Rectovaginal fistulas can pose treatment challenges.(Gynecology)

FORT LAUDERDALE, FLA. -- Obstetric trauma is the most common cause of rectovaginal fistulas, Eric G. Weiss, M.D., said at a symposium on pelvic floor disorders sponsored by the Cleveland Clinic Florida.

Reported series suggest such trauma accounts for 50%-90% of fistulas, said Dr. Weiss, director of surgical endoscopy and a staff colorectal surgeon at Cleveland Clinic Florida, Weston.

"We don't really have a good way to prevent these--it's just one of those things that can happen after delivery," he said, noting that such fistulas occur in fewer than 1% of vaginal deliveries.

But for such tiny holes--sometimes the size of a pinhole--these defects can lead to extensive symptoms, and can be very difficult to repair.

Rectovaginal fistulas associated with obstetric trauma usually are the result of unrecognized third- or fourth-degree perineal tears or repairs that break down as a result of infection or hematoma. Other causes include inflammatory bowel disease, infection, and other types of trauma, such as pelvic radiation therapy, Dr. Weiss noted.

A number of treatment options exist, but for simple fistulas--or those that are less than 2.5 cm in diameter, distal, surrounded by otherwise healthy tissue, and caused by trauma or infection--Dr. Weiss' treatment of choice is the transanal endorectal advancement flap.

Reported success rates for this type of advancement flap range from 41% to 100%, and the variation may be explained by differences in the way results are reported. For example, some studies include patients who also underwent sphincteroplasty, which would most likely improve results.