Urinary tract stone management

 

Urinary tract stones are frequent and they affect 2-3% of the world's population with twice as many men affected than women. When affected by a urolithiasis, the chance of recurrence is around 50%. Why do urinary tract stones form and how can they be treated?

 

Introduction

What is the urinary system and how does it work?

Urinary system

The urinary tract, or system, consists of the kidneys, ureters, bladder and urethra. The kidneys are two bean-shaped organs that maintain balance by removing extra water and wastes from the blood and converting it to urine. Urine is carried by narrow muscular tubes, the ureters, from the kidneys to the bladder, a reservoir in the lower abdomen. The bladder's walls stretch and expand to store urine and then flatten when urine is emptied through the urethra outside the body.

What is a kidney stone?

Kidney stonesKidney stones form when there is an imbalance of chemical substances (calcium, oxalate, phosphate) in the kidneys. This imbalance causes abnormal crystallization of minerals that end up forming a kidney stone. The stone starts very small and grows if it does not pass into the urine flow when it is still small enough to go through the ureter without any problem. When the stone grows bigger inside the kidney, it can block off the urine flow out of the kidney or can make its way down to the ureter until it meets a narrow part of the ureter and blocks the urine flow.

What are the symptoms?

Kidney painThe most common symptom of a kidney stone is extreme pain. The pain occurs when the stone is blocked while travelling down the ureter and is due to irritation and contractions of the ureter muscles trying to force the stone down. Sometimes a person will also have blood in the urine, nausea and/or vomiting. One may feel the need to urinate more often or feel a burning sensation during urination. If the stone is close to the lower end of the ureter at the opening into the bladder, a person will frequently feel like they have not fully completed urination. If fever or chills accompany any of these symptoms, there may be an infection.

How can kidney stones be treated?

Treating kidney stone disease depends largely on the size, position and number of stones. During a medical examination, the urologist decides on the recommended treatment. The evaluation may include routine blood and urine tests, X-ray, ultrasound and CT-scan.
 
Extracorporeal Shock-Wave Lithotripsy (ESWL)
It is a non-invasive technique for disintegration of urinary calculi. Since its introduction in clinical practice more than 30 years ago, ESWL has become the standard treatment for urinary calculi.
 
Percutaneous nephrolithotomy (PCNL)
This procedure is the treatment of choice for patients with larger kidney stones. In this procedure, the surgeon makes a tiny cut in the flank area and then uses an instrument called a nephroscope to locate and remove the stone. For larger stones, a type of energy probe (ultrasonic, electrohydraulic or laser) may be needed to break the stone into small pieces. All of this is done while the patient is under anesthesia.
 
Ureteroscopy (URS)
Ureteroscopes are small flexible or semi-rigid endoscopes that can be inserted up the urethra, through the bladder and into the ureter without an incision. These instruments allow the doctor to view a ureteral stone directly. They also have small working channels through which various devices can be passed to remove or fragment the stone. Anesthesia is generally used, and a stent is left in the ureter for a few days after treatment while healing takes place. 
ESWL treatment

What is ESWL treatment for urinary tract stones?

Ultrasound localizationExtracorporeal Shockwave Lithotripsy (ESWL) is the least invasive technique commonly used for treatment of urolithiasis when possible (depending on stone location, stone dimension and patient medical condition). This non-surgical procedure using shock waves, developed in the mid-1980's, fragments stones into small pieces which pass spontaneously several days or weeks later from the kidney and bladder in most patients. After localization through X-ray or ultrasound, the stone is targeted by a series of shock waves generated outside of the body.

ESWL treatment

The patient is positioned on a treatment table. Once the stone is precisely localized via X-ray or ultrasound, shockwaves can be triggered and focused on the targetted stone. During the procedure, fragmentation is carefully monitored with real-time imaging. In general, ESWL treatment lasts between 30 to 50 minutes with 3000 to 4500 shocks.

Is ESWL treatment painful?

ESWL treatment with Sonolith<sup>®</sup> is almost pain-free and no anesthesia is required. The patient is given a light analgesia to guarantee a comfortable treatment and to avoid patient movements during treatment.

What happens after treatment?

Only a few hours after treatment, the patient can go back home and return to normal activity just 24 hours after treatment.
The following days, the stone debris will naturally pass through the urine. The evacuation of these debris may result in discomfort when they actually pass through the urethra.
The physician may ask to filter the urine in order to collect the debris and have them analyzed by a laboratory. This analysis will determine the stone composition and may be used to implement a preventive treatment to avoid recurrence.

