1. Urinary tract stones, treatment possibilities
Matyas Benyo MD FEBU
Based on the guideline of the European Association of Urology

2. Epidemiology
Between 120 and 140 per 1000,000 will develop urinary stones each year with a male/female ratio of 3:1.

3. Classification of stones
Correct classification of stones is important since it will impact treatment decisions and outcome.
Urinary stones can be classified according to the following aspects (tables 1-3):
stone size,
stone location,
X-ray characteristics of stone,
aetiology of stone formation,
stone composition (mineralogy), and
risk group for recurrent stone formation

7. High risk stone formers
General factors
Early onset of urolithiasis in life (especially children and teenagers)
Familial stone formation
Brushite containing stones (calcium hydrogen phosphate; CaHPO4.2H2O)
Uric acid and urate containing stones
Infection stones
Solitary kidney

8. High risk stone formers
Diseases associated with stone formation
Hyperparathyroidism
Nephrocalcinosis
Gastrointestinal diseases or disorders
Sarcoidosis

9. High risk stone formers
Genetically determined stone formation
Cystinuria (type A, B, AB)
Primary hyperoxaluria (PH)
Renal tubular acidosis (RTA) type I
2,8-dihydroxyadenine
Xanthinuria
Lesh-Nyhan-Syndrome
Cystic fibrosis

10. High risk stone formers
Anatomical abnormalities associated with stone formation
Medullary sponge kidney (tubular ectasia)
UPJ obstruction
Calyceal diverticulum, calyceal cyst
Ureteral stricture
Vesico-uretero-renal reflux
Horseshoe kidney
Ureterocele
Urinary diversion (via enteric hyperoxaluria)
Neurogenic bladder dysfunction

11. Diagnostic imaging
Standard evaluation of a patient includes taking a detailed medical history and physical examination.
The clinical diagnosis should be supported by an appropriate imaging procedure.
Ultrasonography should be used as the primary procedure.
KUB should not be performed in case an NCCT is considered.
Non-contrast enhanced computed tomography (NCCT) has become the standard for diagnosis of acute flank pain and has higher sensitivity and specificity than IVU.

13. Basic analysis Emergency stone patient
Urine
Urinary sediment/dipstick test out of spot urine sample for: red cells / white cells / nitrite / urine pH
Urine culture or microscopy
Blood
Serum blood sample creatinine / uric acid / ionized calcium / sodium / potassium
Blood cell count
CRP
If intervention is likely or planned:
Coagulation test (PTT and INR)

14. Stone analysis Analysis of stone composition should be performed in:
All first-time stone formers
Recurrence under pharmacological prevention
Early recurrence after interventional therapy with complete stone clearance
Late recurrence after a prolonged stone-free period
The preferred analytical procedures are:
X-ray diffraction
Infrared spectroscopy

15. High-risk patients: Stone-specific metabolic work-up and pharmacological recurrence prevention
Pharmacological stone prevention is based on a reliable stone analysis and the laboratory analysis of blood and urine including two consecutive 24-hours urine samples.

16. Acute treatment of a patient with renal colic
Pain relief is the first therapeutic step in patients with an acute stone episode.
If pain relief cannot be achieved by medical means, drainage, using stenting or percutaneous nephrostomy, or stone removal, should be carried out.

17. Management of sepsis in the obstructed kidney
The obstructed, infected kidney is a urological emergency.
The collecting system should be urgently decompressed (percutaneous drainage or ureteral stenting).
Definitive treatment of the stone should be delayed until sepsis is resolved.
Collect urine following decompression for antibiogram.
Start antibiotic treatment immediatedly thereafter (+ intensive care if necessary).
Revisit antibiotic treatment regimen following antibiogram findings.

18. Treatment
Kidney stones should be treated in case of stone growth, formation of de novo obstruction, associated infection, and acute and/or chronic pain.
Patient’s comorbidities and preferences (social situation) need to be taken into consideration when making a treatment decision.
If kidney stones are not treated, periodic evaluation is needed.

19. Medical expulsive therapy (MET)
For patients with ureteral stones that are expected to pass spontaneously, NSAID tablets or suppositories (i.e. diclofenac sodium, mg/day, over 3-10 days) may help to reduce inflammation and the risk of recurrent pain.
Alpha-blocking agents, given on a daily basis, also reduce the number of recurrent colic.
Patients, who elect for an attempt at spontaneous passage or MET, should have wellcontrolled pain, no clinical evidence of sepsis, and adequate renal functional reserve.

20. Chemolytic dissolution of stones
Oral or percutaneous irrigation chemolysis of stones can be a useful first-line therapy or an adjunct to ESWL, PNL, URS, or open surgery to support elimination of residual fragments.
However, its use as first-line therapy may take weeks to be effective.
Oral chemolitholysis is efficient for uric acid calculi only.
The urine pH should be adjusted to between 7.0 and 7.2.

