EHL has a narrower safety margin than pneumatic, ultrasonic, or laser lithotripsy and shoul d be kept as far away as possible from the wall of the ureter, renal pelvis, or bladder to limit damage to these structures and at least 2mm away from the cystoscope, ureteroscope, o r nephroscope to prevent lens fracture. Principal uses: bladder stones (wider safety margin than in the narrower ureter). Pneumatic (ballistic) lithotripsy A metal projectile contained within the handpiece is prop elled backwards and forwards at great speed by bursts of compressed air (Fig. 9.4a). It str ikes a long, thin, metal probe at one end of the handpiece at 12Hz (12 strikes per second) transmitting shock waves to the probe which, when in contact with a rigid structure such as a stone, fragments the stone. Used for stone fragmentation in the ureter (using a thin pro be to allow insertion down a ureteroscope) or kidney (a thicker probe may be used, with an inbuilt suction device \200\224 \200\230Lithovac \200\231 \200\224to remove stone fragments ). Pneumatic lithotripsy is very safe since the excursion of the end of the probe is about 1mm and it bounces off the pliable wall of the ureter. Ureteric perforation is, therefore, rar e. Also low cost and low mainte- nance. However, its ballistic effect has a tendency to cau se stone migra- tion into the proximal ureter or renal pelvis where the stone may be inacce ssible to further treatment. The metal probe cannot bend around corners so it cannot be use d for ureteroscopic treatment of stones within the kidney. Principal uses: ureteric stones. Ultrasonic lithotripsy An electrical current applied across a piezoceramic plate located in the ultrasound transducer generates ultrasound waves of a speci \201 c frequency (23 000 \200\22325 000Hz). The ultrasound energy is transmitted to a hollow metal probe which, in t urn, is applied to the stone (Fig. 9.4b). The stone resonates at high frequency and this ca uses it to break into small fragments (the opera singer breaking a glass) which are then su cked out through the center of the hollow probe. Soft tissues do not resonate when the prob e is applied to them and, therefore, are not damaged. Can only be used down straight instru ments. Principal uses: fragmentation of renal calculi during PCNL. INTRACORPOREAL TECHNIQUES OF STONE FRAGMENTATION 451 (a) probe metal projectile to generator (b) GENERATOR piezoceramic elements USS probe (longitudinal vibration) acoustic end parts suction foot pedal Fig. 9.4 (a) The Lithoclast: a pneumatic lithotripsy device (b) The Calcuson: an ultrasonic lithotripsy device. (Reproduced from Walsh PC, Retik AB, Vaughan D, et al. (2002) Campbell \200\231s Urology, 8th edn. Amsterdam: W.B. Saunders/Elsevier, pp. 3395 \200\2237 with per mission from Elsevier). CHAPTER 9 Stone disease 452 Laser lithotripsy The holmium:YAG laser. Principally, a photothermal mechanism of action, c ausing stone vaporization. Minimal shock wave generation and, therefore, less risk of causi ng stone migration. The laser energy is delivered down \201 bres which vary in diameter f rom 200 to 360 m. The 200 m \201 bre is very \202 exible and can be used to gain acce ss to stones even within the lower pole of the kidney (Figs. 9.5 and 9.6). A 275 m \201 bre delivers more laser energy at the expense of a reduction in \202 exibility and, there fore, a reduced chance of lower pole access. The zone of thermal injury is limited from 0.5 to 1mm from the laser tip. No stone can withstand the heat generated by the Ho:YAG laser. Laser lithotripsy takes time, however, since the thin laser \201 bre must be \200\230pai nted \200\231 over the surface of the stone to vaporize it. Principal uses: ureteric stones, small intrarenal stones. INTRACORPOREAL TECHNIQUES OF STONE FRAGMENTATION 453 Fig. 9.5 A laser \201 bre. Fig. 9.6 Access to the lower pole of the kidney with a \202 exible ureteroscope. CHAPTER 9 Stone disease 454 Flexible ureteroscopy and laser treatment The development of small caliber ureteroscopes wi th active de \202 ecting mechanisms and instrument channels, in combination with the devel op- ment of laser technology, small diameter laser \201 bres, and stone baskets and grasp ers, has opened the way for intracorporeal, endoscopic treat- ment of kidney stones. Access to virtually the entire collecting system is possible with modern instruments. The holmium :YAG laser has a minimal effect on tissues at distances of 2 \200\2233mm from the laser tip and so \200\230collat- eral \200\231 tissue damage is minimal with this laser type. Flexible ureteroscopy and laser fragmentation offer a more effective treatment option compa red with ESWL, with a lower morbidity than PCNL, but usually requires a general anesthetic (some patients will toler- ate it with sedation alone). It can also allow access to areas o f the kidney where ESWL is less ef \201 cient or where PCNL cannot reach. It is most suite d to