Derivation of the Genital Injury Severity Scale (GISS): A concise instrument for description and measurement of external female genital injury after sexual intercourse

Abstract Introduction Inconsistencies abound in the current forensic literature regarding the definition, and as a result, the significance of female genital injury after sexual intercourse. These definitions are based on variables related to the anatomic locations that are examined, the actual physical findings types, and the methods used to detect the findings. Purpose To derive and perform initial clinimetric analyses on a simple instrument that defines, and based on severity, quantifies external genital injury after sexual intercourse. The scale utilizes standard injury definitions and a standardized examination method. Methods After empirical investigation, it was determined that the application of the tool would require the use of magnification and toluidine blue in order to have the sensitivity to detect the majority of injuries that occur after sexual intercourse. Separate matrices were constructed based on anatomic locations and injury types from data collected from sexual assault genital injury examination forms. Principal Components Analyses were applied. A clinical model was constructed from the resultant variables, utilizing operational definitions and forming a template for the instrument. Results A twelve-factor instrument measuring five variables along five “types” of severity and two “classes” of severity ensued. The resultant instrument was tested for internal consistency and differential validity. Very good internal consistency was attained (Cronbach's Coefficient α = 0.8). In a pilot study, the scale was able to distinguish a cohort of sexual assault patients from one of consensual intercourse subjects based on type and class of injury ( p