Tag Archive for: urolithiasis

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Infographic: The origins of urinary stone disease: upstream mineral formations initiate downstream Randall’s plaque

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Figure 1 The medullo-papillary complex. A total of 8–12 paraboloid complexes are contained within each human kidney. Each complex can be separated into three zones (Zones 1–3) distinguished by distinct segments of the loop of Henle. There are short- and long-looped nephrons and vessels. Owing to the paraboloid geometry of the medullo-papillary complex, shorter looped nephrons and vessels are contained in the periphery, and the longest looped nephrons and vessels are located centrally. Non-fenestrated descending vasa recta are surrounded by layers of smooth muscle, in contrast to the ascending vasa recta comprised of fenestrated endothelium. Within Zone 3, a transition occurs where pericytes replace smooth muscle.

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Figure 2 Spatial relationships and size distributions of the tubules and vessels within the medullo-papillary complex. From Zone 1 to Zone 2, the ascending and descending vasa recta become organised into vascular bundles (dotted line) and interbundle regions. In Zone 3, the descending thin limbs join the vascular bundles (light dotted line), and these are separate from collecting duct clusters. Collecting ducts grow larger in diameter towards Zone 3 and coalesce to form the 6–12 ducts of Bellini. These anatomically specific compartments contribute to radial and axial concentration gradients along the course of the complex.

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Figure 3 Medullo-papillary function is characterised by pressure and chemical gradients. Pressure gradients are present from Zone 1 to Zone 3. Due to the paraboloid form of the complex, larger diameter vasa recta are located centrally within the vascular bundles and have higher pressure gradients and flow rates than in the peripherally located vasa recta. Poiseuille’s law relates flow rate as proportional to pressure and radius to the fourth power, and inversely proportional to fluid viscosity and tube length. Within each tube, velocity of fluid is highest at the centerline, but decreases near the wall due to resistance. Over time, within a concentrated fluid, solutes are expected to accumulate along the walls. From Zone 1 to Zone 3, an increasing osmolarity gradient, contributed by primarily sodium salts and urea, generates the urine concentrating ability through countercurrent exchange. Areas vulnerable to hypoxic injury include the tip of the Zone 3, and Zone 2 because of the metabolically active thick ascending limbs and their relative physical separation from the descending vasa recta.

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Figure 4 Biomineralisation of the medullo-papillary complex leading to Randall’s plaque. Over time, lower pressure gradients in the peripheral tubules relative to the centrally located tubules lead to intratubular mineralisation within Zones 1 and 2. The functional volume of the complex gradually decreases, and at a certain threshold, the change in pressure gradient drives a mechanoresponsive switch that leads to interstitial mineralisation in Zone 3. The accumulation of biominerals in the interstitial space eventually becomes endoscopically visible as Randall’s plaque, the foundation for a future urinary tract stone.

 

Abstract

Objectives

To describe a new hypothesis for the initial events leading to urinary stones. A biomechanical perspective on Randall’s plaque formation through form and function relationships is applied to functional units within the kidney, we have termed the ‘medullo-papillary complex’ – a dynamic relationship between intratubular and interstitial mineral aggregates.

Methods

A complete MEDLINE search was performed to examine the existing literature on the anatomical and physiological relationships in the renal medulla and papilla. Sectioned human renal medulla with papilla from radical nephrectomy specimens were imaged using a high resolution micro X-ray computed tomography. The location, distribution, and density of mineral aggregates within the medullo-papillary complex were identified.

Results

Mineral aggregates were seen proximally in all specimens within the outer medulla of the medullary complex and were intratubular. Distal interstitial mineralisation at the papillary tip corresponding to Randall’s plaque was not seen until a threshold of proximal mineralisation was observed. Mineral density measurements suggest varied chemical compositions between the proximal intratubular (330 mg/cm3) and distal interstitial (270 mg/cm3) deposits. A review of the literature revealed distinct anatomical compartments and gradients across the medullo-papillary complex that supports the empirical observations that proximal mineralisation triggers distal Randall’s plaque formation.

Conclusion

The early stone event is initiated by intratubular mineralisation of the renal medullary tissue leading to the interstitial mineralisation that is observed as Randall’s plaque. We base this novel hypothesis on a multiscale biomechanics perspective involving form and function relationships, and empirical observations. Additional studies are needed to validate this hypothesis.

Ryan S. Hsi*, Krishna Ramaswamy*, Sunita P. Ho† and Marshall L. Stoller*

 

*Department of Urology, and Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, USA

 

Article of the Week: Assessing the impact of various treatment optimisation strategies in SWL

Every week the Editor-in-Chief selects the Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying editorial written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation.

Finally, the third post under the Article of the Week heading on the homepage will consist of additional material or media. This week we feature a video from Mr Mahesh Desai discussing his paper. 

If you only have time to read one article this week, it should be this one.

