A rectovaginal fistula (RVF) is a serious medical condition where an abnormal channel develops between the rectum (the final section of the large intestine) and the vagina. This tunnel allows contents from the digestive tract to pass into the vaginal canal, profoundly affecting a person’s quality of life.
Defining the Condition and Its Classification
An RVF is an epithelialized, pathological tract that forms an unnatural communication between the rectum and the vagina.
Fistulas are categorized by size, location, and complexity to guide treatment. Size classifications include small (less than 0.5 cm), medium, or large. Location is defined relative to the vagina and anal sphincter, categorized as low (closer to the vaginal opening), mid, or high (deeper, near the cervix). Simple fistulas are typically small and low. Complex fistulas are often large, high, or associated with underlying diseases like Crohn’s.
Primary Causes and Risk Factors
The most frequent cause of RVFs is trauma sustained during childbirth, often resulting from severe third- and fourth-degree perineal lacerations that extend into the rectum. Operative vaginal deliveries (forceps or vacuum extraction) and complications from an episiotomy also increase risk. These injuries frequently damage the anal sphincter muscles, complicating repair.
Inflammatory Bowel Disease (IBD), primarily Crohn’s disease, is the second most common cause. Chronic inflammation from Crohn’s can break down the rectovaginal septum, leading to fistula formation. IBD-associated fistulas are often complex due to ongoing inflammation and poor tissue quality, requiring medical management of the underlying disease before surgical repair.
Other factors that can lead to an RVF include radiation therapy for pelvic cancers and complications following pelvic surgery. Radiation causes long-term inflammation and damage to surrounding tissues, resulting in poor blood supply and healing capacity. A fistula caused by radiation often manifests between six months and two years after the initial exposure. Surgical complications from procedures like a hysterectomy or colorectal surgery can also create an abnormal tract.
Recognizing Symptoms and Diagnostic Procedures
The symptoms of a rectovaginal fistula are distressing and usually prompt medical attention. The primary sign is the involuntary passage of gas or stool through the vagina, which is a direct consequence of the abnormal connection. This leakage frequently results in a foul-smelling vaginal discharge and chronic irritation of the external genitalia.
Continuous contamination from rectal contents can lead to recurrent vaginal or urinary tract infections. Less commonly, women may experience pain during intercourse or pelvic pain. The severity of these symptoms often correlates with the size and location of the fistula.
Diagnosis starts with a thorough medical history, focusing on past childbirth experiences, pelvic surgeries, and any history of IBD. A physical examination, including pelvic and rectal exams, is performed to visually identify the fistula opening or palpate the tract. Sometimes, a probe or dye test (placing colored liquid in the rectum) is used to trace the fistula path.
Specialized imaging is required to confirm the diagnosis and map the tract. Pelvic Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans provide detailed anatomical images. An endoanal ultrasound is frequently used to assess the integrity of the anal sphincter muscles, as injury often accompanies obstetrical fistulas. If the cause is unknown, a tissue biopsy may be taken to rule out cancer or other underlying diseases.
Treatment Options and Recovery
Most RVFs require treatment because they will not close spontaneously, though a small percentage of simple, post-traumatic fistulas may resolve without intervention. Initial management prepares the tissue for repair by controlling infection and inflammation. This involves antibiotics for infection, and for Crohn’s patients, medical therapy (anti-inflammatory medications or biologics) is used to stabilize the underlying condition.
Surgery is the definitive treatment for many patients, but it is often delayed for three to six months after the inciting event to ensure tissue health and reduced inflammation. The surgical approach depends on the fistula’s size and location. Simple, low fistulas may be treated with a fistulotomy, where the tract is opened, cleaned, and allowed to heal.
Complex or higher fistulas often require a tissue advancement flap procedure. This involves removing the tract and covering the opening with a flap of healthy, well-vascularized tissue taken from the rectal or vaginal wall. If the anal sphincter muscles were damaged, a sphincteroplasty may also be performed. Success rates are high (90% to 95%) for fistulas not caused by radiation or Crohn’s disease.
For large, complex, or recurrent fistulas, particularly those linked to active IBD or radiation damage, a temporary fecal diversion may be recommended. This involves creating a temporary colostomy, redirecting a portion of the bowel to an abdominal opening so stool exits into a bag. Diverting the fecal stream allows tissues to heal in a clean environment, improving the chances of successful repair. Once the fistula is healed, the colostomy is surgically reversed.
Post-operative care involves a short hospital stay and careful management of bowel habits. Patients use dietary modifications and fiber supplements to ensure soft, formed stools. Avoiding constipation and diarrhea is important, as straining can disrupt the repair and increase recurrence risk. Complete healing takes several months, and long-term follow-up monitors the repair and addresses potential remaining symptoms, such as fecal incontinence.