Fistula Operations: A Colour Atlas of Rectovaginal and Vesicovaginal Fistula (Volume 34) Narendra Malhotra, Arun Nagrath, Shipra Rajat Misra
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61Vesicovaginal Fistula
  • Introduction
  • Genitourinary Fistulas
  • Postoperative Care
62

IntroductionChapter 3

 
Genitourinary Fistula
A genitourinary fistula is defined as an abnormal communication between the urinary (ureters, bladder and urethra) and the genital (uterus, cervix and vagina) systems. The true incidence of genitourinary fistula is unknown, although the generally accepted incidence approximates 1% or less of all genitourinary operations. This is most likely an underestimation because many are unreported or unrecognised. The most common type of genitourinary fistula is the vesicovaginal fistula (VVF).
 
Pathophysiology
Knowledge of the principles and phases of wound healing are important in understanding the pathogenesis of genitourinary fistula. After injury, tissue damage and necrosis stimulate inflammation, and the process of cell regeneration begins.
Initially at the injury site, new blood vessels form, termed angiogenesis. Three to five days after injury, fibroblasts proliferate and subsequently synthesise and deposit extracellular matrix, in particular collagen.
This fibrosis phase determines the final strength of the healed wound. Collagen deposition peaks about 7 days after injury and continues for a number of weeks. Subsequent maturation and organisation of the scar, termed remodeling, augments wound strength. These phases are interdependent and are intrinsically involved in wound healing. Any disruption of this sequence eventually results in fistula formation. Most fistulas tend to present 1–3 weeks after tissue injury, a time during which tissues are most vulnerable to alterations in the healing environment, such as hypoxia, ischaemia, malnutrition, radiation and chemotherapy. Edges of the wound eventually epithelialise and a chronic fistulous tract is thus formed.
 
Classification
Although many classification systems exist for genitourinary fistula, there is no single accepted standardised scheme. Fistulas can develop at any point between the genital and urinary systems. Thus, one method of classification is based on anatomic communication.64
 
Classification of Genitourinary Fistula Based on Anatomic Communication
Ureter
Urinary Bladder
Urethra
Vagina
Ureterovaginal
Vesicovaginal
Urethrovaginal
Vesicoureterovaginal
Cervix
Ureterocervical
Vesicocervical
Urethrocervical
Uterus
Ureterouterine
Vesicouterine
Not reported
Vesicovaginal fistulas can also be characterised by their size and location in the vagina. They are termed high vaginal when found proximally in the vagina, low vaginal when noted distally or midvaginal when identified centrally.
Recently, a new classification system is developed which divides genitourinary fistulae into four main types, depending on the distance of the fistula's edge from the external urinary meatus. These four types are further sub-classified by the size of the fistula, extent of the associated scarring, vaginal length or special considerations.
Type 1: Distal edge of fistula greater than 3.5 cm from external urinary meatus.
Type 2: Distal edge of fistula greater than 2.5–3.5 cm from external urinary meatus.
Type 3: Distal edge of fistula 1.5 to less than 2.5 cm from external urinary meatus.
Type 4: Distal edge of fistula less than1.5 cm from external urinary meatus
  • Size less than 1.5 cm, in the largest diameter
  • Size 1.5–3 cm, in the largest diameter
  • Size greater than 3 cm, in the largest diameter.
  • None or only mild fibrosis (around fistula and/or vagina) and/or vaginal length greater than 6 cm, normal capacity
  • Moderate or severe fibrosis (around fistula and/or vagina) and/or reduced vaginal length and/or capacity
  • Special consideration, e.g. postradiation, ureteric involvement, circumferential fistula or previous repair.
 
