Except in obvious cases, there is no way for a layperson to know if an infant has been sexually abused.
Physical signs such as stained or torn or bloody underwear are obvious clues.
But only an examination by an MD EXPERT in this area has any real level of reliability.
If you have any such concern, a trip to the Emergency Department would be appropriate for as prompt an exam as possible.
Please click ACCEPT.
Feel free to ask a follow-up question.