stones <2cm in diameter. Indications for \202 exible ureteroscopic kidney stone treatment - - ESWL Lower pole stone (reduces the likelihood of stone passage post- ESWL \200\224fragments have to pass \200\230uphill \200\231). Cystine stones. Obesity such that (nephroscopes ma y not be long enough to reach the stone). Obesity such that ESWL is technically dif \201 c ult or impossible. BMI >28 is associated with lower ESWL success rates. Treatment distance may exceed the focal length of the lithotripter. Musculoskeletal deformities such that ston e access by is dif \201 cult or impossible (e.g. kyphoscoliosis). Stone in a calyceal dive rticulum (accessing stones in small diverticulae in upper and anterior calyces is dif \201 cult and carries signi \201 cant risks). Stenosis of a calyceal infundibulum or \200\230 tight \200\231 angle between the renal pelvis and infundibulum. The \202 exible ureterosc ope can negotiate acute angles and the laser can be used to divide obstructions. Bleeding d iathesis where reversal of this diathesis is potentially dangerous or dif \201 cult. Horse shoe or pelvic kidney. ESWL fragmentation rates are only 50% in such cases1 due to dif \201 culties of shock wave transmission through overlying organs (bowel). PCNL for such kid neys is dif \201 cult because of bowel proximity and variable blood supply (blood supply d erived frommultiple sources). Patient \200\231s preference. failure. PCNL access is technically dif \201 cult or impossible PCNL or ESWL Disadvantages Ef \201 cacy diminishes as stone burden increases \200\224it simply takes a long time to \200\230paint \200\231 the surface of the stone with laser energy so destroyi ng it. A dust cloud is produced as the stone fragments and this temporarily obscures FLEXIBLE URETEROSCOPY AND LASER TREATMENT 455 the view until it has been washed away by irrigation. Stone fragmentation rates for those e xpert in \202 exible ureteroscopy (not every stone surgeon will be able to achieve these results) are 770 \200\22380% for stones <2cm in diameter and 50% for those >2cm in diameter 2 and 710% of patients will require two or more treatment sessions.2 1 Kupeli B, Isen K, Biri H, et al. (1999) Extracorporeal shockwave lithotripsy in anomalous kid- neys. J Endourol 13:39 \200\22352. 2 Dasgupta P, Cynk MS, Bultitude MF, Tiptaft RC, Glass JM. (2004) Flexible ureterorenoscopy : prospective analysis of the Guy \200\231s experience. Ann R Coll Surg 86:367 \200\22370. CHAPTER 9 Stone disease 456 Kidney stone treatment: percutaneous nephrolithotomy (PCNL) Technique PCNL is the removal o f a kidney stone via a \200\230track \200\231 developed between the surface of the skin an d the collecting system of the kidney. The \201 rst step requires \200\230in \202 ation \200\231 of the renal collecting system (pelvis and calyces) with \202 uid or air instil led via a ureteric catheter inserted cystoscopically (Fig. 9.7). This makes subsequent perc utaneous puncture of a renal calyx with a nephrostomy needle easier (Fig. 9.8). Once the ne phrostomy needle is in the calyx, a guide wire is inserted into the renal pelvis to act as a guide over which the \200\230track \200\231 is dilated (Fig. 9.9). An access sheath is p assed down the track and into the calyx and through this, a nephroscope can be advanced int o the kidney (Fig. 9.10). An ultrasonic lithotripsy probe is used to fragment the stone and remove the debris. A posterior approach is most commonly used, below the 12th rib (to avoid the pleura and far enough away from the rib to avoid the intercos- tals, vessels, and nerve). The preferred a pproach is through a posterolat- eral calyx rather than into the renal pelvis because this avoids damage to posterior branches of the renal artery which are closely associated with t he renal pelvis. General anesthesia is usual, though regional or even local anesthesia (wit h sedation) can be used. Indications for and outcomes of PCNL PCNL is generally recommended for stones >3cm in diame ter, those that have failed ESWL, and/or an attempt at \202 exible ureteroscopy and laser treatment. It is the \201 rst-line option for staghorn calculi,1 with ESWL and/ or repea t PCNL being used for residual stone fragments. For staghorn stones, the stone-free rate of PCNL, when combined with post-operative ESWL for residual stone fragments, is in the order of 80 \200\22385%. For middle and upper pole stones 2 \200\2233cm in diameter, options include ESWL (with a JJ stent in situ), \202 exible ureteroscopy and laser treatment, and PCNL. PCNL gives the b est chance of complete stone clearance with a single procedure, but this is achieved at a h igher risk of morbidity. Some patients will opt for several sessions of ESWL or \202 exib le ureteroscopy/ laser treatment and the possible risk of ultimately requiring PCNL because of failure of ESWL or laser treatment rather than proceeding with PCNL \200\230up front \200\231. About 50% of