Evolution of shockwave lithotripsy (SWL) technique: a 25-year single centre experience of >5000 patients

Jitendra Jagtap, Shashikant Mishra, Amit Bhattu, Arvind Ganpule, Ravindra Sabnis and Mahesh Desai

Department of Urology, Muljibhai Patel Urological Hospital, Nadiad, India

OBJECTIVE

To assess the impact of various treatment optimisation strategies in shockwave lithotripsy (SWL) used at a single centre over the last 25 years.

PATIENTS AND METHODS

In all, 5017 patients treated between 1989 and 2013 were reviewed and divided into groups A, B, C and D for the treatment periods of 1989–1994 (1561 patients), 1995–2000 (1741), 2001–2006 (1039) and 2007–2013 (676), respectively. The Sonolith 3000 (A and B) and Dornier compact delta lithotripters (C and D) were used. Refinements included frequent re-localisation, limiting maximum shocks and booster therapy in group B and Hounsfield unit estimation, power ramping and improved coupling in group D. Parameters reviewed were annual SWL utilisation, stone and treatment data, retreatment, auxiliary procedures, complications and stone-free rate (SFR).

RESULTS

The SFR with Dornier compact delta was significantly higher than that of the Sonolith 3000 (P < 0.001). The SFR improved significantly from 77.58%, 81.28%, 82.58% to 88.02% in groups A, B, C, and D, respectively (P < 0.001). There was a concomitant decrease in repeat SWL (re-treatment rate: A, 48.7%; B, 33.4%; C, 15.8%; and D, 10.1%; P < 0.001) and complication rates (A, 8%; B, 6.4%; C, 4.9%; and D, 1.6%; P < 0.001). This led to a rise in the efficiency quotient (EQ) in groups A–D from 50.41, 58.94, 68.78 to 77.06 (P < 0.001).The auxiliary procedure rates were similar in all groups (P = 0.62).

CONCLUSION

In conclusion, improvement in the EQ together with a concomitant decrease in complication rate can be achieved with optimum patient selection and use of various treatment optimising strategies.

 

Editorial: Evolution of extracorporeal shockwave lithotripsy (ESWL)

Much has changed since the introduction of extracorporeal shockwave lithotripsy (ESWL); however, in many ways the principles remain constant. This manuscript by Jagtap et al. [1] is a large series of patients over 25 years and encapsulates the changes in ESWL over that time. This paper has all the limitations inherent in a retrospective review but within this offers interesting data. In particular the use of two different machines and refinements in technique are eloquently described. This shows an improvement due to both the change in technology but also in the importance of modifications of technique. The particular factors improving stone-free rate (SFR) were; better localisation with ultrasonography and X-ray, better coupling and use of coupling gel, change in selection criteria for both the patient and stone, ramping up the power and a staff training programme. This emphasis on technique is especially pertinent in healthcare systems where mobile lithotripters are still in use. These are renowned to have lower SFRs than static machines, which may be due to the technical delivery of treatment as much as the efficacy of the lithotripter.

What is the future for ESWL? The paper reflects the perception globally that whilst the incidence of urolithiasis is increasing, the use of ESWL is not increasing at the same rate, particularly for ureteric stones, and they cite the potential factors for this. This has also been noted in the UK and our own recent review of Hospital Episode Statistics (HES) data even suggest the rate of ESWL has plateaued for both ureteric (3000/year) and renal (19 500/year) stones in the last 3 years [2, 3]. There has been discussion within the UK about centralising endourology services using the same model as for cancer, with provision of static lithotripters within those centres. This would potentially have the advantage of creating high-volume centres with quality being easier to standardise and monitor; however, this would have to be balanced against patients probably having to travel further to access ESWL. The use of Hounsfield units remains a topic of debate with conflicting data and limited clinical application [4, 5]. Optimising targeting to minimise tissue damage with maximal stone fragmentation remains a challenge and modifications to lithotripters with dual-imaging modalities, dual heads, alterations in shockwave delivery rate, control of respiratory effort and novel feedback devices have had limited success. Increasing levels of obesity within developed countries are a factor in the utilisation of ESWL, as there is a limit on focal distance. All of these factors along with the continued improvement in the optics, miniaturisation of ureteroscopes and advent of holmium laser have contributed to a surge in the use of ureteroscopy, despite publications and guidelines showing similar success rates [6].

Kay Thomas

Clinical lead for Urology, Honorary Senior Lecturer Kings College London, UK

References

1 Jagtap J, Mishra S, Bhattu A, Ganpule A, Sabnis R, Desai M. Evolution of shockwave lithotripsy (SWL) technique: a 25-year single centre experience of >5000 patients. BJU Int 2014; 114: 748–53

2 Turney BW, Reynard JM, Noble JG, Keoghane SR. Trends in urological disease. BJU Int 2011; 109: 1082–7

3 Withington J. Personal communication from Royal College of Surgeons. July 2014

4 Pareek G, Armenakas A, Fracchia JA. Hounsfield units on computerized tomography predict stone free rates after extracorporeal shock wave lithotripsy. J Urol 2012; 169: 1679–81

