What Causes A Tear In The Vagina?

hello, I have a problem in my virgin. one lady doctor operation my virgin & she sew that. I don't know it. when i go to toilet i saw a something sew there. there fore i pulled it. after that i got bleed. i spoke my doctor. she said me one side of virgin is broken. but it s not big issue. because other 3 sides are oki. can u please tell me is it ture?