Vesicovaginal fistula

Authors


Miss Smith Department of Urology, Wexham Park Hospital, Slough SL2 4HL, UK.

Introduction

The development of a vesicovaginal fistula (VVF) is a devastating condition with profound effects on both the physical and psychological health of the patient. In developing countries, such patients also have major social problems. Although VVFs have been recognized since ancient times, the first successful repairs were not documented until 1852, when James Marion Sims described his transvaginal technique using silver wire sutures [ 1]. The modern era of fistula repair began in the mid-20th century with major improvements in transabdominal [ 2] and then transvaginal approaches [ 3]. Despite these advances, VVF repair remains technically challenging.

Epidemiology and aetiology

In the developed world, VVF is uncommon; in modern urological practice, ≈90% of cases are caused by inadvertent injury to the bladder during surgery [ 4]. Gynaecological procedures are the most common culprit, with hysterectomy (abdominal or vaginal) accounting for 75% of fistulae [ 4[5]–6]. Urological or gastrointestinal pelvic surgery may also be responsible; the reported incidence of iatrogenic VVF after pelvic surgery is 0.5–2% [ 7]. Previous uterine surgery, pelvic irradiation or endometriosis may increase the risk [ 8]. In addition, anatomical distortion by fibroids or an ovarian mass may increase the risk, which is also greater in those with compromised healing, e.g. patients who are anaemic, malnourished or using steroids.

Other less common causes of VVF include pelvic malignancy, pelvic irradiation, obstetric trauma and infection, including tuberculosis [ 9]. VVFs caused by erosion of a foreign body such as a pessary [ 10] or vigorous intercourse [ 11] have also been reported. This usually occurs in those who have married at a very young age or those who have been raped.

In developing countries, prolonged obstructed labour is responsible for the overwhelming majority of VVFs. It has been estimated that a VVF occurs in 1–3 per 1000 deliveries in West Africa [ 12]. The high incidence of VVF reflects the lack of modern obstetric care in these nations. The prevalence is particularly high in areas where early marriage is practised. Mothers may experience labour before reaching full physical maturity. As a result cephalopelvic disproportion is common [ 13]. Other obstetric causes include accidental injury at the time of Caesarean section, forceps delivery and ‘traditional surgical practices’.

During normal labour the bladder is displaced upwards and the anterior vaginal wall, bladder base and urethra are compressed between the fetal head and the posterior surface of the pubis. In prolonged obstructed labour, pressure necrosis of the anterior vaginal wall and the underlying bladder neck occurs, although sometimes the area of necrosis is more extensive and the urethra, trigone and anterior lip of the cervix are involved. If the mother survives, a macerated fetus is usually expelled 3–4 days later, and the slough from the devitalized bladder around 10 days later. It is then that the mother becomes incontinent. Half of these women will be subsequently divorced by their husband.

In some areas of the world where female genital mutilation (circumcision) is still common, the deliberately narrowed vaginal introitus results in obstructed labour. The traditional practice in other areas includes cutting of young women with a knife, a piece of glass or a razor blade anteriorly to enlarge the vagina. This invariably results in a urethrovaginal fistula and division of the bladder continence mechanism. Congenital VVF is very rare and may result from an abnormality of fusion of the lower end of the Müllerian duct with the urogenital sinus. The condition is usually associated with other urinary tract anomalies; isolated cases are extremely rare [ 14[15]–16].

Prevalence

In the developing world, many people with fistula remain unknown to the medical services. The Addis Ababa Fistula Hospital in Ethiopia, opened in 1975 as a charity hospital to specifically manage women with vesicovaginal and rectovaginal fistulae, treated 603 women in 1987 and over 1200 in 1997. It is estimated that there are some 500 000 untreated cases worldwide.

Pathogenesis

VVFs occurring after hysterectomy probably begin with an unrecognized injury to the bladder, which results in urinoma formation. Taking the path of least resistance, the urinoma drains through the suture line of the vaginal cuff. A mucosa-lined tract between the bladder and vagina then develops [ 17]. Alternatively, incorrect placement of sutures between the vaginal cuff and the posterior aspect of the bladder may lead to a VVF through tissue necrosis [ 18]. Complicating factors such as haematoma formation, infection or obstruction are often present.