5 Foda K, Abdeldaeim H, Youssif M, Assem A. Calculating the number of shock waves, expulsion time and optimum stone parameters based on noncontrast computerized tomography characteristics. Urology 2013; 82: 1026–31

6 Türk C, Knoll T, Petrik A et al. EAU Guidelines on Urolithiasis, 2014. Available at: https://www.uroweb.org/gls/pdf/22%20Urolithiasis_LR.pdf. Accessed July 2014

 

Video: Evolution of SWL technique. A 25 year single centre experience of over 5000 patients

Evolution of SWL technique. A 25 year single centre experience of over 5000 patients

Jitendra Jagtap, Shashikant Mishra, Amit Bhattu, Arvind Ganpule, Ravindra Sabnis and Mahesh Desai

Department of Urology, Muljibhai Patel Urological Hospital, Nadiad, India

OBJECTIVE

To assess the impact of various treatment optimisation strategies in shockwave lithotripsy (SWL) used at a single centre over the last 25 years.

PATIENTS AND METHODS

In all, 5017 patients treated between 1989 and 2013 were reviewed and divided into groups A, B, C and D for the treatment periods of 1989–1994 (1561 patients), 1995–2000 (1741), 2001–2006 (1039) and 2007–2013 (676), respectively. The Sonolith 3000 (A and B) and Dornier compact delta lithotripters (C and D) were used. Refinements included frequent re-localisation, limiting maximum shocks and booster therapy in group B and Hounsfield unit estimation, power ramping and improved coupling in group D. Parameters reviewed were annual SWL utilisation, stone and treatment data, retreatment, auxiliary procedures, complications and stone-free rate (SFR).

RESULTS

The SFR with Dornier compact delta was significantly higher than that of the Sonolith 3000 (P < 0.001). The SFR improved significantly from 77.58%, 81.28%, 82.58% to 88.02% in groups A, B, C, and D, respectively (P < 0.001). There was a concomitant decrease in repeat SWL (re-treatment rate: A, 48.7%; B, 33.4%; C, 15.8%; and D, 10.1%; P < 0.001) and complication rates (A, 8%; B, 6.4%; C, 4.9%; and D, 1.6%; P < 0.001). This led to a rise in the efficiency quotient (EQ) in groups A–D from 50.41, 58.94, 68.78 to 77.06 (P < 0.001).The auxiliary procedure rates were similar in all groups (P = 0.62).

CONCLUSION

In conclusion, improvement in the EQ together with a concomitant decrease in complication rate can be achieved with optimum patient selection and use of various treatment optimising strategies.

 

Article of the Week: Pain relief after ureteric stent removal: think NSAIDs

Every week the Editor-in-Chief selects the Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying blog written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation. QC Kinetix’s charleston pain management relief center has decades of collective experience treating patients with all kinds of conditions. We make a concerted effort to treat each patient with professionalism and dignity as they work their way back to a pain-free life. We do everything in our power to earn the trust of each person that walks through our doors for treatment. Regenerative medicine is the future of medical care. QC Kinetix is offering non-invasive treatments that allow people to avoid going under the knife, while accelerating their recovery times and minimizing side effects. Discover why people across the state of South Carolina trust QC Kinetix when it comes to pain relief. At our clinic for pain management in Mt. Pleasant, SC, our specialists take the time to understand each patient’s needs and symptoms. We go out of our way to understand each person’s unique situation and how we can best treat their condition. Then, we very carefully formulate a plan to get them back to an active and healthy lifestyle. One of our most common treatments is laser therapy. We use non-invasive laser energy to target the affected area and reduce inflammation and pain. This triggers a photochemical response that initiates tissue repair and quickly improves a patient’s range of motion and functionality. Laser therapy is often the first step in our pain management plan before moving onto stem cell-based treatments.

Finally, the third post under the Article of the Week heading on the homepage will consist of additional material or media. This week we feature a video of  Michael Conlin discussing his paper.

If you only have time to read one article this week, it should be this one.

A single dose of a non-steroidal anti-inflammatory drug (NSAID) prevents severe pain after ureteric stent removal: a prospective, randomised, double-blind, placebo-controlled trial

Nicholas N. Tadros, Lisa Bland, Edith Legg, Ali Olyaei and Michael J. Conlin

OBJECTIVES

• To determine the incidence of severe pain after ureteric stent removal.

• To evaluate the efficacy of a single dose of a non-steroidal anti-inflammatory drug (NSAID) in preventing this complication.

 PATIENTS AND METHODS

• A prospective, randomised, double-blind, placebo-controlled trial was performed at our institution.

• Adults with an indwelling ureteric stent after ureteroscopy were randomised to receive either a single dose of placebo or an NSAID (rofecoxib 50 mg) before ureteric stent removal.

• Pain was measured using a visual analogue scale (VAS) just before and 24 h after stent removal.

• Pain medication use after ureteric stent removal was measured using morphine equivalents.

