The assessment and treatment of rectovaginal fistulae (RVFs) is an area of pelvic floor disorders where the collaboration between medical disciplines including gynecologists and colorectal surgeons will produce the best outcomes. Success rates of anatomical closure and good functional outcome can be low due to the high risk of infection and tissue breakdown when operating in an area contaminated with fecal material and on damaged denervated muscles and scarred devascularized tissue. Colorectal surgeons have experience in abdominal and rectal surgery of colorectal conditions and fistulae and diversion colostomies, whereas gynecologists have expertise in vaginal and perineal surgery and experience in obstetrics and obstetric injury; the commonest cause of RVF.

Rectovaginal and anorectal fistulae are abnormal epithelial communications between the rectum or anus and the vagina. The RVF can be divided into low, mid, and high fistula. The low RVF is situated between the lower third of the vaginal and the lower half of the rectum. The mid and high fistula is situated between the middle and upper rectum and the mid and upper vagina. The low RVF can be further classified whether the anal sphincter complex (ASC) is involved and the functional and anatomical state of the ASC. This is important because it decides whether the ASC needs to be reconstructed during the RVF repair.

RVF can be classified into simple and complex based on position (low mid or high vagina), size less than 2.5 cm, and causation (traumatic or infectious). Complex RVFs are larger than 2.5 cm, high vaginal position, secondary to inflammatory bowel disease, radiation, neoplasia, and had failed previous repair.¹

The commonest cause of anorectovaginal fistulae is obstetric trauma and are frequently associated with anal sphincter injury which potentially further contributes to the risk of fecal incontinence even after successful repair (Table 57.1). Rectal fistula may be a result of an unrecognized fourth-degree tear or a poorly repaired thirdor fourth-degree tear with secondary infection and the breakdown (Fig. 57.1). The vaginal delivery may be spontaneous but more commonly associated with forceps or vacuum vaginal delivery. In developing countries, prolonged obstructed labor leading to tissue ischemia and necrosis and fistula development occur 10 to 14 days following delivery. Twenty-five percent of vesicovaginal fistula (VVF) following prolonged obstructed labor have coexisting RVF. It is rare for RVF to occur without a coexisting VVF in these circumstances.² In developed countries, Goldaber et al.³ reported an incidence of 1.7% for fourth-degree perineal trauma and 0.5% for RVF in 24,000 vaginal births. This rate is now decreasing with less instrumental vaginal deliveries and a higher rate of cesarean sections.

In our experience, the second commonest cause is iatrogenic following surgery including vaginal hysterectomy, rectocele repair, hemorrhoidectomy, low anterior resection, and proctocolectomy. A contributing factor can occasional be the use of stapling devices with rectoanal resections and hemorrhoidectomy.

Trauma to the rectum can occur during posterior compartment prolapse repair; therefore, a routine postoperative rectal digital examination is essential after surgery and is also recommended after vaginal delivery, episiotomy, vaginal-perineal tears, and perineal repair. Foreign bodies inappropriately placed in the vagina and neglected vaginal pessaries are becoming more common with the more frequent use of pessaries to conservatively treat pelvic organ prolapse (POP). Synthetic mesh used for POP surgery in the posterior compartment increases the risk of fistula formation especially following a rectal injury (Fig. 57.2).

Colorectal diseases can cause fistulas from the gastrointestinal tract into the vagina. In practice, most high vaginal fistulas are secondary to diverticular disease of the sigmoid colon. Less commonly, colorectal cancer can directly invade the upper vagina. Repair of these high fistulas usually involves colonic resection and is best done abdominally.

Perianal Crohn disease may result in the formation of RVFs. Typical features of perianal Crohn such as skin tags, fissures, hidradenitis, and anal stenosis may
or may not be present and perianal Crohn occasionally occurs without associated Crohn proctitis, colitis, or ileitis. Clinicians need to have a high index of suspicion for Crohn, and send tissue for biopsy and refer for colonoscopy as appropriate.

Injury to the gastrointestinal tract may arise following therapeutic radiotherapy with the incidence of complications increasing when the radiation dose exceeds 5,000 cGy. Ionizing radiation can cause obliterative endarteritis even when used within the therapeutic dosage and may result in urinary and RVF formation many years later.

