FREQUENCY OF PARVOVIRUS B19 INFECTION IN NONIMMUNE HYDROPS-FETALIS AND UTILITY OF 3 DIAGNOSTIC METHODS

The rate of parvovirus B19 (PV) infection in cases of ''idiopathic'' n onimmune hydrops fetalis (NIHF) is reported to be approximately 16% wi th polymerase chain reaction (PCR)-based methods. Antibodies for use i n paraffin-embedded tissue have not been systematically compared with PCR or with the presence of inclusions at varying gestational ages. Al l autopsy cases of NIHF and those with effusions of multiple serous me mbranes examined between 1991 and 1996 (n = 29) were evaluated for the presence of PV DNA by PCR analysis of paraffin-embedded liver tissue. PCR-positive cases and ''idiopathic'' cases were examined for the pre sence of inclusions in routine histological sections and for PV protei n using a monoclonal antibody (NovoCastra R92F6). Among the four clini cally idiopathic cases, one (25%) was positive for PV using PCR. The t hree negative idiopathic cases had no inclusions and were negative for PV by PCR and immunohistochemistry (IHC); all were third-trimester ge stations (28, 31, and 32 weeks). Identifiable risk factors for NIHF ot her than Win the remaining 25 cases included cystic hygroma, seven (th ree 45,X; two 46,XX; two no growth); complex cardiac anomaly, sbr; inf ection, three (two CMV, one chlamydia); twin-twin transfusion, two; ly mphangiectasia, two; diaphragmatic hernia, tracheal atresia, trisomy 2 1, congenital cystic adenomatoid malformation, one each. One of these nonidiopathic cases, a fetus with cystic hygroma and a 45,X karyotype, tvas positive for PV DNA only on the blot, consistent with a low tite r; no inclusions were present, and MC was negative in multiple organs in this instance. One of four (25%) cases of idiopathic NIHF cases con tained PV DNA by PCR analysis; there were abundant inclusions in multi ple organs, and IHC was strongly positive as well. Of 25 cases of noni diopathic NIHF, one (4%) was also positive for PV DNA by PCR. PV prote in was detected by IHC only in the presence of inclusions; MC thus may be useful for highlighting sparse inclusions. No second-trimester cas e of NIHF was unexplained. Late (third-trimester) cases of ''idiopathi c'' NIHF are likely to be negative by all methods, either because they are not attributable to PV infection or because PV protein and DNA ar e below detectable levels or are no longer present Maternal serology f or PV and TORCH agents may be the best method for investigating third- trimester losses to otherwise unexplained NIHF. Copyright (C) 1998 by W.B. Saunders Company.