stones >2cm in diameter will be fragmented by \202 exible ureteros copy and laser treatment. For lower pole stones PCNL achieves substantially higher stone clear- ance than ESWL for al l stones sizes (<1cm, 100% vs 63%; 1 \200\2232cm, 93% vs 23%; >2 \200\2233cm, 86% vs 14%)2. It is also achieves superior stone-free rates compared to \202 exible ureteroscopy/laser treatment for lower pole stones between 1 \200\2232.5cm (71% vs 37%).3 Again, better stone -free rates must be balanced against higher morbidity. PERCUTANEOUS NEPHROLITHOTOMY (PCNL) 457 Post-PCNL tube drainage vs tubeless PCNL? PCNL is traditionally followed by the placement o f a large bore neph- rostomy tube, the rationale being to tamponade bleeding from the track (less frequently, the tube is used to keep the track patent to allow the option of check n ephroscopy if post-operative imaging \200\224a CT scan or nephrostogram \200\224demonstrate s residual stone). The disadvantage is more post-operative pain and requirement for analges ics and longer hospital stay (though some reports suggest tubed PCNL does not increase any of these parameters). As a consequence, tubeless PCNL is now in vogue \200\224tubeless mean ing no nephrostomy tube, but usually some form of ureteric drainage, e.g. a J stent or uret eric catheter (i.e. \200\230tubeless \200\231 PCNL is actually \200\230relatively tubeles s \200\231; there are occasional reports of \200\230totally tubeless \200\231 PCNL). The use of track sealants has been suggested, but there is no convincing proof that they re duce bleeding or urinary extravasation. Track diathermy and cryoablation (a 10min freeze \200\223thaw cycle) have also been reported. A recent review4 suggests that tubeless PCNL should be the default, but that the decision t o place a tube should be individualized \200\224partly based on the surgeon \200\231s exper ience and erring on the side of tube placement in cases with more than two access tracks; i nfection stones (most stag- horns); signi \201 cant intraoperative bleeding; collecting sy stem perforation (though one could argue that antegrade J stent insertion or ureteric cathe - ter drainage might be just as effective); where a second look is anticipated (e.g. especi ally large stone burden). Fig. 9.7 A ureteric catheter is inserted into the renal pelvis to dilate it with air or \202 uid. CHAPTER 9 Stone disease 458 Fig. 9.8 A nephrostomy needle has been inserted into a calyx. Fig. 9.9 A guide wire is inserted into the renal pelvis and down the ureter; over this guid e wire, the track is dilated. PERCUTANEOUS NEPHROLITHOTOMY (PCNL) 459 Fig. 9.10 An access sheath is passed down the track and into the calyx and through this, a nephroscope can be advanced into the kidney. Supine vs prone PCNL? Traditionally, PCNL is performed in the prone position (once access t o the renal collecting system has been gained with the patient in the supine position, the patient is turned from supine to prone after the initial ure- teric catheterization). \200 \230Supine \200\231 PCNL (keeping the patient in the supine position throughout the procedu re, rotated to one or other side to allow access to the appropriate \202 ank) has recentl y been proposed as an alterna- tive approach, the potential advantages being:5 (1) reduced operating time (no time is wasted turning the patient), (2) lower anesthetic morbidity (the prone position reduces cardiac output), (3) easier management of airway problems (it is di f \201 cult to access the airway in a prone patient), (4) should hemorrhage occur, arteria l and central venous line insertion is easier, (5) it allows the potential for manipulating the renal stone burden not only percutaneously, but also ureteroscopically (the argument b eing that a \200\230two-handed \200\231 approach is better than a one-handed one). Whether the supine position will become the preferred option remains to be seen. What treatment is best for the smaller (<3cm) lower pole kidney stone? It is more dif \201 cult to achieve a stone-free status for lower pole kid- ney stones compared with stones in the upper and middle pole calyces because of poor clearance of stone fragments from the de pendent lower pole. Lower Pole I1 and another randomized study comparing stone-free rates f or lower pole stones treated either by \202 exible ureterorenoscopy vs ESWL or \202 exi ble ureterorenoscopy vs PCNL inform treatment decisions (Tables 9.4 and 9.5). CHAPTER 9 Stone disease 460 Table 9.4 Stone-free rates for lower pole stones: PCNL vs ESWL2 Stone size (cm) PCNL (%) ESWL (%) <1 100 63 1 \200\2232cm 93 23 >2 \200\2233cm 86 14 Table 9.5 Stone-free rates for lower pole stones: \202 exible ureterorenoscopy (F-URS) vs ESWL and \202 exible ureterorenoscopy vs PCNL3 Stone size (cm) ESWL (%) F-URS (%) PCNL (%) Group 1: <1 35 50 \200\223 Group 2: 1 \200\2232.5 \200\223 37 71 The convenience of ESWL over \202 exible ureterorenoscopy (outpatient procedure, no