Rectovaginal Fistula

Definition

Any communication between the rectum/anus and the vagina/perineal skin is classically referred to as a rectovaginal fistula (RVF). RVF is an accepted term for any fistula that originates in the distal rectum and anus and is connected to the vagina, perineal body, or labial area, because the evaluation and treatment are similar. In contrast, a fistula between the colon and vagina (such as may occur after a hysterectomy when the sigmoid communicates with the top of the vagina) is a completely different problem and will not be discussed in this chapter.

Causes

An obstetrical injury is the most common cause of RVF. Other common causes are cryptoglandular sepsis, Crohn disease, cancer, radiation therapy, and trauma (e.g., after excision of a mass in the rectovaginal septum). Identifying the source of the fistula is critical because it may alter the evaluation and treatment plan.

History and Physical Examination

Obtaining an accurate history is important, beginning with an exact description of symptoms. Passage of gas, stool, or purulent fluid and the presence of dyspareunia, perineal pain, vaginal irritation, and recurrent urinary tract infections should be noted. The patient should describe her bowel habits both before and after the symptoms started, including a complete description of fecal incontinence. The effect of the symptoms on daily life is important. Other factors that affect bowel habits such as chronic diseases (e.g., diabetes, lupus) and all medications should be reviewed. The patient’s radiation, pelvic/anal surgery, and obstetrical history is noted, and in preparation for surgery, a full medical and surgical history is obtained and a review of systems is performed. Box 6-1 outlines specific areas to be covered.

During the physical examination, the abdomen is evaluated for body habitus, scars, hernias, and masses. Any debris at the vaginal introitus should be noted at the beginning of the perineal examination. Particular attention is directed to the status of the anus (i.e., closed or open), the width of the perineal body, and the movement of the anal muscle when the patient is asked to strain and squeeze. A more detailed evaluation of the vagina is performed next; one should look for the actual vaginal opening, the presence of stool in the vagina, and any prolapse of the vaginal wall with straining. The rectovaginal septum is critically appraised with a finger in the anus and a finger in the vagina, feeling for induration or a sense of fullness. During the digital anal examination, the anal tone at rest and while squeezing along with early fatigue (i.e., reduced strength of anal contractions during several repetitive squeezes) is assessed. Recruitment of buttock muscles when the patient is asked to squeeze versus levator contraction versus actual anal muscle contraction is noted, along with the presence of masses, stool in the rectum, and induration (particularly anteriorly). At times the internal opening of the fistula can actually be felt during the digital examination. The shape of the upper medial thighs should be noted because gas or stool can escape the anus and pass forward into the vagina, later to be expelled, suggesting a fistula. In such cases the patient does not have a fistula, of course, and instruction in the management of anal incontinence is provided. Patients with loose upper thighs are prone to this phenomenon because the anatomy directs the seeping material forward toward the vagina.

The next step is anoscopy and proctoscopy (either flexible or rigid) to seek the internal opening of the fistula and to note the condition of the rectal and anal mucosa. Noting the presence of anal or distal rectal ulceration at the internal opening is important because repair is avoided when inflammation is present. Sometimes rigid or flexible endoscopy of the vagina provides valuable information regarding the size and location of the fistula and assists in visualizing debris in the vagina. If the completeness of the examination is in question, an examination is performed after the induction of anesthesia to fully delineate the size and location of the fistula. Another benefit of performing an examination after the patient has been anesthetized is that it provides the opportunity to drain any trapped sepsis by unroofing a cavity or placing a draining seton. Before any repair can be entertained, all sepsis must be eliminated so the tissue is as soft and supple as possible. If the cause of the fistula is related to cancer, liberal biopsies of the area are performed to rule out recurrence.

Other testing depends on findings uncovered during the history and physical examination. Any women older than 50 years should have a colonoscopy. Other indications for a colonoscopy include a history of loose stool, the possibility of Crohn disease, or a change in stool habits. Areas of inflamed mucosa or other lesions are biopsied. Additionally, random biopsies are performed in women with diarrhea to rule out microscopic colitis. Diarrhea and irritable bowel–type symptoms may warrant a consultation with a gastroenterologist. Bowel habits should be optimized prior to plans for surgical repair of the fistula. Also, if Crohn disease is proven or suspected, a complete bowel evaluation is beneficial because medical therapy or surgery may be included in the treatment algorithm.

The role of anal physiology testing in the workup of a patient with an RVF is debated. Such testing should only be performed if the caregiver believes it would alter the treatment approach. In contrast, anal endosonography is overall probably the most beneficial test because it provides full details regarding sphincter integrity, which influences the choice of surgical procedure.

After all data are gathered, treatment is proposed. When discussing treatment with the patient, realistic goals should be elucidated. Surgery may not be the best option for women with a small internal opening and minimal symptoms. It is important to remember that surgery could make the situation and symptoms worse, as well as create additional scarring. If Crohn disease is present, it should be treated or managed surgically before embarking on a surgical course to close the fistula. Additionally, diarrhea should be under optimal control. Occasionally a diverting stoma (typically an ileostomy) is required for the tissue to become supple enough to perform a repair, particularly when the fistula is related to radiation. Hyperbaric oxygen treatment may improve radiated or scarred tissue to a sufficient degree to permit a repair to be attempted. Use of a vaginal hormone cream for a month before performing a repair also may improve the elasticity of tissues in postmenopausal women.

Treatment Options

Options for treatment ( Box 6-2 ) are classified as medical, nonsurgical closure, or surgical closure. The route for closure is accomplished via the vagina, perineum, anus, or abdomen or through a combination of these approaches.