Obstetric fistulae result from pressure of the part of the fetus that presents, imposed over a relatively wide anatomical area during prolonged obstructed labour. This often leads to large fistulae and may also cause scarring or reduced vascularity in tissues adjacent to the defect. The bladder neck and urethra are often involved and type III incontinence is therefore common even after successful closure of the fistula [ 13]. Poor vascularity is a feature of tissues adjacent to radiation-induced fistulae and influences the success of repair.

Clinical features

Most VVFs present with leakage of urine from the vagina. After pelvic surgery, leakage may become apparent in the immediate postoperative period but more commonly manifests after 5–10 days [ 19]. The possibility of urinary tract injury (and therefore impending fistula) should also be considered in patients with prolonged paralytic ileus, excessive pain or haematuria after pelvic surgery [ 17]. Women with fistulae as a result of prolonged obstructed labour usually present with total incontinence 10 days after delivery. Fistulae may occur at any interval after pelvic irradiation or in patients with a history of pelvic malignancy. VVFs have been reported up to 20 years after radiotherapy [ 20]. The differential diagnosis of VVF includes uterovaginal fistula, ureterovaginal fistula, drainage of peritoneal fluid or exudate, vaginal infection or a draining pelvic abscess.

Investigation

Characteristically, the woman presents with continuous incontinence both day and night. In women with a fistula after surgery, the diagnosis can be more difficult and a high index of clinical suspicion must be maintained. In doubtful cases measurement of the creatinine, potassium or urea levels in the fluid draining from the vagina may help to establish the presence of a connection between the vagina and the urinary tract.

Once a diagnosis of urinary tract fistula is suspected, its presence can often be confirmed by examination with a Sims speculum. This is better than the three-swab test, which can mask the presence of multiple fistulae. The site of the fistula is best identified by direct inspection with the patient in the lithotomy position, with head-down tilt. A urethral catheter is passed and the bladder filled with a solution of methylene blue; the bladder must be adequately distended. If leakage of clear urine continues after the bladder has been filled with blue dye, then a ureteric fistula is present. If blue dye is seen issuing from the cervical os, a uterovesical fistula is present.

IVU is not usually helpful in the diagnosis of a vesicovaginal fistula but 10–15% of patients with VVFs have coexistent ureteric injury [ 5]. IVU is therefore mandatory to identify ureterovaginal fistulae or ureteric obstruction before management is decided. Cystography is not particularly helpful and a dye test is more sensitive. If IVU has failed to detect the ureteric anatomy in sufficient detail or if ureteric injury is suspected, retrograde ureteropyelography should be undertaken at the time of cystoscopy and examination under anaesthesia. In patients with a history of pelvic malignancy, both the vaginal and vesical openings of the fistula should be biopsied, as the presence of malignancy will alter management significantly. At the time of examination under anaesthesia, the mobility of the tissues and the feasibility of a vaginal repair can be assessed, along with the condition of the tissues. This is particularly important in fistulae occurring after obstetric procedures or radiotherapy. It is also important to exclude evidence of schistosomiasis, tuberculosis and lymphogranuloma, as these conditions all require treatment prior to repair of the fistula.

Management

Conservative treatment

In most cases, definitive cure of a VVF requires surgery [ 6]; in particular, large VVFs never resolve with conservative management. In contrast, spontaneous closure of small VVFs after catheter drainage alone has been reported. Of 151 VVFs, three (2%) were successfully managed by catheterization in one series [ 4]. In another series, four patients who developed a fistula after abdominal and vaginal hysterectomy were treated with bladder drainage for periods of 19–54 days; all remained dry after removal of the catheter [ 21]. It has been suggested that if healing has not occurred within 4 weeks it is unlikely that the fistula will close spontaneously [ 22]. Urethral catheterization before surgical repair may reduce skin excoriation and discomfort. However, these benefits must be balanced against the risk that the catheter will promote infection and exacerbate intravesical inflammation.

Transvesical or transvaginal electrocautery has been advocated as a treatment for small fistulae. Stovsky et al. [ 23]successfully treated 11 of 17 women with VVFs of 1–3 mm in diameter using electrocoagulation of the fistula tract, followed by 2 weeks of urethral catheterization. The main risk with this approach is that the introduction of the electrode into the tract may increase the size of the fistula. The use of a paediatric Bugbee electrode and minimal coagulation current minimizes this risk. The technique can also be used in women with small residual fistulae after attempted surgical closure.

Two cases of successful closure of a VVF after injection with a fibrin mixture into the tract have been reported. However, success with this technique has not been reported in many patients and its application must therefore be regarded as experimental [ 24, 25].

