Management of kidney stones

Reducing postoperative morbidity of mini-invasive percutaneous nephrolithotomy: Would it help if blood vessels are left unharmed during puncture? A CONSORT-prospective randomized trial

BACKGROUND

The aim of this study was to provide a randomized controlled trial comparing single B-mode ultrasound guidance and color doppler ultrasound guidance in minimally invasive percutaneous nephrolithotomy.

METHODS

Three hundred patients with renal calculus were prospectively randomly assigned into 2 groups. In group 1 (150 patients), minimally invasive percutaneous nephrolithotomy (m-PCNL) were managed with single B-mode ultrasound guidance; In group 2 (150 patients), m-PCNL were managed with color Doppler ultrasound guidance and a needle bracket in order to guide placement at a target location beneath the skin. The characteristics of patients, operation, complications and prognosis, including body temperature, urine culture, and hematologic tests after the operation were recorded and compared.

RESULTS

Our vessel-sparing technique showed a statistically significant decrease in hemoglobin drop, postoperative procalcitonin values, the frequency of postoperative fever, systemic inflammatory response syndrome, and urosepsis (P < .05).

CONCLUSION

Using color Doppler ultrasound in real time and a needle bracket to detect and avoid main renal blood vessels decreased incidences of hemorrhagic complications and postoperative infection.

Does extracorporeal shockwave lithotripsy therapy affect thiol-disulfide homeostasis?

Objective:

Extracorporeal Shockwave Lithotripsy (ESWL) is a non-invasive method that is effective at crushing stones in the upper urinary tract. Disturbance of the thiol/disulfide homeostasis, in favor of the disulfide, has been shown to be involved in the disease pathogenesis.

Methods:

A total of 36 individuals that underwent ESWL had blood samples collected before ESWL (0hrs), 6hrs, and one week after the ESWL. Sera native and total as wells as disulfide amount was measured using an automated method sodium borohydrate (NaBH₄) reduction. In addition, Ischemia Modified Albumin (IMA) levels were measured using colorimetric assay method.

Results:

Native thiol level was reduced at the 6th hour following ESWL compared to baseline. While the ratios of disulfide level, Disulfide/Total Thiol (DTT), Disulfide/Native Thiol (DNT) and IMA level were increased at the 6th hour following ESWL compared to baseline, they were found to be similar with their baseline values at the end of 1st week. Total thiol and native /total thiol did not show any significant change.

Conclusions:

ESWL treatment disrupts thiol/disulfide homeostasis and the structure of albumin at the acute term. Therefore, it increases protein oxidation and leads to increased oxidative stress. However, this state is transient and returns to normal within the proceeding days.

Risk factors for acute kidney injury after percutaneous nephrolithotomy: Implications of intraoperative hypotension

Percutaneous nephrolithotomy (PNL) is a minimally invasive technique for renal stone removal but can cause renal parenchymal injury. Renal stones can also affect renal function. We evaluated the risk factors for acute kidney injury (AKI) after PNL.The study cohort included 662 patients who underwent PNL. Patient characteristics, preoperative laboratory values, intraoperative data, and stone characteristics were collected. Univariate and multivariate logistic regression analyses were performed to identify risk factors for AKI after PNL. Postoperative outcomes such as hospitalization, intensive care unit admission rate and stay duration, and chronic kidney disease were also evaluated.Of the total study series, there were 107 (16.2%) cases of AKI after PNL (AKI group), and 555 (83.8%) patients who showed no injury (no-AKI group). The risk factors for AKI after PNL were found to be a higher preoperative serum uric acid level [odds ratio (OR) = 1.228; 95% confidence interval (95% CI) = 1.065-1.415; P = .005], longer operation time (OR = 1.009; 95% CI = 1.004-1.014; P < .001), and intraoperative hypotension (OR = 12.713; 95% CI = 7.762-20.823; P < .001). Hospitalization and intensive care unit stay duration were significantly longer in the AKI group (8.7 ± 5.2 vs 6.6 ± 2.8 days, P < .001; 0.34 ± 1.74 vs 0.07 ± 0.48 days, P = .002, respectively). Chronic kidney disease was also significantly higher in the AKI group (63.6% vs 32.7%, P = .024).As intraoperative hypotension is an important risk factor for AKI after PNL, which leads to poor postoperative outcomes, it should be prevented or managed vigorously during PNL.

Surgical management of urolithiasis - a systematic analysis of available guidelines

Background

Several societies around the world issue guidelines incorporating the latest evidence. However, even the most commonly cited guidelines of the European Association of Urology (EAU) and the American Urological Association (AUA) leave the clinician with several treatment options and differ on specific points. We aimed to identify discrepancies and areas of consensus between guidelines to give novel insights into areas where low consensus between the guideline panels exists, and therefore where more evidence might increase consensus.

Methods

The webpages of the 61 members of the Societé Internationale d’Urologie were analysed to identify all listed or linked guidelines. Decision trees for the surgical management of urolithiasis were derived, and a comparative analysis was performed to determine consensus and discrepancies.

Results

Five national and one international guideline (EAU) on surgical stone treatment were available for analysis. While 7 national urological societies refer to the AUA guidelines and 11 to the EAU guidelines, 43 neither publish their own guidelines nor refer to others. Comparative analysis revealed a high degree of consensus for most renal and ureteral stone scenarios. Nevertheless, we also identified a variety of discrepancies between the different guidelines, the largest being the approach to the treatment of proximal ureteral calculi and larger renal calculi.

Conclusions

Six guidelines with recommendations for the surgical treatment of urolithiasis to support urologists in decision-making were available for inclusion in our analysis. While there is a high grade of consensus for most stone scenarios, we also detected some discrepancies between different guidelines. These are, however, controversial situations where adequate evidence to assist with decision-making has yet to be elicited by further research.

Dietary Plants for the Prevention and Management of Kidney Stones: Preclinical and Clinical Evidence and Molecular Mechanisms

Kidney stones are one of the oldest known and common diseases in the urinary tract system. Various human studies have suggested that diets with a higher intake of vegetables and fruits play a role in the prevention of kidney stones. In this review, we have provided an overview of these dietary plants, their main chemical constituents, and their possible mechanisms of action. Camellia sinensis (green tea), Rubus idaeus (raspberry), Rubia cordifolia (common madder), Petroselinum crispum (parsley), Punica granatum (pomegranate), Pistacia lentiscus (mastic), Solanum xanthocarpum (yellow-fruit nightshade), Urtica dioica (stinging nettle), Dolichos biflorus (horse gram), Ammi visnaga (khella), Nigella sativa (black-cumin), Hibiscus sabdariffa (roselle), and Origanum vulgare (oregano) have received considerable interest based on scientific evidence. Beside these dietary plants, phytochemicals—such as catechin, epicatechin, epigallocatechin-3-gallate, diosmin, rutin, quercetin, hyperoside, and curcumin—as antioxidant dietary phyto-phenols were found to be effective for the prevention of urolithiasis (the process of stone formation in the urinary tract). The main underlying mechanisms of these dietary plants and their isolated phytonutrients in the management of urolithiasis include diuretic, antispasmodic, and antioxidant activity, as well as an inhibitory effect on crystallization, nucleation, and aggregation of crystals. The results as presented in this review demonstrate the promising role of dietary plants and phytophenols in the prevention and management of kidney stones. Further investigations are required to confirm the safety and efficacy of these compounds.

