Physical information of a sexual assault must be collected within about 120 hours of the assault for it to be useful in a criminal prosecution. If you believe you have been a victim of a sexual assault, you should go to a hospital emergency room before washing yourself or your clothing. A sexual assault health professional (a specially trained nurse called a SANE) at the hospital is on call and will counsel you. If you go to the hospital, local police will be called but you are not obligated to talk to the police or to prosecute. The exam will help to keep that option open for you should you decide later to exercise it.
The hospital staff will collect information, check for injuries and address the possibility of exposure to sexually transmitted infections. If you have changed clothing since the assault, bring the clothing you had on at the time of the assault with you to the hospital in a clean, sanitary container such as a clean paper grocery bag or wrapped in a clean sheet. (Plastic containers do not breathe, and may render forensic information useless.) If you have not changed clothes, bring a change of clothes with you to the hospital, if possible, as they will likely keep the clothes you are wearing as information. You can take a support person with you to the hospital, and they can accompany you through the exam, if you want. Do not disturb the crime scene—leave all sheets, towels, etc. that may bear information for the police to collect.