Investigation of PSA Antigen in 350 Probable Raped Cases with Positive Acid Phosphatase Test

Generally, semen detection in samples referred to the forensic lab is used to assume that the rape has occured. Due to different samples contamination that referred to the forensic lab and the difference of time intervals between sampling and sending them to the serological lab, the obtained results may be different. So, in this study the sensitivity and specificity of a routine test as “AP” and “Rapid PSA” are compared with “RIA PSA assay” as a Gold standard method. This study is done on random with different samples; for example, different sources, rectal or vaginal soabs – the things has been used at the rape time – clothes, carpet and other things had been found at a crime scene. After performing the “AP” test, all positive tests are selected to compared with another method, (PSA rapid and PSA RIA test). For detection of a false positive “AP” test, 350 positive “AP” are selected to test by PSA Rapid and RIA methods. 1- 95٪ of “positive AP reaction” samples were positive in “PSA RIA” method too. 74٪ of “positive AP reaction” samples were positive in PSA rapid method. 2- 3- The more given time after sampling, the more negative test results are coming. For example after 10 days, the negative results increased by 3٪. The “AP” method has high positive predictive value and the “rapid PSA” is the perefered method for confirmation of a positive “AP” result; but, because of increasing false negative results with time, it’s negative predictive isn’t valuable and must be adjusted by an accurate method such as PSA.