Factors affecting the urologist's decision to administer ureteral stone therapy: a retrospective cohort study

Objective

We aimed to evaluate the factors influencing treatment option selection among urologists for patients with ureteral stones, according to the stone diameter and location.

Methods

We retrospectively reviewed the records of 360 consecutive patients who, between January 2009 and June 2014, presented to the emergency department with renal colic and were eventually diagnosed with urinary stones via computed tomography. The maximal horizontal and longitudinal diameter and location of the stones were investigated. We compared parameters between patients who received urological intervention (group 1) and those who received medical treatment (group 2).

Results

Among the 360 patients, 179 (49.7%) had stones in the upper ureter and 181 (50.3%) had stones in the lower ureter. Urologic intervention was frequently performed in cases of upper ureteral stones (P<0.001). In groups 1 and 2, the stone horizontal diameters were 5.5 mm (4.8 to 6.8 mm) and 4.0 mm (3.0 to 4.6 mm), stone longitudinal diameters were 7.5 mm (6.0 to 9.5 mm) and 4.4 mm (3.0 to 5.5 mm), and ureter diameters were 6.4 mm (5.0 to 8.0 mm) and 4.7 mm (4.0 to 5.3 mm), respectively (P<0.001). The cut-off values for the horizontal and longitudinal stone diameters in the upper ureter were 4.45 and 6.25 mm, respectively (sensitivity 81.3%, specificity 91.4%); those of the lower ureter were 4.75 and 5.25 mm, respectively (sensitivity 79.4%, specificity 79.4%).

Conclusion

The probability of a urologic intervention was higher for patients with upper ureteral stones and those with stone diameters exceeding 5 mm horizontally and 6 mm longitudinally.

Pain Relieving Effect of Sublingual Glycerol Trinitrate in Renal Colic: a Randomized Placebo-Controlled Trial

Introduction:

Renal colic is caused by colicky spasms of ureters. As has been shown in previous experiments, glycerol trinitrate (TNG) can inhibit these muscular spasms.

Objective:

This study was performed to assess the pain relieving effect of TNG among patients referred due to renal colic pain to the emergency department (ED).

Methods:

This study is a randomized, placebo-controlled study on 60 patients with renal colic who were referred to the ED, who were diagnosed clinically to have renal colic, and their pain was more than 5 based on a visual analogue scale (VAS). The patient's pain was recorded at the moment of clinical diagnosis, and each one received one capsule, either 0.4 mg TNG or placebo, plus a 100 mg indomethacin suppository. The pain score was re-assessed after 5 and 30 min. The values were recorded and compared using SPSS-16 software.

Results:

Sixty patients with a mean age of 35.75 ± 11.99 years were enrolled (73.3% male). Patients in the two groups were matched for age (p = 0.290), sex (p = 0.559), and the presence of microscopic hematuria (p = 0.292). Pain relief from the start point until the end of the intervention was statistical different in all studied patients (p < 0.05); but the comparison between the two groups showed no significant difference in this regard (p = 0.440).

Conclusion:

It is likely that adding TNG to an indomethacin suppository had no significant effects on better pain management of patients referred with renal colic to the ED.

How to accelerate the upper urinary stone discharge after extracorporeal shockwave lithotripsy (ESWL) for < 15 mm upper urinary stones: a prospective multi-center randomized controlled trial about external physical vibration lithecbole (EPVL)

OBJECTIVE

To asset the efficacy and safety of EPVL plus ESWL compared with ESWL alone for the treatment of simple upper urinary stones (< 15 mm).

MATERIALS AND METHODS

All patients with upper urinary stones (< 15 mm) were prospectively randomized into two groups. In treatment group, patients were assigned to immediate EPVL after ESWL, while in control group, ESWL alone was offered. All patients were reexamined at 1, 2, and 4 weeks after ESWL. Stone size, stone location, stone-free rate (SFR), and complication rate were compared.

RESULTS

56 males and 20 females in treatment group were compared to 52 male and 25 females in control group (p = 0.404). Median ages were 42.9 ± 1.5 years in treatment group and 42.7 ± 1.3 years in control group (p = 0.943). Median stone size was 10.0 ± 0.4 mm (3-15 mm) in treatment group and 10.4 ± 0.4 mm (4-15 mm) in control group (p = 0.622). The stone clearance rate in treatment and control group at 1 week after ESWL was 51.3% (39/76) and 45.4% (35/77) (p > 0.05), at 2 weeks was 81.6% (62/76) and 64.9% (50/77) (p < 0.05), and at 4 weeks was 90.8% (69/76) and 75.3% (58/77) (p < 0.05), respectively.

CONCLUSIONS

EPVL is a noninvasive, effective, and safe adjunctive treatment which increases and accelerates upper urinary stones discharge after ESWL treatment.

Evaluation of selected Doppler parameters of renal blood flow in patients undergoing extracorporeal shock wave lithotripsy

Introduction

Despite the risk of complications, which does not exceed several percent, extracorporeal shock wave lithotripsy (ESWL) causes morphological and functional changes in kidneys as a result of the effect of the generated shock wave energy on the renal parenchyma structure.

Material and methods

Forty-two patients were included in the study. The mean age in the studied group was 50.9 years (SD ±13.7). Extracorporeal lithotripsy treatments were carried out during the period from January 2014 to April 2014 using an electromagnetic shock wave generator. The spectrum of blood flow of the interlobar arteries of both the treated and the opposite kidney was investigated. On the basis of these spectrums, parameters such as: resistive index (RI), pulsatility index (PI) and acceleration time (AT) were calculated.

Results

The ESWL treatment causes a statistically significant increase of the RI parameter in the ipsilateral kidney (p <0.0001) as well as in the opposite kidney (p <0.0001). The RI value decreases after 92 hours after the treatment, reaching statistical significance in both kidneys (p <0.005). The PI parameter substantially increases after treatment in both kidneys (p <0.0001), and decreases after 92 hours (p <0.0001). Statistically significant correlations are shown between RI as well as the PI parameters and the patient's age.

Conclusions

Extracorporeal shock wave lithotripsy (ESWL) of renal stones causes temporary impairment of the renal perfusion in both ipsilateral and contralateral kidneys. The main factor that determines the value of the RI and PI parameters is the patient's age.