Aetiology/Epidemiology
The aetiology of urogenital fistulae may be categorised as congenital or acquired, the latter being associated with childbirth, gynaecologic surgery, malignancy and radiation therapy. When VVF occurs in childhood, antecedent events include penetrating trauma, retained or neglected foreign bodies and genitourinary surgery. Congenital VVFs are extremely rare and most coexist with other congenital urinary tract abnormalities.
Relative incidence of VVF: gynecologic surgery is responsible for 82% of the fistulae, 11% were from obstetric procedures, 7% followed treatment for malignant disease and 3% from trauma.
Culture and geography are reflected in the frequencies and aetiologies of VVFs. In developed countries 95% of the VVF occurr with nonobstetric causes. In contradistinction, obstructed labour cause 98% of the VVF in developing countries. Most often the inciting event is prolonged and obstructed labour, which results in pressure necrosis. Introital stenosis secondary to female circumcision, cephalopelvic disproportion (from inadequate pelvic dimensions associated childbearing at a very early age), an android pelvis, malnutrition, orthopaedic disorders including rickets and hydrocephalus contribute to dystocia. Fistulae may be caused by the misuse of forceps, destructive instruments used to deliver stillborn infants or surgical abortion.65
Symphysiotomy and the postpartum use of intravaginal caustic agents also have a role. Thirteen percent of VVF resulted from gishiri cuts, a traditional tribal practice of cutting the anterior vagina with a razor blade to treat a variety of conditions, including obstructed labour, infertility, dyspareunia, backache and goiter.
Primiparous girls who married during early adolescence are more likely to experience VVF than those who married at an older age. Uneducated women and those married to men who were unskilled labourers were 14 times more likely to sustain a VVF than their cohorts. Predisposing risk factors for VVF include a history of pelvic irradiation, caesarean section, endometriosis, prior pelvic surgery, pelvic inflammatory disease, diabetes mellitus, concurrent infection, vasculopathies and tobacco abuse. Patients undergoing total abdominal hysterectomy are a particular risk.
The incidence of VVF is 1 in 1,200 hysterectomies; 1 in 455 after laparoscopic hysterectomy; 1 in 958 after total abdominal hysterectomy and 1 in 5,636 after vaginal hysterectomy. Risk of ureteral injury has seven times greater with laparoscopic procedures than with open procedures. The underlying mechanism of posthysterectomy fistula formation is probably multifactorial, but actual aetiologies remain enigmatic.
With prompt intraoperative recognition, the success rate for immediate repair was 98.4%.
Bladder injury and urogenital fistulae are also known complications of incontinence surgery.
Radiation-induced fistulae occasionally are associated with treatment for carcinoma of the cervix or other pelvic malignancies. Radiation-induced VVF formation does not always correlate with the absolute dose and distribution of radiation, or with the patient's weight or age; this suggests that some women are more sensitive to radiation therapy than others. Healthy tissues of the anterior vaginal wall tolerate radiation doses as high as 8,000 rads.
Fistulae may appear during the course of radiotherapy (usually from necrosis of the tumour itself) or remote from completion of therapy. Endarteritis obliterans progresses during the first 2 years and may lead to ischaemic changes that result in the delayed occurrence of a fistula. In planning repair, recurrent malignancy must be excluded with biopsies of the fistula margins. Because of decreased vascularity of the adjacent tissue, healing is impaired and techniques incorporating revascularisation must be considered when planning repair of a radiation-induced fistula.
 
Trauma and Foreign Body
Trauma sustained during sexual activity or sexual assault can result in genitourinary fistula formation and has been estimated to cause 4% of these defects. Foreign bodies, such as a neglected pessary, an aerosol cap and vesical calculi are also documented agents. Foreign bodies introduced during surgery, such as collagen injected transurethrally and synthetic materials used in urethral sling procedures have also been reported. During sling surgeries, placement of the synthetic mesh under excess tension may contribute to increased tissue stress and necrosis.
Miscellaneous: Other rare causes of fistula formation include infections, such as lymphogranuloma venereum, urinary tuberculosis, pelvic inflammation and syphilis, inflammatory bowel disease and autoimmune disease. Moreover, conditions that interfere with healing, such as poorly controlled diabetes mellitus, smoking, local infection, peripheral vascular disease, chronic steroid use and malignancy are risk factors.66
Approach to management cannot be generalised in these situations. Care must be individualised in these situations. Urethrovaginal fistulae are uncommon and usually occur after surgery for urethral diverticulum, anterior vaginal wall prolapse or urinary incontinence, and after radiation therapy. Urethrovaginal fistulae may also be congenital, although these are extremely rare.
Vesicouterine and vesicocervical fistulae are rare. They are usually complications of caesarean section. Cyclic haematuria (menouria) is common.
 
