Kidney Stones

HOW AND WHERE KIDNEY STONES OCCUR

Most urinary stones (urolithiasis in medical terms) arise as a result of a change in the natural balance of minerals and water in the urine. They consist of salt and minerals in the urine, which stick together and form small clots. The stones are rarely larger than a grain of rice, but they can grow to several centimeters in diameter and in some cases they even fill the entire renal collecting system.

They can stay in the kidneys or exit the body through the urinary tract. The urinary tract is the system that generates and excretes urine. It comprises the kidneys, the ureters (which connect the kidneys to the bladder), the bladder and the urethra, through which urine is transported from the bladder out of the body. Depending on the diagnosed condition, a distinction is made between kidney, urinary and bladder stones. Doctors distinguish between the type of salt that the stone comprises, for example:

• Calcium oxalate stones (70-75%) [1, 2]
• Uric acid stones (up to 10%) [1, 2]
• Infectious stones, e.g. “Struvite stones” consisting of magnesium ammonium phosphate (approx. 10-15%) [1-3]

Factors that can change the balance of substances in the urine and are therefore a common cause of kidney and urinary stones include the following:

• Insufficient water intake, which can result in salts and minerals sticking together to form small stones. [2, 4]
• A protein- or sodium-rich diet [5, 6]
• Frequent urinary tract infections [2, 4]
• Metabolic syndrome, obesity, diabetes and gout [1, 7-10]
• A regulatory disorder of the parathyroid glands (hyperparathyroidism) [1, 2, 4]
• Bowel surgery, gastric bypass and chronic bowel disease (Crohn’s disease) [1, 2, 4]

Endoscopic Removal of Kidney or Urinary Stones (URS)

Larger kidney stones are often surgically removed. Endoscopic removal of kidney or urinary stones is usually carried out under general anesthetic with the patient in the lithotomy position (on their back with legs spread apart). With the help of an endoscope, fine instruments are inserted through the urethra and bladder and up into the ureter until they reach the stone. The stone is then broken up, either mechanically or by laser, so that the pieces can be excreted or removed endoscopically using small forceps or baskets. The technical term for this endoscopic treatment is ureterorenoscopy (URS), or retrograde intrarenal surgery (RIRS) if the stone is located in the kidney. Usually the patient can leave the hospital after a recovery time of two days. [11]

At the end of this endoscopic operation, a ureteral stent (double-J catheter) is usually inserted under general anesthetic to prevent any obstruction of the urine flow and to avoid putting any strain on the patient. The double-J catheter is removed again in an outpatient procedure after one to two weeks. [11]

Videos:

http://www.maestro-portal.eu/procedure/detail/1 (Dornier laser)

http://www.maestro-portal.eu/procedure/ (Dornier laser)

Which Kidney Stone Treatment Method is Right for Me?

Kidney stones are treated using either extracorporeal shock wave lithotripsy (ESWL) or a surgical procedure such as URS or PCNL. The relevant medical associations (e.g. the German Society of Urology or the European Association of Urology) make recommendations on how to choose the best treatment method. These medical association recommendations are made available to urologists in the form of guidelines. They are based on the latest scientific knowledge obtained from medical studies. As of October 2017, the guidelines issued by the European Association of Urology (EAU)[1] on treating kidney and urinary stones are as follows:

The key factors are the location and size of the stone (first box), which are estimated first of all through diagnostic investigation. The second box shows the recommended treatment methods, which are listed either in order of preference (1 and 2) or as equal options. If, for example, you have an 8 mm stone in the proximal ureter (in a section of the ureter close to the bladder), the EAU recommends treatment with ESWL or URS.

References

1. C. Türk (Chair), A.N., A. Petrik, C. Seitz, A. Skolarikos, A. Tepeler, K. Thomas Guidelines Associates: S. Dabestani, T. Drake, N. Grivas, Y. Ruhayel. European Urolithiasis Guidelines. 2017 [cited 2017 27 September]; Available from: https://uroweb.org/guideline/urolithiasis/.
2. EAU Patient Information. [cited 2018 January 9]; Available from: http://patients.uroweb.org/wp-content/uploads/sites/2/06_Basic-info.pdf.
3. Flannigan, R., et al., Renal struvite stones–pathogenesis, microbiology, and management strategies. Nat Rev Urol, 2014. 11(6): p. 333-41.
4. EAU Patient Information – Causes of kidney and ureteral stones. [cited 2018 January 9]; Available from: http://patients.uroweb.org/wp-content/uploads/sites/2/01_Causes-of-kidney-and-ureteral-stones.pdf.
5. Breslau, N.A., et al., Relationship of animal protein-rich diet to kidney stone formation and calcium metabolism. J Clin Endocrinol Metab, 1988. 66(1): p. 140-6.
6. Kok, D.J., et al., The effects of dietary excesses in animal protein and in sodium on the composition and the crystallization kinetics of calcium oxalate monohydrate in urines of healthy men. J Clin Endocrinol Metab, 1990. 71(4): p. 861-7.
7. Ferraro, P.M., et al., Dietary and Lifestyle Risk Factors Associated with Incident Kidney Stones in Men and Women. J Urol, 2017. 198(4): p. 858-863.
8. Weinberg, A.E., et al., Diabetic severity and risk of kidney stone disease. Eur Urol, 2014. 65(1): p. 242-7.
9. Nerli, R., et al., Type 2 diabetes mellitus and renal stones. Adv Biomed Res, 2015. 4: p. 180.
10. Grassi, W. and R. De Angelis, Clinical features of gout. Reumatismo, 2012. 63(4): p. 238-45.
11. EAU Patient Information – In depth information – Treatment of Kidney and Ureteral Stones. [cited 2018 January 10]; Available from: http://patients.uroweb.org/wp-content/uploads/sites/2/03_Treatment_of_Stones.pdf.
12. Tailly, G.G. and M.M. Tailly-Cusse, Optical coupling control: an important step toward better shock wave lithotripsy. J Endourol, 2014. 28(11): p. 1368-73.
13. M. Mohammadi, T.A., N. Milz, S. Osswald, A. Zintl, H. P. Bastian, G. Lümmen, Initial Clinical Experience with the New Dornier Shock Wave Source EMSE 180 for ESWL, in 60 Congress of the North Rhine-Westphalian Society of Urology. 2014: Düsseldorf, Germany.
14. Sheir, K.Z., K. Madbouly, and E. Elsobky, Prospective randomized comparative study of the effectiveness and safety of electrohydraulic and electromagnetic extracorporeal shock wave lithotriptors. J Urol, 2003. 170(2 Pt 1): p. 389-92.
15. Lingeman, J.E., et al., Shock wave lithotripsy: advances in technology and technique. Nat Rev Urol, 2009. 6(12): p. 660-70.