Urinary calculus disease is one of the oldest known to man. Egyptian mummies from 3500 bc have been discovered to have renal and bladder calculi. Practical and ingenious methods of stone management have evolved over the millennia. Anticipating modern lithotripsy, the Egyptians used gum to attach a diamond to the tip of a hollow reed, inserted it into the bladder per urethram, and the patient ambulated, allowing the diamond to fragment the more fragile bladder stone. In ancient Greece, the seriousness and ubiquity of stone disease stimulated the development of a specialty of practitioners, non-physicians, who treated the problem, leading Hippocrates to include in his oath the promise of physicians not to ‘cut for stone but to leave that to the practitioners of the art’. The Arab physicians, renowned pharmacologists during the European Dark Ages, were reported to have developed solvents to dissolve calculi; unfortunately, these formulae have been lost to history. During the Middle Ages, itinerant barber-surgeons, many of whom were clergymen, developed a technique for perineal bladder stone removal that relieved many sufferers and killed many others. The technique required the patient to be held by strong men in the exaggerated lithotomy position (Fig. 1) 1561. A perineal incision was made and in under 1 min, a long knife was used to incise the plane between the rectum and prostate, creating a perineal vesicostomy. Using abdominal pressure, the bladder stone was pushed towards the perineum and grasped by two fingers inserted in the perineum. The most famous of these stone surgeons was ‘Frère Jacques’ of nursery rhyme fame. Over the centuries, more sophisticated methods of stone crushing were developed. With the advent of anaesthesia in 1846, surgical removal of calculi evolved as the most common treatment for stones which could not be passed spontaneously. Surgical treatment of upper urinary calculi and stone crushing forceps placed in the bladder per urethra remained the technique of choice until the last decade when less invasive methods of stone management were developed.

Stone fragmentation by extracorporeal shock wave lithotripsy revolutionized stone management. Percutaneous nephrostolithotomy has now been substituted for surgery in the majority of patients who have a stone too large for fragmentation. For removal of ureteral calculi that will not pass, surgery has been almost completely replaced by endoscopic techniques, including ureteroscopy with basket extraction or in-situ fragmentation by electrohydraulic, ultrasonic, or laser techniques. In fully equipped major centres, surgery is now performed on less than 2 per cent of patients with calculi who require intervention. However, because of the expense of the technology, it is unlikely that these new techniques will be available for more than 30 per cent of the world population.

Urinary calculi develop as a result of hyperexcretion of calcium, uric acid, cystine, or oxalate. Hypercalciuria may be idiopathic or may be a consequence of increased intestinal absorption of calcium (hyperparathyroidism) or decreased renal calcium reabsorption (renal leak). Hyperoxaluria may occur as a result of increased intestinal absorption of oxalate after ileal resection or colon bypass surgery. Uric acid stones are associated with hyperuricosuria (>1000 mg/day) and may occur without associated hyperuricosaemia. Cystinuria may result from a heterozygous (>75 mg/day) or the more severe homozygous (>400 mg/day) disorder, and result in cystine stone formation.

Magnesium ammonium phosphate stones occur as a consequence of the combined presence of a foreign body or obstruction and infection by a urea-splitting organism, usually Proteus. Urinary calculi may also occur in patients with sarcoidosis, renal tubular acidosis, or excessive intake of calcium and alkali (antacids). Patients with prolonged recumbency (paraplegia) or chronic acidosis may have increased bone reabsorption, hypercalciuria, and stone formation.

Urinary calculi may be composed of calcium oxalate (80 per cent), magnesium ammonium phosphate and apatite (15 per cent), uric acid (5 per cent), calcium phosphate (3 per cent) and cystine (1 per cent) or any combinations of these elements. The likelihood of the occurrence of one type of stone or another depends on geographic location: uric acid stones occur with higher frequency in parts of Asia where genetic influences or nutritional deficiencies occur.

Calcium oxalate calculi (‘jackstones’) are the most radiodense. They are brown and black, and may have diagnostic spicules (Fig. 2) 1562. Magnesium ammonium phosphate stones are less dense and are composed of very fragile yellow and white chalky substances; they often fill the entire calices and are known as ‘staghorn’ calculi (Fig. 3) 1563. Cystine stones are less radiodense than calcium oxalate calculi. They have a yellow/tan appearance of maple sugar. Uric acid stones are radiolucent unless they fill the caliceal system, when their large mass will cause them to be minimally radiodense.

