History of the Procedure
For thousands of years, women simply tolerated the distressing symptoms generated by rectovaginal fistulas (RVFs). Such tolerance is no longer necessary, because most RVFs can be surgically corrected via a number of approaches. A small percentage, however, cannot be corrected, because of patient comorbidity or disease-related factors; in these cases, patients can be helped only by fecal diversion. 
An RVF is an epithelial-lined tract between the rectum and vagina. This article discusses only acquired RVFs. Most RVFs are located at or just above the dentate line. Fistulas below the dentate line are not true RVFs but, rather, anovaginal fistulas; the treatment required for these differs from that required for RVFs.
Among reported series, the frequency with which RVFs occur varies according to the cause. RVFs are classified on the basis of location, size, and etiology (see Etiology), each of which affects the treatment plan and prognosis.
RVFs can be divided into the following two groups by location:
Low RVFs, which are located between the lower third of the rectum and the lower half of the vagina, are closest to the anus and can be corrected with a perineal approach
High RVFs, which occur between the middle third of the rectum and the posterior vaginal fornix, require a transabdominal approach for repair
RVFs may vary greatly in size, but most are less than 2 cm in diameter. They are stratified by size as follows:
Small RVFs are less than 0.5 cm in diameter
Medium-sized RVFs are 0.5-2.5 cm in diameter
Large RVFs exceed 2.5 cm in diameter
Several traumatic mechanisms for the development of RVF exist. Perineal lacerations during childbirth, especially those due to episioproctotomy, predispose patients to RVFs. Perineal lacerations are more common in primigravidas, in precipitous births, or when forceps or vacuum extraction is used. Failure to recognize and correctly repair perineal lacerations, or secondary infection of perineal lacerations, further increases the chance of RVF. Prolonged labor with pressure on the rectovaginal septum can produce necrosis and result in RVF.
Vaginal or rectal operative procedures, especially those performed near the dentate line, may cause RVFs. The stapled hemorrhoidopexy and STARR (stapled transanal rectal resection) and TRANSTAR (transanal stapled resection) have had increasing complications of RVFs.  Pelvic operations can be complicated by the development of a high RVF.
Traumatic injury (penetrating or blunt) and forceful coitus also have produced RVFs.
Crohn disease  and, less often, ulcerative colitis have been associated with RVFs. The fistula may arise primarily or, more often, in relation to a perirectal abscess or fistula, manifesting as complicated perianal sepsis.
Radiation used in the treatment of pelvic malignancies may result in RVF.  Fistulas that occur during such therapy usually result from tumor regression. Most other fistulas become apparent 6 months to 2 years after completion of treatment. Diabetes, hypertension, smoking, and previous abdominal or pelvic surgery increase the risk of fistula formation. The use of biopsy to differentiate radiation-related change at the fistula from a recurrent tumor is imperative, because neoplasms (primary, recurrent, or metastatic) can produce RVFs.
A variety of infectious conditions can produce RVF. The most common are perirectal abscess/fistula and diverticulitis. Less commonly, tuberculosis, lymphogranuloma venereum, and Bartholin gland abscess can cause RVFs.
The clinical presentation of RVF varies little. A few patients are asymptomatic, but most report the passage of flatus or stool through the vagina, which is understandably distressing. Patients may also experience vaginitis or cystitis. At times, a foul-smelling vaginal discharge develops, but frank stool through the vagina usually occurs only when the patient has diarrhea. The clinical picture may include fecal incontinence due to associated anal sphincter damage or bloody, mucus-rich diarrhea caused by the underlying clinical etiology.
Physical examination is essential. This usually confirms the diagnosis of RVF and provides a great deal of information regarding its size and location, the function of the sphincters, and the possibility of IBD or local neoplasm. (Anal sphincter disruptions are commonly seen in association with RVFs of obstetric origin. Sphincter function should be evaluated prior to any repair.)
Office examination usually consists of a rectovaginal examination (visual and palpation) and proctosigmoidoscopy. The fistula opening may be seen as a small dimple or pit and occasionally can be gently probed for confirmation.
The suspicion of Crohn disease should be high if there is any other abnormality of the rectal mucosa or a previous or currently coexisting fistula-in-ano. Failure to recognize Crohn disease can lead to inappropriate operative intervention and can worsen the patient's situation.
Placing a vaginal tampon, instilling methylene blue into the rectum, and examining the tampon after 15-20 minutes can often establish the presence of RVF. If the tampon is unstained, another part of the gastrointestinal (GI) tract may be involved.
Because the symptoms of RVF are so distressing, surgical therapy is almost always indicated. Exceptions include patients who are moribund and those for whom the proposed anesthesia and surgery pose prohibitive risks. Note that surgical therapy means repair in most cases. Some patients, however, are better served by a diverting stoma than by an ill-advised repair attempt.
The rectovaginal septum is the thin septum separating the anterior rectal wall and the posterior vaginal wall. The caudal portion of the septum is the perineal body. The anal sphincters are located in the posterior portion of the perineal body. The transverse perineal muscle traverses the perineal body and is often used in anal sphincteroplasty and rectovaginal fistula repair.
The dentate line is the grossly visible demarcation between the squamous anal epithelium and the transitional-columnar epithelium of the rectum. The anal glands open into the bases of the anal crypts at this location.
The lowest extent of the peritoneal cavity in the female lies in the pelvis and may be anterior to the cervix uteri, posterior to it, or both. The occupation of this space by the small bowel is called an enterocele; when the space is occupied by the sigmoid colon, this is termed a sigmoidocele.
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