This depends on many factors, in some cases it can be found out, in some cases it is not. Following are the examples:
1. If a young woman who is a virgin, will have bruises and swelling locally for 72 hours.
2. If a woman who is not much used to sex, may have genital edema for 24 hours, increased vaginal secretions can be seen.
3. If a woman who is used to sexual intercourse on regular basis like married woman, local swelling can be appreciated for about 4-6 hours only.
4. If a woman is a sex worker, the duration may be 1-2 hour.
5. It depends on the male partner too, if he is weak or sex is superficial, then there is no chance of detection.
6. If the woman is an unwilling partner, less vaginal secretions would be detected.