Prevention
There can be grave social consequences of VVF, including divorce, poverty, depression and societal isolation.
Many of the techniques advocated to reduce the incidence of fistulae are directed toward protecting the bladder during hysterectomy. The base of the bladder rests on the anterior lower uterine isthmus and the cervix, whereas the trigone is caudad to the internal os. The bladder is subjected to trauma during dissection from the cervix and upper vagina. A fistula following injury in this area will be found in the posterior wall of the bladder superior to the interureteric ridge in almost all cases.
Because the trigone overlies the upper one-third of the anterior vagina, it is unlikely to be injured because dissection at this level is rarely needed during hysterectomy for benign conditions. Bladder injury associated with supracervical hysterectomy is rare because bladder dissection is minimal.
Suggestions on avoiding injury to the bladder during total abdominal hysterectomy:
 
Clinical Presentation
Vesicovaginal fistula may present days to weeks after the initial inciting surgery and those following hysterectomy typically present at 1–3 weeks.
In the case of posthysterectomy VVF, early symptoms and early diagnosis may be delayed by postoperative vaginal cuff oedema.
Vesicovaginal fistula classically presents with unexplained continuous urinary leakage from the vagina after a recent operation.67
The patient may present with recurrent cystitis or pyelonephritis; unexplained fever; haematuria; flank, vaginal or suprapubic pain; abnormal urinary stream; ileus, and bladder irritability. Irritation of the vagina, vulvar mucosa, and perineum follows, and women report a foul ammoniacal odour. This constant leakage of urine may make the patient a social recluse, disrupt sexual relations, and lead to depression, low self-esteem and insomnia.
Haematuria and symptoms of bladder irritability are also noted in women suffering from fistula.
 
History and physical examination
A thorough history and physical examination identifies most cases of VVF. Accordingly, historical information regarding obstetric deliveries, prior surgeries, previous management of fistula, and treatment of malignancy, especially involving pelvic surgery and radiation therapy, should be documented.
The physical examination is equally important and often visual inspection during physical examination will identify the defect. A meticulous assessment for other fistulous tracts should be performed, and their location and size noted. Vaginoscopy has been described by some to improve fistula identification. For this evaluation, a laparoscope is inserted into a vagina, whose walls are held apart by a translucent plastic speculum.
During evaluation, it is mandatory to differentiate urinary leakage through a fistula (extraurethral leakage) from stress urinary incontinence (transurethral leakage). Moreover, occasionally the source of fluid present in the vagina is unclear and a small amount of urine can easily be mistaken for vaginal discharge. Measurement of the vaginal fluid's creatinine content, however, is an inexpensive test that may be used to confirm urine.
 