RESULTS

• In all, 22 patients were enrolled and randomised into the study before ending the study after interim analysis showed significant decrease in pain level in the NSAID group.

• The most common indication for ureteroscopy was urolithiasis (14 patients).

• The proportion of patients with severe pain (VAS score of [1]7) during the 24 h after ureteric stent removal was six of 11 (55%) in the placebo group and it was zero of 10 in the NSAID group (P < 0.01).

• There were no complications related to the use of rofecoxib.

 CONCLUSIONS

• We found a 55% incidence of severe pain after ureteric stent removal.

• A single dose of a NSAID before stent removal prevents severe pain after ureteric stent removal.

Read Previous Articles of the Week

Editorial: Stent removal need not be painful

Matthew Bultitude

Matthew Bultitude
Urology Centre, Guy’s and St Thomas’ NHS Foundation Trust, London, UK

Ureteric stents are undoubtedly a significant cause of morbidity while in situ [1].Whilst there are different options for removal, they are usually removed under local anaesthetic with the aid of a flexible cystoscope. This is an uncomfortable procedure and a proportion of patients seem to get fairly severe pain afterwards, which may be attributable to ureteric spasm. The pain after stent removal has not been well reported in the literature. In this issue of the BJUI we present a randomised controlled trial of a non-steroidal anti-inflammatory (NSAID) to dramatically reduce pain after stent removal.

This beautifully simple study by Tadros et al. [2] had simple aims: to determine the incidence of pain after stent removal and whether this could be reduced using a single oral dose of a NSAID given before the procedure. In a prospective randomised double-blind placebo controlled trial, the authors have shown a clear advantage to the use of active medication over placebo, such that the trial was stopped after an interim analysis. Using a visual analogue scale (VAS) the mean pain after stent removal was 2.7 in the NSAID group compared with 5.5 with placebo.More impressively the proportion of patients with severe pain (as defined as aVAS >=7) within 24 hours of stent removal was 0% vs. 55%. A corresponding reduction in narcotic use was seen (1.67 mg vs. 4.77 mg).

With increasing healthcare pressures on emergency departments and beds, and in the UK with financial penalties for re-admissions, this simple intervention has the potential to improve our own patients pain ratings and satisfaction and also reduce emergency consultations and even re-admissions. It should be noted that in this trial, there were two visits to the emergency department and one re-admission, all in the placebo group.

NSAIDs are thought to work through a number of mechanisms such as direct effect on pain pathways, reduced ureteric contractility and renal blood flow. This is thought to be a class effect for all NSAIDs. The drug used in this trial (rofecoxib) has subsequently been withdrawn from the market, although one would expect similar outcomes with other NSAID medications.

References
1 Joshi HB, Stainthorpe A, MacDonagh RP et al. Indwelling ureteral stents: evaluation of symptoms, quality of life and utility. J Urol 2003; 169: 1065–9
2 Tadros NN, Bland L, Legg E et al. A single dose of a non-steroidal anti-inflammatory drug (NSAID) prevents severe pain after ureteric stent removal: a prospective, randomised, double-blind, placebo-controlled trial. BJU Int 2013; 111: 116–20

Michael Conlin’s commentary on NSAIDs

Pain relief after ureteric stent removal: think NSAIDs

Nicholas N. Tadros, Lisa Bland, Edith Legg, Ali Olyaei and Michael J. Conlin*
Oregon Health & Science University and *Portland Veterans Administration Medical Center, Portland, OR, USA

OBJECTIVES

• To determine the incidence of severe pain after ureteric stent removal.

• To evaluate the efficacy of a single dose of a non-steroidal anti-inflammatory drug (NSAID) in preventing this complication.

PATIENTS AND METHODS

• A prospective, randomised, double-blind, placebo-controlled trial was performed at our institution.

• Adults with an indwelling ureteric stent after ureteroscopy were randomised to receive either a single dose of placebo or an NSAID (rofecoxib 50 mg) before ureteric stent removal.

• Pain was measured using a visual analogue scale (VAS) just before and 24 h after stent removal

• Pain medication use after ureteric stent removal was measured using morphine equivalents.

RESULTS

• In all, 22 patients were enrolled and randomised into the study before ending the study after interim analysis showed significant decrease in pain level in the NSAID group.

• The most common indication for ureteroscopy was urolithiasis (14 patients).

• The proportion of patients with severe pain (VAS score of ≥7) during the 24 h after ureteric stent removal was six of 11 (55%) in the placebo group and it was zero of 10 in the NSAID group (P < 0.01).

• There were no complications related to the use of rofecoxib.

CONCLUSIONS

• We found a 55% incidence of severe pain after ureteric stent removal.

• A single dose of a NSAID before stent removal prevents severe pain after ureteric stent removal.

Tadros NN, Bland L, Legg E, et al. A single dose of a non-steroidal anti-inflammatory drug (NSAID) prevents severe pain after ureteric stent removal: a prospective, randomised, double-blind, placebo-controlled trial. BJU Int 2013, 111: 101–105.

