Bladder stones
Definition
A primary
bladder stone is one that develops in sterile urine; it often originates in
a kidney and passes down the ureter to the bladder, where it enlarges.
A
secondary bladder stone occurs in the presence of infection,
bladder outflow obstruction, impaired bladder emptying or a foreign body such
as nonabsorbable sutures, metal staples or catheter fragments.
Incidence
Until the twentieth century, bladder stone was
one of the most prevalent disorders among the poor, and the incidence was
especially high in childhood and adolescence. Owing to improved diet, especially
an increased protein—carbohydrate ratio, primary vesical calculus is rare in
Western society —particularly among children.
Composition and
cystoscopic appearance
Most vesical calculi are mixed but have one
component in excess, and assume the appearance of that variety.
Oxalate calculus is a primary calculus that grows slowly. Usually, it is of moderate size
and is solitary. Its surface is
Uric acid and urate calculi are round or oval, fairly smooth, and vary in colour
from pale yellow to light brown:
Cystine calculus occurs only in the presence of cystinuria and is radio-opaque owing to
its high sulphur content.
Triple phosphate calculus is composed of ammonium, magnesium and calcium
phosphates, and occurs in urine infected with urea-splitting organisms. It tends
to grow rapidly. In some instances, it occurs on a nucleus of one of the
foregoing types of calculus; much more rarely on a foreign body (Figs 65.27
and 65.28). In others, the nucleus is composed of desquamated epithelium
and bacteria. It is dirty white in colour and of chalky consistency.
A
bladder stone is usually free to move in the bladder. It gravitates to the
lowest part of the bladder which is the outflow when the patient is erect or
sitting. In the recumbent position (and at cystoscopy) the stone occupies a
position behind the interureteric ridge. Less commonly, the stone is wholly or
partially in a diverticulum where it may be hidden from view.
Clinical
features
Males are eight times more often affected than females. It may be
asymptomatic and found incidentally during cystoscopy before a prostatectomy
is carried out.
Symptoms
Frequency is the earliest symptom, although it is often more common during the daytime. There may be a sensation of incomplete bladder emptying.
Pain (Strangury) is most often found in patients with a spiculated oxalate calculus. It
usually occurs at the end of micturition and is referred to the tip of the penis
or to the labia majora, more rarely to the perineum or suprapubic region. The
pain is worsened by movement. In young boys, screaming and pulling at the penis
with the hand at the end of micturition are indicative of bladder stone.
Haematuria is characterised by the passage of a few drops of bright red blood at
the end of micturition, and is due to the stone abrading the vascular trigone
— a fact that also accounts for the pain.
Interruption of the urinary stream is due to the stone blocking the internal
meatus and may develop into acute
retention of urine which occurs infrequently in adults.
Symptoms of urinary infection. Urinary infection is a common presenting symptom.
Examination
Rectal or
vaginal examination is usually normal, occasionally a large calculus is palpable in the
female.
Examination of the urine usually reveals microscopic haematuria, pus or
crystals typical of the calculus, for example envelope like in the case of an
oxalate stone, or hexagonal plates with cystine calculi.
Radiography — in most patients, the stone is visible on a plain X-ray (Fig. 65.29).
If the stone is radiolucent, a filling defect may be visualised on IVU.
Radiographs of the whole of the urinary tract should be taken to exclude upper
tract stone.
Cystoscopy is essential and most stones nowadays can be dealt with endoscopically.
Frequently, on introducing the sheath of the cystoscope, a significant
‘click’ will be felt when a free lying stone comes in contact
with the instrument.
The
whole of the bladder should be inspected: basal or generalised inflammation may
be seen. In men with bladder outflow obstruction endoscopic resection of the
prostate should be performed at the same time as the stone is dealt with.
Treatment
In most patients, the cause of the underlying
stone should be sought and treated. This may include bladder outflow obstruction
plus infection and incomplete bladder emptying in patients with neurogenic
bladder dysfunction. In most patients, treatment can be delivered endoscopically.