Analgesia for patients undergoing shockwave lithotripsy for urinary stones - a systematic review and meta-analysis

Background

Shock wave lithotripsy (SWL) is the first line treatment modality for a significant proportion of patients with upper urinary tracts stones. Simple analgesics, opioids and non-steroidal anti-inflammatory drugs (NSAIDs) are all suitable agents but the relative efficacy and tolerability of these agents is uncertain.

Objectives

To determine the efficacy of the different types of analgesics used for the control of pain during SWL for urinary stones.

Materials and Methods

We searched the Cochrane Renal Group’s Specialised Register, MEDLINE, EMBASE and also hand-searched reference lists of relevant articles (Figure-1). Randomised controlled trials (RCT’s) comparing the use of any opioid, simple analgesic or NSAID during SWL were included. These were compared with themselves, each-other or placebo. We included any route or form of administration (bolus, PCA). We excluded agents that were used for their sedative qualities. Data were extracted and assessed for quality independently by three reviewers. Meta-analyses have been performed where possible. When not possible, descriptive analyses of variables were performed. Dichotomous outcomes are reported as relative risk (RR) and measurements on continuous scales are reported as weighted mean differences (WMD) with 95% confidence intervals.

Results

Overall, we included 9 RCTs (539 participants from 6 countries). Trial agents included 7 types of NSAIDs, 1 simple analgesic and 4 types of opioids. There were no significant differences in clinical efficacy or tolerability between a simple analgesic (paracetamol) and an NSAID (lornoxicam). When comparing the same simple analgesic with an opioid (tramadol), both agents provided safe and effective analgesia for the purpose of SWL with no significant differences. There were no significant differences in pain scores between NSAIDs or opioids in three studies. Adequate analgesia could be achieved more often for opioids than for NSAIDs (RR 0.358; 95% CI 043 to 0.77, P=0.0002) but consumed doses of rescue analgesia were similar between NSAIDs and opioids in two studies (P=0.58, >0.05). In terms of tolerability, there is no difference in post-operative nausea and vomiting (PONV) between the groups (RR 0.72, 95% CI 0.24 to 2.17, P=0.55). One study compared outcomes between two types of NSAIDs (diclofenac versus dexketoprofen). There were no significant differences in any of our pre-defined outcomes measures.

Conclusion

Simple analgesics, NSAIDs and opioids can all reduce the pain associated with shock wave lithotripsy to a level where the procedure is tolerated. Whilst there are no compelling differences in safety or efficacy of simple analgesics and NSAIDs, analgesia is described as adequate more often for opioids than NSAIDs.

Postrenal acute kidney injury in a patient with unilateral ureteral obstruction caused by urolithiasis: A case report

RATIONALE

In patients with bilateral ureteral obstruction, the serum creatinine levels are often elevated, sometimes causing postrenal acute kidney injury (AKI). In contrast, those with unilateral ureteral obstruction present normal serum creatinine levels, as long as their contralateral kidneys are preserved intact. However, the unilateral obstruction of the ureter could affect the renal function, as it humorally influences the renal hemodynamics.

PATIENT CONCERNS

A 66-year-old man with a past medical history of hypertension and diabetes mellitus came to our outpatient clinic because of right abdominal dullness.

DIAGNOSES

Unilateral ureteral obstruction caused by a radio-opaque calculus in the right upper ureter and a secondary renal dysfunction.

INTERVENTIONS

As oral hydration and the use of calcium antagonists failed to allow the spontaneous stone passage, extracorporeal shock wave lithotripsy (ESWL) was performed.

OUTCOMES

Immediately after the passage of the stone, the number of red blood cells in the urine was dramatically decreased and the serum creatinine level almost returned to the normal range with the significant increase in glomerular filtration rate.

LESSONS

Unilateral ureteral obstruction by the calculus, which caused reflex vascular constriction and ureteral spasm in the contralateral kidney, was thought to be responsible for the deteriorating renal function.

A pilot study evaluating changes to haematological and biochemical tests after Flexible Ureterorenoscopy for the treatment of kidney stones

BACKGROUND

Currently there is limited research documenting the changes in blood parameters, following Flexible Ureterorenoscopy. This study aims to determine whether there are any changes in haematology and biochemistry parameters, following Flexible Ureterorenoscopy for the treatment of kidney stones.

METHODS

40 consecutive patients aged between 27-87 years (median 49 years) undergoing Flexible Ureterorenoscopy for the treatment of kidney stones were recruited (26 male, 14 female). Blood samples were collected from each patient at four time points: baseline (pre-operatively) followed by 30 minutes, 120 minutes and 240 minutes post-operatively. On these samples, routine haematological and biochemistry tests were carried out. In addition to the assessment of clinical parameters prospectively from the medical notes.

RESULTS

There was a significant decrease observed following Flexible Ureterorenoscopy in the following parameters: lymphocytes (p = 0.007), eosinophils (p = 0.001), basophils (p = 0.001), haemoglobin (p = 0.002), red blood cells (p = 0.001), platelet count (p = 0.001), fibrinogen concentration (p = 0.001), von Willebrand factor (p = 0.046), C reactive protein (p = 0.01), total protein (p = 0.001), albumin (p = 0.001), globulin (p = 0.001) and alkaline phosphatase (p = 0.001). In addition, there was a significant increase observed in the following parameters: white blood cells (p = 0.001), neutrophils (p = 0.001), activated partial thromboplastin time (p = 0.001), total bilirubin (p = 0.012), creatinine (p = 0.008), sodium (p = 0.002) and potassium (p = 0.001). Limiting factors for this study were the sample size, and restriction on the recruitment time points.

CONCLUSIONS

Significant changes were noted to occur in haematology and biochemistry parameters following Flexible Ureterorenoscopy. Some of the data presented in this study may represent the 'normal' post-operative response following FURS, as no major complications occurred, in the majority of our patients. This data on the 'normal response' will need to be validated but may ultimately aid clinicians in distinguishing patients at risk of complications, if reproduced in larger multi-centre studies.

Prevalence of diabetes mellitus after extra corporeal shock wave lithotripsy in 15 years follow-up

Objective:

To investigate the hypothesis that extracorporeal shock wave lithotripsy (ESWL) increases the risk of new onset diabetes mellitus (DM) or significant changes in fasting blood sugar (FBS).

Materials and Methods:

A total number of 307 patients enrolled in this study. All of them had undergone ESWL for kidney stone from 1991 to 1994. In 2009, after 15-19 years, we invited patients to check their blood sugar.

Results:

There were 307 patients, 19.8% females, and 80.1% males. The mean age of the patients was 44 for females and 42 years for males. 47.5% had kidney stone in the left side, 42.9% in the right side and 9.4% bilateral. The mean FBS increasing was 11.86 g/dl. It was 14.54 g/dl for the right side, 8.57 g/dl for left and 16.24 g/dl for bilateral ESWL.

