Significance of placental pathology and CMV PCR in assessing clinical outcomes of congenital CMV infection

Congenital cytomegalovirus (CMV) infection is one of the most common congenital infections with adverse outcomes such as intrauterine growth restriction (IUGR), hearing loss, and neurologic deficits. The aim of this study was to investigate the significance of histopathologic features and CMV PCR results of placentas with clinical manifestation of congenital CMV infections. We retrospectively collected the placentas of 27 newborns with congenital CMV infections from January 2009 to December 2020. Clinical information and placental histology were reviewed. Immunohistochemistry and PCR for CMV were performed with placental tissues. Typical histological findings of CMV infection were detected in 18 placentas (66.7 %), including chronic villitis (66.7 %), plasma cell infiltration (29.6 %), viral inclusions (22.2 %), and hemosiderin (33.3 %). CMV was identified in 12 (44.4 %) cases by immunohistochemistry and 19 (70.4 %) cases by PCR. PCR detected CMV in 2 (22.2 %) out of 9 cases without CMV-typical histology. IUGR was more frequent in the CMV-typical histology group than in the no CMV-typical histology group (12/18 (66.7 %) vs 0/9 (0 %), P = 0.001) as well as in the PCR-positive CMV group than in the PCR-negative CMV group (11/19 (57.9 %) vs. 1/8 (12.5 %), P = 0.043). Hearing loss was associated with the presence of hemosiderin and calcification in placental villous tissues (6/7 (85.8 %) vs. 3/12 (25 %), P = 0.02, 7/7 (100 %) vs. 6/12 (50 %), P = 0.044). The associations of placental pathologic findings and CMV PCR results with clinical outcomes of congenital CMV infection suggest that a comprehensive examination of the placenta is important in congenital CMV infection.