CALCITE UROLITHIASIS IN PATIENT WITH ACROMEGALY CONFIRMED BY PERCUTANEOUS REMOVAL AND INFRARED SPECTROSCOPIC ANALYSIS

Calcite is considered to rarely ever be a true component of urolithiasis being present only in 0.01% to 0.25% of all stones [1, 3, 4]. When found within analyzed stone material calcite is often characterized as “artifact”[5, 6] or “factitious”[5, 7, 8]. We report a 70 year-old gentleman with acromegaly found to have calcite stones among the stone mixture extracted from his kidney and mid-ureter. Thus we are certain that these calcite stones are not artifactual.

Authors: Viers, Boyd ; Williams, James; Lieske, John; Krambeck, Amy
Corresponding Author: Viers, Boyd

Boyd Viers, MD, James C. Williams, Jr., PhD, John Lieske, MD, Amy Krambeck, MD

 

Introduction
With urinary stone disease affecting approximately 4%-12% [1] of the population, many persons require evaluation and treatment to prevent recurrence. Determining the composition of calculi is an important piece of the workup, since the pathogenesis (and hence effective treatments) differ by stone type [2]. The most frequent components of calculi found in humans include whewellite (calcium oxalate monohydrate, or COM) in 78%, weddellite (calcium oxalate dihydrate, or COD) in 43% and calcium phosphate in the form of apatite in 33% [3]. Calcium carbonate (CaCO3) crystallizes as calcite, aragonite and vaterite. It is often found in pancreatic, biliary and salivary stones; however, calcite is considered to be a true component of urolithiasis only rarely, being present in 0.01% to 0.25% of all stones [1, 3, 4]. When found within analyzed stone material calcite is often characterized as “artefact” [5, 6] or “factitious”[5, 7, 8]. We report a 70 year-old gentleman with acromegaly found to have calcite stones among the stone mixture extracted from his kidney and mid-ureter. Thus we are certain that these calcite stones are not artefactual.

Case Report
A 70 year-old Caucasian male with a remote history of a single stone passage, acromegaly, type 2 diabetes and atrial fibrillation presented with a one month history of mild dysuria, intermittent left flank pain and dark urine. Urinalysis demonstrated microscopic haematuria. He was treated for presumed urinary tract infection without resolution of symptoms. CT urogram was obtained and demonstrated a 1.3 x 1.0 x 0.6 cm stone in the left mid-ureter with associated severe pyelocaliectasis and ureterectasis, with delayed excretion of contrast and two calyceal stones in the left kidney measuring 1.3 x 0.6 and 1.0 x 0.6 cm. The patient did not have a history of prior urological surgery, metabolic evaluation for stone prevention, or stone analysis.

The patient underwent attempted left retrograde ureteroscopy with conversion to percutaneous nephrolithotomy and removal of a 1.2 cm impacted mid-ureteric stone and 2 cm of stone material from the lower pole of the left kidney. Analysis of the left kidney stone in the Mayo clinical laboratory by infrared (IR) spectroscopy demonstrated 80% COM, 10% COD and 10% calcium phosphate in the form of apatite. One piece of stone from the lower pole was sent for culture, and it was negative for bacterial or fungal growth. The remainder of the stone material removed from the lower pole and mid-ureter (a total of 8 pieces; Figure 1) was sent to Indiana University, where it was analyzed using microscopic computed tomography (micro CT) and infrared spectroscopy[9]. By micro CT all 8 pieces appeared to be composed of admixtures of COM, COD, and apatite. However, two of the fragments had a smooth surface and were black, rather than the brown/gray appearance of the rest (Figure 2). Fourier Transform Infrared (FT-IR) spectroscopy analysis revealed that they were composed of calcite (Figure 3). A 24-hour urine collection revealed a low urine pH (5.2) high citrate (1273 mg) and calcium (333 mg). The resulting supersaturations for calcium oxalate (CaOx) (2.03 DG ; reference mean 1.77 DG) and uric acid (3.72 DG; reference mean 1.04 DG) were increased while for calcium phosphate it was low (-1.05 DG; reference mean 0.21 DG).

Discussion
About 1% of urinary stones presented for analysis are felt to have factitious features [1]. Some proportion of these false stones are due to contamination, for example when a specimen is dropped and another material is picked up in its place. But presentation of a false stone can also be a sign of psychiatric problems or drug addiction[10], so correct identification of factitious calculi is clinically important.

It is understandable that a stone would be assumed factitious if identified as calcite [10], since calcite is a common mineral in soil and gravel and its occurrence in urinary stones has not been well-documented. In the largest series in the literature Gault et al.[11] reported a series of 15 patients with 67 stones containing carbonate. All the specimens were spontaneously passed by the patients and later presented for analysis, although in many evidence was felt to be strong that these represented true and not factitious stones. A unique feature of the present study is that the stone specimens were removed from the patient’s kidney and mid-ureter by percutaneous access—with video recording of the procedure—thereby ruling out any possibility of the material being of foreign origin.