Discussions:

The increasing of FBS is more significant in shock wave intensities higher than 15.5 KV. And there wasn't any significant relationship between age, sex, body mass index (BMI) and total number of shock waves with increasing of FBS. ESWL treatment might associate with increasing FBS without any relation to age, sex and BMI.

Retrograde intrarenal surgery for renal stones - Part 1

The main aim in the treatment of renal stones is to clearance of the stones completely with the least morbidity. Parallel to the improvements in technology during recent years, new flexible ureterorenoscopes and effective lithotripters such as holmium laser have been developed, thus retrograde intrarenal surgery (RIRS) has become an efficient and safe option in the management of urinary system stone disease with a gradually increasing popularity. Therewithal, innovations in auxiliary equipment such as guide-wires, ureteral access sheath and stone baskets have made this procedure more effective. With this modality, nowadays, the vast majority of renal stones can be treated successfully without need of open surgery or percutaneous nephrolithotomy. RIRS can be used as a primary treatment in patients with renal stones smaller than 2 cm, in cases with prior unsuccessful shock wave lithotripsy (SWL), infundibular stenosis, renoureteral malformation, musculoskeletal deformity, bleeding diathesis as well as obese patients. The efficiency of this procedure has been also proved in pediatric patients. In the first part of this detailed review for RIRS, history, indications and contraindications, preoperative preparation, antibiotic prophylaxis, anesthesia, surgical technique related to flexible ureteroscopes and auxiliary equipment being used, postoperative care and complications of this operation are discussed with up-to-date literature.

[S2k guidelines on diagnostics, therapy and metaphylaxis of urolithiasis (AWMF 043/025) : Compendium]

Every tenth German citizen will suffer from at least one urinary calculus during the lifetime. The diagnostics, treatment and follow-up treatment of urolithiasis are, therefore, part of the daily routine practice for all urologists in hospitals and private practices as well as in many other disciplines, such as general practitioners, internists, nephrologists and pediatricians. Although the diagnostics and therapy have experienced substantial alterations over the last 10 years, the possibilities of metabolic diagnostics and secondary prevention for patients at risk are, unfortunately and unjustly, in many places very poorly represented. The present S2k guidelines, which for the first time were established in an interdisciplinary consensus process, represent the current practical recommendations and, whenever possible, use tables and algorithms in order to facilitate easy reference in the routine daily work. Last but not least, this greatly simplifies the measures for metaphylaxis.

Current ESWL practice and outcomes in the UK: A multicentre snapshot

Objectives:

The objective of this article is to investigate the current clinical practice and outcomes of extracorporeal shock wave lithotripsy (SWL) in the United Kingdom.

Patients and methods:

Patient demographics, stone characteristics and SWL protocols were collected prospectively for 30 consecutive new patient referrals at each of seven contributing UK institutions performing SWL. Final outcomes in terms of stone-free rates (SFRs), and complications were recorded.

Results:

Completed demographic data were available for 204 patients. Treatment protocols varied between centres. Mean patient age was 51 years. Over 70% of stones treated measured between 5 and 10 mm, and one-third were in the ureter, with two-thirds in the kidney, where the majority (31% overall) were in the lower pole. The overall cumulative SFR was 50.3% (range 33–70% between centres). SWL was notably more effective for ureteric stones (SFR 59.3% overall) than for renal calculi (SFR 45.6% overall). Complications were noted in six patients.

Conclusion:

This study provides a valuable snapshot of real-life clinical practice and demonstrates considerable variability in the application of SWL in the UK. The results support existing data which suggest that SWL is a safe and well tolerated treatment modality; however, overall SFRs were low.

Kidney stones: pathophysiology, diagnosis and management

The prevalence of kidney stones is increasing, and approximately 12 000 hospital admissions every year are due to this condition. This article will use a case study to focus on a patient diagnosed with a calcium oxalate kidney stone. It will discuss the affected structures in relation to kidney stones and describe the pathology of the condition. Investigations for kidney stones, differential diagnosis and diagnosis, possible complications and prognosis, will be discussed. Finally, a detailed account of management strategies for the patient with kidney stones will be given, looking at pain management, medical procedures and dietary interventions.

Supracostal Punctures for PCNL: Factors that Predict Safety, Success and Stone Free Rate in Stag Horn and Non-Stag Horn Stones: A Single Centre Experience and Review of Literature

INTRODUCTION

Supra-costal Percutaneous Nephrolithotomy (PCNL) procedure has now become an established standard of care in patients with renal stone disease, in terms of morbidity, stone clearance, duration of stay and shorter convalescence period. Gone are the days when supracostal punctures were considered to be associated with a high morbidity. With increased expertise gained in performing multiple punctures and further refinements in focusing techniques, more and more of these procedures are being performed with an intention to achieve a maximum stone clearance with least morbidity.

AIM

To prospectively analyze the various factors that predict the safety, efficacy and stone clearance rate in patients who have undergo supracostal punctures for PCNL procedures.

MATERIALS AND METHODS

Three hundred seventy six patients underwent PCNL for renal stones. Ninety two (n=92) of them needed supra-costal puncture. All patients were subdivided into groups 1 and 2 based on the size, location of the stone and the stone burden. In all, 132 tracts were established.

RESULTS

About 83% of patients achieved a complete stone free rate after initial PCNL. Stones more than 3 centimeters were found to be associated with significant residual stones. Radio opacity under image intensifier also had a significant impact on the ultimate stone free status. About 23% of those (n=5/22) who needed longer duration of surgery had a clinically significant residual stones, needing ancillary procedures. Fifteen patients (16%) had complications related to the procedure, of which 13 were in group 1 (87%). High percentage of complications in patients with larger stone burden was found to be statistically significant. In about 76% (n=70), the procedure required only less than 90 minutes. Also, in those 22 patients in whom the duration of procedure exceeded 90 minutes, 12 of them had complications, with a p-value of <0.0001.

CONCLUSION

Supra-costal punctures are safe and effective options in a selected group of patients. The overall results are almost on par with that of the infra costal punctures, with an acceptable morbidity.

Percutaneous Nephrolithotomy Increases the Risk of New-onset Hypertension: A Nationwide 6-Year Follow-up Study

OBJECTIVE

To determine whether percutaneous nephrolithotomy or ureteroscopic lithotripsy leads to the development of hypertension, using the Taiwan National Health Insurance database.

METHODS

Data were sourced from the Longitudinal Health Insurance Database (LHID2000) of Taiwan, Republic of China, compiled by the Taiwan National Health Insurance database from 1996 to 2010. Percutaneous nephrolithotomy and ureteroscopic lithotripsy were studied as time-dependent covariates in a Cox proportional hazard model to estimate the hazard ratio for the effect of new-onset hypertension.