anest hetic, much shorter recovery time) means that many patients prefer ESWL over \202 exible ureterorenoscopy if given the choice. Comparing \202 exible ureterorenoscopy vs PCNL, sto ne-free rates strongly favor PCNL. For stones <3cm, convalescence time is similar. For the 1cm or smaller stones, ESWL or \202 exible ureterorenoscopy are reasonable \201 rst-line approaches, but warn the patient that stone clearance is relatively low for both (35% vs 50%). For stones between 1 and 2cm, PCNL achieves higher clearance rates, although the potential for morbidity is higher. In the above well-designed study, \202 exible ureterorenoscopy w as able to clear stones in only one-third of patients (no doubt this relatively low success rate was due to the use of very accurate non-enhanced CT scanning to determine stone-free status 3 months after treatment as opposed to plain radiography).6 For stones >2cm, PCNL achieves higher clearance rates than any other modality. PERCUTANEOUS NEPHROLITHOTOMY (PCNL) 461 1 Segura JW, Preminger GM, Assimos DG, et al. (1994) Nephrolithiasis clinical guidelines pa nel summary report on the management of staghorn calculi. J Urol 151:1648 \200\22351. 2 Albala DM, Assimos DG, Clayman RV, et al. (2001) Lower pole I: a prospective randomized t rial of ESWL and PCNL for lower pole nephrolihiasis \200\223initial results. J Urol 166:207 2. 3 Pearle MS, Lingeman JE, Leveillee R, et al. (2005) Prospective randomized trial comparing shock wave lithotripsy and ureteroscopy for lower pole calyceal calculi 1 cm or less. J Ur ol 173:2005 \200\2239. 4 Zilberman DE, Lipkin ME, de la Rosette JJ, et al. (2009) Tubeless percutaneous nephrolith o- tomy \200\223 the new standard of care? J Urol 184:1261 \200\2236. 5 Atkinson CJ, Turney BW, Noble JG, Reynard JM, Stoneham MD (2011) Supine v prone percu- ta neous nephrolithotomy: ananaesthetist \200\231s view. BJU Int 108:306 \200\2238. 6 Dasgupta P, Cynk MS, Bultitude MF, Tiptaft RC, Glass JM (2004) Flexible ureterorenoscopy: prospective analysis of the Guy \200\231s experience. Ann R Coll Surg Engl 86:367 \200\223 70. CHAPTER 9 Stone disease 462 Kidney stones: open stone surgery Indications - Complex stone burden (projection of stone into multiple calyces such that multiple PCNL tra cks would be required to gain access to all the stone). Failure of endoscopic treatment (te chnical dif \201 culty gaining access to the collecting system of the kidney). Anatomic ab normality that precludes endoscopic surgery (e.g. retrorenal colon). Body habitus that prec ludes endoscopic surgery (e.g. gross obesity, kyphoscoliosis \200\224open stone surgery can be dif \201 cult). Patient \200\231s request for a single procedure where multiple be req uired for stone clearance. Non-functioning kidney. PCNLs might Non-functioning kidney Where the kidney is not working, the stone may be left in situ if it is not causing symptoms (e.g. pain, recurrent urinary infection, haematu- ria). However, s taghorn calculi should be removed unless the patient has comorbidity that would preclude sa fe surgery because of the substantial risk of developing serious infective complications. I f the kidney is non-func- tioning, the simplest way of removing the stone is to remove the kidney. Functioning kidneys \200\224options for stone removal Small- to medium-sized stones - - Pyelolithotomy. Radial nephrolithotomy. Staghorn calculi - - Anatrophic (avascular) nephrolithotomy. Extended pyelolithotomy with radial nephrotomies (s mall incisions over individual stones). Excision of the kidney, \200\230bench \200\231 sur gery to remove the stones, and autotransplantation. Speci \201 c complications of open stone surgery Wound infection (the stones operated on a re often infection stones), \202 ank hernia, wound pain. (With PCNL these problems do not occur, blood transfusion rate is lower, analgesic requirement is less, mobilization is mor e rapid, and discharge earlier \200\224all of which account for PCNL hav- ing replaced open surgery as the mainstay of treatment of large stones.) There is a signi \201 cant chance of stone recurrence after open stone surgery (as for any other treatment modality) and the scar tissue that develops around the kidney will make subsequent open stone surgery technic ally more dif \201 cult. This page intentionally left blank CHAPTER 9 Stone disease 464 Kidney stones: medical therapy (dissolution therapy) Uric acid and cystine stones are poten tially suitable for dissolution ther- apy. Calcium within either stone type reduces the cha nces of successful dissolution. Uric acid stones Urine is frequently supersaturated with uric acid (derived from a purine- rich diet, i.e. animal protein). Fifty percent of patients who form uric acid stones have g out. The other 50% do so because of a high protein and low \202 uid intake ( \200\230west ern \200\231 lifestyle). In patients with gout, the risk of develop- ing stones is 71% per