Surgery

The principles of successful surgical repair are that it is tension-free, watertight and uninfected, using a well-vascularized interposition flap if required. Regardless of the approach used, it is important to recognize that the first attempt at surgical closure has the highest success rate [ 8, 12]. Subsequent attempts are much less likely to achieve definitive repair. Interposition flaps play an important role in the integrity of more complex fistula repairs and those involving the urethra and bladder neck mechanism.

Timing

Surgical repair of VVFs has traditionally been deferred for 3–6 months to allow inflammation and oedema to subside. This advice was based mainly on experience with obstetric fistulae, which tend to be larger and more complex than the iatrogenic fistula most commonly encountered in modern urological practice. Several surgeons have now reported excellent results with the early repair of VVFs, within the first 3 months after presentation [ 26[27]–28]. Early repair does not appear to affect closure rates adversely and avoids the discomfort and psychosocial consequences of prolonged urinary leakage [ 29].

However, early repair is not appropriate in all cases. In developing countries many women are anaemic and malnourished, and may have intestinal parasites which require treatment. They may also suffer from untreated tuberculosis or malaria. In addition to the fistula, many such women develop contractures of their hips, consequent to traditional ‘cures’ of tying the thighs together. Because they are neglected by their husband and families, they tend to adopt the fetal position and are too weak to move. Some 20% of women with vesicovaginal fistulae as a result of prolonged obstructed labour also have unilateral or bilateral foot-drop caused by traction ischaemia of the common peroneal nerve. Prolonged physiotherapy may be required to allow adequate access to the vagina to perform a repair. Deferred surgery allows time for tissue to recover and infection to be cleared. Consequently, early repair may be inappropriate in complex cases such as those associated with radiation, infection, extensive tissue loss or devascularization. Optimal timing of surgery therefore varies according to the individual characteristics of the patient and her fistula. Carr and Webster [ 30] suggested that patients are examined every 2 weeks after diagnosis of a VVF until vaginal tissues are judged to have regained pliability (usually 4–8 weeks after injury).

Preoperative management

Preoperatively, oestrogen replacement may improve the vascularity and general quality of the vaginal tissues [ 31]. Prophylactic broad-spectrum antibiotics are usually administered perioperatively, although a recent randomized controlled trial conducted in West Africa suggested that they did not improve the outcome for obstetric fistulae repaired in the developing world [ 32].

Surgical technique

VVFs can be repaired via abdominal, vaginal or combined abdominal/vaginal approaches.

Transvaginal

Most VVFs are amenable to transvaginal repair. Advantages of this approach include a low complication rate, minimal blood loss, rapid postoperative recovery and shorter hospital stay [ 3, 27, 33]. If the VVF is a result of pelvic surgery, the vaginal approach also avoids re-exploration of the previous operative field. If access is poor and the fistula cannot be brought down, the abdominal approach should be used.

The patient is positioned in either the exaggerated lithotomy position with severe head-down tilt, or placed prone in the reverse lithotomy position with head-up tilt. The fistula tract is catheterized from the vaginal side using a small Foley catheter. The tissues are then infiltrated with a 1:200 000 solution of adrenaline, to prevent oozing and to separate the tissue planes.

A U-shaped incision is made with the fistula at the base of the ‘U’. For the common post-hysterectomy fistula, which opens into the vaginal cuff, the flap of the U is sited anteriorly, but posterior-based flaps may be used when appropriate. The vaginal wall is mobilized and the fistula circumscribed. Some authors advocate excision of the fistula at this point [ 19], while others advocate circumscription but not excision on the grounds that this will increase the size of the fistula and may decrease the strength of the closure [ 8, 33]. The ureteric orifices should be identified and if they are likely to encroach on the fistula repair, should be catheterized, the catheters being brought out through the urethra. The vaginal wall is mobilized widely from the fistula and the vaginal wall beyond the fistula excised to allow the vaginal flap to be advanced and closed a short distance beyond the fistula repair site. The fistula is closed transversely with interrupted absorbable sutures. The repair should be started at either end, working towards the midline. The sutures should be placed so that they do not penetrate the mucosa of the bladder, which should be inverted. The second layer strengthens the repair by suturing the bladder wall. At this stage the repair should be tested by filling the bladder with a methylene blue solution. A third layer of interrupted mattress sutures is used to evert and close the vaginal wall. These sutures should pick up the posterior bladder wall to close the dead space.