RESULTS

A total of 2552 patients were included, with 232 PNL percutaneous nephrolithotomy, 1160 ureteroscopic lithotripsy patients, and 1160 comparison patients. There was a significant difference between the incidence of new-onset hypertension between the percutaneous nephrolithotomy and comparison groups (adjusted hazard ratio 1.48, 95% confidence interval 1.13-1.95, P = .005). The percutaneous nephrolithotomy group also had a higher incidence of new-onset hypertension than the ureteroscopic lithotripsy group (adjusted hazard ratio 1.39, 95% confidence interval 1.06-1.83, P = .018). The incidence rate of new hypertension during the follow-up period was 44.5 per 1000 person-years in the percutaneous nephrolithotomy group, 33.0 per 1000 person-years in the ureteroscopic lithotripsy group, and 30.2 per 1000 person-years in the comparison group.

CONCLUSION

An association exists between nephrolithiasis patients who were treated with percutaneous nephrolithotomy and subsequent hypertension diagnosis. Although the exact mechanisms for this phenomenon are not clear, patients who undergo percutaneous nephrolithotomy may need close monitoring of blood pressure during postoperative follow-up.

Risk factors for pulmonary complications after percutaneous nephrolithotomy: A retrospective observational analysis

Although percutaneous nephrolithotomy is minimally invasive, it is associated with several complications, including extravasation of fluid and urine, the need for a blood transfusion, and septicemia. However, little is known about pulmonary complications after this procedure. Therefore, we aimed to evaluate the risk factors for and outcomes of pulmonary complications after percutaneous nephrolithotomy.All consecutive patients who underwent percutaneous nephrolithotomy between 2001 and 2014 were identified and divided into group A (no clinically significant pulmonary complications) and group B (clinically significant pulmonary complications). Preoperative and intraoperative variables and postoperative outcomes were evaluated. Independent risk factors for postoperative pulmonary complications were evaluated by univariate and multivariate logistic regression analyses.The study included 560 patients: 378 (67.5%) in group A and 182 (32.5%) in group B. Multivariate logistic regression analysis revealed that the independent risk factors for pulmonary complications after percutaneous nephrolithotomy were a higher body mass index (odds ratio = 1.062, P = 0.026), intraoperative red blood cell transfusion (odds ratio = 2.984, P = 0.012), and an intercostal surgical approach (odds ratio = 3.046, P < 0.001). Furthermore, the duration of hospital stay was significantly longer (8.4 ± 4.3 days vs 7.6 ± 3.4 days, P = 0.010) and the intensive care unit admission rate was significantly higher [13 (7.1%) vs 1 (0.3%), P < 0.001] in group B than in group A.Risk factors for pulmonary complications after percutaneous nephrolithotomy were a higher body mass index, intraoperative red blood cell transfusion, and an intercostal surgical approach. Postoperative pulmonary complications were associated with poor outcomes. These results may provide useful information for the perioperative management of pulmonary complications after percutaneous nephrolithotomy.

Comparison of safety and efficacy of laparoscopic pyelolithotomy versus percutaneous nephrolithotomy in patients with large renal pelvic stones: a meta-analysis

To compare percutaneous nephrolithotomy (PCNL) and laparoscopic pyelolithotomy (LP) for surgical management for large (>2 cm) renal stones. We searched MEDLINE, Cochrane, and EMBASE databases until March 11, 2015, using the following search terms: renalpelvic stone, percutaneous nephrolithotomy, laparoscopic pyelolithotomy. Randomized controlled and prospective and retrospective two-armed studies were included. Sensitivity analysis and assessment of the quality of the included studies and publication bias were performed. Nine studies were included in the study with a patient population of 622. The studies were homogeneous with respect to the primary end point of stone-free rate, but were heterogeneous with respect to operation time, length of hospital stay, and blood loss. A higher percentage of patients who received LP remained stone-free following surgery compared with patients who were treated with PCNL (p=0.001). However, the mean operation time was longer for patients with LP than for those treated with PCNL (p=0.002). There was no difference between procedures with regard to length of hospital stay or blood loss (p≥0.071). Sensitivity and quality analysis indicated that the data are reliable and the included studies are of good quality. No publication bias was observed. The study suggests that both procedures are effective and safe for removing large renal stones. However, LP may be more efficacious than PCNL in treating large kidney stones.

The Efficacy of Percutaneous Nephrolithotomy Using Pneumatic Lithotripsy vs. the Holmium Laser: a Randomized Study

The objective of the study is to compare the efficacy of percutaneous nephrolithotomy using holmium laser vs pneumatic lithotripsy. From August 2010 to March 2014, 200 patients with double kidney and single kidney stones without previous operations or other diseases were randomized into two groups according to the type of lithotripter used: pneumatic (n = 100) and laser (n = 100). The preoperative, intraoperative, and post-operative follow-up findings were analyzed and compared. The average stone size was similar in both the pneumatic and holmium laser lithotripsy groups (202.8 ± 52.6 mm² vs. 200.3 ± 50.8 mm²). No significant difference was found between the operation time for the two groups (55.9 ± 16.5 min vs. 62.4 ± 17.6 min). The concentrations of creatinine in both groups increased 2-24 h after the operation and decreased to a normal level 1-4 days after the operation in both groups. Renal diuretic scan revealed that the peak and the renal index were both abnormal after the operation but became normal 4 days after the operation in both groups. No significant difference of creatinine concentration or the diuresis renogram was observed between the two groups. However, two cases in the holmium laser group had almost lost the renal function of the operated kidney 1 year later. Both pneumatic and holmium laser lithotripsy can be associated with acute renal injury in some patients after the operation without any significant difference. However, some infrequent severe renal function damage in laser lithotripsy should be noted.

Management behaviors of the urology practitioners to the small lower calyceal stones: the results of a web-based survey

Lower pole calyceal stones (LPS) represent lower spontaneous passage rates and, therefore, require several interventional treatment approaches. The aim of this survey study was to investigate the attitudes of the urology practitioners and the factors affecting their decision making in the management of small asymptomatic LPS. A total of 149 urologists participated to the study via email through the internet-based website. Participating urologists were asked to complete a 29-question survey including personal and academic data, level of surgical experience, available equipment for interventional approaches, which treatment do they prefer for small LPS (≥5 mm and <1 cm), and factors affecting their treatment decision. All data were analyzed to make inferences related with treatment decision and factors affecting decision-making. Mean participant age was 41.57 (26-62) years. The most preferred approach was observation/medical treatment option (52.3 %), subsequently SWL (25.5 %), RIRS (16.1 %), miniPNL (5.4 %) and standard PNL (0.7 %) were chosen by the participants. On the other side, SWL and medical treatment were at the forefront (52 and 16.1 %) among children. In the multivariate analysis of participants' age, academic status, surgical experience and institution, none was significantly associated with treatment decision-making (p > 0.05). The most important factors associated with decision making were calyceal dilatation (85.9 %) and patient preferences (81.2 %). The other factors effecting treatment decision were reported to be recurrent disease (70.5 %), the duration of the stone (74.5 %), patient age (95.3 %), current guidelines (87.9 %), stone density (50.3 %), body mass index (BMI) (73.8 %) and other morbid diseases (91.9 %). Our surveys' greatest value is in demonstrating the preferred treatment options and factors effecting decision-making in the treatment of LPS. The most preferred option in our population was follow-up and medical treatment. The most influencing factors on decision-making were age, patients' preferences, presence of calyceal dilatation, body mass index, comorbid conditions, available options for stone treatment and the surgeon's experience on the existing opportunities.