The highest incidence of calculi occurs between the ages of 30 and 50; the 3:1 male to female ratio is unexplained. Three per cent of the population of the United States form a stone some time during their lives. There is a recurrence rate of approximately 7 to 8 per cent a year; within 5 years, the first-time stone former has a 40 per cent chance of developing another calculus. Although the disease is more common in family members, with the exception of cystine stones (autosomal recessive), there is no genetic pattern of the usual forms of calculus disease.

The treatment of urinary stone disease includes open surgery, percutaneous techniques, and the use of extracorporeal or ureteroscopic technology to fragment calculi to spontaneously passable concretions.

The electrohydraulic lithotripter was conceived in the 1930s in St Petersburg. It depends on the creation of an electrical spark, lasting 2 to 5 &mgr;s, in a fluid medium. The spark vaporizes water, creating a tiny ‘cavitation bubble’; this expands and then implodes, creating a pressure wave by both expansion and contraction. The pressure wave overcomes the tensile strength of the calculus' crystal bonds and induces fragmentation. Its effectiveness depends on the relative fragility of the calculus; struvite, calcium oxalate dihydrate (yellow), and uric acid stones are the most fragile, while calcium oxalate monohydrate (black), cystine, and calcium phosphate stones are harder and more difficult to fragment.

The spark must be kept 2 mm from the urothelial wall to avoid mucosal injury or perforation. The electrohydraulic lithotripter must be used under direct vision; extreme care and an experienced operator are required to prevent tissue injury. It is used through the operating port of cystoscopes, ureteroscopes, and percutaneous equipment.

The ultrasonic lithotrode is a hollow tube placed under direct vision into the bladder by a cystoscope, into the ureter through a ureteroscope, and into the kidney by percutaneous access (Fig. 4(a-c)) 1564. The ultrasonic probe is hollow and vibrates in four directions, causing a jack-hammer effect on the stone. The stone is fragmented and the pieces are desiccated and removed by suction through the hollow centre of the lithotrode. The vibrations may cause tissue injury. The sonotrode is rigid and cannot be placed in the urinary tract via flexible instruments. It is an efficient form of lithotripsy and is especially effective for the larger, harder renal calculi which do not respond to less invasive techniques.

The pulsed dye laser operates at 504 nm wavelength for 1 ms through a 320 nm core diameter silica-coated quartz fibre. It delivers 140 mJ of energy with each pulse. The low energy per pulse, the selective absorption of this wavelength by the stone, and the minimal absorption of 504 nm light by tissue makes this a safe and effective method of stone fragmentation. The laser fibre is passed through the operating port of a ureteroscope. The small fibre size, accuracy, and safety allow successful ureteral stone fragmentation with minimal invasiveness.

Perhaps no treatment in urology has changed the basic approach to a condition as swiftly and as effectively as this technique. It was developed in Munich in the late 1970s and by 1990, where available, is the most widely accepted treatment for the majority of renal calculi.

The first generation lithotripter used a spark plug-like electrode placed underwater at the base of a semi-ellipsoid. This apparatus was submerged in the bottom of a tub of water. The spark created from the electrode vaporized water, creating shock waves which were reflected from the side walls of the semi-ellipsoid and focused at a point (F2) 13 to 15 cm from the origination (F1) (Figs 5, 6) 1565,1567. Biplanar fluoroscopy is used to site the patient's stone at the point F2. Using a power of 18 to 24 KV, shock waves are propagated and the stones are slowly and completely crumbled to spontaneously passable fragments. ( Fig. 7(a) 1566, (b)). Each shock is triggered so that it occurs during the refractory period of the QRS complex, preventing cardiac arrhythmias. Each treatment was limited to 2000 shocks to prevent renal injury.

