Comorbid fetal myocarditis may induce hydrops with lesser degrees of anemia.
Depending on gestational age, fetal transfusion for hydrops may improve outcome in some cases (Enders, 2004). Mortal ity rates as high as 30 percent have been reported in hydropic fetuses without transfusions. With transfusion, 94 percent of hydrops cases resolve within 6 to 12 weeks, and the overall mortality rate is <10 percent. Most fetuses require only one transfusion because hemopoiesis resumes as infection resolves.
Concurrent fetal thrombocytopenia worsens the prognosis (Melamed,r2015).
Reports describing neurodevelopmental outcomes in fetuses transfused for B 19 infection-induced anemia are conlicting. In one review of 24 transfused hydropic fetuses, abnormal neurodevelopment was noted in ive of 16 survivors-32 percent-at 6 months to 8 years (Nagel, 2007). Outcomes were not related to severity of fetal anemia or acidemia, and these investigators hypothesized that the infection itself induced cerebral damage. In another study of 28 children treated with intrauterine transfusion, 11 percent had neurodevelopmental impairment during evaluation at a median age of 5 years (de long, 2012). Conversely, Dembinski (2003) found no signiicant neurodevelopmental delay despite severe fetal anemia.
Currently, no parvovirus vaccine is available, and no evidence suggests that antiviral treatment prevents maternal or fetal infection. Decisions to avoid higher-risk work settings are complex and require assessment of exposure risks. Pregnant women should be counseled that risks for infection approximate 5 percent for casual, infrequent contact; 20 percent for intense, prolonged work exposure such as for teachers; and 50 percent for close, frequent interaction such as in the home. Workers at day-care centers and schools need not avoid infected children because infectivity is greatest before clinical illness. Finally, infected children do not require isolation.
This mosquito-borne RNA flavivirus is a human neuropathogen. It has become the most common cause of arthropod-borne viral encephalitis in the United States (Centers for Disease Control and Prevention, 2017f; Krow-Lucal, 2017). West Nile viral infections are typically acquired through mosquito bites in late summer or perhaps through blood transfusion. The incubation period is 2 to 14 days, and most persons have mild or no symptoms. Fewer than 1 percent of infected adults develop meningoencephalitis or acute laccid paralysis (Granwehr, 2004). Presenting symptoms may include fever, mental status changes, muscle weakness, and coma (Stewart, 2013).
Diagnosis of West Nile infection is based on clinical symptoms and the detection of viral IgG and IgM in serum and IgM in cerebrospinal fluid. There is no known efective antiviral treatment, and management is supportive. he primary strategy for preventing exposure in pregnancy is the use of insect
Clinical disease: exposure or infection Sonographic evidence of fetal infection: hydrops fetalis, hepatomegaly, splenomegaly, placentomegaly, elevated
FIGURE 64-4 Algorithm for evaluation and management of human parvovirus B 19 infection in pregnancy. eBe = complete blood count; IgG = immunoglobulin G; IgM = immunoglobulin M; MeA = middle cerebral artery; peR = polymerase chain reaction; RNA = ribonucleic acid.