year after the \201 rst attack of gout. Uric acid stones form in concentrated acid urine. Dissolution therapy is based on hydration , urine alkalinization, allopurinol, and dietary manip- ulation \200\224the aim being to re duce urinary uric acid saturation. Maintain a high \202 uid intake (urine output 2 \200 \2233L/day), \200\230alkalinize \200\231 the urine to pH 6.5 \200\2237 (sodium bicarbonate 650mg tds or qds or potassium citrate 30 \200\22360mEq day, equivalent to 15 \200\22330mL of a potassium citrate solution tds or qds). In those with hyperuricaemia or urinary uric a cid excretion >1200mg/day, add allopurinol 300 \200\223600mg/day (inhibits the conversion o f hypoxanthine and xanthine to uric acid). Dissolution of large stones (even staghorn cal- culi) is possible with this regimen. Cystine stones Cystinuria is an inherited kidney and intestinal transepithelial transportat ion defect for the amino acids cystine, ornithine, arginine, and lysine ( \200\230COAL \200 \231), leading to excessive urinary excretion of cystine. Autosomal recessive inheritance; prevalence of 1 in 700 are homozygous (i.e. both genes defec- tive); occurs equally in both sexes. About 3% of adult stone formers are cystinuric and 6% of stone-forming children. Most cystinuric patients excrete about 1g of cystine per day, which is well above the solub ility of cystine. Cystine solubility in acid solutions is low (300mg/L at pH 5, 400mg/L at pH 7). Patients with cystinuria pres- ent with renal calculi, often in their teens or twent ies. Cystine stones are relatively radiodense because they contain sulfur atoms. The cyanid e nitroprusside test will detect most homozygote stone formers and some heterozygotes (fals e positives occur in the presence of ketones). Treatment of existing stones and prevention of further stones The aim is to: - Reduce cystine excretion (dietary restriction of the cystine precursor amino acid methionin e and also of sodium intake to <100mg/day). Increase solubility of cystine by alkalinizatio n of the urine to pH >7.5, maintenance of a high \202 uid intake, and use of drugs which convert cystine to more soluble compounds. D-penicillamine, N-acetyl-D-penicillamine, and mercaptopropionylgly- cine (Tiopronin) bind to cysteine as does captopril \200\224the compounds so KIDNEY STONES: MEDICAL THERAPY (DISSOLUTION THERAPY) 465 formed are more soluble in urine than is cystine alone. D-penicillamine has potentially unp leasant and serious side effects (allergic reactions, nephrotic syndrome, pancytopenia, pro teinuria, epidermolysis, thrombo- cytosis, hypogeusia). Therefore, reserved for cases where alkalinization therapy and high \202 uid intake fail to dissolve the stones. Treatment for failed dissolution therapy Cystine stones are very hard and are, therefore, r elatively resistant to ESWL. Nonetheless, for small cystine stones, a substantial proportio n will still respond to ESWL. Flexible ureteroscopy (for small) and PCNL (for larger) cysti ne stones are used where ESWL fragmentation has failed. CHAPTER 9 Stone disease 466 Ureteric stones: presentation Ureteric stones usually present with sudden onset of severe \202 ank pain which is colicky (waves of increasing severity are followed by a reduction i n severity, but it seldom goes away completely). It may radiate to the groin as the stone p asses into the lower ureter. About 50% of patients with classic symptoms for a ureteric sto ne do not have a stone con \201 rmed on subsequent imaging studies nor do they physically ever pass a stone. Examination Spend a few seconds looking at the patient. Ureteric stone pain is colicky \200 \224 the patient moves around, trying to \201 nd a comfortable position. They may be doub led up with pain. Patients with conditions causing peritonitis (e.g. appendicitis, a ruptur ed ectopic pregnancy) lie very still: movement and abdominal palpation are very painful. Pregnancy test Arrange a pregnancy test in premenopausal women (this is mandatory in any pr emenopausal woman who is going to undergo imaging using ionizing radiation). If positive, r efer to a gynecologist; if negative, arrange imaging to determine whether they have a urete ric stone. Dipstick or microscopic haematuria Many patients with ureteric stones have dipstick or micr oscopic haema- turia (and more rarely, macroscopic haematuria), but 10 \200\22330% have no blood in their urine.1,2 The sensitivity of dipstick haematuria for detecting ureteric ston es presenting acutely is 795% on the \201 rst day of pain, 85% on the second day, and 65% on the third and fourth days.2 Therefore, patients with a ureteric stone whose pain starte d 3 \200\2234 days ago may not have blood detectable in their urine. Dipstick testing is sl ightly more sensitive than urine microscopy for detecting stones (80% vs 70%) because blood cells lyse and, therefore, disappear if the urine specimen is not examined under the micro scope within a