Since introduction of the original unit, modifications and variations have been developed. The shock waves may now be created by electronically stimulating a ceramic dish (piezoelectric) or by electromagnetically stimulating a membrane. Newer models are portable and may be used without a water bath, using only a water-filled membrane to allow propagation of the shock wave. The force and configuration of the shock waves required the patient to be anaesthetized when using the early models; however, decreasing the size of the F2 focal point, decreasing the power at the focal point and enlarging the site of shock wave entry have all contributed to the use of extracorporeal shock wave lithotripsy without anaesthesia. The newer machines are less powerful, and are often less efficient; patients may require multiple treatments. The current debate is whether one treatment with anaesthesia is preferable to a course of treatments without anaesthesia. Second and third generation lithotripsy use lower pressures and therefore a higher number of shocks per treatment is allowed.

Extracorporeal shock wave lithotripsy is used to treat stones in the kidney and ureter and has been used to fragment bladder calculi. It is more efficient in the kidney and upper ureter than in the presacral and lower ureter. Its major complication is perinephric bleeding secondary to shock wave trauma; this is rarely severe enough to require intervention. Extracorporeal shock wave lithotripsy has been suggested, but not proved, to be a cause of hypertension.

The endoscopic approach to the ureter is a natural extension of cystoscopy. The ureteroscope may vary from 7 to 12 F in circumference. The smaller diameter ureteroscopes can be introduced into the ureter without the need for ureteral dilation. Ureteroscopes have a fibreoptic (rigid or flexible) light channel and a working port through which catheters, baskets, lasers, ultrasonic lithotrodes, or electrohydraulic probes may be inserted and through which irrigation fluid is infused. Ureteroscopy is usually performed under regional or general anaesthesia. The ureteroscope is inserted under direct vision and advanced to the level of the calculus (Fig. 8(a)) 1568. The calculus is then engaged in a basket and extracted, or fragmented by one of the above noted lithotripsy techniques ( Fig. 8(b) 1568, (c)). Early ureteroscopes were all rigid, encased in metal and had inflexible light bundles. The newest generation of ureteroscopes are flexible and, when necessary, may be advanced to the kidney for diagnosis or treatment.

The percutaneous method was the first non-surgical technique developed for the removal of renal calculi. A trocar needle is inserted into the kidney and a guidewire is passed through the trocar. After dilation over the guidewire, a 28 to 30 F sheath is placed through the parenchyma to the collecting system. Intrarenal calculi are then grasped and extracted or ultrasonically desiccated and aspirated, or fragmented and extracted. This technique is now used for calculi less than 2.5 cm diameter that do not respond to extracorporeal shock wave lithotripsy or those smaller than 2.5 cm diameter that appear non-fragile and would not be successfully fragmented by the extracorporeal procedure. Complications of percutaneous nephrolithotomy include parenchymal bleeding and incomplete stone removal.

The clinical presentation will be determined by the site of the calculus.

A calculus that obstructs the urethra is infrequent, since the calculi which spontaneously migrate down the ureter are usually small enough to be passed per urethra.

The symptoms of urethral obstruction secondary to a calculus are classic: the patient complains of the sudden onset of a midstream obstruction to the flow of urine. The outflow obstruction may be complete, or a decreased or split stream may be described.

Palpation of the penile, scrotal or perineal urethra will usually reveal the calculus. An abdominal radiograph that includes the genitalia will usually show the stone. Prior to endoscopic examination, the diagnosis may be confirmed by a retrograde urethrogram.

Urgent relief of obstruction may be attempted by passage of a urethral catheter. The urethra should be anaesthetized with 2 per cent lidocaine jelly and the well-lubricated catheter passed, attempting to relieve the obstruction and manipulate the calculus to the bladder, where it may be crushed at a later date. If the catheter fails to dislodge the calculus and the patient is unable to void, relief of obstruction must be obtained by means of suprapubic drainage. The patient's urethral stone may then be treated by endoscopic methods. A cystoscope with biopsy forceps or stone crushing forceps is placed in the urethra under regional or general anaesthesia. The stone can usually be dislodged to the bladder where it is grasped and extracted or crushed. A calculus that cannot be dislodged, manipulated, or crushed may require open surgical removal. This is accomplished by incising the urethra at the site of the palpable calculus. The urethra is closed with 4–0 absorbable sutures and a stenting catheter is left in place for 7 to 10 days and removed when a urethrogram shows no extravasation. Appropriate broad-spectrum antibiotic coverage is given.

