Update on Urinary Stone Treatment
The American Urological Association (AUA) and the European Association of Urology (EAU) co-operated to develop new guidelines for urolithiasis. The current article is necessary because major advances have been made in the field of urolithiasis, and the most significant changes in the last few years will be presented here.
Diagnosis
What we need to know has remained the same throughout the decades if urolithiasis is suspected, and includes confirmation of the diagnosis of urolithiasis, the position and size of stones, anatomy of the urinary tract, grade of obstruction and differentiation between radiolucent and radiopaque stones.
In addition to medical history and the required clinical investigation and laboratory examination of blood and urine, other diagnostic procedures are available, including ultrasound, plain films of the kidneys, ureters and bladder (KUB), non-enhanced helical computed tomography (CT) and excretory urography. However, the importance of the individual procedures has changed.
Ultrasound
This is the most widespread method of investigation. It creates no radiation load and causes no pain for the patient. Stones in the kidney can usually be well visualised by ultrasound, and some stones are also seen in the proximal and distal portions of the ureter. Visualisation of the distal ureter is facilitated by a full bladder. Additionally, the grade of dilatation of the urinary collecting system can be visualised, but not the grade of obstruction.
Plain Film, Kidney–Ureter–Bladder
KUB provides additional information about the radiopacity of a previously detected stone after ultrasound or CT. In comparison with earlier X-rays of the patient, this method may provide a diagnosis on its own. KUB is a perfect imaging modality for follow-up after treatment of radiopaque stones.
Non-enhanced Helical Computed Tomography
CT is marked by the highest sensitivity (91–100%) and specificity (95–100%) to demonstrate urinary stones and may also reveal other pathologies. Information about renal function cannot be obtained without the administration of contrast medium. CT can demonstrate not only radiopaque but also uric acid and xanthine stones, which are radiolucent on plain films. However, it is not always possible to differentiate between radiolucent and radiopaque stones by the use of CT. Today CT without contrast medium is regarded as the most important detailed imaging investigation after ultrasound, and has partly surpassed the value of intravenous urography despite its higher radiation dose.1
Excretory Urography
Excretory urography or intravenous pyelography (IVP) has been established as the gold standard in cases of acute renal colic. The administration of contrast medium, which is required for this investigation, limits its use. The administration of contrast medium is contraindicated in cases of allergy, limited global renal function, untreated hyperthyroidism, the intake of metformin and paraproteinaemia, and it may aggravate the pain of acute colic. Its sensitivity and specificity are a little below those of CT. The excretion of contrast medium provides additional information about renal function.
Observation and Medical Expulsive Therapy
In cases of symptomatic stones and stone fragments after shock-wave lithotripsy (SWL), it is increasingly considered important to combine observation with medical therapy. Apart from symptomatic therapy and non-steroidal antiphlogistics (NSARs), data exist concerning calcium channel blockers such as nifedipine and alpha-receptor blockers. The application of alpha-receptor blockers in particular appears to be beneficial in cases of stones or stone fragments in the distal ureter. These medications, such as tamsulosin, are primarily known from the treatment of symptomatic prostate hyperplasia. Their application in cases of ureteral stones has been incorporated in all new guidelines but they are used on an ‘off-label’ basis, depending on national laws. A meta-analysis of six studies examining alpha blockers revealed a stone passage rate of 81% (range 72–88%) for ureteral stones measuring ≤10mm. This signifies a clear and partly statistically significant increase regarding the likelihood of stone passage.2
Chemolitholysis
Only uric acid stones can be dissolved by oral chemolitholysis. For this purpose the urinary pH must be set between 7.0 and 7.2 by the application of alkaline citrates or sodium bicarbonate. Irrigation chemolitholysis can be performed only in the presence of stones composed of magnesium ammonium phosphate and carbonate apatite, and is performed with a solution of hemiacidrin (renacidin). The method is not given much importance in the new guidelines. Irrigation litholysis requires careful planning and great expertise.3
2. Preminger GM, et al., Eur Urol, 2007;52(6):1610–31.
3. Tiselius HG, et al., Guidelines on Urolithiasis, EAU, 2008.
4. Sheir KZ, et al., BJU Int, 2008; 101(11):1420–26.
5. Loske AM, et al., J Acoust Soc Am, 2008;123(5):3366.
6. Wendt-Nordahl G, et al., J Endourol, 2007;21(12):1439–44.
7. Nagele U, et al., Urologe A, 2008;47(7):875–84.
8 Lahme S, et al., Urologe A, 2008;47(5): 563–8.
9. Preminger GM,et al., J Urol, 2005;173(6): 1991–2000.
10. Hruza M, et al., Urologe A, 2008;47(5): 578–86.
11. Straub M, et al., World J Urol, 2005; 23(5):309–23.
12. Straub M, et al., World J Urol, 2005; 23(5):309–23.
