Fistula Primer of Sorts.

A rectovaginal fistula is a medical condition where there is a fistula or abnormal connection between the rectum and the vagina. Rectovaginal fistula may be extremely debilitating. If the opening between the rectum and vagina is wide it will allow both flatulence and feces to escape through the vagina, leading to fecal incontinence. There is an association with recurrent urinary and vaginal infections.
Causes
Rectovaginal fistulae are often the result of trauma during childbirth (in which case it is known as obstetric fistula) in situations where there is inadequate health care, such as in some poor third world countries. Rates in Eritrea are estimated as high as 350 per 100,000 vaginal births. Women with rectovaginal fistulae are often stigmatized in these countries, and become outcasts.

Women in the West suffer similarly, mainly due to the fact that most people do not take the condition seriously and often, much to the mortification of the sufferer, find it to be hysterically funny. As such, discussing the disorder publicly is not something that many women feel they can do.

Rectovaginal fistulae can also be symptoms of various diseases, including infection by Lymphogranuloma venereum, or the unintended result of surgery, such as episiotomy or sexual reassignment surgery. They may present as a complication of vaginal surgery, including vaginal hysterectomy. They are a recognized presentation of rectal carcinoma or rarely diverticular disease of the bowel or Crohn's disease. They are seen rarely after radiotherapy treatment for cervical cancer.
Theories about pregnancy
There has apparently been discussion in pop-medical circles at some time in the past of there being a possibility of semen travelling through a rectovaginal fistula during anal sex and potentially resulting in a pregnancy. While this is possible in theory—a rectovaginal fistula is, after all, a passageway between the two related cavities through which other (semi)liquids are known to pass—the obvious symptoms of the condition, including the severe, apparent pain that may be associated with it, makes an unwitting instance of this phenomenon functionally impossible.

Full article and source here. While I cannot be certain that this information is from a scholarly site, I can say from my own experiences with my Crohn's Disease related RV fistula, my personal exoperience coincides with the info given. Got Guts? Check out CCFA to get info, make donations, and help further the knowledge base for Inflammatory Bowel Disease.