Extracorporeal shockwave lithotripsy without radiation: Ultrasound localization is as effective as fluoroscopy

CONTEXT

Extracorporeal shockwave lithotripsy (SWL) is the first-line treatment for renal calculi in most cases. Recent technology has allowed lithotriptor machines to localize stones using fluoroscopy or ultrasound (US).

AIM

The aim of this study is to compare stone free rates (SFR) using two techniques.

METHODS

This is a single center retrospective cohort study. We have studied 95 patients with renal calculi undergoing first SWL treatment with localization using US (48 pts) and fluoroscopy (47 pts). SFR was defined as fragments ≤2 m at 4 weeks post procedure on x-ray or US. Patient records were reviewed.

RESULTS

Stone size and location, age and body mass index were comparable between groups. Stones ≤7 mm had better SFR with US 86% (18/21) compared to fluoroscopy 59% (10/17) P= 0.08. Overall the US group had similar SFR to the fluoroscopy group for stones of all sizes and locations with 60% (29/48) compared to 45% (21/47)P= 0.18. Radiation exposure was the biggest difference between techniques with a mean radiation dose (mGy/cm²) in the US group of 103 (0-233) and 2113 (241-7821) in the fluoroscopy group. Radiation use in the US group was due to the use of a single shot pre- and post-procedure, this could be reduced to zero.

CONCLUSIONS

Our data show equivalent outcomes using US compared to the traditional fluoroscopy localization technique. We would encourage departments to develop the use of US localization to reduce radiation exposure to patients.

Citrate salts for preventing and treating calcium containing kidney stones in adults

BACKGROUND

Kidney stones affect people worldwide and have a high rate of recurrence even with treatment. Recurrences are particularly prevalent in people with low urinary citrate levels. These people have a higher incidence of calcium phosphate and calcium oxalate stones. Oral citrate therapy increases the urinary citrate levels, which in turn binds with calcium and inhibits the crystallisation thus reduces stone formation. Despite the widespread use of oral citrate therapy for prevention and treatment of calcium oxalate stones, the evidence to support its clinical efficacy remains uncertain.

OBJECTIVES

The objective of this review was to determine the efficacy and adverse events associated with citrate salts for the treatment and prevention of calcium containing kidney stones.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 29 July 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that assessed the efficacy and adverse events associated with citrate salts for the treatment and prevention of calcium containing kidney stones in adults treated for a minimum of six months.

DATA COLLECTION AND ANALYSIS

Two authors assessed studies for inclusion in this review. Data were extracted according to predetermined criteria. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes.

MAIN RESULTS

We included seven studies that included a total of 477 participants, most of whom had oxalate stones. Of these, three studies (247 participants) compared potassium citrate with placebo or no intervention; three (166 participants) compared potassium-sodium citrate with no intervention; and one (64 participants) compared potassium-magnesium citrate with placebo. Overall, quality of the reporting of the included studies was considered moderate to poor, and there was a high risk of attrition bias in two studies.Compared with placebo or no intervention, citrate therapy significantly reduced the stone size (4 studies, 160 participants: RR 2.35, 95% CI 1.36 to 4.05). New stone formation was significantly lower with citrate therapy compared to control (7 studies, 324 participants: RR 0.26, 95% CI 0.10 to 0.68). The beneficial effect on stone size stability was also evident (4 studies, 160 participants: RR 1.97, 95% CI 1.19 to 3.26). Adverse events were reported in four studies, with the main side effects being upper gastrointestinal disturbance and one patient reported a rash. There were more gastrointestinal adverse events in the citrate group; however this was not significant (4 studies, 271 participants: RR 2.55, 95% CI 0.71 to 9.16). There were significantly more dropouts due to adverse events with citrate therapy compared to control (4 studies, 271 participants: RR 4.45, 95% CI 1.28 to 15.50). The need for retreatment was significantly less with citrate therapy compared to control (2 studies, 157 participants: RR 0.22, 95% CI 0.06 to 0.89).

AUTHORS' CONCLUSIONS

Citrate salts prevent new stone formation and reduce further stone growth in patients with residual stones that predominantly contain oxalate. The quality of reported literature remains moderate to poor; hence a well-designed statistically powered multi-centre RCT is needed in order to answer relevant questions concerning the efficacy of citrate salts.

Intrarenal Surgery vs Percutaneous Nephrolithotomy in the Management of Lower Pole Stones Greater than 2 cm

Purpose

To compare the efficacy of RIRS and PNL in lower pole stones ≥2 cm. Materials and and Methods: A total of 109 patients who underwent PNL or RIRS for solitary lower pole stone between April 2009 and December 2012, were retrospectively analyzed. Lower pole stone was diagnosed with CT scan. Stone size was assessed as the longest axis of the stone. All patients were informed about the advantages, disadvantages and probable complications of both PNL and RIRS before the selection of the procedure. Patients decided the surgery type by themselves without being under any influences and written informed consent was obtained from all patients prior to the surgery. Patients were divided into two groups according to the patients’ preference of surgery type. Group 1 consisted of 77 patients who underwent PNL and Group 2 consisted of 32 patients treated with RIRS. Stone free statuses, postoperative complications, operative time and hospitalization time were compared in both groups.

Results

There was no statistical significance between the two groups in mean age, stone size, stone laterality, mean follow-up periods and mean operative times. In PNL group, stone-free rate was 96.1% at first session and 100% after the additional procedure. In Group 2, stone-free rate was 90.6% at the first procedure and 100% after the additional procedure. The final stone-free rates and operative times were similar in both groups.

Conclusions

RIRS should be an effective treatment alternative to PNL in lower pole stones larger than 2 cm, especially in selected patients.

Incidence of retrorenal colon during percutaneous nephrolithotomy

OBJECTIVE

The aim of this study was to investigate retrorenal colon incidence in percutaneous nephrolithotomy (PNL) interventions made in our clinic.

