If an attacker appears intent on using a knife or a gun in order to get his way or demonstrates overpowering force and brutality don't put up a physical fight. You don't have to show battle scars to press charges successfully. First of all, get to a safe place. Call the police immediately, and then contact a family member or friend to be with you. It is important that all physical evidence of the attack be preserved, so do not shower, bathe, douche or even change clothes.
Most rape victims feel an overwhelming urge to rid themselves of every trace of the attack.
They don't want to deal with what happened, and they may wait days or weeks to report it. But doing so destroys important evidence, reduces credibility and makes prosecution of the attacker more difficult. Reporting the assault right away helps regain a sense of control, ensures proper medical care and guarantees your personal safety. Unfortunately only five to 10 percent of rapes are ever reported because of embarrassment or outright shame, fear of reprisal, and apprehension over dealing with police, doctors and attorneys. But the attacker has assumed he could have his way without any consequences.