few hours. Both ways of detecting haematuria have roughly the same speci \201 city for diagnosing ureteric stones (760%). Remember, blood in the urine on dipstick testing or microscopy may be a coincidental \201 nding because of non-stone urological disease (e.g. neoplasm, infection) or a false positi ve test (no abnormality is found in 770% of patients with microscopic haematuria despite fu ll urological investigation). Temperature The most important aspect of examination in a patient with a ureteric stone con \201 rmed on imaging is to measure their temperature. If the patient has a stone and a fe ver, they may have infection proximal to the stone. A fever in the presence of an obstructi ng stone is an indication for urine and blood culture, IV \202 uids and antibiotics, and nephrostomy drainage or J stent insertion if the fever does not resolve within a matter of hours.1,2 URETERIC STONES: PRESENTATION 467 1 Luchs JS, Katz DS, Lane DS, et al. (2002) Utility of hematuria testing in patients with s uspected renal colic: correlation with unenhanced helical CT results. Urology 59:839. 2 Kobayashi T, Nishizawa K, Mitsumori K, Ogura K (2003) Impact of date of onset on the abse nce of hematuria in patients with acute renal colic. J Urol 1770:1093 \200\2236. CHAPTER 9 Stone disease 468 Ureteric stones: diagnostic radiological imaging The IVU, for many years the mainstay of im aging in patients with \202 ank pain, has been superseded by CT-KUB, an unenhanced (i.e. no contrast) CT of the kidneys, ureters, and bladder (except in the rare situation of suspe cted indinavir stones which are not visible on CT-KUB) (Fig. 9.11). Compared with IVU, CT-K UB: - Has greater speci \201 city (97%) and sensitivity (94 \200\223100%) for diagnosing ureteri c stones.1 Can identify non-stone causes of \202 ank pain (Fig. 9.12). Requires no contra st administration so avoiding the chance of a contrast reaction (risk of fatal anaphylaxis following the administration of low osmolality contrast media for IVU is in the order of 1 in 100 000).2 Is faster, taking just a few minutes to image the kidneys and ureters. An IVU , particularly where delayed \201 lms are required to identify a stone causing high-grade obstruction, may take hours to identify the precise location of the obstructing stone. Is equivalent in cost to IVU in high CT volume hospitals.3 CT-KUB radiation dose: approximately 4.7mSv compared to 1.5mSv for IVU (fatal cancer risk i s estimated at 1 in 2000 for a 10mSv radiation expo- sure). Ultra-low dose CT (ULDCT) lower s radiation exposure (0.6 \200\2232mSv), but at the expense of a lower sensitivity (68 \200 \22386%) for small (<3mm) ure- teric stones. Contrast-enhanced ultra-low dose CT (CEULDCT) uses con- trast which increases sensitivity (97%) and speci \201 city (100%) for detecting small ureteric stone disease while limiting radiation dose to levels compa- rable with IVU (1.7mSv vs 1.4mSv).4 If you only have access to IVU, remember it is contraindicated in patients with previous co ntrast reactions. Avoid in those with hay fever, a strong history of allergies or asthma wh o have not been pretreated with high- dose steroids 24h before the IVU. Patients taking met formin for diabetes should stop this for 48h prior to an IVU. Clearly, being able to perfor m an alternative test such as CT-KUB in such patients is very useful. Where 24h CT-KUB access is not available, admit patients with sus- pected ureteric colic fo r pain relief and arrange a CT-KUB the follow- ing morning. When CTU is not immediately ava ilable, we arrange urgent abdominal ultrasonography in all patients aged >50y who present w ith \202 ank pain suggestive of a possible stone to exclude serious pathology, e.g. a lea king abdominal aortic aneurysm and to demonstrate any other gross abnormalities due to non- stone associated \202 ank pain. Plain abdominal X-ray and renal USS are not suf \201 ciently sensitive or speci \201 c for their routine use for diagnosing ureteric stones. MR urography Very accurate for identifying ureteric stones.5 However, at the present time, cost and restricted availability limit its usefulness as a routine diag- nostic method of i maging in cases of acute \202 ank pain. This may change as MR scanners become more widely available. URETERIC STONES: DIAGNOSTIC RADIOLOGICAL IMAGING 469 Fig. 9.11 A CT urogram. Fig. 9.12 A leaking aortic aneurysm identi \201 ed on a CTU in a patient with loin pain. 1 Niemann T, Kollmann T, Bongartz G (2008) Diagnostic performance of low dose CT for the de tection of urolithiasis. AJR Am J Roentgenol 191:396 \200\223401. 2 Caro JJ, Trindale E, McGregor M (1991) The risks of death and severe non-fatal reactions with high vs low osmolality contrast media. Am J Roentgen 156:825 \200\22332. 3 Thomson JM, Glocer J, Abbott C, et al. (2001) Computed tomography versus intravenous urog raphy in diagnosis of acute \202 ank pain from urolithiasis: a randomized study comparing imaging costs and radiation dose. Australas Radiol 45:291 \200\2237. 