Evaluation of a Vesicovaginal Fistuala
Even though a diagnosis is obvious in many patients, a thorough urologic investigation is mandatory, especially to rule out coexistent fistulae.
An evaluation begins with a history and physical examination facilitated by use of a speculum, good lighting and positioning. A history of large-volume vaginal leakage with no voided urine suggests a sizable defect, whereas lesser vaginal fluid drainage associated with regular voiding raises the possibility of a small VVF or one that only leaks intermittently.
Small volumes of drainage may be associated with a vesicouterine or vesicocervical fistula. Only rarely urine is seen actually coming from the cervical os. Vaginal fluid may be collected for measurement of urea concentration to confirm that it is urine as opposed to peritoneal fluid or ascites. Urinalysis and urine culture may identify the presence of a concomitant infection. Intravenous urography may aid in localising the fistula, assessing ureteral anatomy and determining the adequacy of renal function. Leakage from the vagina both during and after voiding suggests a urethrovaginal fistula. These fistulae are usually easily distinguished on examination. Otherwise, a double balloon Tratner catheter may be used to perform positive pressure urethrography with contrast medium.
Dye flowing into the vagina demonstrates the fistula. Dye tests traditionally have been performed to evaluate patients for a urinary tract fistula. With the patient in lithotomy position for a pelvic examination, a transurethral catheter is placed and a speculum is inserted into the vagina to facilitate inspection. In the case of a larger VVF, urine is encountered immediately; in most cases, the fistula itself is visualised and the diagnosis confirmed. In the event that the fistula is not easily visualised, the vaginal apex is sponged dry, and 100 cc of a dilute solution of methylene blue or indigo carmine is instilled in the bladder via a Foley catheter.68
This is done with the speculum in place and the vaginal cuff or cervix and upper vagina in full view. Appearance of blue dye indicates a vesical fistula. The vaginal apex should be carefully scrutinised to identify the site of the fistula. If no dye is seen, it is possible that the open speculum is occluding the fistula. In this situation, the speculum should be slowly rotated, partially closed and slowly withdrawn to see if dye begins to leak into the vagina as the speculum blades are repositioned. If dye is still not seen in the vagina, a tampon is inserted, and the patient is asked to sit up and ambulate for 15 or 20 minutes. With the patient on the examining table once again, the tampon is carefully removed. If blue dye stains the end adjacent to the vaginal apex, a small VVF probably is present. If the distal end of the tampon near the vaginal introitus is blue, urethral integrity may be compromised. If the tampon is wet with urine, but not blue, a ureterovaginal fistula is likely. The patient's symptoms of vaginal fluid leakage may result from leakage of urine from the ureter with pooling in the vagina and subsequent loss of this urine from the vagina when the patient changes position or moves about.
When the tampon does not stain blue with retrograde bladder filling, further dye studies may be done to demonstrate a ureterovaginal fistula. The bladder is emptied and flushed with saline and 2 cc of sterile methylene blue or indigo carmine is injected intravenously.
An alternate method is administration of phenazopyridine hydrochloride orally. One advantage of phenazopyridine is ease of administration. A second is that it stains urine an orange colour, which eliminates any confusion with blue in the bladder.
With either option, a fresh tampon is inserted and left in place for 15 minutes. If the upper end of the new tampon is stained, a ureterovaginal fistula is probably present. The vaginal apex is inspected carefully. Leakage of dye from one side of the postoperative vaginal apex strongly suggests the ipsilateral ureter is most likely the site of the fistula, but this is not definitive. An intravenous urogram or retrograde pyelogram is indicated not only to confirm the side of involvement, but also the level of the fistula. Before any attempt at surgical repair, all patients should undergo cystourethroscopy, with careful attention paid to the bladder neck, ureteral orifices and urethra. The exact location of the fistula in relation to the ureteral orifices, its size, and its possible underlying cause should be determined. Additional fistulous communications need to be excluded to reduce the risk of surgical failure. Larger fistulae may prohibit or cause difficulty in performing liquid-based cystoscopy. In that case, the vagina may be packed with gauze to limit egress of fluid. Alternatively, the bladder may be allowed to fill with air and dry cystoscopy performed with the patient in a jackknife or knee-chest position. Carbon dioxide also may be also used as a distention medium.
The ureteral orifices should be identified and evaluated. Urine fails to spurt through the orifice of a damaged or obstructed ureter. On rare occasions, a compromised ureter continues to spurt urine from the ureteral orifice. With a previously ligated ureter or damaged kidney, the ureters may look atrophic and no urine flow is seen. Attempts to pass a ureteral catheter usually fail when the tip reaches the point of obstruction. A retrograde pyelogram sometimes is needed to fully evaluate the ureter. A ureterovaginal fistula is associated commonly with hydronephrosis and hydroureter because stenosis of the ureter occurs at the site of the injury. Scarring at the edges of a VVF in the region of the ureteral orifice may also lead to ureteral stenosis and proximal dilatation.
The use of computed tomography (CT) with intravaginal contrast has been reported with limited success. CT may be more helpful in evaluating 69for coexistent disease involving the upper tracts before surgical correction. Recently, colour Doppler ultrasound with contrast media has been described as a diagnostic tool. Sonography was positive in 11 of 12 (92%) patients with VVF (A jet phenomenon was demonstrated through the bladder wall, in the direction of the vagina, which was distinguishable from ureteral flow). The benefits of colour Doppler are that is it easy to learn, noninvasive, results in no radiation exposure, and can evaluate the distance from the “fistula” to the ureteral orifices.
Currently available ultrasonography and CT are unlikely to replace the traditional diagnostic methods of intravenous urography, retrograde pyelograms and cystoscopy.
Preoperative urodynamic testing is defended by some authors for its use before surgical repair of urogenital fistulae to establish the presence of abnormal lower urinary tract function. Abnormal urodynamic findings may protect the surgeon medicolegally and prepare patients for a less than perfect outcome. However, for the typical vaginal repair of a posthysterectomy VVF, de novo detrusor instability is rare.
 
