Unrecognized viral infections and chromosome abnormalities as a cause of fetal death – examination with fluorescence in situ hybridization, immunohistochemistry and polymerase chain reaction

Abstract

Fifteen to 50% of fetal deaths remain unexplained after post-mortem examination depending on inclusion criteria and classification systems. Our aim was to examine a selection of unexplained fetal deaths in order to investigate whether any common chromosome aberrations or viral infections were present. Reports from 351 fetal autopsies performed at the Department of Pathology and Medical Genetics at St. Olavs University Hospital from 2001 through 2010 were reviewed. Of these, 105 fetal deaths were classified as unexplained. Tissue samples from 30 cases were further examined with fluorescence in situ hybridization (FISH) to detect abnormalities in chromosomes 13, 18, and 21. The samples were also examined with immunohistochemistry (IHC) and polymerase chain reaction (PCR) to detect infections with cytomegalovirus, parvovirus B19, herpes simplex virus 1 and 2, enterovirus, and parechovirus. In two cases, a possible trisomy 13 mosaicism was found. No viruses were detected. In our selection of 30 unexplained cases, possible trisomy 13 mosaicism was found in two cases, and no viruses were detected. High degree of maceration and missing placental examination often complicate the investigation of fetal death, and extensive ancillary examinations do not necessarily contribute to a more specific diagnosis.