In this Health Topic
A rectovaginal fistula is an abnormal passage, or opening, between the rectum and vagina. While some women may have no symptoms, most complain of an uncontrollable passage of gas and/or stool through the vagina. This may be associated with rectal bleeding, foul-smelling discharge from the vagina, or recurrent vaginal or urinary tract infections. It is usually the incontinence of gas and stool that leads a woman to seek treatment. She may not know an abnormal passage is present between the rectum and vagina.
The majority of rectovaginal fistulas are caused by childbirth injury. Trauma related to operative vaginal deliveries such as forceps and vacuum deliveries, as well as third- and fourth-degree tears, increases the risk for rectovaginal fistulas to develop. Rectovaginal fistulas can also develop following radiation to the pelvis or in women with inflammatory bowel disease. There are rare cases of congenital rectovaginal fistulas.
Risk factors for development of rectovaginal fistula include:
- Congenital anorectal anomalies
- Obstetric trauma
- Gynecologic or colorectal surgery
- Violent trauma
- Inflammatory bowel disease
- Perianal infections
- Radiation to pelvis
A discussion with your primary care doctor is the first step of the assessment. A review of your health history and recent surgeries will help your doctor suspect a possible rectovaginal fistula. A pelvic exam should be done to assess the perineum (area of skin between the vagina and anus). Applying rectal pressure during the exam may express stool into the vagina to see the fistula. A thin probe may also be used to identify the fistula.
Rectovaginal fistulas may involve disruption to the internal and external anal sphincter muscles. Further testing may be done to help assess these muscles. This may involve anal manometry, which assesses the muscle tone and ability of these muscles to contract. Endoanal ultrasound may also be used to look for disruption of the muscles. Further imaging studies like a CT scan or colonoscopy may be utilized to rule out fistulas involving the colon or small bowel. Other medical conditions should be ruled out including inflammatory bowel disease and cancer.
Not all fistulas need surgical intervention. Rectovaginal fistulas associated with inflammatory bowel disease often close on their own without surgery. If diagnosed early after a traumatic event, immediate closure may be considered. Most often, rectovaginal fistula repairs are delayed until inflammation around the fistula subsides.
The success rate following rectovaginal fistula repair is high, ranging from 90-95%. Patients with recurrent fistulas or a history of radiation may have a poorer prognosis.
Irrespective of the approach, the fistula tract should be removed to allow normal tissue with a good blood supply to knit together. Often the tissue near the fistula tract has poor blood supply and may need a graft to help promote healing. Grafts, or flaps, can come from a women’s own fat tissue or muscle that is placed over the repaired fistula tract. Other biologic grafts taken from animal tissue or human cadavers can also be used. The repair may also involve reconstruction of the internal and external anal sphincter muscles.
Following rectovaginal fistula surgery, women should monitor their bowel habits with the goal of having daily bowel movements of soft, formed stool. Avoiding constipation and diarrhea is important as this can disrupt the repair and increase the risk of wound infection.
The success rate for rectovaginal fistula repair is high, ranging from 90-95%. Patients with recurrent fistulas or a history of radiation may have a poorer outcome.
Some women are never ‘cured’ of their fistula, meaning it never fully closes. However, surgery often shrinks the fistula to such a small size that an acceptable outcome is reached, and further surgery is declined. Sometimes a surgical thread, called a seton, is placed through the fistula to help control drainage and again, symptoms are controlled such that no further surgery is required.