Diverticula
of the bladder Definition
The normal intravesical pressure during voiding is about 35—50 cmH2O.
Pressures as great as 150 cmH2O may be reached by a hypertrophied
bladder endeavouring to force urine past an obstruction. This pressure causes
the mucous lining between the inner layer of hypertrophied muscle bundles to
protrude, so forming multiple saccules. If one or more, but usually one, saccule
is forced through the whole thickness of the bladder wall, it becomes a
diverticulum (Fig. 65.32). Congenital diverticula are due to
developmental defect.
Aetiology
of diverticulum
• Pulsion diverticulum — the usual causative obstructive lesion is bladder outflow obstruction
Pathology
Usually the mouth of the diverticulum is situated above and to the outer
side of one ureteric orifice. Exceptionally, it is near the midline behind the
interureteric ridge. The size varies from 2 to 5 cm, but may be larger.
It is lined by bladder mucosa and the wall is composed of fibrous tissue only
(compare traction diverticulum). A large diverticulum enlarges in a downward
direction and sometimes may obstruct a ureter
Complications
Most patients who develop a small bladder diverticulum secondary to
bladder outflow obstruction develop no symptoms after the prostate is resected.
The presence of a diverticulum per se is not an indication for open resection
and surgical treatment.
Recurrent
urinary infection
As the pouch cannot empty itself there remains a stagnant pool of urine
within it. Once infected, the infection persists. In long standing cases,
peridiverticulitis causes dense adhesions between the diverticulum and
surrounding structures. Squamous cell metaplasia and leucoplakia are infrequent
complications.
Bladder
stone
This develops as a result of stagnation and infection. The stone often
protrudes into the bladder.
Hydronephrosis
and hydroureter
This is extremely rare and is a consequence of peridiverticular
inflammation and fibrosis.
Neoplasm
Neoplasm arising in a diverticulum is an uncommon complication (< 5
per cent). The prognosis is dependent on the stage of the tumour (see a
later section).
Clinical
features
An uninfected diverticulum of the bladder usually causes no symptoms.
The patient is nearly always male (95 per cent) and over 50 years of age.
There
are no pathognomonic symptoms; they are those of lower urinary tract
obstruction, recurrent urinary infection and pyelonephritis. Haematuria (due to
infection, stone or tumour) is a symptom in about 30 per cent. In a few
patients, micturition occurs twice in rapid succession (the second act may
follow a change of posture).
Cystoscopy
This is the usual means of discovering the diverticulum. Most often its
orifice is seen as a clear-cut hole about 5 mm in diameter, the depths of
which are black and un-illuminated (Fig. 65.33).
With inadequate
distension of the bladder, the mouth of the diverticulum is closed with
epithelium thrown into radiating pleats (Fig. 65.34).
Full distension of
the bladder is needed if searching for a diverticulum.
Intravenous
urography
IVU may give information regarding the size of the diverticulum.
Retrograde
cystography
In practice, this is only used during a video urodynamic investigation
which may have been carried out in the investigation of voiding dysfunction.
This test will also give information about the emptying characteristics of the
bladder and diverticulum.
Ultrasonography
A diverticulum may be detected during an ultrasound scan carried out to
measure the residual urine after voiding (Fig. 65.35).
Indications
for operation
Operation is only necessary for the treatment of complications. Provided
the diverticulum is small and the associated outflow obstruction has been dealt
with, there is no reason to resect the diverticulum. Even a large diverticulum
may not require treatment in the absence of infection or other complications.
Preoperative
treatment
When the urine is infected, suitable preoperative antibiotic treatment
is given. In the presence of gross sepsis and retention of urine, it is
necessary to resort to an indwelling urethral catheter for a period.
Combined
intravesical and extravesical diverticulectomy
This is the standard operation. Cystoscopy is performed, a ureteric
stent is passed up the ureter on the affected side, as damage or devascularisation of the ureter is the most common serious
complication. The anterior bladder wall is exposed through a suprapubic
incision, the peritoneum is displaced upwards and the side of the bladder
bearing the diverticulum is cleared from surrounding structures until the pouch
is identified. The bladder is then incised in the mid-line and the diverticulum
is packed with a strip of gauze. Usually the neck of the diverticulum can be
separated from the ureter and when the pouch is free it is severed from its
attachment to the bladder with a diathermy knife. The resulting defect is closed
in two layers. A suprapubic catheter is left in place and an extravesical drain
is inserted.
An
alternative method, if the sac is densely adherent, is to carry the incision in
the bladder down to the rim of the diverticular orifice, then to detach the
diverticulum, together with its fibrous rim. The incision in the bladder is
closed and the diverticulum left in position with a corrugated drain into it for
2—3 days. The track fibroses rapidly after removal of the drain.
If
bladder outlet obstruction is part of the picture, prostatectomy should be
carried out at the same time as the diverticulectomy.
Traction
diverticulum (syn. hernia of the bladder)
A portion of the bladder protruding through the inguinal or femoral
hernial orifice occurs in 1.5 per cent of such herniae treated by operation