MATERIALS AND METHODS

Clinical data of 804 PNL patients, accumulated over a 7 year period (2006-2012), was surveyed. The patient files were reviewed retrospectively, and only those who had abdominal computed tomography (CT) images before PNL intervention were included in the study. In the CT images, the position of both the ascending and descending colon in relation to the right and left kidneys were evaluated.

RESULTS

According to our hospital reports, 394 patients with CT images were included in the present study 27 patients (6.9%) had retrorenal colon, of which 18 (4.6%) were on the left side, 4 (1.0%) on the right side and 5 (1.3%) had bilateral retrorenal colons. Colonic perforation complication was seen only in two patients and the colonic perforation rate was 0.3%. These two cases had no CT images.

CONCLUSIONS

PNL, in the process of becoming the standard treatment modality, is a safe and reliable technique for renal stone treatment. Colonic injury should be taken into consideration during PNL interventions of the lower pole of the kidney (especially on the left side) due to the location of retrorenal colon.

Effective radiation exposure evaluation during a one year follow-up of urolithiasis patients after extracorporeal shock wave lithotripsy

Introduction

To determine and evaluate the effective radiation exposure during a one year follow-up of urolithiasis patients following the SWL (extracorporeal shock wave lithotripsy) treatment.

Material and methods

Total Effective Radiation Exposure (ERE) doses for each of the 129 patients: 44 kidney stone patients, 41 ureter stone patients, and 44 multiple stone location patients were calculated by adding up the radiation doses of each ionizing radiation session including images (IVU, KUB, CT) throughout a one year follow-up period following the SWL.

Results

Total mean ERE values for the kidney stone group was calculated as 15, 91 mSv (5.10-27.60), for the ureter group as 13.32 mSv (5.10-24.70), and in the multiple stone location group as 27.02 mSv (9.41-54.85). There was no statistically significant differences between the kidney and ureter groups in terms of the ERE dose values (p = 0.221) (p >0.05). In the comparison of the kidney and ureter stone groups with the multiple stone location group; however, there was a statistically significant difference (p = 0.000) (p <0.05).

Conclusions

ERE doses should be a factor to be considered right at the initiation of any diagnostic and/or therapeutic procedure. Especially in the case of multiple stone locations, due to the high exposure to ionized radiation, different imaging modalities with low dose and/or totally without a dose should be employed in the diagnosis, treatment, and follow-up bearing the aim to optimize diagnosis while minimizing the radiation dose as much as possible.

Unplanned Hospital Return for Infection following Ureteroscopy-Can We Identify Modifiable Risk Factors?

PURPOSE

Genitourinary infection after ureteroscopy with laser lithotripsy is a clinically significant event that may lead to expensive and morbid return to the hospital. We evaluate factors associated with infection after ureteroscopy with laser lithotripsy leading to unplanned hospital return.

MATERIALS AND METHODS

We performed a retrospective chart review evaluating all ureteroscopy with laser lithotripsy performed at a single academic institution from April 2011 to August 2014. Data were extracted including patient demographics, comorbidities, surgical encounter characteristics, preoperative urine culture status, antibiotic type/duration and compliance with the AUA Best Practice Statement for antibiotic prophylaxis. Bivariate and multivariate analyses were performed to determine factors associated with unplanned return to the hospital.

RESULTS

Among 550 patients undergoing ureteroscopy with laser lithotripsy 45% (248) were female with an average age of 56.8 (± 14.8) years. Overall 3.4% (19 patients) had an unplanned return for genitourinary infection, with most (78.9%, 15 of 19) requiring inpatient readmission. Overall compliance with AUA Best Practice Statement for antibiotic prophylaxis was 48.7% (268 of 550). Rates of infection related returns were higher in patients undergoing preoperative stenting (84.2% vs 58.6%, p=0.025), those with an operative time greater than 120 minutes (89.5% vs 32.6% p <0.001) and those for whom there was AUA Best Practice Statement compliance for antibiotic prophylaxis (78.9% vs 47.6%, p=0.007). These factors remained significant on multivariate analysis (p <0.05).

CONCLUSIONS

Preoperative stenting and longer operative time were associated with a greater likelihood of serious genitourinary infection after ureteroscopy with laser lithotripsy. These patients may warrant additional antibiotic prophylaxis but further research is needed to answer this question more definitively. Interestingly the AUA Best Practice Statement compliance for antibiotic prophylaxis was also associated with a higher risk of infection, underscoring the need for locally appropriate prophylaxis strategies and further study of optimal prophylaxis regimens.

Shock Wave Lithotripsy in Ureteral Stones: Evaluation of Patient and Stone Related Predictive Factors

Purpose:

To evaluate the patient and stone related factors which may influence the final outcome of SWL in the management of ureteral stones.

Materials and Methods:

Between October 2011 and October 2013, a total of 204 adult patients undergoing SWL for single ureteral stone sizing 5 to 15 mm were included into the study program. The impact of both patient (age, sex, BMI,) and stone related factors (laterality, location, longest diameter and density as CT HU) along with BUN and lastly SSD (skin to stone distance) on fragmentation were analysed by univariate and multivariate analyses. Results: Stone free rates for proximal and distal ureteral stones were 68.8% and 72.7%, respectively with no statistically significant difference between two groups (p=0.7). According to univariate and multivariate analyses, while higher BMI (mean: 26.8 and 28.1, p=0.048) and stone density values (mean: 702 HU and 930 HU, p<0.0001) were detected as statistically significant independent predictors of treatment failure for proximal ureteral stones, the only statistically significant predicting parameter for the success rates of SWL in distal ureteral stones was the higher SSD value (median: 114 and 90, p=0.012).

Conclusions:

Our findings have clearly shown that while higher BMI and increased stone attenuation values detected by NCCT were significant factors influencing the final outcome of SWL treatment in proximal ureteral stones; opposite to the literature, high SSD was the only independent predictor of success for the SWL treatment of distal ureteral stones.

Predictive value of low tube voltage and dual-energy CT for successful shock wave lithotripsy: an in vitro study

This study investigates the capabilities of low tube voltage computed tomography (CT) and dual-energy CT (DECT) for predicting successful shock wave lithotripsy (SWL) of urinary stones in vitro. A total of 33 urinary calculi (six different chemical compositions; mean size 6 ± 3 mm) were scanned using a dual-source CT machine with single- (120 kVp) and dual-energy settings (80/150, 100/150 Sn kVp) resulting in six different datasets. The attenuation (Hounsfield Units) of calculi was measured on single-energy CT images and the dual-energy indices (DEIs) were calculated from DECT acquisitions. Calculi underwent SWL and the number of shock waves for successful disintegration was recorded. The prediction of required shock waves regarding stone attenuation/DEI was calculated using regression analysis (adjusted for stone size and composition) and the correlation between CT attenuation/DEI and the number of shock waves was assessed for all datasets. The median number of shock waves for successful stone disintegration was 72 (interquartile range 30-361). CT attenuation/DEI of stones was a significant, independent predictor (P < 0.01) for the number of required shock waves with the best prediction at 80 kVp (β estimate 0.576) (P < 0.05). Correlation coefficients between attenuation/DEI and the number of required shock waves ranged between ρ = 0.31 and 0.68 showing the best correlation at 80 kVp (P < 0.001). The attenuation of urinary stones at low tube voltage CT is the best predictor for successful stone disintegration, being independent of stone composition and size. DECT shows no added value for predicting the success of SWL.

