How specific is the test in determining the presence of human seminal fluid?

PSA is now known to be found at very low levels in many different fluids and tissues including breast tissue and tumors, periurethral glands, breast milk, amniotic fluid and female urine. However, PSA levels in semen average 800,000 ng/mL. So by proper dilution of the sample, it is possible to determine that a positive result is unequivocally due to the presence of human seminal fluid.