21. ESWL (extracorporeal shock wave lithotripsy)
The success rate for ESWL will depend on the efficacy of the lithotripter and on:
Size, location of stone mass (ureteral, pelvic or caliceal), and composition (hardness) of the stones
Patient’s habitus
Performance of ESWL

22. Shock waves- a special form of sound waves that have a sharp peak in positive pressure followed by a trailing negative wave
The positive pressure and the short rise time are responsible for the direct shock wave effect
the tensile wave for the cavitation, which is called the indirect shock wave effect.
The disintegration of a kidney stone is a combination between direct and indirect shock wave
An airplane, which breaks the sound barrier, generates a very loud bang, which can lead to the jingle (csilingel) of glasses in a cupboard. The shock wave has transmitted energy from the airplane to the glasses.
Tensile –elnyúló
The change in density and acoustic impedance when traveling from water to stone results in fragmentation

23. History February 1980 in Germany by Dornier
1983 First commercial lithotripter HM3 (Dornier) .
First commercial lithotripter HM3 (Dornier) with bathtub.
The sedated or anesthetized patient lies down in the apparatus' bed, with the back supported by a water-filled coupling device placed at the level of kidneys. A fluoroscopic x-ray imaging system or an ultrasound imaging system is used to locate the stone and aim the treatment.

24. Localisation system during the operation Fluoroscopic x-ray Ultrasound
Shock wave generator
Electrohydraulic,
Electromagnetic
Piezoelectric
Localisation system during the operation
Fluoroscopic x-ray
Ultrasound
Shock wave coupling
(water bath)
Ultrasonography gel
Auxiliary equipment (table) (control of pain)
Lithotripters are, therefore, composed of four essential parts, which differ significantly between the devices – Shock wave generation is based on electrohydraulic, electromagnetic or piezoelectric sources.
Fluoroscopy is the most frequently used system.
Stones in all positions of the kidney and ureter can be localised, except for very small and less radiodense
stones. The technique is easy and fast to handle but has the disadvantage of higher investment and maintenance costs and X-ray exposure.
UH can be used with sufficient handling comfort to localise smaller and non-radiodense
stones in the kidney and intramural ureter.
Unfortunately, stones in most parts of the ureter cannot be localised by ultrasound.
The learning curve for this technique is longer than for fluoroscopy.
The optimal coupling of the shock wave is a water bath, in which the patient is completely or partially
positioned. The use of a water cushion (víz párna) increases comfort for both the patient and medical assistants.
The disadvantage, however, is that each layer incorporated in the shock wave path can reduce the shock wave efficacy.
Ensure correct use of the coupling gel because this is crucial for effective shock wave transportation
Ultrasonography gel is probably the optimum agent
The table has to be movable in all three dimensions

25. Figure 1: The Electrohydraulic Electrode Generating Acoustic Pressure on the Focal Point
electrohydraulic generator, which uses the tips of an electrode as a point source. This electrode is placed in the first focal point F1
high voltage is switched to the tips of the electrode.
Between this tips an electrical spark is generated and a shock wave is released right from the beginning by the vaporization of the water between the tips.
into the second focal point F2 which for the therapy is adjusted to the therapeutically volume inside the patients body.
In the electrohydraulic generator (see Figure 1) an underwater electrode is discharged,
inducing evaporation of water with a resulting high-pressure wave.
This is focused by an ellipsoid to generate a shock wave within the focal point F2.
This principle of shock wave generation reaches high disintegrative capacity, but also causes pain.
Deep analgosedation or anaesthesia is therefore necessary for highly effective stone disintegration.
The burning of electrodes results in significant variation of the different shock waves applied at the same generator setting (generator power) and necessitates electrode exchange after a few treatments. This explains the higher running cost of the electrohydraulic shock wave source.
The urinary stone is positioned on the focal point and disintegrates after
multiple shots.

26. Figure 2: Cylindric Electromagnetic Shock Wave Source Within the Parabolic Reflector
Electromagnetic generators (see Figure 2) work in a way that is comparable to loud speakers. Highenergy
acoustic waves are focused by an acoustic lens or by using a paraboloid reflector. The resulting
shock wave is constant. The energy is focused to a smaller focal point with higher peak energy.
uses an electromagnetic coil and a metal membrane opposite to it. A high current pulse is released through the coil generating a strong varying magnetic field, which induces a high current in the opposite membrane. The electromagnetic forces accelerate the metal membrane away from the coil creating a slow and low-pressure acoustical pulse. To focus the wave an acoustical lens is used. The focal point is defined by the focal length of the lens. The amplitude of the focused acoustical wave is increasing by nonlinearities when the acoustical wave propagates towards the focal point. The rise times of electromagnetic generated shock waves are in the range of a few hundred nano seconds (10-9 s).

27. Figure 3: Piezoelectric Shock Wave Source with Multiple Piezoelements
Piezoelectric generators (see Figure 3) consist of multiple, spherically (gömbszerűen) aligned piezoelements
inducing a very high peak pressure within a very small focal point.
The resulting shock wave induces low pain and can be used without any analgosedation.
A few hundred to some thousand piezoelectric crystals are mounted to a spherical surface. When switching a high voltage pulse to the crystals they immediately contract and expand generating a low pressure pulse in the surrounding water.
The disadvantage is the large diameter of the source and the limited total energy in the focus.