Calcium carbonate has been commonly described as a component of “milk of calcium” stones, which can rarely form as partially calcified fluid collections within obstructed regions of the upper urinary collecting system including hydronephrosis[12-15]. In Gault’s series, several patients had medullary sponge kidney, and he hypothesized that that high urine concentrations of bicarbonate, carbonate or calcium in an alkaline urine pH were important features. Furthermore, Gault demonstrated that calcite stones dissolved in vitro at a pH of 5.0 but not at 6.5, suggesting they would not persist in an acid milieu [11]. An interesting aspect of the current case is that not all of the stone fragments had the same composition. This diversity in stone composition and appearance has been described for medullary sponge kidney[16], and the calcite case described by Gault et al.[11]. In the current case a majority (6 of the 8 pieces recovered from the kidney and ureter) had the obvious appearance of mixed calcium oxalate stones, while 2 were darker in color and possessed a smoother surface. Computer tomography imaging and direct visualization of this patient’s kidney during percutaneous nephrolithotomy demonstrated no evidence of medullary sponge kidney, however his initial CT urogram demonstrated severe pyelocaliectasis and ureterectasis proximal to the obstructing mid-ureteral stone. In addition, it is interesting that the 24 hour urinary pH of this patient was quite acidic, which is not consistent with the formation or persistence of calcium carbonate crystals. Therefore, it seems likely that these particular stone fragments formed secondary to the isolated urinary space caused by the obstructing mid-ureteral stone, leading to severe proximal hydroureteronephrosis and urinary stasis.

Conclusion

Calcite is commonly found in salivary and biliary sones, and in the relatively unusual case of milk of alkali stones that can form behind renal obstructions. The current study and review of the literature suggests calcite can sometimes be a mineral component of true renal calculi. However, the mechanisms underlying their formation are likely to be unique and involve a microenvironment of stasis, alkalinity, and abundant calcium. If calcite occurs in mixture with other minerals—as in the present case—its presence will likely go undetected by typical analysis methods, and as such may be underreported in the literature. Furthermore, physicians should not automatically assume that all calcite stones are artefactual or factitious in nature.

Acknowledgments
This work was supported by grants from the National Institutes of Health including the Mayo Clinic O’Brien Urology Research Center P50 DK083007 and the Mayo Clinic Center for Translational Science Activities. We are also thankful to Brittni Barnett for coordinator support during the study. This study was approved by the Mayo Clinic Institutional Review Board.

References
[1] Daudon M, Donsimoni R, Hennequin C, et al. Sex- and age-related composition of 10 617 calculi analyzed by infrared spectroscopy. Urol Res. 1995: 23:319-26
[2] Miller NL, Lingeman JE. Management of kidney stones. BMJ. 2007 Mar 3: 334:468-72
[3] Schubert G. Stone analysis. Urol Res. 2006 Apr: 34:146-50
[4] Leusmann DB, Blaschke R, Schmandt W. Results of 5,035 stone analyses: a contribution to epidemiology of urinary stone disease. Scand J Urol Nephrol. 1990: 24:205-10
[5] Sabot JF, Bornet CE, Favre S, Sabot-Gueriaux S. The analysis of peculiar urinary (and other) calculi: an endless source of challenge. Clin Chim Acta. 1999 May: 283:151-8
[6] Hesse A, Miersch WD. Special aspects of stone composition and aetiology of different types of urinary calculi. Int Urol Nephrol. 1989: 21:257-67
[7] Chettouh-Harrache D, Amar A, Taleb S, Bouhacina N, Auberthie R. [Factitious lithiasis: Case report from Western Algeria]. Sante. 2004 Oct-Dec: 14:257-60
[8] el Khader K, el Mamoun M, Koutani A, Ibn Attya A, Hachimi M, Lakrissa A. Unusual case of Munchausen’s syndrome: factitious vesical lithiasis. Acta Urol Belg. 1998 Dec: 66:33-5
[9] Krambeck AE, Khan NF, Jackson ME, Lingeman JE, McAteer JA, Williams JC, Jr. Inaccurate reporting of mineral composition by commercial stone analysis laboratories: implications for infection and metabolic stones. J Urol. 2010 Oct: 184:1543-9
[10] Gault MH, Campbell NR, Aksu AE. Spurious stones. Nephron. 1988: 48:274-9
[11] Gault MH, Chafe L, Longerich L, Mason RA. Calcium and calcium magnesium carbonate specimens submitted as urinary tract stones. J Urol. 1993 Feb: 149:244-9
[12] McCorkell SJ, Hefty TR, Dowling AD. Bilateral milk-of-calcium urine and hydronephrosis. J Urol. 1985 Jan: 133:77-8
[13] Uesugi T, Ichikawa T. Atypical findings in a patient with a renal milky stone including a cake of stone. Int J Urol. 2006 Aug: 13:1109-11
[14] Ulusan S, Koc Z. Milk of calcium collection in the differential diagnosis of giant renal calculus. Br J Radiol. 2008 Feb: 81:e35-6
[15] Melekos MD, Kosti PN, Zarakovitis IE, Dimopoulos PA. Milk of calcium cysts masquerading as renal calculi. Eur J Radiol. 1998 Aug: 28:62-6
[16] Daudon M, Bader CA, Jungers P. Urinary calculi: review of classification methods and correlations with etiology. Scanning Microsc. 1993 Sep: 7:1081-104; discussion 104-6

fig 1 w text final2

Figure 1. Left Lower Calyx and Mid-Ureter Stone Material

Fig 2 w text final2

Figure 2.