Litholapaxy
Historically, the blind lithotrite (Fig. 65.30)
was an early type of minimally invasive technique. Other methods include the
optical lithotrite and the electrohydraulic probe or ultrasound probe (Fig.
65.31). Nevertheless, the blind lithotrite is still a satisfactory instrument in
the right hands for the treatment of a large, hard stone. Other devices include
the stone punch which is useful to crush small fragments further so that they
can be evacuated with an Ellik evacuator.
Contraindications
to perurethral litholopaxy are given below.
Contraindications to perurethral litholopaxy
•
Urethral:
— A urethral stricture that
cannot be dilated sufficiently
— When the patient is below
10 years of age
•
Bladder:
— A contracted bladder
•
Stone characteristics:
— A very large stone
Technique. The patient should receive
appropriate antibiotics treatment before operation. The major advantage of the
blind lithotrite is that, because of its solidity and strength, harder stones
can be crushed than is the case with the optical instrument. A cystoscopic
lithotrite, stone punch or stone loop enables the stone or stone fragments to be
seized under vision. To carry out litholapaxy, the bladder is filled with about
200—300 ml of saline and the instrument is introduced with its obturator in
place so that its closed jaws point downwards. After irrigation of the bladder
and insertion of the telescope, the stone is seen. The distal blade is hooked
over the centre of the stone and grasped. After withdrawing the telescope
slightly to prevent damage to the optics, the screw is turned slowly, breaking
the stone. Large fragments are crushed into small ones by repeating the
manoeuvre. With the jaws closed the lithotrite is rotated so that the jaws point
upwards, and after removing the telescope and allowing the saline and stone
fragments to escape, the instrument is withdrawn. The use of an Ellik evacuator
is necessary to ensure complete removal of all stone fragments.
Mechanohydraulic lithotripsy
The lithoclast generates energy by purely
mechanical means using a steel ball which is fired in a closed chamber at the
proximal end of the endoscopic probe. Also, an energy source is generated
between paired or concentric electrodes. With repeated discharges, the stone is
broken into small pieces. The probes come in two or three sizes and it is
sensible to use the largest (9 F) for bladder calculi. The patient is
cystoscoped and the probe placed close to the stone, but away from the end of
the telescope, and fired. It is important not to damage the bladder wall by
discharging the electrode on the mucosa. A newly developed device
Evacuation
of the fragments. Fluid (200 ml) is introduced into the bladder. The evacuator,
filled with solution, is fitted on to the sheath. The bulb is compressed slowly
and then permitted to expand. The returning solution carries with it fragments
of stone which sink into the glass receptacle. Alternate compression of the bulb
and aspiration is continued until no further fragments -fall. The beak of the
cannula is turned to the left and to the right, and suction is applied in these
situations. After checking that no fragments are left in the bladder, a Foley
catheter is introduced and left in Situ for
24 hours.
Suprapubic
lithotomy
The alternative to litholapaxy is removal of
the stone through a
Percutaneous
suprapubic litholapaxy
It is possible to insert a needle into the
bladder and then pass a guide wire. As in percutaneous nephrolithotomy, Alken
metal dilators can be passed over the guidewire to dilate the track, an Amplatz
sheath is inserted and a large-bore nephroscope can be inserted. This is the
best method to use if it is not possible to carry Out litholapaxy per urethram because
of a narrow urethra.
Extracorporeal
shock wave lithotripsy (ESWL)
These devices can be used in the treatment of
bladder calculi, but if the stone is large endoscopic litholapaxy is preferable.
Removal of a
retained Foley catheter
This is not an uncommon problem and is usually
caused by the channel which connects the balloon to the side arm becoming
blocked, usually at the very distant end. The best way of dealing with this
problem is to further inflate the balloon with 20 ml of water and then burst the
balloon percutaneously using a spinal needle under ultrasound screening. The
instillation of fluid such as ether to dissolve the balloon is not recommended
because fragments of balloon may be left behind. However the balloon is burst,
it is important to subsequently cystoscope the patient to ensure that any
fragments are removed before they can form a foreign body calculus.