PATHOPHYSIOLOGY

It is important to consider the underlying cause of the rectovaginal fistula in preparing for a successful repair. The most common cause of rectovaginal fistula remains obstetric trauma,^1,2 usually caused by an unrecognized injury with traumatic vaginal de-livery, wound infection, or an inadequate repair of a third- or fourth-degree perineal laceration. Up to 5% of vaginal deliveries result in these lacerations. Most heal when repaired at the time of labor. Prolonged labor and compression can result in ischemic necrosis of the vaginal septum, predisposing the delivering woman to development of a rectovaginal fistula. This is a greater concern in developing nations and likely not a large factor in industrialized countries such as the United States and Canada.

Vaginal, rectal, and pelvic operations, such as rectocele repair, low anterior resection, and hemorrhoidectomy, may lead to rectovaginal fistula as a result of intraoperative injury or postoperative infection. Rectovaginal fistula can result from nonobstetric blunt and penetrating trauma. Inflammatory processes of the bowel, such as diverticulitis, Crohn’s disease, and ulcerative colitis, can produce a rectovaginal fistula.

Rectal, cervical, uterine, and vaginal malignancy and radiation therapy are known causes of rectovaginal fistulas. The incidence of rectovaginal fistula after irradiation is 0.3% to 6%.^3,4 The fistula may occur up to 2 years after irradiation because of progressive radiation damage. Any fistula associated with radiation therapy and malignancy must be biopsied to rule out recurrent malignancy before formal repair.

Inflammatory or infectious processes near the rectovaginal septum or cul-de-sac may result in formation of a rectovaginal fistula. Prolonged use of a vaginal pessary can result in a rectovaginal fistula.

The location of rectovaginal fistulas may mandate a particular surgical approach. The fistula may be in the high, middle, or low rectal region. Most fistulas associated with obstetric trauma are classified as low types. Diverticular disease and other intra-abdominal pathologic conditions are associated with higher rectovaginal fistula. The high fistula usually is associated with intra-abdominal conditions such as diverticulitis or abscess formation, and it may require a laparotomy. The low fistula of rectal origin can be repaired transvaginally, avoiding the morbidity of an abdominal approach.

EVALUATION

The diagnosis is obvious in patients with a large rectovaginal fistula because bowel content is evacuated through the vagina. Patients with a smaller fistula may be completely asymptomatic.

A thorough history and physical examination are mandatory for every patient suspected of having a fistula. The interview should include questions about prior malignancy, radiation therapy, complicated obstetric history, inflammatory bowel disease, and prior anorectal surgery. Physical examination should reveal the size, location, and number of fistulous tracts. The perineal body must be examined to determine the function and tone of the anal sphincter. Bimanual examination allows the physician to palpate the thickness of the perineal body and identify the fistula. Multiple fistulas and perianal fissures may suggest Crohn’s disease. If the fistula is not easily identified, vaginal speculum examination should be performed.

If the diagnosis is still in doubt, a dye test can be performed. Methylene blue dye is instilled into the rectum, and a tampon or sponge inserted into the vagina. Staining of the pad confirms the diagnosis and can be helpful in identifying a small fistula. Proctoscopy, colonoscopy, barium examination, and computed tomography should be performed if indicated. Any area of suspicious inflammation, ulceration, or mass should be biopsied to rule out a malignant process or recurrence. Examination under anesthesia can be performed to make the diagnosis if all of the previous measures fail and the physician still suspects a fistula.

Before formal repair, it is necessary to evaluate the patient for fecal incontinence. A review of 52 patients at the University of Minnesota revealed a 48% incidence of coexistent fecal incontinence.⁵ Among women who develop rectovaginal fistula after obstetric trauma, the incidence is probably much higher. It is essential to assess the function of the anal sphincter before surgical repair. Endoanal ultrasonography, anal manometry, and pudendal nerve terminal motor latency testing remain valuable tools to aid with the clinical evaluation. Ultrasound can easily identify defects in the internal anal sphincter. Defects in the external anal sphincter are more difficult to identify because of the hyperechoic pattern. Manometry can help quantify the resting and squeezing pressures of the sphincter muscle. Pudendal nerve testing helps identify underlying neuropathy.

