There are three methods of diagnosing CMV infection: viral cultures, antigenemia, and PCR assays [32] . Culture-based assays (conventional and shell-vial cultures) are considered obsolete because of their low sensitivity and time-consuming nature. The antigenemia assay is based on direct detection of the CMV protein pp65 using monoclonal antibodies. It is sensitive and quantitative, although it requires sufficient leukocytes in peripheral blood and is more labor-intensive than the PCR assays. Finally, the PCR assays have been considered gold standard given their high sensitivity and rapid turnover time, although these are not fully standardized [33] . In our review, the assays used to assess CMV infection were viral cultures in five studies [8, 10, 13, 14, 16] , antigenemia in three studies [7, 12, 16] , and PCR in six studies [7, [10] [11] [12] 14, 15] . CMV infection rate was 0 to 20% (median 4%), 0 to 32% [ 