Wood's Lamp Utility in the Identification of Semen

Abstract

Background. The accurate detection of semen is critical to forensic, medical, and legal personnel. The Wood's lamp (WL) emits ultraviolet light (UVL) and has been identified as useful in rape evaluations because it is purported to cause semen to fluoresce. This study was intended to determine if semen can be distinguished from other products by WL analysis. Methods. Investigators reviewed the previous training and frequency of use of the WL by emergency medicine and pediatric emergency medicine physicians at 2 medical centers. The participants were asked to use a WL to distinguish between a semen sample (<6 hours old) and 13 commonly used products. Next, 29 semen samples were collected and evaluated under high-power microscopy and under UVL. Results. A total of 41 physicians participated in the study (68% male). The number of years practicing in an emergency setting spanned from .3 to 25 years with a mean of 7.1 years. A total of 51% of participants trained in emergency medicine, 23% in pediatrics and pediatric emergency medicine. A total of 22% reported formal training in the collection of forensic evidence. A total of 62% of the physicians believed they have identified semen in the past; one third felt they could differentiate semen from other products under UVL. None of the 41 physicians were able to differentiate semen from other products using a WL. Moreover, the semen samples used for the study did not fluoresce under WL analysis. None of the 29 semen samples fluoresced whether wet or dry. The medicaments most commonly mistaken for semen were A&D ointment (Cardinal Health, Inc, Dublin, OH), Surgilube (Division of Atlanta, Inc, Melville, NY), Barrier cream (Carrington Laboratories, Inc, Irving, TX), and bacitracin (Division of Atlanta, Inc, Melville, NY). Conclusions. Participating physicians were unable to distinguish between semen and other common products, using the WL. Although the WL has been purported to be a useful tool as a screening device for the detection of seminal stains, the investigators have found it to be unreliable. Semen, previously reported to fluoresce under WL analysis, does not appear to do so. The correct identification of semen may be complicated by the presence of previously existing ointments and creams, some of which may be iatrogenically introduced (ie, Surgilube).