Urinary fistulae

A urinary fistula is an abnormal communication between any part of the urinary system and the skin or some internal hollow viscus. The persistence of a fistula on the skin implies the presence of distal obstruction or the presence of chronic infection, such as tuberculosis, or a foreign body, such as a stone or nonabsorbable ligature.

Congenital urinary fistula

  Ectopia vesicae;

  from a patent urachus — the presence of a urinary leak from the umbilicus present at birth or commencing soon after suggests this diagnosis. In adult life infection in a urachal cyst may produce a fistula and adenocarcinoma may occur (Figs 65.37 and 65.38). 

    Treatment is by means of excision of the urachal tract and closure of the bladder once distal obstruction has been excluded;

  in association with imperforate anus (see Chapter 61).

Traumatic urinary fistula

Perforating or penetrating wounds, damage not recognised during surgery, or poor healing and avascular necrosis fol­lowing a combination of radiotherapy and surgery may lead to fistula formation. Also, clot retention occurring after a transvesical prostatectomy or diverticulectomy may lead to dehiscence of the bladder wound and a temporary fistula, which will heal quickly, provided the bladder is kept empty with an indwelling catheter.

Vesicovaginal fistula

This is a common condition which rapidly leads to loss of morale and serious social disruption in countries where surgical treatment is not readily available.

A etiology

Obstetrics — the usual cause is protracted or neglected labour;

   Gynaecological — the operations chiefly causing this compli­cation are total hysterectomy and anterior colporrhaphy;

   Radiotherapy — the main cause is radiotherapy used in the treatment of carcinoma of the cervix; to a lesser extent external beam irradiation of the pelvic viscera for other reasons is responsible;

  Direct neoplastic infiltration — exceptionally, carcinoma of the cervix ulcerates through the anterior fornix to impli­cate the bladder.

When a wound of the bladder is recognised and repaired at once, leakage is uncommon, but escape of urine will quickly follow if such damage passes unnoticed. However, most vesicovaginal fistulas are the result of ischaemic necrosis of the bladder wall due to prolonged pressure of the foetal head in obstetric cases. In gynaecological cases, the ischaemia is brought about by grasping the bladder wall in a haemostat, including the bladder wall in a suture, or perhaps even by local oedema or haematoma. Leakage due to necrosis of tis­sue seldom manifests itself before 7 days after the operation.

An intractable fistula following radium treatment of carci­noma of the cervix uteri may arise from avascular necrosis years after the apparent cure of the original lesion.

Clinical features

There is leakage of urine from the vagina and as a consequence excoriation of the vulva occurs. Digital examination of the vagina may reveal a localised thickening on its anterior wall, or in the vault in the case of posthysterectomy fistula. On inserting a vaginal speculum, urine will be seen escaping from an opening in the anterior vaginal wall. It is usually possible to pass a bent probe from the vagina into the bladder. Cystoscopy may be difficult, owing to the contraction of the bladder from cystitis and the escape of urine from the fistula. However, usually the tip of the probe that has been passed can be seen emerging through an area of granulation tissue.

Differential diagnosis between a ureterovaginal and vesicovaginal fistula can be made if a swab is placed in the vagina and a solution of methylene blue is injected through the urethra; the vaginal swab becomes coloured blue if a vesico-vaginal fistula is present. With the advent of good, portable X-ray image intensifiers, a cystoscopy and bilateral retrograde ureterograms provide a more reliable demonstration of the anatomy. Ureterovaginal fistula is discussed in Chapter 62. An IVU should be performed to exclude a coincidental ureterovaginal fistula. Usually it demonstrates some upper tract dilatation owing to partial obstruction.

Treatment

Just occasionally, conservative management of a vesicovaginal fistula following hysterectomy by urethral bladder drainage is successful. Usually, operative treatment is required and the traditional teaching has been to delay surgery for some months. This has recently been questioned. The low fistula (subtrigonal) is best repaired per vaginam. The fistula is exposed with dissection of the edges which are freshened. The bladder is then closed using absorbable sutures and the vagina subsequently closed with a separate layer. A urethral catheter should be left in situ for at least 10 days. For the higher (supratrigonal) fistula, a transvaginal approach can be extremely difficult. These patients should always be cystoscoped prior to a repair procedure and bilateral ureterograms performed as occasionally one of the ureters is also involved. For the high fistula, a suprapubic approach is the best method in most hands. The Pfannenstiel incision should be re opened, the bladder should be dissected free from the peritoneum and bisected posteriorly in the midline down to the level of the fistula. The bladder is then separated from the vagina and, occasionally, careful dissection from the rectum is also required. The vagina is then closed with a heavy catgut suture and omentum brought down to lie between the closed vagina and the bladder anteriorly. This is lightly sutured in place and the bladder then closed. A urethral and suprapubic catheter should be left in situ for 10—14 days.