What are the side effects of ESWL?

ESWL treatment is very safe and has little and mild side effects that go in only a few days.
  • Blood in the urine (hematuria): this is very frequent after ESWL treatment as a result of trauma to the renal parenchyma. However the amount of blood in the urine is minor and the symptom stops spontaneously within 24-48 hours after treatment.
  • Pain (nephretic colic/pain): this pain is caused by the evacuation of stone debris through the urethra. The pain naturally wears off in a few days at the most. Painkillers may be prescribed to stop pain.
  • Petechia (small red or purple spot on the body, caused by a minor bleeding of capillary vessels on the skin) is caused by the shock-waves and it wears off in a few days.
  • Urinary tract infections may appear in rare cases (in 1 to 7% of patients): it is caused by bacteria being released when infected stones are broken. It is generally treated with prophylactic antibiotics.
  • Urinary obstruction (in up to 6% of patients): such obstructions are caused by stone fragments lodging in the ureter. The patient usually feels persistent pain and a procedure may be necessary to clear the ureter if the fragments are not eliminated spontaneously.
  • Intra-renal/perineal hematoma: it is reported by less than 1% of patients. Although severe hematoma may clear up with no need for anything other than observation, there have been some cases of severe hemorrhaging and death. Blood transfusions, perfusions or surgery may be required in the event of severe renal hemorrhaging.

What is the medical follow-up after treatment?

After the ESWL treatment, the patient goes home the same day with a prescription for anti-inflammatory medicine. About 3 weeks after treatment, the patient is asked to have a follow-up visit with imaging to assess stone evacuation.
Clinical publications

Peer reviewed Articles

2013: ESWL to distal ureteric stones: the transgluteal approach significantly increases stone-free rates
S. Phipps et al., UK BJU International
"In conclusion, transgluteal ESWL to stones within the distal ureter with the patient in the supine position leads to a significantly higher SFR than for those treated in the prone position. The majority of patients are rendered stone-free after one session of treatment and the overall success rates are similar to those of ureteroscopic management. This technique is now in routine use in our institution."

2013: New ultrasound stone locking system in ESWL : Decreased duration of fluoroscopy and radiation doses
N. Abid, et al. Progrès en urologie
"The stone locking system Visio-Track reduced fluoroscopy in our first group of patients, which decreased the patient's individual absorbed irradiation dose."

2010: SWL is more cost-effective than ureteroscopy and Holmium:YAG laser lithotripsy for ureteric stones: A comparative analysis for a tertiary referral centre?
A.N. Argyropoulos, et al.
"Records of 228 patients with previously untreated solitary radiopaque ureteric stones ?15mm were reviewed. The total cost for SWL (cSWL) was £1491/patient, while the total cost for URSL (cURSL) was £2195/patient. The difference was highest in the upper ureter (over £1000), and lowest in the distal part (URSL about 40% more expensive). For lower ureteric stones >10mm, SWL was over £500 more expensive than URSL."

2009: Failure after shockwave lithotripsy: is outcome machine dependent??
Athanasios N. Argyropoulos et al. The international journal of clinical practice
"These data presents an argument against the term 'ESWL-resistant stones'. A second lithotriptor was highly successful in a group of stones where another machine failed. A very high success rate was achieved, leaving only a small number of patients requiring other more invasive procedures. Lithotripters with different characteristics can have a huge difference in the results of ESWL. Future research in ESWL should focus on stone characteristics and development of machines with the ability to adapt to specific stone features."

2007: Outcomes using a fourth-generation lithotripter: a new benchmark for comparison??
Michael S. Nomikos, et al. BJU International
"When similar populations of stone formers were assessed the Sonolith Vision achieved a high success rate, comparable with that using the HM-3 machine but with lower analgesia requirements and very low re-treatment rates. This method of comparison belies the commonly held view that newer lithotripters are less effective than the original spark-gap machines."

2006: Comparison of a New-Generation Electroconductive Spark Lithotripter and the Dornier Compact Delta for Ureteral Calculi in a Quaternary Referral Center?
Richard J. Pemberton et al Journal of Endourology
"This latest-generation electroconductive lithotripter in its first 6 months of use has shown stone-free and re-treatment rates superior to those of the Dornier Compact Delta and approaching that of the Dornier HM-3. Lithotripsy remains our first-line treatment for all radiopaque ureteral calculi."