PREOPERATIVE CONSIDERATIONS

Management of rectovaginal fistulas depends on several factors: cause, size, number, and location of the fistulas and the surgeon’s preference. Anal sphincter integrity and prior operations influence the choice of treatment. Regardless of the approach chosen, several principles require consideration before repair.

Antibiotic coverage and topical hormonal replacement help optimize the health of local tissues and decrease any associated infection and inflammation. The health of the surrounding tissues influences the waiting period before surgical repair. Any inflammation or infection should be resolved. Waiting 3 to 6 months in these cases allows resolution and increases the chance of successful repair. In patients with prior failed repair, a longer waiting period may be necessary. In patients with postirradiation rectovaginal fistulas, a much longer waiting period may be required. Patients with complex fistulas (e.g., large size, radiation induced, neoplasm induced, multiple failed repairs) may require a diverting colostomy before formal repair. After diversion, a waiting period of 2 to 3 months before vaginal repair allows local tissue healing. Complete bowel preparation is given before surgery.

Excellent exposure allows good mobilization of tissue flaps. The fistulous tract should be exposed in its entirety and left intact. We tend to not excise the tract. This prevents iatrogenic enlargement of the fistula and allows us to use it in our repair. The rectal opening is closed in multiple, tension-free layers. Interposition of healthy tissue between the rectum and vagina should be used routinely. Common sources include labia fatty tissue (i.e., Martius flap), labial skin and underlying fatty tissue, gluteal skin, gracilis muscular flaps, and omentum. Case reports have described pudendal thigh fasciocutaneous island flaps and gluteal-fold flap repairs to aid in rectovaginal fistula repair.^6,7 Several common techniques of tissue interposition can be found in Chapters 81 and 82. After closure of the fistula, anal sphincter defects should be addressed to restore normal sphincter function.

SURGICAL REPAIRS

Surgical options can be divided into transvaginal repair, transanal repair, transperineal repair, and abdominal repair. Reconstructive urologists and gynecologists typically use a transvaginal approach, whereas colorectal surgeons prefer a transanal approach. An abdominal approach is often used in treating radiation-induced rectovaginal fistulas. We use a multilayered transvaginal approach, avoiding the morbidity of a laparotomy, in most rectovaginal fistula repairs.

Complete bowel preparation is done, and antibiotics are given preoperatively. The patient is given general or spinal anesthesia and placed in the high lithotomy position. A Foley catheter is placed in the bladder. Use of a surgeon’s headlight and a ring retractor help to optimize exposure. A Foley catheter is inserted into the fistulous tract (Fig. 83-1). A circumferential incision is made around the Foley catheter, and the tract is dissected to the rectal wall (Fig. 83-2). A flap of distal vaginal is also prepared. The fistulous tract is then excised, leaving the rectal wall with an indwelling catheter (Fig. 83-3). The rectal wall is closed in two layers using 2-0 absorbable sutures (Fig. 83-4). The levator musculature is included in the closure.

Figure 83-1 The fistulous tract is catheterized.

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DEVELOPMENTAL ANATOMY AND UROGENITAL ABNORMALITIES USE OF CADAVERIC FASCIA FOR PUBOVAGINAL SLINGS EPIDEMIOLOGY OF INCONTINENCE AND VOIDING DYSFUNCTION IN THE ELDERLY SURGERY FOR REFRACTORY URINARY INCONTINENCE: SPIRAL SLING FEMALE SEXUAL FUNCTION AND DYSFUNCTION FUNCTIONAL ANATOMY AND PATHOPHYSIOLOGY OF PELVIC ORGAN PROLAPSE

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