Does a semen stain really glow in the dark? We’ve all seen the crime shows that have investigators wandering around a dark room with a UV, or “black light”, looking for clues. They inevitably throw back the sheets to find a bright, glowing stain. But can you really use a UV light for semen detection?
While semen will fluoresce, so do many other bodily fluids. Substances such as sweat, urine, and saliva will all glow under UV light. Likewise, some cosmetics, oils, foods, cleaning products, even pet stains will emit a glow. So while using a black light can be helpful in discovering bodily fluids that are not visible to the naked eye, it’s not definitive proof a stain is semen. Using a UV light for semen detection is a starting point—not proof of its presence. Any stains detected must be tested to confirm their source.
This follow up semen detection test is done by looking for several components unique to semen. You can buy home test kits, but most look for AP or acid phosphatase. This is an enzyme that is present in semen; however, it’s also present in vaginal secretions and other bodily fluids. That’s why you have to follow up a positive test with a definitive lab test to confirm it’s actually semen. Another type of home test is PSA kit, or prostate specific antigen. This is a protein produced in the prostate gland and emitted during ejaculation. This test is considered presumptive as it’s not found only in semen. It too must be followed with a confirmatory test. A sperm detection test can be done, but if a man’s had a vasectomy, there would be semen but no sperm.
Currently, the only conclusive, confirmatory semen detection test is a semenogelin test. This is a protein in semen that controls the viscosity of the semen following ejaculation. It’s the test used by forensic and crime labs to conclusively prove the presence of semen in legal cases.
If you need definitive proof whether or not a stain is semen, let us test it with our lab certified semen detection test. Get proof positive answers to your questions.