Internal
and external urinary diversion
This chapter closes with an account of the principles of this important
subject, and includes indications, the methods employed and their attendant
problems, and some operative details.
Indications
Diversion of the urine may be either a temporary expedient to relieve
distal obstruction, or a permanent procedure when:
(1) the bladder has been removed; (2) the sphincters of the bladder have
been damaged or have lost their normal neurological control; (3) there is an
incurable fistula; (4) there is an irremovable obstruction; and (5) in
late cases of ectopia vesicae.
Methods
of urinary diversion
The urinary tract may be diverted at most sites extending from the
kidney, the ureter, the bladder and the urethra or it may involve the creation
of new structures such as an ileal or colonic conduit, continent diversions or
bladder substitutions (Fig. 65.55). The diversion may be achieved by any
of the following methods, but the choice in each case will be decided largely
by the primary disease, patient comorbidity and motivation:
• pyelostomy on nephrostomy (now
carried out percutaneously by means of interventional percutaneous nephrostomy
—Chapter 62) on catheter drainage (or urethrostomy);
• cutaneous uneterostomy or the use of indwelling ‘double J’
pigtail ureteric stents;
• suprapubic cystostomy (with
indwelling catheter);
• cutaneous vesicostomy (cystostomy);
• ureterosigmoidostomy: (1) in
continuity; (2) making a rectal bladder and colostomy; or (3) creating a
rectal reservoir;
• external diversion of urine by a number of surgical techniques. The
following problems may occur: (1) collection of the urine; (2) stricture
formation at any anastomosis; and (3) reflux and reabsorption of urinary
solutes. The problems of infection are intimately related to all three;
• internal urinary diversion by means of bladder replacement.
Collection
of urine
Catheters
In the past, indwelling catheters have been used for permanent
diversion. They invariably result in bacteriuria and carry a risk of infection,
and they often become blocked by phosphate encrustation. Temporary nephrostomy
drainage is very useful in the management of patients with acute upper tract
obstruction. For temporary cutaneous ureterostomy drainage, the tubes should
be of soft silicone.
Bladder
drainage. In elderly patients unfit for prostatectomy and in some terminal
cases of carcinoma of the prostate, an indwelling silicone urethral Foley
catheter changed every 3 months is a satisfactory method of drainage. Other
methods include the use of prostatic urethral stents passed under ultrasound or
direct vision to hold open the prostatic urethra and bladder neck.
Cutaneous
stomas
Suprapubic vesicostomy or urethrostomy. Collection from a formal
suprapubic vesicostomy (cystostomy) is unsatisfactory because the local
incisions result in skin creases which make it difficult to apply a water-tight
collecting appliance.
Cutaneous
ureterostomies. These are very liable to stricture formation. In addition, two
openings (Fig. 65.55d) and appliances add to the patient’s burden.
Mobilisation of the ureters and the making of a central abdominal stoma may be
useful in children with grossly dilated ureters as a temporary measure (Fig.
65.55e).
Ileal
or colonic conduit. At present, the most generally useful form of external
diversion is to implant each ureter with as little mobilisation as possible into
an isolated segment of gut (ileum on colon), which conducts the urine onwards to
a cutaneous stoma (Fig. 65.55a). Urine is then collected in an ileostomy
bag. This form of diversion limits infection and avoids the problems of
reabsorption of urine as contact time with the mucosa is minimal. In some cases
in which the pelvic area has been subjected to radiation, the lower ureters may
be unhealthy. A high division with insertion of the ureters into an ileal loop
above the root of the mesentery may be wiser (Fig.
65.56).
Siting
of stoma. The site for the stoma must be chosen before operation in consultation
with a stoma care therapist. The site of the future stoma is marked indelibly on
the skin.
Colon
and rectum
The advantage of diverting urine into the colon is that no collecting
apparatus is necessary (Fig. 65.55b and f). Clearly, however, the anal
sphincter must be competent. Before ureterosigmoidostomy is undertaken, the
patient must prove that he or she can control at least 200 ml of fluid in the
rectum. The disadvantage of the operation is that the renal tract is exposed
continuously to infection from the faeces. This can be minimised by performing
some type of antireflux procedure or by establishing a terminal left iliac
colostomy, and closing the upper rectum to make a rectal bladder (Fig. 65.55c).
This prevents the urine refluxing retrogradely round the colon to the caecum.
diminishes reabsorption (see below) and protects renal function. Cancer can
develop at longstanding ureterocolic junctions (Fig. 65.57).
More
recent developments include the formation of a detubularised sigmoid segment
that provides a low-pressure reservoir in continuity.
Stricture
formation
Ureterosigmoidostomy was first used by Chaput (1894). Subsequent
modifications included those made by Coffey and Grey Turner. In these methods,
the ureters were cut obliquely and pulled into the
Reflux of urine and
reabsorption of urinary solutes
Re flux of urine
High-pressure activity
within a segment of gut can cause reflux of infected urine at high pressure to
the kidneys. In the long term this can cause renal impairment.
