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 uneven (mulberry type); sometimes it bristles with spines (Fig. 65.25). Although calcium oxalate is white, the stone is usually dark brown or black because of the incorporation of blood pigment on to it.

Uric acid and urate calculi are round or oval, fairly smooth, and vary in colour from pale yellow to light brown: they may be single or multiple (Fig. 65.26). They may occur in patients with gout, but are also found in patients with ileostomies or with bladder outflow obstruction.

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 suprapubic incision, after which the bladder is closed and drained by a urethral catheter.

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.