Transabdominal

A transabdominal technique is preferable when the fistula site cannot be adequately visualized and exposed vaginally, either because of vaginal stenosis or because musculoskeletal conditions preclude optimal positioning. One of the main advantages of the abdominal approach is that the omentum can be readily mobilized as an interposition flap. It is therefore the approach of choice when associated pelvic pathology is present and when the fistula is complex or associated with previous radiotherapy. The abdominal approach also facilitates simultaneous ureteric reimplantation and bladder augmentation when required. A synchronous abdominoperineal approach allows full mobilization of the omentum while the fistula is exposed from below. This approach affords great flexibility when dealing with VVFs complicating pelvic malignancy or radiotherapy [ 34].

Ideally, the patient is positioned in the low lithotomy position, as this allows bimanual examination and facilitates a combined abdominal/vaginal approach when necessary [ 30]. A lower midline incision or a suprapubic V incision [ 35] provides good access. Access via a Pfannenstiel incision is more restricted but may be adequate in less complicated cases.

Abdominal approaches may be either extra- or intraperitoneal. In extraperitoneal repairs, the fistula is approached through an anterior cystotomy. This route affords limited exposure and precludes use of the omentum as an interposition flap. Most surgeons therefore prefer an intraperitoneal technique [ 30], which involves bisection of the bladder from the dome down to the fistula posteriorly. Ureteric catheters may be placed to protect the ureters during the procedure. The bladder is widely mobilized from the vagina and the fistula completely excised. The vagina and bladder are then closed separately with absorbable sutures. A suprapubic catheter is inserted before closing the bladder. When bladder augmentation is required, the bowel segments to be used is anastomosed to the bivalved bladder, including the site of repair.

The use of a free bladder mucosal graft to close VVFs via an extraperitoneal approach has been described for simple VVFs as an alternative to traditional transabdominal techniques [ 36]. A disk of mucosa is harvested from an unaffected segment of the bladder and sutured over the vesical opening of the fistula. This technique is relatively simple and involves minimal dissection. The peritoneum is not opened and interposition flaps are not required. The graft dimensions can be tailored to the size of the fistula, making this technique suitable for a wide range of VVFs. The laparoscopic repair of a VVF has been reported [ 37] but is not in widespread use.

Interposition flaps

Regardless of the approach selected, vascularized interposition flaps may be required to reinforce the repair. Their value in uncomplicated fistulae is unclear. Some surgeons recommend the use of flaps in repairing all but the smallest fistulae [ 13]. However, similar closure rates are reported from centres where flaps are not routinely used for uncomplicated fistulae [ 38]. In contrast, when the viability of tissues used in the repair is doubtful or in women who have had radiotherapy, the importance of bringing well vascularized tissue into the repair site is undisputed. Interposition flaps are critical for successful repair of such complex fistulae.

The Martius labial fat pad is the most convenient source of an interposition flap in transvaginal VVF repair [ 18, 29]. This flap is obtained by making a vertical incision over one of the labia majora to expose the deep labial fat pad. The fat pad is then mobilized starting anteriorly and preserving the pudendal vascular supply, which enters posteriorly. A tunnel is created medial to the labium towards the vagina through which the fat pad is passed on its posterior vascular pedicle. The flap is then sutured over the first two layers of the fistula repair using absorbable sutures. The vaginal flap is then closed over the Martius flap. The labial incision is closed in two layers over a drain. The use of a Martius flap is essential in patients with a urethrovaginal fistula, a fistula involving the bladder neck and in large obstetric fistulae.

If the fistula is very proximal or large, a gracilis flap may be considered [ 8]. The muscle is separated from its attachment to the medial femoral condyle and mobilized. The blood supply, which is derived from the profunda femoris artery and enters the muscle in its proximal third is preserved. A tunnel is created from the medial thigh to the vagina and the muscle is passed through this and sutured over the repair.

The omentum is the preferred interposition flap in transabdominal VVF repair. In a third of patients, the omentum reaches the pelvis with no additional mobilization. In other cases, it can be mobilized on the right gastroepiploic artery from the transverse colon, to achieve sufficient length to place the omentum over the repair [ 30]. Alternatives include a flap of lateral pelvic peritoneum [ 39], appendices epiploicae of the sigmoid colon or a bladder flap. Gil-Vernet et al. [ 40]reported successful closure of 42 complex fistulae using an advancement flap derived from the posterosuperior wall of the bladder.

