According to a report infertility in healthy women may sometimes be caused by the presence of fetal bone fragments left embedded in the uterus after a previous abortion. There were evidence over the years that small pieces of fetal bone left behind after abortion cause chronic irritation which could interfere with subsequent pregnancies. Doctors at the University of Ottawa found that in some cases these bone fragments can work their way into the muscular uterine lining, making them invisible even with a hysteroscope. Is a case, a 36 year old woman who ended a pregnancy 15 years earlier and was not able to become pregnant again. When diagnosed through normal hysteroscope her uterus appeared normal. However when doctors conducted an ultrasound exam they found white evidence of embedded bone fragments. Using the ultrasound images to guide them, the doctors scraped the uterine lining and removed the fragments. Four months later, she became pregnant and went on to deliver a healthy boy. It is not clear how often abortions result in such complications, but the doctors note that any fetus at least 12 weeks old can have bony tissues. In previous studies, they say, virtually all women who had such fragments removed were able to get pregnant soon afterward.