2009: Ureteric stents compromise stone clearance after shockwave lithotripsy for ureteric stones: results of a matched-pair analysis?
Athanasios N. Argyropoulos et al. ?BJU International
"These results show that the presence of a stent is associated with a worse outcome after ESWL for ureteric stones. Ureteric stents should still be used in cases of obstruction, when there is a risk of sepsis, and in patients with intolerable pain or deteriorating renal function. However, their use in patients offered ESWL for ureteric stones should be considered with caution."

2002: Role of adjunctive medical therapy with Nifedipine & Deflazacort after extracorporeal shock wave lithotripsy of ureteral stones
F. Porpiglia et al. Urology
"The results of this study have shown the role that adjunctive medical therapy with nifedipine and deflazacort given after ESWL procedure can play in increasing the success rate of ureteral stone treatment. Furthermore, these results would suggest that adjunctive medical therapy can reduce total analgesic consumption after the ESWL procedure."

1994: Design and characterization of a shock wave generator using canalized electrical discharge: application to lithotripsy
M. Bourlion et al. Review of Scientific Instruments
"In order to improve the existing technique, a new shockwave generator, using an electrolyte within the gap between the two electrodes, has been developed. This technology, named electroconductive, leads to; drastically enhanced fragmentation efficacy, production of very stable and reproducible shock wave pressure at the second focus, with relative standard deviation of less than 5%; a better focalization, giving a smaller focal zone and a higher acoustic energy density."

Posters & Abstracts

2013: Outcome from SWL to Ureteric Calculi in Patients with High Skin-to-Stone Distance
S. Ramsey et al. - AUA, San Diego
"The use of a contemporary lithotriptor in an experienced centre can produce excellent stone free rates following treatment of ureteric calculi in patients with SSDs of 13cm or greater. The use of machines with greater focal depths will allow more patients to undergo SWL for urinary calculi despite increasing obesity."

2013: New ultrasound stone locking system in ESWL : Decreased duration of fluoroscopy and radiation doses
N. Abid et al. - AUA, San Diego
"These preliminary results obtained after the first 3 months of Visio Track® system use clearly shows the interest of this technique for the daily use of ESWL. The decrease in fluoroscopy time was 67.3% and correlates with the 61.7% decrease in irradiation doses. This leads to a safer treatment for both patients and medical staff."

2010: Prospective evaluation of pain during the treatment of urinary lithiasis with extracorporeal shock-wave lithotripsy: study on 293 patients
Long J.A. et al. - AFU, Paris
"The repetition of visual analog pain scale during ESWL procedure showed a constant increase of pain with procedure duration and the increase of shock-wave power (increase of visual analog pain scale beyond 50% of maximum power). Pain evaluation during ESWL with a 4th generation lithotripter shows the procedure can be performed in satisfactory comfort conditions."

2010: Emergency shockwave lithotripsy for ureteric calculi is superior to elective shockwave lithotripsy following stent placement: results from a matched-pair analysis
Simon Phipps et al. - AUA, San Francisco
"Our study shows a difference in SFR of 28% in favour of emergency treatment, which is statistically significant. We suggest that clearance is superior in these patients as treatment takes place before the development of ureteric oedema around the calculus; we have already shown that ureteric stents compromise the efficacy of SWL and the passage of fragments. We recommend emergency SWL as primary treatment for uncomplicated solitary ureteric calculi."

2009: Fourth-Generation Lithotripter in Treatment of Lower Calyceal Stones
Hejj R et al. - SIU, Shanghai
"Our results confirm good efficacy of the Sonolith Vision lithotripter for treatment of lower calyceal stones <10 mm in diameter. For stones between 11-20 mm, question of the best treatment option remains controversial and it's important to involve patient in decision making process by explaining pros and cons of all available treatment options (ESWL, PCNL, Flexible ureterorenoscopy)."

2009: Trans-Gluteal SWL for distal ureteric stones substantially increases stone free rate
CA Stephenson et al. - BAUS, Glasgow
"Supine Trans-gluteal ESWL results in:

  • 93% stone free rate
  • Greater immediate post treatment stone fragmentation
  • Easier localization of stones
  • Easier patient positioning and less discomfort"

2009: Early SWL for Ureteric Stones with the Technomed Sonolith Vision Lithotriptor improves Stone Free Rates
McLornan L et al. - EAU, Stockholm
"Our previously reported overall SFR for elective SWL for ureteric stones is 82% (Argyropooulos et al). The 94% SFR observed here is significantly higher than previously recorded in the literature (72% Tombal et al, 82% Seitz et al ) and also matches ureteroscopy SFRs in many centres. We currently use an early trial of SWL as primary treatment in patients with acute ureteric colic."

