Reverse transcriptase-PCR (RT-PCR) is a nucleic acid amplification test (NAAT) designed to detect RNA viruses in patient samples. In this procedure, the enzyme reverse transcriptase (RT) is first used to synthesize complementary DNA (cDNA) from the small amount of viral RNA present in the specimen, and the resulting cDNA is then amplified via polymerase chain reaction (PCR) to confirm the presence of the viral nucleic acid.