The symptoms of bladder calculi may include haematuria, dysuria, and urinary frequency. Except in areas of the world where protein deficiency leads to endemic metabolic bladder stone disease, bladder calculi occur as a result of bladder outlet obstruction, chronic bladder infection, or the presence of a foreign body (urinary catheter). When obstruction is the cause, the calculi may be composed of uric acid, calcium oxalate, or struvite (magnesium ammonium phosphate).

The urinalysis will show red and white blood cells. Urine culture may be positive but is not diagnostic of a bladder calculus. The urine cytology report may show cells with inflammatory changes characterized as ‘atypical’. An abdominal radiograph will show bladder calculi only if they are radio-opaque. An ultrasound examination of the bladder will show the shadowing of a lucent calculus. An intravenous urogram may disclose the filling defect of a radiolucent calculus but this finding may be confused with the lucent defect of a blood clot or bladder tumour.

Bladder calculi are usually treated in conjunction with measures to relieve urinary outlet obstruction, the most common cause of which is benign prostatic hyperplasia. Calculi less than 2.5 cm in diameter can be fragmented during transurethral endoscopic procedures by using the electrohydraulic lithotriptor to fracture the calculus. Stone-crushing forceps can then be used to fragment the stone to pieces that may be irrigated from the bladder. Calculi larger than 3 cm are more difficult to fragment and extract transurethrally and may be best approached by suprapubic cystotomy. If the suprapubic route is used, outlet obstruction may be treated by simultaneous prostate removal; alternatively, a suprapubic tube may be left for 7 days and a transurethral resection of the prostate performed as a secondary procedure. Broad-spectrum antibiotics should be administered, regardless of the route of treatment.

Complications include perforation of the bladder from the use of the electrohydraulic lithotriptor, mucosal bleeding, and systemic infection.

Ureteral calculi account for two-thirds of all calculi brought to the attention of a physician. One-half of all ureteral calculi pass spontaneously; the other 50 per cent require intervention. Figure 9 1569 shows the likelihood of spontaneous stone passage over a period of time. Note that the width of the calculus, not its length, is the factor that correlates best with spontaneous passage. Calculi less than 8 mm in diameter may be allowed to pass spontaneously if they are not causing pain or obstruction or are associated with an infection. However, the patient must be monitored because calculi may cause silent obstruction. As shown in Fig. 9 1569, calculi over 5 mm in diameter may take many months to pass. Since irreversible renal injury begins after 1 month of marked obstruction, following a stone's progress with abdominal radiography is not sufficient and ultrasound must be used to rule out obstruction. As a rule of thumb, an asymptomatic, non-obstructing stone more than 5 mm wide, that stays in one position for more than 3 months, has a very small chance of spontaneous passage. Similarly, it must be appreciated that a calculus which becomes symptomatic while in the upper ureter has less likelihood of passing spontaneously than a similar sized calculus discovered in the distal ureter.

Perhaps no other medical condition has as characteristic a clinical presentation as that of the colic caused by the movement of a ureteral calculus. Typically, the patient presents with the sudden onset of excruciating flank or abdominal pain which may radiate to the scrotum or labia and/or into the ipsilateral costovertebral angle. Pain in the testes or scrotum may not be diagnostic of a lower stone and may indicate a stone as high as the ureteropelvic junction, since the T-12, L-1 ilio-inguinal nerves share a common root with the innervation of the upper ureter. Unlike the patient with a perforated viscus, who will be silent and ashen-faced, the patient passing a ureteral calculus will be writhing in agony, unable to lie quietly, and may alternatively lie, sit, or stand, and may be inconsolable. Physical examination will rarely elicit any signs of peritoneal irritation. However, calculi in the right lower ureter may be confused with inflammation of the appendix. If the ureter is partially or totally obstructed, tenderness may be present in the ipsilateral costovertebral angle. Although it is rare to have point tenderness over the course of the ureter, deep palpation may elicit pain over the area of the impacted stone.

