Comparable between rapid one step immunochromatographic assay and ELISA in the detection of prostate specific antigen in vaginal specimens of raped women.

BACKGROUND: Rape is a crime found in Thailand nowadays. The crime is often lacking of eyewitnesses. Therefore, examination for forensic biological evidence becomes quite important, especially investigating sperm and semen in vaginal specimens of the victim. Acid phosphatase test for semen is commonly used in Thailand but is just a presumptive test. Recently, confirmatory kit tests became available in Thailand for detecting the prostate specific antigen (PSA) from semen. This test is simpler and cheaper than ELISA. OBJECTIVE: To compare the rapid one-step immunochromatographic assay with ELISA for the detection of prostate specific antigen in vaginal specimens of raped women. MATERIAL AND METHOD: A diagnostic test was conducted on the vaginal specimens of raped women that were sent to the laboratory of the Pathology Department, Faculty of Medicine, Ramathibodi Hospital, Mahidol University during April-August 2006. One hundred vaginal specimens were examined for prostate specific antigen by rapid one step immunochromatographic assay and compared with ELISA. RESULTS: There were 85% and 83% of sensitivity, 85% and 85% of specificity, 85% and 85% of accuracy, 89% and 89% of positive predictive value, and 79% and 77% of negative predictive value from rapid one-step test kit and ELISA respectively CONCLUSION: The result showed that there was no difference on specificity, accuracy and positive predictive value between the two methods but sensitivity and negative predictive value of rapid one-step test kit was better than ELISA. The research team recommends that rapid one-step test kit for prostate specific antigen should be routine service in vaginal specimens of raped women.

An autopsy report case of rape victim by the application of PSA test kit as a new innovation for sexual assault investigation in Thailand.

The case of a 30 year-old Thai female found dead on the floor at the base of a small monument on Rajadumnern Road, Bangkok, Thailand with blood stains around the body and a naked bottom. The scene investigation and autopsy findings suggested a sexual assault and multiple sharp force injuries. The approach to the postmortem examination using different laboratory tests is reviewed. The specificity and sensitivity of prostate specific antigen (PSA) in specimens from rape victims is better than acid phosphatase test. The ELISA test for PSA was tested to confirm the PSA test kit. The present report suggests the PSA test kit in addition to conventional sperm smear and acid phosphatase test for sexual assault investigation in Thailand.