Anatomic Considerations
Posthysterectomy fistulae are usually supratrigonal and medial to both ureteral orifices. Vaginally, this corresponds to the cuff. Fistulae from obstetric causes are typically larger, more distal and may be associated with urethral injury. Obstetric fistulae have been classified according to their anatomic location in relation to the cervix. They may have a single channel or multiple channels. There may be a single orifice on one side that tracks to multiple orifices on the other side, although this presentation is very unusual. Cystourethroscopy and possible hysteroscopy are absolutely indicated before surgical repair to delineate the anatomy of the fistula or fistulae.
 
Preoperative Care
Cystitis, vaginitis and perineal dermatitis should be treated with the appropriate antibiotic. Acute cystitis is uncommon in conjunction with a VVF; therefore, suppressive antibiotic therapy is unnecessary unless upper tract infection is suspected. Perineal care is important and makes the patient more comfortable and tolerant of delayed closure. Frequent pad changes are required to minimise inflammation, oedema and vulvar irritation. Incontinence products are much preferred over menstrual hygiene products because incontinence products are designed for the larger volume associated with drainage of urine and the low viscosity of urine. Zinc oxide ointment or a cream containing lanolin may be especially helpful in the treatment of perineal and vulvar dermatitis. Inventive collection and drainage systems have been described for this purpose as well (by using dental prosthetic techniques to create a vaginal appliance: by gluing a Pezzer catheter to a fitted contraceptive diaphragm with rubber cement. This device traps urine in the vagina and diverts it to a collecting leg bag. It may be worn for the weeks or months before repair is carried out.
Every attempt should be made to divert the urinary stream to protect the perineum and allow the fistula margins to mature. In fact, fistulae smaller than 5 mm in greatest dimension may close with catheter drainage alone.
Medical therapy as an adjunct to surgery also is important. In the case of the malnourished patient, healing is improved if nutrition needs are optimised and anaemia corrected before surgery. Some have described the preoperative use of steroids to reduce tissue inflammation. Despite earlier reports of efficacy, in theory, steroid therapy could even interfere with healing when an early repair is attempted. Oestrogen therapy may be used to improve tissue thickness and vascularity provided there are 70no contraindications. Hyperbaric oxygen has been described as an adjuvant to surgery for radiation-induced fistulae.
 
Conservative Treatment
Occasionally, genitourinary fistulas may spontaneous close during continuous bladder drainage using an indwelling urinary catheter.
But generally, the larger the fistula, the less likely it is to heal without surgery. If the fistula has not closed within 4 weeks, however, it is unlikely to do so, probably secondary to collagen deposition and epithelialisation of the fistulous tract. Moreover, continued urinary drainage may lead to further inflammation and irritation of the bladder.
Fibrin sealant has been described for the treatment of VVF. However, its use has been limited to an adjunctive capacity rather than primary surgical treatment. Compared with surgical treatment, fibrin sealant monotherapy has not been as durable and recurrence results.
 