4 Fowler JC, et al. (2011) Clinical evaluation of ultra-low dose contrast-enhanced CT in pa tients presenting with acute ureteric colic. Br J Med Surg Urol 4:56 \200\22363. 5 Leyendecker JR, Gianini JW (2009) Magnetic resonance urography. Abdominal Imaging 34: 527 \200\22340. CHAPTER 9 Stone disease 470 Ureteric stones: acute management While appropriate imaging studies are being organized, pa in relief should be given. - NSAID s (e.g. diclofenac) by intramuscular or IV injection, by mouth or per rectum. Provides rapid and effective pain control. Analgesic effect \200\224p artly anti-in \202 ammatory, partly by reducing ureteric peristalsis. NSAIDs are inadequat e, opiate analgesics such as pethidine or Where morphine are added. There is no need to encourage the patient to drink copious amounts of \202 uids nor to gi ve them large volumes of \202 uids intravenously in the hope that this will \200\230 \202 ush \200\231 the stone out. In a randomized trial of forced IV hydra- tion vs minimal hydration, there was no signi \201 cant difference in analgesic requirement, pain scores, or spontaneous stone passage rates.1 Renal blood \202 ow and urine output from the affected kidney falls during an episode of acute partial obstruction due to a stone. Excess urine output will tend to cause a greater degree of hydronephrosis in the affected kidney, which may make ureteric peristalsis* even less ef \201 cient than it already is. The exception to this rule may be those with radiolucent uric acid stones (suspected if low urinary pH and stones not visible on plain X-ray or with lower attenuation on CT compared with calcium, cystine, and struvite stones). High \202 uid intake and oral potassium citr ate, sodium cit- rate, or sodium bicarbonate (to elevate urine pH to 6 \200\2237) may disso lve uric acid stones or at least reduce their size so increasing stone spontaneous passage rates. Watchful waiting In many instances, small ureteric stones will pass spontaneously within da ys or a few weeks, with analgesic supplements for exacerbations of pain. Data on the rate of spontaneous stone passage are surprisingly limited.2 Chances of spontan eous stone passage depend principally on stone size. Sixty-eight percent of stones 5mm or l ess will pass spontaneously (95% CI 46 \200\22385%; meta-analysis of 224 patients); 47% of stones 6 \200\22310mm in diameter will pass spontaneously (95% CI 36 \200\22359%; meta-anal ysis of 104 patients).2 Average time for spontaneous stone passage for stones 4 \200\2236mm in diam- eter is 3 weeks.3 Stones that have not passed in 2 months are unlikely to do so. Of those stones that do eventually pass, those 2mm or less do so within 30 days and those 2 \200\2236mm in size do so within 40 days (but not all stones do pass and we cannot predict the chance of spontaneous passage in the individual patient). Therefore, accurate determin ation of stone size (on plain abdominal X-ray or by CTU) helps predict chances of sponta- n eous stone passage. Medical expulsive therapy (MET) There is growing evidence for the ef \201 cacy of MET, the preferred agents being the smooth muscle relaxing A1-adrenergic adrenoceptor block- ers.2, 4 These increase spontaneous stone passage rates, reduce stone passage time, and reduce fre quency of ureteric colic.4 The EAU/AUA Nephrolithiasis Guideline Panel meta-analysis showed that 29% more URETERIC STONES: ACUTE MANAGEMENT 471 patients (CI: 20 \200\22337%) taking tamsulosin passed their stones compared with controls. 2 Tamsulosin has been most studied in this setting, but tera- zosin and doxazosin seem to b e equally effective. Whether stones in all segments of the ureter are equally responsive to A-blockers remains to be determined. Another meta-analysis (7 studies, 484 patients)5 suggests that tamsulosin also seems to enc ourage stone clearance after ESWL for ureteric (and possibly renal) stones, the pooled abso lute risk difference being between 16 \200\22319% (0.2 vs 0.4mg) in favor of tamsulosin (so if 70% pass their stones spontaneously without tamsulosin, 89% pass their stones while on 0.4mg tamsulosin). Five patients needed to be treated with tamsulosin to achieve stone clea rance in one. There was a mean difference of 8 days in terms of time to stone expulsion in favor of those on tamsulosin. In the same meta-analysis, there was no signi \201 cant difference in stone passage rates between those taking the calcium channel blocker, nifedi- pine, and control patients. Glyceryl trinitrate patches do not aid stone passage or reduce the frequency of pain episod es and corticosteroids are of minimal, if any, bene \201 t.4,6 A trial of MET is a very reasonable approach for many patients, but individual circumstance s may dictate \200\230up front \200\231 ESWL or ureteroscopy, e.g. the possible disruption to work and daily living activities from