimating the risk?

      Objective

      To describe the natural history of parvovirus infection in pregnancy and evaluate influence of gestational age at seroconversion on fetal outcomes.

      Study Design

      A retrospective cohort study was performed evaluating maternal parvovirus infection over a 2 year period in a tertiary fetal medicine unit. Cases were identified from laboratory and prenatal diagnosis databases. Demographic data and pregnancy outcomes were collected. Fetal anemia was defined as an increase in middle cerebral artery Doppler peak systolic velocity, or sonographic evidence of fetal hydrops. Rates of fetal anemia, need for intrauterine transfusion (IUT) and intra-uterine fetal demise (IUFD) were compared between those that seroconverted prior to and after 20 weeks gestation.

      Results

      Of 434 patients screened for parvovirus, 39.2% (n=170) were IgG negative. The rate of seroconversion was 15.3% (n=26) in these 170 non-immune patients. Outcome data were available for 20 of these 26 cases. 55% (n=11) of seroconverted patients had sonographic evidence of fetal anemia, 6 underwent IUT, 1 IUFD occcured prior to planned IUT and spontaneous resolution occurred in 36.4% (n=4). Rate of IUFD following acute infection was 15% (3/20). Mean gestation at seroconversion was 20 weeks (range 4-29 weeks), 37.5% seroconverted prior to 20 weeks and 62.5% at 20 weeks or later. There were no differences between the rate of anemia in those that seroconverted at early versus late gestations. 2 of the 3 cases of IUFD occurred in the group that seroconverted after 20 weeks, despite IUT being performed in both cases.

      Conclusion

      In our cohort we noted a higher rate of fetal anemia secondary to infection with parvovirus than previously expected. Over one third of cases demonstrated spontaneous resolution, reinforcing the importance of intense fetal surveillance with judicious use of fetal intervention. Additionally fetal demise was not limited to seroconversion in the first half of pregnancy as previously reported, with 2/3 cases of fetal demise following late seroconversion.