Viral detection in hydrops fetalis, spontaneous abortion, and unexplained fetal death in utero

This study was undertaken to investigate the occurrence of viral infection in fetal death by examining tissues for the presence of DNA of several viral agents. Tissue specimens including heart, kidney, liver, lung, and placenta of 73 cases of fetal death were examined with 27 cases of elective termination of pregnancy as a control group. DNA extracted from these samples was tested for the presence of HSV, CMV, EBV, VZV, HHV-6, HHV-7, and PVB19. Viral DNA was found in one or more tissue samples from 25/73 cases (34%): CMV in 20, HSV in 5, parvovirus B19 in 5, HHV-7 in 3, and HHV-6 in 2. The presence of HHV-6 in fetal tissue has been reported rarely. No study so far has reported the detection of HHV-7 in fetal tissues with normal or adverse outcomes. Viral DNA was not found in any of the termination of pregnancy samples. Among the positive cases, eight had dual infection. One further case was positive for three viruses: HSV, CMV, and HHV-7. HHV-6 was the sole infectious agent in two cases, HHV-7 in one case, PVB19 in three, and CMV in ten cases. The finding of multiple viral DNA in 12% of the cases suggests the involvement of complex risk factors in cases of fetal loss. Although the cause of fetal death often includes other factors (e.g., chromosomal abnormalities) these data suggest the incidence of viral infective etiology may be higher than considered previously. However, larger studies are required to establish this link.