episodes of pain occurring while a stone is progr essing towards eventual spontaneous passage may prompt the patient to request ESWL or urete roscopy (e.g. commercial airline pilots cannot \202 y until stone-free nor can those who \202 y for leisure). MET is contraindicated where there is clinical evidence of sepsis (essen- tially fever) or deteriorating renal function. If you use a trial of MET, warn patients of the risks (drug s ide effects, possible need for intervention in the form of ESWL, ureteroscopy, or J stentin g) and mention it is an \200\230off-label \200\231 (i.e. non-licensed) therapy. Arrange pe riodic follow-up imaging (usually a plain X-Ray) to monitor stone position. Peristalsis, the forward propulsion of a bolus of urine down the ureter, can only occur if the walls of the ureter above the bolus of urine can coapt, i.e. close \201 rmly together . If they cannot, as occurs in a ureter distended with urine, the bolus of urine cannot mov e distally. 1 Springhart WP, Marguet CG, Sur RL, et al. (2006) Forced versus minimal intravenous hydrat ion in the management of acute renal colic: a randomized trial. J Endourol 20:713 \200\2236 . 2 Preminger GM, Tiselius HG, Assimos DG, et al. (2007) 2007 Guideline for the management of ureteral calculi (Joint EAU/AUA Nephrolithiasis Guideline Panel. J Urol 178:2418 \200\2233 4. 3 Miller OF, Kane CJ (1999) Time to stone passage for observed ureteral calculi. J Urol 162 :688 \200\22391. 4 Dellabella M, Milanese G, Muzzonigro G (2003) Ef \201 cacy of tamsulosin in the medical manage- ment of juxtavesical ureteral stones. J Urol 170:2202 \200\2235. 5 Zhu Y, Duijvesz D, Rovers MM, Lock TM (2009) Alpha blockers to assist stone clearance aft er extra-corporeal shock wave lithotripsy: a meta-analysis. BJU Int 106:256 \200\22361. 6 Hussain Z, Inman RD, Elves AW, et al. (2001) Use of glyceryl trinitrate patches in patien ts with ureteral stones: a randomized, double-blind, placebo-controlled study. Urology 58:5 21 \200\2235. CHAPTER 9 Stone disease 472 Ureteric stones: indications for intervention to relieve obstruction and/or remove the ston e - Pain controlled with additional pain relief. : in the presence of an obstructing stone can lead to the Bacteriuria development of urosepsis. The EAU/AUA Nephrolithiasis Guideline Pan el recommends that patients with ureteric stones and bacteriuria be treated with appropriat e antibiotics (level IV evidence, i.e based on the opinions or clinical experience of respe cted authorities). Where intervention is planned (ESWL or ureteroscopy), appropriate antibi otics should be given in advance of the treatment. Fever percutaneous nephrostomy or JJ ste nt).1 Impaired renal function (solitary kidney obstructed by a stone, bilateral ureteric st ones, or pre-existing renal impairment which gets worse as a consequence of a ureteric ston e): threshold for intervention is lower. Prolonged unrelieved obstruction of renal function .1 How long it takes for this loss of renal function to occur is uncertain, but generally s peaking, the period of watchful waiting for spontaneous stone passage tends to be limited t o 4 \200\2236 weeks. Social reasons surgical treatment because they need to get back to wor k or because of their childcare duties whereas some patients will be happy to sit things ou t. Airline pilots and some other professions are unable to work until they are stone-free. : that fails to respond to analgesics or recurs and cannot be : have a low threshold for draining the kidney (either : this can result in long-term loss : young active patients may be very keen to opt for Emergency temporizing and de \201 nitive treatment of the stone Where the pain of a ureter ic stone fails to respond to analgesics or where renal function is impaired because of the stone, then temporary relief of the obstruction can be obtained by the insertion of a JJ st ent or percuta- neous nephrostomy tube. (Percutaneous nephrostomy tube can restore ef \201 cient peristalsis by restoring the ability of the ureteric wall to coapt.) JJ stent insertion or percutaneous nephrostomy tube can be done quickly, but the stone is s till present (Fig. 9.13). It may pass down and out of the ureter with a stent or nephrostom y in situ, but in many instances, it simply sits where it is and subsequent de \201 nitive treatment is still required. While JJ stents can relieve stone pain, they can cause bother some irrita- tive bladder symptoms (pain in the bladder, frequency, and urgency) (see Table 9.6). JJ stents do make subsequent stone treatment in the form of ureteroscopy technically easier by causing passive dilatation of the ureter. The patient may elect to proceed to de \201 nitive stone treatment by immediate ureteroscopy (for stones at any location in the ureter) or ESWL (if the stone is in the upper and lower ureter \200\224ESWL cannot be used for stones in the mid-ureter because this region is surrounded by bone,