Post-operative care

Continuous bladder drainage via a urethral Foley catheter is essential. In patients with a fistula involving the bladder neck the balloon should not be inflated, but the catheter sutured in place. The postoperative management is of vital importance. A high fluid input and output should be maintained until the urine is clear of blood; continuous bladder drainage is essential. If the catheter becomes blocked, this is the most likely cause of failure of the repair and nurses should be instructed to ensure hourly that the catheter is freely draining, both day and night. Some authors use both a suprapubic catheter and a urethral catheter, so that if one becomes blocked then free drainage is maintained. The bladder should remain catheterized for 2–3 weeks after repair. Cystography is undertaken before catheter removal if there is any doubt about the integrity of the repair. Anticholinergic drugs should be administered if bladder spasms occur. As well as causing discomfort to the patient, it has been suggested that these contractions may compromise healing of the repair [ 30].

Complications

About 85% of VVFs can now be repaired successfully at the first attempt [ 2, 3, 5, 26, 29]. Closure rates are similar for transvaginal and transabdominal techniques. The main complications of VVF surgery are recurrent fistula formation, ureteric injury or obstruction and vaginal stenosis. Recurrent fistulae are initially managed conservatively with bladder catheterization and observation. A further repair may be undertaken after resolution of the inflammatory response to the initial procedure; a vaginal approach is successful in most repeat procedures [ 8]. Vaginal stenosis is rarely severe except in large obstetric fistulae. Occasionally, vaginal-relaxing incisions or split-thickness skin grafting may be required to restore vaginal capacity [ 8]. Short-term complications include irritative lower urinary tract symptoms and reduced bladder capacity if the bladder has been empty for a prolonged period. In general, VVF repairs are well-tolerated by patients [ 22].

Conclusion

Successful closure of a VVF requires accurate diagnostic evaluation, timely repair using techniques that exploit basic surgical principles and the judicious application of interposition flaps. Management must be tailored to the individual case. With this approach, most patients can now be cured of this distressing condition.

Appendix

MCQs

1 Iatrogenic vesicovaginal fistulae (VVFs):

(a) are more common in patients who have previously received pelvic radiotherapy

(b) usually present in the immediate postoperative period

(c) commonly involve large defects

(d) usually present with haematuria

2 VVFs occur after:

(a) 0.1% of pelvic surgical procedures

(b) 0.5–2% of pelvic surgical procedures

(c) 1% of pelvic surgical procedures

(d) 2–5% of pelvic surgical procedures

3 Obstetric fistulae are:

(a) less likely to involve the bladder neck and urethra than iatrogenic fistulae

(b) less likely to lead to type III urinary incontinence after closure than iatrogenic fistulae

(c) usually small

(d) most likely to present approximately 10 days after delivery

4 Which of the following investigations is mandatory in patients with a suspected VVF?

(a) cystography

(b) intravenous urography

(c) retrograde ureteropyelography

(d) pelvic CT

5 Which of the following is true?

(a) post-hysterectomy VVFs probably result from an unrecognized injury to the bladder during the operation

(b) 10–15% of VVFs are associated with a rectovaginal fistula

(c) congenital vesicovaginal fistulae are usually isolated anomalies

(d) hysterectomy is responsible for 75% of VVFs in the developing world

6 VVFs:

(a) usually close spontaneously

(b) should be repaired within 2 weeks of diagnosis

(c) should be treated by electrocautery in the first instance

(d) may benefit from preoperative topical oestrogen therapy

7 For VVF repair

(a) the majority of VVFs can be repaired via a transvaginal approach

(b) the transabdominal approach should be reserved for recurrent fistulae

(c) non-absorbable sutures should be used for the closure

(d) the bladder should be drained by a catheter for 2–3 months after the procedure

8 VVFs are associated with ureteric injury in:

(a) 1-5% of cases

(b) 5-10% of cases

(c) 10-15% of cases

(d) 15-20% of cases

9 In transabdominal VVF repair:

(a) a Pfannenstiel incision gives the best exposure

(b) an extraperitoneal approach is usually preferred

(c) the omentum can be readily mobilised as an interposition flap if an extraperitoneal approach is used

(d) a free bladder mucosal graft may be used to close the fistula

10 The following may be used as interposition flaps in transvaginal VVF repair:

(a) omentum

(b) gracilis

(c) lateral pelvic peritoneum

(d) appendices epiploicae of sigmoid colon

Ancillary