Surgical Treatment
General principles: Fundamental principles of repair include:
 
Cure Rate
Factors that affect this success rate include viability of the surrounding tissue, duration of the fistulous tract, prior irradiation, surgical technique and surgeon experience. Surgical repair of obstetric fistula has higher success rates, and 81% are corrected with the first attempt, and 65% with the second.
 
Timing of Repair
Traditional teaching recommends delayed repair of fistulas at 3–6 months after injury. The delay allows the inflammatory or necrotic fistula margins that are thought to be responsible for surgical failure to resolve and the outcome of cancer therapy to be reevaluated. However, this old dictum is probably no longer applicable. Most agree that unless there is severe infection or acute signs of inflammation, waiting is not necessary.
Early surgical intervention of uncomplicated fistulas does not affect closure rates, yet appears to reduce social and psychological patient distress. Fistulas identified within the first 24–48 hours postoperatively can be safely repaired immediately with success rates of 90–100%.
 
Route of Surgical Repair
Although there are many different types of surgical repair for VVF, data that support an optimal route are limited, and the lack of consensus may reflect the disparity in surgeon expertise and experience. Among important surgical considerations, ability to gain access to the fistula is essential and commonly dictates surgery selection. Fortunately, success rates are high whether the route of repair is transvaginal or transabdominal.
 
Vaginal
The transvaginal approach to genitourinary fistula repair is straightforward and direct. Compared with abdominal approaches, it is associated with shorter operative time, decreased blood loss, less morbidity 71and shorter hospital stay. The transvaginal route also allows the use of ancillary equipment, such as ureteral stents. This is particularly useful if the fistula is located near ureteral orifices.
 
Abdominal (Transperitoneal)
Difficult fistulas or those requiring supravesical urinary diversion require an abdominal approach. The fistula is accessed through an intentional cystotomy. Similar to the transvaginal approach, the bladder and vaginal epithelia at the fistula site are undermined for approximately 1.5 cm in all directions. After adequate mobilisation, the fistula site is closed in layers.
This approach is used in situations in which:
Laparoscopic: Evidence-based support for laparoscopic genitourinary fistula repair has been limited to case reports and expert opinion and requires advanced laparoscopic surgical skills. As a result, success with this approach appears to be highly dependent on surgeon expertise and experience.
 
Preoperative
 
Patient Evaluation
Prior to repair, a fistula should be well characterised. Complex fistulas with multiple tracts or a ureterovaginal fistula should be identified. For this, proper evaluation should include intravenous pyelography (IVP) and cystoscopy. Ureterovaginal fistulas are usually associated with upper tract abnormalities, such as hydroureter and hydro-nephrosis. Therefore, normal IVP findings should reassure the surgeon that ureteral involvement is absent. Additionally, this testing enables the surgeon to identify the proximity of ureters relative to a fistula for surgical planning. In general, routine posthysterectomy VVF develop at the vaginal apex. This is well away from the ureters, which enter the bladder at the level of the midvagina.
Whether or not surgery can be performed vaginally depends on the ability to obtain adequate exposure of a fistula. Therefore, during physical examination, the surgeon must assess if a fistula can be brought down into the surgical field and if a patient's pelvis affords adequate space for vaginal surgery. Some degree of prolapse of the vaginal apex is helpful for a vaginal approach to fistula repair.
Additionally, tissue infection or inflammation should be excluded. If these are identified, fistula repair should be delayed until resolution.
If a fistula is recognised within a few days following hysterectomy, it may be repaired immediately, prior to a brisk inflammatory response. However, if surgical repair is not undertaken within a few days following the initial surgery, then a delay of 4–6 weeks is recommended to decrease tissue inflammation.72
 
Consent
There is a significant recurrence rate with fistula repair and patients should be aware that initial surgery may not be curative. With the Latzko procedure, the vagina is moderately shortened in most cases. Therefore, the risk of postoperative dyspareunia should be included in the consent.
Bowel preparation is administered the evening prior to surgery. This decompresses the rectosigmoid and minimises faecal contamination of the surgical field. Immediately prior to surgery, intravenous antibiotic prophylaxis is commonly administered to decrease postoperative wound infection risks.
 
