Child with prolapsed rectum

My friend has a child who is 3 years old and recently had a prolapsed rectum. I had never heard of this condition before, but it's when the rectum comes out of the anus when trying to make a bowel movement. I was horrified to hear about this happening to her child, and especially horrified when someone told me this often happens to children who are sexually abused. I looked on Google and could not find any credible sources that confirm this.