Fig 3 w text final2

Figure 3. Fourier Transform Infrared (FT-IR) Spectroscopy

Date added to bjui.org: 11/11/2012

DOI: 10.1002/BJUIw-2012-057-web

 

Second-degree burn after shock wave lithotripsy: an unusual complication

We present an unreported complication of a second-degree burn sustained by a 62-year-old male who underwent shockwave lithotripsy for two renal calculi. 

 

Authors: Sriram Rangarajan1, Hossein Mirheydar1, Roger L. Sur1,2

1. UC San Diego Health Sciences, Department of Surgery, Division of Urology; San Diego, CA
2. VA San Diego Medical Center, San Diego, CA

Corresponding Author: Roger L. Sur, MD, UC San Diego Health Sciences, Division of Urology, 200 W Arbor Dr. #8897, San Diego, CA 92103-8897. T: 619-543-2630   E-mail: [email protected]

Abstract
We present an unreported complication of a second-degree burn sustained by a 62-year-old male who underwent shockwave lithotripsy for two renal calculi.  The patient was treated conservatively for his burn injury but did require several ancillary procedures to render him stone free.  We speculate that the number of shocks and bubbles associated with an unapproved coupling medium for this particular lithotripter may have led to this highly unusual adverse event.

 

Introduction
 
Shockwave lithotripsy is considered a minimally invasive procedure for upper tract urinary stone disease with the obvious benefit of minimal side effects and rare adverse events.  These advantages have helped evolve it into a common surgical treatment modality especially due to its safety profile.  We report an unusual adverse event following shockwave lithotripsy involving a second degree skin burn at the coupling site.

 

Case Report
 
A 62-year-old Caucasian male presented with gross hematuria and left-flank pain. He had been seen in the emergency department 18 months prior for left-flank pain associated with two calcifications (a 9 mm midcalyceal calculus and an 8 mm lower pole calculus).  The patient’s past medical history was unremarkable. His medications included allopurinol, 300 mg, and aspirin, 81 mg, both of which he had discontinued one week prior to procedure. Physical examination revealed mild left costovertebral angle tenderness.  Computerized tomography (CT) urogram of the abdomen and pelvis demonstrated the two previously noted renal calculi  (10 mm,1500 HU in the left calyx and 9mm,1000 HU in the left calyx ).  Cystoscopy and cytological examination of two urine specimens did not reveal any abnormality.
The patient opted for shockwave lithotripsy (SWL). An electromagnetic lithotripter (Medispec EM1000, Germantown, MD), which our institution leases from Medispec, was used, and 4000 shocks (2000 to each calculus) were delivered at 90 shocks/minute after gradually increasing the power to 20kV. The Medispec technician did not have the standard coupling gel recommended by Medispec and instead used ultrasound gel available from the hospital.  In the recovery unit, the entire skin overlying the area where the gel had been placed was noted to be moderately erythematous with 3-4 cm central area of subcutaneous hemorrhage (figure 1).

 

Figure 1. demonstrates the immediate post-operative changes noted in the recovery unit: erythema and central region of petechiae
The patient returned on postoperative day 1 with significantly increased erythema and the development of large blisters (figure 2).  He also noted some abdominal pain, gross hematuria and passage of small fragments. The burn surgery service was consulted. A second-degree burn was confirmed, and local debridement was performed along with application of Collegnase, polymyxin B, xeroform, and gauze dressings.

 

Figure 2 demonstrates development of marked erythema and bullae on post-operative day 1

 

 

The patient returned again on postoperative day 5 complaining of left-flank pain and vomiting. The  wound remained erythematous with denuded skin. A noncontrast CT of his abdomen and pelvis CT  demonstrated an interval decrease in stone burden but multiple fragmented calculi (900HU) in the lower calyx as well as at least two adjacent 6 mm calculi in the proximal ureter (HU 1000). The patient consented to ureteroscopy with Ho:YAG laser lithotripsy.  During the left ureteroscopy with Ho:YAG laser lithotripsy and ureteric stenting, the ureteric calculi migrated into the kidney and one large calculus was fragmented.  A significant amount of mucous material in the urine precluded good visualization. The indwelling stent was removed 6 days later at outpatient cystoscopy.
Renal ultrasound performed 5 weeks later demonstrated a moderate left hydronephrosis and CT of the abdomen and pelvis revealed a 2 cm column of distal ureteral calculi. Subsequent ureteroscopy was aborted because of an iatrogenic extraperitoneal bladder perforation during dilation of an unexpected bulbar urethral stricture encountered during initial cystoscopy.  After documenting healing of the bladder, left ureteroscopy with Ho:YAG laser lithotripsy and ureteraic stenting was performed 10 days later. This rendered the patient stone free, as confirmed by direct visualization. Outpatient cystoscopic stent removal was performed 5 days later. He was asymptomatic two months afterwards with normal voiding and a  normal appearance on renal ultrasound.