2009: Ureteric stents compromise stone clearance following SWL for ureteric stones – Results of a matched-pair analysis
Argyropoulos AN et al. - USANZ, Australia
"The presence of a stent leads to a worse outcome following SWL for ureteric stones. Therefore unless indicated for severe colic, obstruction, deteriorating renal function or when there is a risk of sepsis, their use in patients offered SWL for ureteric stones should be avoided."

2009: SWL or ureteroscopic laser lithotripsy (URSL) for ureteric stones? A cost-comparison analysis
Argyropoulos AN et al. - USANZ, Australia
"In this study, SWL was more cost-effective than ureteroscopy thoughout the ureter, despite the assumption that URSL had a better SFR. Although cost should never be the over-riding factor; it should be taken into account during assessment of individual data in order ensure that cost effective decisions are made in treatment selection."

2008: ESWL with sonolith vision - initial experience
R. Hejj et al. - 26th WCE, Shanghai, China
"Our initial experience supports findings of larger centres (e.g. Scottish Lithotriptor Centre, Edinburgh) that Sonolith Vision(TMS) is effective and safe with high efficacy for stones in all positions (overall SFR of 72%), including lower calyceal stones (SFR for lower calyceal stones was 66,7%). More patients need to be treated until definitive conclusions can be made."

2008: The initial experience of 4-month long use of the Sonolith i-sys electroconductive shockwave lithotriptor in an outpatient setting
P. Humaski et al. - 11th International Symposium on Urolithiasis, Nice, France
"Sonolith i-sys is a sufficient, easy to operate and reliable machine enabling to treat renal and ureteral calculi in a completely outpatient manner, without any sedation or anelgesia, with complete safety ond moderate pain complains from the patients. The immediate stone fragmentation at the time of the procedure was observed in 52% of cases. Our conclusions, as based on a short period of time, have an initial character and obviously need a prolonged further analysis and observation for final and accurate assessment."

2007: SWL for ureteric stones by Technomed Sonolith Vision lithotripor : results and failure factors
Argyropoulos A. et al. - 5th EULIS Symposium, Lisbon, Portugal
"The EDAP TMS Vision lithotripter offered a very effective treatment for patients with upper and middle ureteric stones and should be considered as the initial approach; at least two sessions should be attempted. In distal stones over 10 mm ureteroscopy might offer better chances for the patient to become stone-free. Stenting prior to SWL resulted in significantly lower SFR and should be avoided, if possible."

2007: Outcomes using the Sonolith Vision Technomed Lithotripter at a tertiary care centre. A new benchmark for comparison?
Michael Nomikos et al. - 5th EULIS Symposium, Lisbon, Portugal
"The Sonolith Vision lithotripter matches the historical results obtained wit HM3 but with the significant advantage for the patient to be treated as an outpatient under minimal analgesia. Results of treatment with this machine should be therefore considered as the contemporary benchmark for the comparative assessment of new generation lithotripters."

2005: Role and indication for extracorporeal lithotripsy in pediatric patients
P. Caione et al. - SIUP (Italian Society of Pediatric Urology), Italy
"ESWL plays an excellent role in the treatment of kidney-stones in children, better than in adults. Therefore the indications for ESWL in adults are also valid in pediatric patients."

2003: Extracorporeal lithotripters: is there a new gold standard? In-vivo multifunctional comparison between 6 mobile devices
C. Saltutti et al. - AURO.IT (Associazione Urologi Italiani) Congress Abstract, Roma, Italy
"The highest percentage with 54% of stone-free patients after 30 days was achieved with the Sonolith 4000 model."

2003: The first US experience in lithotripsy with the Sonolith Praktis (*)
D.T. Peterson et al. - (*) Poster presented at the TMS booth during the AUA Congress, Chicago, USA
"This new electroconductive lithotripter reduces the variability of electrohydraulic shockwaves at the second focus, F2, improving the amount of energy transfer to the stone. The clinical results are very encouraging and compare most favorably with the reported literature. The Praktis lithotripter is user friendly and efficient. Our patients experienced minimal morbidity and no significant bleeding."