Intraoperative
 
Anaesthesia and Patient Positioning
In most cases, repair is performed under general or regional anaesthesia, and the need for postoperative hospitalisation is individualised.
Most prefer lithotomy position for a typical fistula at the vaginal cuff. However, others feel that adequate visualisation, especially of the proximal urethra and bladder neck, can best be achieved by the knee-chest or Lawson position. Dropping the head of the table and elevating the buttocks may further facilitate exposure.
Technical difficulties encountered at surgery are likely to be avoided by optimal exposure and accessibility of the fistula rather than a change in specific instrumentation. Because the vaginal walls normally are very pliable, retraction usually is sufficient for adequate exposure of the fistula. However, a constricted vaginal introitus, scarring of the vagina, a narrow subpubic arch, or a deep and fixed vaginal vault may limit exposure. An episiotomy or a Schuchardt's incision may allow improved access to the cuff in these situations. In current practice, many surgeons hesitate to use these incisions because of the increased morbidity. However, such incisions are invaluable and should be made without hesitation if exposure and accessibility are improved. In addition, the surgery may be facilitated by the placement of stay or traction sutures at the margins of the fistula or gentle traction on a Foley or Fogarty catheter placed through the fistula. These techniques help to identify the fistula's edges and may bring the tract closer to the surgeon. The Young prostatic retractor may be used in a similar fashion. Infiltration of the vaginal epithelium with saline or a dilution solution of epinephrine (1:200,000) may aid dissection and decrease oozing. This latter technique is not our current practice for repair of fistulae.
The vagina is surgically prepared. If ureters lie close to a fistula, ureteral stents should be placed. Cystoscopy is required during the procedure to document ureteral patency and assess bladder integrity.
 
Delineating a Fistulous Tract
The course of a fistulous tract must be identified. If the tract is large enough to accept a paediatric Foley catheter, the tube is threaded through the fistulous opening, and the balloon is inflated within the bladder. If a tract cannot be delineated this manner, then lacrimal duct probes or other suitable narrow dilators should be used to trace the tract course and direction. Subsequently, attempts should be made to dilate the tract and place a paediatric catheter.
 
Exposure
The fistula must be brought into the operative field. If catheterisation of a fistulous tract is possible, tension on the catheter will allow this. 73Alternatively, four sutures can be placed in the vaginal wall surrounding a fistula and used to pull the fistula into the operative field. Some advocate performing a mediolateral episiotomy to gain exposure, although this is not our practice.
 
Vaginal Incision
A vaginal incision is made circumferentially approximately 1 cm around the fistuious tract. Vaginal mucosa surrounding the tract then is mobilised sharply and excised using Metzenbaum scissors.
 
Tract Excision
The fistula tract may or may not be excised. If the tract is excised, surgeons should be aware that a larger defect for repair will result. However, in situations in which a tract is indurated, excision is warranted.
 
Fistula Closure
If the tract is excised, the bladder mucosa is re-approximated with 3-0 delayed-absorbable sutures. Subsequently, anterior and posterior edges of the vaginal fibro-muscular layers are approximated over this repair with interrupted stitches of 3-0 delayed-absorbable sutures. After the first suture line is placed through the fibromuscular layer, a second and possibly a third line are created on top of the first. Following this closure, the bladder should be filled with 100 mL of fluid to document a watertight repair. If it is not watertight, additional reinforcing sutures can be placed.
After fibromuscular layers of the vaginal wall are closed, the epithelium is closed in a continuous running fashion using 3-0 delayed-absorbable suture.
 
Saucerisation
The original Marion Sims' technique may be used for a very small fistula, particularly for residual fistula after previous surgery. A bevelled cut through the vagina to the small visceral aperture should clear scar tissue to allow healthy tissues for apposition. It is as well to remember that with a small residual fistula there may be more than one track.
The Marion Sim's technique is demonstrated in the case that follows