28. Example of a High-End Urologic Workstation
high-end lithotripter for a urological workstation (see Figure 4) with capital
costs of approximately E300,000 to E350,000.
The highly effective shock wave source is integrated in a multipurpose table with a
fluoroscopic and ultrasound imaging system.

29. Pressure Distribution and Configuration of Focal Point Depending on
Shock Wave Source
The parameter ‘pressure flow density’ in the focal point seems to be highly correlated with stone
fragmentation.
Whether a wide focal area with moderate peak pressure
(electrohydraulic lithotripter) Or
a narrow focus diameter with higher peak pressure (electromagnetic lithotripter)
is of advantage, is a subject of intensive discussion (see Figure 8).
Very small focal points with high peak pressures (piezoelectric lithotripter) cannot reach the pressure flow density of other lithotripter systems.
It seems reasonable that, for different stone material or localisations, different configurations of the focus configuration are favourable. Since the parameter of pressure flow density is not standardised and is not
published for the different lithotripters, the disintegrative efficacy cannot be estimated from the
technical characterisation.

30. Efficacy of the lithotripter
size, location (ureteral, pelvic or calyceal)
composition (hardness) of the stones
best result: 4 mm and 2 cm in diameter that are still located in the kidney
ureters - a lower rate of success
patient’s habitus (non-obese)

31. Contraindications of extracorporeal shock wave lithotripsy
pregnancy, due to the potential effects on the foetus
bleeding diatheses, which should be compensated for at least 24 h before and 48 h after treatment
uncontrolled urinary tract infections
severe skeletal malformations and severe obesity, which prevent targeting of the stone;
arterial aneurysm in the vicinity of the stone
anatomical obstruction distal to the stone.
Vicinity - környék

32. Optimizing ESWL
Routine use of internal stents before SWL does not improve stone-free rate - JJ stent reduces the risk of renal colic and obstruction
Lowering shock wave frequency from 120 to shock waves/min improves stone-free rate
Tissue damage increases with shock wave frequency
The optimal shock wave frequency is Hz
The number of shock waves that can be delivered at each session depends on the type of lithotripter
Shock wave power. There is no consensus on the maximum number of shock waves.
Maximum threshold of 3000 shocks for renal stones
70SW/min (better) than 100SW/min
to improve the efficiency of disintegration.
the repeated shock wave pressure pulses result in direct shearing forces, as well as cavitation bubbles surrounding the stone, which disintegrate the calculi into smaller pieces.
Hereby, a decreased shock wave frequency may enhance the production of cavitation bubbles and, subsequently, lead to an improved fragmentation rate.
Stone-free rate(kőmentesek aránya)

33. Repeate SWL sessions within 1 day for ureteral stones
Starting SWL on a lower energy setting with stepwise power ramping can achieve vasoconstriction during treatment which prevents renal injury.
Repeate SWL sessions within 1 day for ureteral stones
Animal studies have shown better stone-free rate using stepwise power ramping.
Stepwise power ramping = teljesítmény rámpázás

34. capillary damage, renal parenchymal or subcapsular hemorrhage.

35. Percutaneous nephrolitholapaxy (PNL)
Ultrasonic, ballistic and Ho:YAG devices are recommended for intracorporeal lithotripsy using rigid nephroscopes.
When using flexible instruments, the Ho:YAG laser is currently the most effective device available.

37. Contraindications All contraindications for general anaesthesia apply.
Untreated urinary infection.
Atypical bowel interposition.
Tumour in the presumptive access tract area.
Potential malignant tumour of the kidney.
Pregnancy (conservative stone treatment should be considered first, where possible.

38. Open Surgery
Most complex (staghorn) stones, should be approached primarily with PNL or a combination of PNL and ESWL. Open surgery may be a valid primary treatment option in selected cases.
Laparoscopic urological surgery has increasingly replaced open surgery.

39. Indications for open (/lap) surgery
Complex stone burden
Treatment failure of ESWL and/or PNL, or failed ureteroscopic procedure
Intrarenal anatomical abnormalities: infundibular stenosis, stone in the calyceal diverticulum, obstruction of the ureteropelvic junction, stricture
Morbid obesity
Skeletal deformity, contractures and fixed deformities of hips and legs
Co-morbid medical disease
Concomitant open surgery
Non-functioning lower pole (partial nephrectomy), nonfunctioning kidney (nephrectomy)
Stone in an ectopic kidney where percutaneous access and ESWL may be difficult or impossible

40. Indication for active stone removal
Ureter:
Stones with a low likelihood of spontaneous passage
Persistent pain in spite of adequate pain medication
Persistent obstruction
Renal insufficiency (renal failure, bilateral obstruction, single kidney)

41. Indication for active stone removal
Kidney:
Stone growth
Stones in high-risk patients for stone formation
Obstruction caused by stones
Infection
Symptomatic stones (e.g. pain, haematuria)
Stones > 15 mm
Stones < 15 mm if observation is not the option of choice
Patient preference (medical and social situation)
> 2-3 years persistent stones

44. Ureter stones - treatment

45. General considerations for recurrence prevention (all stone patients)
Drinking advice (2.5 – 3L/day, neutral pH)
Balanced diet
Lifestyle advice

46. Thank you for your attention!