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
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.