For the patient with a ureterovaginal fistula, an extraperitoneal approach to the ureter via the previous Pfannenstiel incision is made. Considerable adhesions will be encountered but the ureter can usually be found above the level of the injury and followed down. Fibrosed or strictured ureter should be discarded and then reimplantation into the bladder is required. Depending on the amount of ureter lost, it may be possible to achieve a simple reimplantation with a psoas hitch procedure. If the gap is too large to be bridged by this manoeuvre, a Boari flap of anterior bladder wall should be cut and brought over to meet the ureter and a reimplant performed. The most important principle of ureteric reimplantation is that there should be no tension on the anastomosis. Results from these repairs need to be good as a failure will cause despair and further enrage the already litigious patient.

Fistula from renal pelvis to skin or gut

Tuberculosis of a kidney may result in caseation and a chronic sinus leading to duodenum, colon or skin in the iliac fossa or lumbar triangle. Similarly, a pyonephrosis may spontaneously discharge into the gut or on to the skin. Cases of duodenal ulcer involving the pelvis of the right kidney and Crohn’s disease involving either renal pelvis or ureter, or cases of xanthogranulomatous pyelonephritis may cause fistulae.

Fistulae arising as a result of infection

The commonest cause is diverticulitis of the colon. They may also follow Crohn’s disease, appendix abscess or pelvis sepsis in association with acute salpingitis, or may be the result of surgery and radiotherapy within the pelvis.

The onset may not be dramatic and may well be treated as a simple urinary infection. The diagnosis can be difficult to make, but on cystoscopy a patch of oedema on the left side of the vault is suggestive and bubbles of gas may be seen (Fig. 65.39). A cystogram may reveal the fistula. However, as the track is not always patent the test may be negative. A contrast enema may be helpful not only to demonstrate the fistula, but also to define the cause. The passage of gas per urethram in a patient is most suggestive (provided that diabetes resulting in urinary infection with a gas-forming organism is excluded).

Treatment

In most patients, a single-stage operation is indicated provided that the surgeon is experienced in colonic surgery. In some cases, a defunctioning colostomy is made above the fistula as the first step and inflammation is allowed to subside over 2—3 months. At laparotomy, the communication is separated, the hole in the bladder being closed and patched with omentum, and the segment of diseased bowel resected; the main feature is to ensure that the left colon, and if necessary the splenic flexure, is fully mobilised to facilitate a tension free, well-vascularised anastomosis. The bladder is drained by a urethral catheter. The colostomy is closed several weeks later provided that a barium enema revels no leaks.

Cases due to carcinoma

By the time a fistula between the bowel and the bladder has developed the tumour is usually locally advanced, but may be operable.

Urethral fistulae

These occur as the result of infection above a stricture producing a para urethral abscess which ruptures into the urethra, allowing extravasation to occur suddenly into the scrotum and perineum. Urine and infection extend into the upper 2.5 cm of thigh and lower abdominal wall. Wide­spread cellulitis and tissue necrosis (which may lead to Fournier’s gangrene) may occur unless drainage of urine is achieved by suprapubic cystostomy, and the tissue planes are freely drained by inguinal and scrotal incisions.

Neoplastic fistulae

Primary bladder tumours very rarely fungate through the abdominal wall unless an open cystotomy has been performed without further treatment, such as low dose irradiation being performed to cut down the risk of wound implantation. Only palliative treatment is possible in most of such cases. Involve­ment of the bladder by tumours of cervix, uterus, colon and rectum can produce fistulae, as may lymphosarcoma of the small gut. Carcinoma of the prostate rarely produces a rectal fistula. Treatment in most such cases is difficult and prolonged, and in most only palliative relief can be given. It is rarely in the patient’s interest to carry out urinary diversion, although minimally invasive techniques such as placement of ureteric stents can be helpful in palliating symptoms.