 

Discussion
 
Complications following SWL are rare but include renal hematoma 1-13 % [1-3], steinstrasse 2-10% [4], acute renal injury, and theoretically, chronic renal injury such as a risk of hypertension [5].  To our knowledge this is the first case documenting a second-degree skin burn following SWL treatment.  There is no obvious explanation for this unusual adverse event, but some facts specific to this individual case deserve mention.  Firstly, we acknowledge that 4000 shocks might be considered marginally high. However, this has been routinely delivered with this particular lithotriptor in appropriate cases where calculi were in different renal locations, and this adverse event had never been experienced previously.  The two stones was located in different regions of the kidney and required 2000 shocks to adequately fragment under fluoroscopy.  It is tempting to surmise that a fewer shocks would have prevented this outcome.
We also note that conventional ultrasound gel was used in lieu of standard coupling gel approved for use with the Medispec EM1000 lithotripter.  The Medispec-recommended coupling medium is Lithoclear gel (Sonotech, Bellingham, WA). It has a density of 1.013 g/cc and is made of water-based couplants with a general composition of >80% water, 5 to 15% propylene glycol, 1 to 5 % glycerine, an acrylic polymer and a cosmetic-grade preservative.  The Lithoclear gel is filled and reportedly packaged under tighter controls than ultrasound gel to ensure that the containers are absolutely free of micro- and macrobubbles that would cause reflection or scattering of shock wave acoustics during SWL [6].  Anecdotally, it has higher viscosity than ultrasound gel. Higher viscosity may result in lower tendency to form bubbles [7].  The ideal medium would mimic the viscosity of water to minimize loss of energy but would be viscous enough that it would not run off the patient during the procedure.  The medium should also be devoid of air bubbles, as they are thought to further attenuate the energy transmission to the patient. Just as cavitation functions to fragment calculi during lithotripsy, some have proposed that cavitation of bubbles within the coupling medium is responsible for skin pain [7].  Could the skin burn be attributed to cavitation of excessive bubbles within the nonapproved ultrasound gel? Ultrasound gel is routinely used as a coupling agent in some centers, though ensuring the presence of bubbles is minimized is commonly advocated [8].  We can only speculate that excessive cavitation from the coupling medium associated with an elevated number of delivered shocks may have been sufficient to generate a thermal injury.  Another explanation is heat generated from the water-filled cushion, though there is no plausible reason to think this is possible.  The specific lithotripter used for this case was evaluated by the maker, Medispec, and no mechanical abnormalities were discovered.

 

References

 

1. Evan AP, Willis LR (2007). Extracorporeal shock wave lithotripsy: complications. In: Smith AD, Badlani G, Bagley D, eds. Smith’s Textbook of Endourology. 2nd ed. Hamilton, ON, BC Decker, 2007; chap 41: 353–65.
2. Orozco Farinas R, Iglesias Prieto JI, Massarrah Halabi J, Mancebo Gómez JM, Perez-Castro Ellendt E. Renal hematoma after extracorporeal shockwave lithotripsy in a series of 324 consecutive sessions with the DOLI-S lithotripter: incidents, characteristics, multifactorial analysis and review. Arch Espan Urol. 2008; 61: 889–914.
3. Mobley TB. Low energy lithotripsy with the lithostar: treatment results with 19,962 renal and ureteral stones. J Urol. 1993; 149: 1419–24.
4. Madbouly K, Sheir KZ, Elsobky E, Eraky I, Kenawy M. Risk factors for the formation of a steinstrasse after extracorporeal shock wave lithotripsy: a statistical model. J Urol. 2002; 167: 1239–42.
5. Lingeman JE, McAteer JA, Assimos DG, Baxley J, Kahn RI, Krambeck A, Matlaga BR, Penson D, Preminger GM, Zhong P. White Paper: Current Perspective on Adverse Effects in Shock Wave Lithotripsy. American Urological Association Education and Research, 2009.
6. Email communication with Sonotech.
7. Heidenreich A, Bonfig R, Wilbert DM, Engelmann UH. Painless ESWL by cutaneous administration of Vaseline. Urologe A. 1995 Jul;34(4):343-7. German
8. Cartledge JJ, CrossWR, Lloyd SN, Joyce AD. The efficacy of a range of contact media as coupling agents in extracorporeal shockwave lithotripsy. BJU Int. 2001; 88: 321–4.

 

Date added to bjui.org: 25/04/2012 


DOI: 10.1002/BJUIw-2012-006-web

 

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