Anal cryptoglandular fistulae arise from infection of the anal glands. Infection leads to the development of perianal and ischiorectal abscesses which spontaneously point or are drained surgically leading to fistula formation.⁴ The majority of cryptoglandular fistulae extend from the anus to the perianal skin, but some can also extend from the anus into the vagina (Fig. 57.3).

A cyptoglandular abscess pointing anteriorly into the vagina can be difficult to differentiate from a Bartholin gland abscess infection. RVFs arising after drainage of a Bartholin gland abscess are more likely to be due to an underlying unexpected cryptoglandular abscess infection rather than iatrogenic injury to the rectal wall.

Bartholin cyst abscess is a common bacterial infection in women and presents as a tender right- or leftsided vulval mass anterior to the rectum. The Bartholin glands (the greater vestibular glands) are pea-sized bilateral masses of erectile tissue on either side of the vaginal opening situated in the vestibular bulbs and is surrounded by a rich plexus of veins within the spongiosis muscle. They open via a 2 cm duct into the vestibule between the hymen and labia minora. They are mucin secreting and produce copious secretions during coitus
for lubrication. The glands are anterior to the transverse perineal muscle but can extend posteriorly to be confused with perianal abscess. Injury to the rectum during surgical treatment can result in RVF and litigation.

The most common symptoms of RVF are the passage of flatus and/or liquid or solid stool into the vagina. Small fistulas may only be symptomatic when the stools are loose. Women may also report a purulent discharge from the vagina, dyspareunia, perineal pain and tenderness, along with vaginal irritation and recurrent genitourinary tract infection which is secondary to the vaginitis and dermatitis caused by the feculent discharge. There may be other symptoms present due to coexisting conditions of Crohn disease or malignancy such as bleeding. A sexual history should be taken particularly as dyspareunia can also develop after vaginal repair and perineal reconstruction.

Physical examination is important to determine the location and etiology of the RVF and aid classification into simple or complex. Examination of the vagina and perineum should be performed to diagnose any associated prolapse or scarring from birth trauma and detect muscular damage to perineal and anal sphincter muscles. If small, the fistulous opening may not be easily visible on inspection of the lower anorectum and vagina, but the clinician must have a high index of suspicion when women present with signs and symptoms consistent with an RVF. Vaginal and anal examination should also assess resting and squeeze pressures of the levator and anal sphincter muscles. Perianal dimpling or the “dovetail sign” with perianal folds posterior to the anus is indicative of a disrupted anal sphincter. Women with RVF may need to be examined under anesthesia for accurate diagnosis as vaginal/rectal examination may be painful because of the scarring and infection usually present. The fistulous tracts may also require gentle probing using lacrimal duct probes to delineate the fistula or fistulae (Fig. 57.4). For pinhole fistula rectal distension with saline and with methylene blue or diluted hydrogen peroxide can be used in the evaluation of complex fistulae to visualize side tracts and areas of fluid collection.

This assessment will help to determine the best surgical approach whether transvaginal, transanal, perineal, or abdominal. We believe that this decision is best done jointly by a urogynecologist and colorectal specialist. Several imaging studies may help to identify and delineate RVF including computed tomography (CT) scan, magnetic resonance imaging (MRI), fistulography, and endoluminal ultrasound (EUS). Assessment of the anal sphincter complex (ASC) with EUS and manometry is frequently useful prior to surgical repair to determine the structural and functional integrity of the anal sphincter.

Patients with no or minimal bothersome symptoms may decide to have no surgical treatment especially if it is a small anovaginal fistula. Normalization of stool consistency and treatment of associated infection, and dermatitis is helpful in improving quality of life.

RVFs associated with Crohn disease require expert gastroenterologic management. Modern treatment of Crohn disease with biological disease modifying antirheumatic drugs such as Adalinumab may result in healing of fistulae.⁵ A randomized, double-blinded, multicenter study⁶ studied infliximab for the treatment of both abdominal and perianal fistulae from Crohn disease. After 18 weeks of infliximab treatment, the authors found significant reduction in the number of fistulae with complete closure occurring in 46% versus 13% of placebo. The follow-up was relatively short (4.5 months), and the study included all enterocutaneous fistulae, not specifically RVF.