Except in the rare situation of total urinary obstruction, the urinalysis will usually show red blood cells. White blood cells may not be seen unless there is an associated infection. An abdominal radiograph will show the presence of the stone along the course of the ureter in 60 to 70 per cent of patients. The absence of a calculus on the abdominal film does not exclude the diagnosis of a ureteral calculus: the calculus may be radiolucent or poorly radio-opaque, may be obscured by the bony pelvis, or be confused with pelvic phleboliths. The distinction between a phlebolith and a calculus is made on the basis that calculi are irregular and solid while phleboliths are round and have a lucent centre. An intravenous urogram is the non-invasive study that is most likely to confirm the diagnosis. There is often delayed function on the side of the calculus, 1 to 2 h or more being needed for the dye to concentrate on the affected side. Follow-up films should be taken hourly until the dye columnates to the site of the obstruction. Calculi over the lumbar transverse processes or the sacrum may be obscured until contrast media reaches that level. If contrast moves into the retrovesical ureter, the overlying contrast-filled bladder may obscure the distal ureter. The patient must be instructed to void and an oblique film of the pelvis obtained. If the stone can be identified on the initial abdominal film, it is less than 5 mm in diameter (high likelihood of passage), and if the patient's symptoms abate, the intravenous urogram may be postponed and obtained if symptoms recur or if spontaneous passage does not occur over an appropriate period of observation. If the patient has a high grade obstruction by a calculus that is unlikely to pass, remains symptomatic, or is infected, intervention is required.

The method of intervention for treatment of ureteral calculi depends on the equipment available, the experience of the operator and the position of the stone.

These are defined as calculi lodged between the ureteropelvic junction and the iliac bone. If extracorporeal shock wave lithotripsy is available, these calculi may be fragmented in situ (60 to 70 per cent success rate) or fragmented after first being dislodged or bypassed by the endoscopic placement of a ureteral stent (95 per cent success rate). Ureteroscopic management of upper ureteral calculi by electrohydraulic lithotripsy, ultrasonic lithotripsy, or laser may be undertaken by experienced endoscopists but usually results in a success rate of only 50 to 60 per cent. Either the stone cannot be reached or it becomes only partially fragmented and is dislodged and migrates to the kidney. If extracorporeal shock wave lithotripsy and an experienced endoscopist are not available, a ureterolithotomy through a subcostal approach is the most definitive and most successful treatment of an impacted upper ureteral stone.

A midureteral stone is defined as one that overlies the iliac bone or sacrum; it often cannot be visualized by non-contrast radiography. A calculus at this level may be treated by extracorporeal shock wave lithotripsy (prone position), endoscopic fragmentation, basket extraction, or surgery. The use of extracorporeal shock wave lithotripsy usually requires endoscopic placement of a stent for adequate visualization, and is successful in less than 80 per cent of patients. Many experienced endoscopists prefer the ureteroscopic approach with stone removal by basket extraction or fragmentation techniques. A ureterolithotomy by a subcostal or Gibson incision is required if extracorporeal shock wave lithotripsy and an experienced endoscopist are unavailable.

The lower ureteral stone is defined as occurring below the level of the sacrum to the ureteral vesical junction. Although extracorporeal shock wave lithotripsy may be used for treatment, the success rate is only 80 per cent. Experienced endoscopists are able to perform ureteroscopy with stone fragmentation or removal in 90 to 99 per cent of these patients. The high success rate and low cost have resulted in ureteroscopy being the most commonly used method of intervention for an impacted lower ureteral stone. Newer generations of extracorporeal shock wave lithotripters may shift the weight to non-invasive therapy for all but the large and most impacted calculi. If these techniques fail or are unavailable, surgical removal through a Gibson or transvesical incision is performed.

This is a new medical term and literally means ‘stone street’. It is a condition which follows the use of extracorporeal shock wave lithotripsy for renal or ureteral calculi. Small pieces of fragmented calculi collect and obstruct in the distal ureter, like sand occluding a straw (Fig. 10) 1570. The endoscopic approach to this condition is difficult: ureteroscopic resolution may take many hours and result in ureteral injury. The most prudent management of pain, sepsis, or obstruction caused by ‘steinstrasse’ is to place a percutaneous nephrostomy tube and allow the fragments to pass spontaneously. If the situation is not resolved in 4 to 6 weeks, endoscopic removal is performed.

