In patients who are immunocompromised, CMV may cause disseminated, severe disease. CMV is also the most common cause of congenital viral infection in humans. Quantitative PCR methods may be useful in monitoring CMV replication in immunosuppressed patients or in determining the viral load of CMV in amniotic fluid. This is a quantitative molecular test, with a linear range of 200-2,000,000 copies/mL.