Though rare, a bladder fistula to the skin can result when the bladder outlet is blocked and the bladder is damaged. This can be due to injury or prior surgery. Vesicovaginal fistulas can be seen after a urological or gynecological surgery. They can also be linked to gynecological cancers. Fistulas to the bowel are mostly a result of a disease that causes inflammation, such as Crohn's disease or diverticulitis. About 2 out of 10 cases of bowel fistula are caused by bowel cancer. Fistulas to both the vagina and the bowel may also form as a result of radiation therapy.