The management of renal calculi depends on the patient's symptoms, the size and suspected composition of the calculus, and its position within the kidney.

The patient with a renal calculus may present with flank pain, fever, and/or gross or microscopic haematuria. If infection is present, pyuria will be seen. Although the patient may be in considerable pain, unless the stone is impacted below the ureteropelvic junction, the degree of colic does not approach that seen with a ureteral stone. Physical examination may reveal flank tenderness over the costovertebral angle or anteriorly over the lower pole of the kidney. A tense, swollen kidney is tender to deep palpation. Severe sepsis and shock may occur as a result of a stone obstructing the outflow of urine.

An ultrasound examination will almost always show the presence of a renal calculus and is useful to determine the degree of obstruction; however, stone size is difficult to ascertain by ultrasound, and an abdominal radiograph is required. An intravenous urogram is then performed to determine the position of the stone within the kidney and the presence of any associated anatomical abnormalities, such as ureteropelvic junction obstruction, ureteral obstruction, or stenotic infundibulum. Once the diagnosis of stone is made and the urinary collecting system is outlined, treatment may be instituted. The treatment of minimally symptomatic calculi less than 1 cm, or asymptomatic larger calculi, will depend on the degree of invasiveness required. Intervention is indicated for significantly symptomatic or obstructing calculi or those which show progressive growth.

Extracorporeal shock wave lithotripsy is the most successful treatment for most renal calculi less than 2.5 cm in greatest diameter in patients who do not have obstruction to the egress of fragments. The exceptions are cystine calculi more than 1 cm in diameter and very radiodense pure calcium exalate monohydrate calculi and calcium phosphate (brushite) calculi more than 1.5 cm in diameter. Renal calculi that are proximal to narrowed infundibulum or ureteral obstructions, and those larger than 2.5 cm are best treated by percutaneous nephrostolithotomy. If extracorporeal shock wave lithotripsy is unavailable and there is no urologist experienced in percutaneous technique available, or if the extracorporeal and/or percutaneous techniques fail, surgical removal is required.

The surgical approach depends on the size and position of the calculus. Calculi in the renal pelvis are approached via an 11th or 12th rib incision and removed via a pyelotomy. If a branch of the calculus extends to an infundibulum and calix, the pyelotomy incision can be extended into the corresponding infundibulum. If the stone cannot be completely removed by this method, a nephrotomy may be used to expose the calculus.

The treatment of most urinary stone disease has been transformed by new technology, both extracorporeal shock wave lithotripsy and endoscopic techniques. However, in most of the world, economic constraints have prevented application of new technology and surgery continues to play a major role in therapy. Despite the recognition of multiple metabolic conditions that predispose to the formation of calculi, the worldwide incidence of urinary stone disease does not appear to have diminished.

Chaussy C, Schmiedt E, Jocham D, Brendel W, Forssmann B, Walther V. First clinical experiences with extracorporeally induced destruction of kidney stones by shock waves. J Urol 1982; 127: 417–20.

Coe FL, Keck J, Norton ER. The natural history of calcium urolithiasis. JAMA, 1977; 238: 1519.

Furlow Wl, Bucchiere JJ. The surgical fate of ureteral calculi: review of Mayo Clinic experience. J Urol 1976; 116: 559.

Herring LC. Observations of 10,000 urinary calculi. J Urol 1962; 88: 545.

Huffman, JL, Bagley DH, Lyon ES. Treatment of distal ureteral calculi using rigid ureteroscope. Urology 1982; 20: 574–77.

Prien EL. Composition and structure of urinary stone. Am J Med 1968; 45: 654.

Segura JW, Patterson DE, LeRoy AJ, May GR, Smith LH. Percutaneous lithotripsy. J Urol 1983; 130: 1051–4.

Smith MJV, Boyce WH. Anatrophic nephrotomy and plastic calicorrhaphy. J Urol 1968; 99: 521–7.

Suby HI, Albright F. Dissolution of phosphatic urinary calculi by the retrograde introduction of a citrate solution containing magnesium. N Engl J Med 1943; 228: 81.

Ueno A, Kawamura T, Ogawa A, Takayasu H. Relation of spontaneous passage of ureteral calculi to size. Urology 1977; 10: 544–6.