Reabsorption
of urinary solutes
The
biochemical changes associated with
urinary diversion are due to a combination of reabsorption of chloride and urea,
and progressively diminishing tubular function as a result of chronically
impaired tubular function due to pyelonephritis. Diarrhoea with loss of
potassium-containing mucus may exacerbate the loss of potassium. The typical
changes of a hypenchloraemic acidosis with potassium depletion occur
frequently in patients with uneterosigmoid diversion. When severe, the patient
develops loss of appetite, weakness, thirst and diarrhoea. Coma may ensue. Mild
acidosis, unrecognised oven a long period, produces osteomalacia. Bone pain
and even pathological fracture can occur. Renal impairment from pyelonephritis
and reabsorption from the mucosa are seen less frequently after ileal or colonic
conduit formation, continent urinary diversion or orthotopic bladder
substitution. In particular, they are seen very infrequently except in patients
with pre-existing renal impairment and unsatisfactory emptying of the urinary
reservoir.
Treatment
Prevention. Patients should be instructed to empty the rectum or
continent reservoir or neo-bladder 3-hourly by day. In cases of
ureterosigmoidostomy where acidosis is present a rectal tube should be inserted
at night to drain the urine continuously. The patient should take a mixture of
potassium citrate and sodium bicarbonate t.d.s. (2 g of each, either as crystals
or as tablets). Regular serum biochemical analyses, including calcium, are
required.
Established
hyperchloraemic acidosis is usually
associated with marked dehydration and the mainstay of treatment is intravenous
saline. The patient may be given small doses of sodium bicarbonate to
half-correct the pH deficit if it is severe and additional intravenous
potassium. This should be coupled with appropriate systemic antibiotic
treatment.
Operative
details
Bowel preparation is by means of 3 litres of balanced polyethylene
glycol solution (Golytely or Kleanprep). The abdomen is opened by a lower
midline incision. The patient is then placed in the Tnendelenberg position.
Ureterocolic
anastomosis
The right ureter is sought at the pelvic brim and dissected towards its
entry into the bladder. The ureter is divided and its distal stump ligated; the
proximal end is trimmed obliquely and split for 1 cm. An incision 3 cm long is
made in the anterior wall of the colon and the peritoneal and muscular coats are
divided, but not the mucous membrane. An incision is made into the extreme lower
end of the exposed mucous membrane and the full thickness of the ureteric wall
is joined by interrupted 4/0 chromic catgut sutures to the mucosal opening. The
incision in the outer coats of the bowel is
Uretero-ileostomy
(ileal loop conduit)
A coil of ileum, approximately 15—20 cm long and 30 cm from the
ileocaecal valve, with its blood supply intact, is isolated. The left ureter is
brought behind the mesorectum. The ureters may be joined to the ileum either
end-to-side or end-to-end after anastomosing of the distal spatulated ureters to
form a plate (Wallace). The ileal loop is tacked lightly to the peritoneum of
the posterior abdominal wall at the level of the pelvic brim. The distal end of
the coil is brought out through an incision at the site which had been
identified before operation; a disc of skin and far is removed, a cruciate
incision is made in the fascia and the muscle is split. The stoma is made about
2—3 cm long. It is evaginated initially by means of four sutures passing
through the skin, the ileal loop as it passes through the opening, and the cut
edge of the ileum (Fig. 65.57).
Bladder
replacement
Over the past decade, various techniques have become available to form a
near spherical urinary reservoir out of various lengths of bowel which are
detubularised. These may consist of ileum, ileum and caecum on sigmoid colon.
The ureters can then be reimplanted in these reservoirs in an antireflux manner
and the reservoir can then be anastomosed to the membranous urethra in the male
(Figs 65.20,65.21,65.22
and 65.23 and 65.53). These reservoirs usually need to be emptied by
means of CISC. The results are good in selected younger men after radical
cystectomy.
Continent
urinary diversion
A similar concept is used in the construction of continent diversions. A
urinary reservoir is made as described above and the ureters are attached to the
reservoir. A continence mechanism is then made to connect the reservoir to the
skin. This is the complication prone part of the operation. The continence
mechanism may be made of an invaginated loop of ileum supported by three rows of
staples (Kock pouch) or made from the appendix buried in an antireflux manner in
a submucosal tube (Mitrofanoff; Fig. 65.58) or a length of ileum can be made
into a tube (of similar size to the appendix) after excision of the
antimesenteric ileum and buried in a submucosal tunnel in an antireflux way.
Clearly, these operations are complex, with the potential for increased
postoperative complication.
Bladder
substitution and augmentation
In patients with contraction of the bladder due to tuberculosis or with
neuropathic dysfunction and a small bladder capacity, the bladder may need to be
augmented. Similar techniques to those used to perform a bladder replacement can
be utilised to make a near-spherical pouch from detubularised bowel which can
then be attached to the tnigone or bladder neck after a near-total cystectomy
(Figs 65.20,65.21,65.22
and 65.23). The ureters are then reimplanted. The facility to provide
a continence mechanism must be available if needed in the neuropathic patient.
This may comprise an artificial urinary sphincter on a colposuspension in the
female.