Rectovaginal fistula: causes and treatment

The rectum and the vagina lie side by side, separated by a thin wall of tissue. A rectovaginal fistula is a tunnel that forms through that wall. Cleveland Clinic explains that it happens when damage to the tissue between the two causes it to die, leaving a hole that lets gas and stool enter the vagina. Fistulas vary in size and shape, and they may develop over days or over several years.

The Your Pelvic Floor patient site describes it as an abnormal passage between the rectum and vagina and notes that while some women have no symptoms, most complain of uncontrollable passage of gas or stool through the vagina. It is the leakage that usually prompts a woman to seek help, and some do not realise an abnormal passage is present.

Cleveland Clinic lists foul-smelling vaginal discharge, gas or stool leaking from the vagina, painful intercourse, pelvic pain, and rectal or vaginal bleeding. The Your Pelvic Floor site also mentions recurrent vaginal or urinary tract infections.

Because the symptoms can be mistaken for an infection or for bowel incontinence, a fistula may take time to identify. If wind or stool comes from the vagina, it is worth saying so plainly to a doctor, since the descriptions are specific. The NHS page on bowel incontinence reminds people to try not to be embarrassed, since clinicians are used to discussing these symptoms.

• Wind or stool passing through the vagina.

• Smelly vaginal discharge that does not settle with usual treatment.

• Vaginal or urinary infections that keep returning.

• Soreness or irritation of the vagina, vulva and skin around the anus.

• Pain during sex, or pelvic pain.

Cleveland Clinic says childbirth injuries, including vaginal tears and episiotomies that do not heal properly, are the most common causes. The Your Pelvic Floor site says the majority are caused by childbirth injury, and that operative deliveries with forceps or vacuum, and third- and fourth-degree tears, increase the risk.

Other causes named by Cleveland Clinic include complications of diverticulitis, inflammatory bowel diseases such as Crohn's disease and ulcerative colitis, abdominal or pelvic surgery, cancer of the cervix or colon, radiotherapy to the pelvis, injury from sex or a foreign object, and infections of the anal or Bartholin glands. Rarely a person is born with a fistula. Radiation causes long-term inflammation with poor healing, which explains the link.

For context, the NHS describes anal fistulas as usually following an anal abscess and lists Crohn's disease and diverticulitis among less common causes. A rectovaginal fistula is a different channel, but some of the same conditions are involved.

A doctor takes a history of births, operations and bowel conditions and performs a pelvic examination. The Your Pelvic Floor site says a thin probe may be used to identify the fistula and that tests may look at the anal sphincter muscles, since these can be damaged. An endoanal ultrasound may show disruption of the muscle.

Cleveland Clinic adds examination under anaesthetic, endoscopy, pelvic MRI or CT, blood and urine tests for infection, and a biopsy if cancer is suspected. Further imaging or colonoscopy may be used to rule out fistulas involving the colon or small bowel, and to exclude inflammatory bowel disease and cancer.

Cleveland Clinic says treatment addresses the cause, the fistula itself and any related complications. Small fistulas may start with conservative measures: antibiotics for infection, medicines for an underlying condition such as inflammatory bowel disease, stool-bulking fibre supplements and wound care. It says most women then need surgery to close the opening.

The Your Pelvic Floor site explains that repairs are usually delayed until inflammation settles. The repair may be done through the vagina or through the anus and rectum, depending on the position and size of the fistula and the surgeon's training. The fistula tract is removed so healthy tissue with a good blood supply can knit together, and a graft or flap may be added if the blood supply is poor. The repair may also rebuild the anal sphincter muscles.

If the fistula is large or complex, a temporary stoma may divert stool away from the repair while it heals. Cleveland Clinic notes the stoma is closed later by another operation. Fistulas linked to inflammatory bowel disease may need joint care from bowel specialists.

Cleveland Clinic says most people return to routine a week or two after surgery, though complete healing can take several months. The Your Pelvic Floor site advises aiming for daily soft, formed stools and avoiding constipation and diarrhoea, which can disrupt the repair and raise the risk of wound infection.

The same site reports repair success rates of 90 to 95%, poorer in recurrent fistulas and after radiotherapy, and says up to 30 to 40% of women may still have leakage of stool or gas from the anus after a successful repair, especially if the sphincter was involved. It adds that some fistulas never close completely, but surgery can often shrink them to a size that is acceptable. These figures come from a US source and may not match UK units exactly.

Cleveland Clinic also stresses that living with a fistula can affect mental health and quality of life, and it encourages seeking support from a mental health specialist if there is distress or isolation. The NHS bowel incontinence page lists treatments such as biofeedback, bowel retraining and specialist incontinence services for leakage that remains.

Any passage of stool or gas from the vagina needs medical assessment. Cleveland Clinic says fistulas require treatment to avoid complications, and names abscess or infection that could become life-threatening if untreated. Fever, increasing pelvic pain or swelling alongside these symptoms should be treated as urgent. Use NHS 111 for urgent advice and call 999 or go to A&E for severe illness or heavy bleeding.

A GP is the usual first step, with referral to colorectal surgery, gynaecology or a urogynaecology team. Specialist units that manage obstetric injury and fistulas exist in both NHS and private settings, and a careful assessment of the cause is needed before any repair is planned.