Can a dual-energy computed tomography predict unsuitable stone components for extracorporeal shock wave lithotripsy?

Purpose

To assess the potential of dual-energy computed tomography (DECT) to identify urinary stone components, particularly uric acid and calcium oxalate monohydrate, which are unsuitable for extracorporeal shock wave lithotripsy (ESWL).

Materials and Methods

This clinical study included 246 patients who underwent removal of urinary stones and an analysis of stone components between November 2009 and August 2013. All patients received preoperative DECT using two energy values (80 kVp and 140 kVp). Hounsfield units (HU) were measured and matched to the stone component.

Results

Significant differences in HU values were observed between uric acid and nonuric acid stones at the 80 and 140 kVp energy values (p<0.001). All uric acid stones were red on color-coded DECT images, whereas 96.3% of the nonuric acid stones were blue. Patients with calcium oxalate stones were divided into two groups according to the amount of monohydrate (calcium oxalate monohydrate group: monohydrate≥90%, calcium oxalate dihydrate group: monohydrate<90%). Significant differences in HU values were detected between the two groups at both energy values (p<0.001).

Conclusions

DECT improved the characterization of urinary stone components and was a useful method for identifying uric acid and calcium oxalate monohydrate stones, which are unsuitable for ESWL.

Micropercutaneous nephrolithotripsy: initial experience

INTRODUCTION

For small renal calculi (< 2 cm) the currently available treatment options include extracorporeal shockwave lithotripsy (ESWL), retrograde intrarenal surgery (RIRS) and standard/mini percutaneous nephrolithotomy (PNL). A new method, microperc, has therefore been developed, in which a smaller tract size and smaller instruments were used.

AIM

To present our clinical experiences with micropercutaneous nephrolithotripsy (microperc) in the treatment of small renal calculi.

MATERIAL AND METHODS

We retrospectively evaluated patients with small renal calculi who underwent microperc between February and June 2013. A 4.8 Fr 'all-seeing needle' was used to achieve percutaneous renal access with the C-arm fluoroscopy guidance in the prone position. Holmium: YAG laser 272 µm fiber was used for stone fragmentation.

RESULTS

A total of 20 patients underwent the microperc procedure. The mean age of the patients was 46.5 ±13.8 years. The mean stone size was 13 ±3 mm. The stone-free rate (SFR) was 90% (18/20). Two patients had clinically significant residual fragments (≥ 4 mm). The mean operation and fluoroscopy times were 107.5 ±37 min and 45 ±40 s respectively. The mean postoperative drop in hemoglobin was 1.2 ±0.9 g/dl, and 1 patient required blood transfusion. The patients were discharged after an average hospitalization of 1.4 ±0.8 days. Two complications, urinary tract infection and blood loss requiring blood transfusion, were observed in 2 patients postoperatively.

CONCLUSIONS

We suggest that microperc should be considered for the treatment of small renal stones.

Computer-aided detection of renal calculi from noncontrast CT images using TV-flow and MSER features

PURPOSE

Renal calculi are common extracolonic incidental findings on computed tomographic colonography (CTC). This work aims to develop a fully automated computer-aided diagnosis system to accurately detect renal calculi on CTC images.

METHODS

The authors developed a total variation (TV) flow method to reduce image noise within the kidneys while maintaining the characteristic appearance of renal calculi. Maximally stable extremal region (MSER) features were then calculated to robustly identify calculi candidates. Finally, the authors computed texture and shape features that were imported to support vector machines for calculus classification. The method was validated on a dataset of 192 patients and compared to a baseline approach that detects calculi by thresholding. The authors also compared their method with the detection approaches using anisotropic diffusion and nonsmoothing.

RESULTS

At a false positive rate of 8 per patient, the sensitivities of the new method and the baseline thresholding approach were 69% and 35% (p < 1e - 3) on all calculi from 1 to 433 mm(3) in the testing dataset. The sensitivities of the detection methods using anisotropic diffusion and nonsmoothing were 36% and 0%, respectively. The sensitivity of the new method increased to 90% if only larger and more clinically relevant calculi were considered.

CONCLUSIONS

Experimental results demonstrated that TV-flow and MSER features are efficient means to robustly and accurately detect renal calculi on low-dose, high noise CTC images. Thus, the proposed method can potentially improve diagnosis.

Incidence and Predictors for Ipsilateral Hydronephrosis Following Ureteroscopic Lithotripsy

OBJECTIVE

To review our experience in using ureteroscopy (URS) with lithotripsy for renal or ureteral calculi to determine the incidence and predictors of postprocedural ipsilateral hydronephrosis.

PATIENTS AND METHODS

Records of 324 URS cases for renal or ureteral calculi with imaging performed 4-12 weeks postprocedure were reviewed. Ipsilateral hydronephrosis was determined by computed tomography scan or renal ultrasound. Univariate and multivariate analyses determined the factors associated with hydronephrosis.

RESULTS

176 men and 148 women with a median age of 50 years were included. Median stone size was 6 mm and operative duration was 60 minutes; 30% of patients had multiple calculi; and 35% had undergone a prior ipsilateral URS. Overall, 49 of 324 patients (15%) had evidence of hydronephrosis, with 65% of these patients having symptoms and 40% requiring ancillary procedures. On multivariate analysis, increasing stone diameter (odds ratio [OR] 8.9, 95% confidence interval [CI] 1.9-23.8, P = .03), prior ipsilateral URS (OR 7.7, 95% CI 1.8-28.2, P = .006), longer operative duration (OR 6.5, 95% CI 1.8-16.3, P = .02), and renal colic symptoms (OR 48.3, 95% CI 14.7-71.4, P <.001) independently predicted hydronephrosis. Conversely, other factors including stone impaction at procedure, ureteral dilation, use of an access sheath, intraoperative perforation, or use of a stent did not associate with ipsilateral hydronephrosis.

CONCLUSION

In this contemporary cohort study, 15% of patients undergoing URS had evidence of ipsilateral hydronephrosis. Larger stone size, longer OR duration, prior ipsilateral URS, and recurrent colic were associated with an increased likelihood for this observation. Patients and stone cases with such characteristics likely warrant imaging modalities beyond plain radiography.

Particle motion induced by bubble cavitation

Cavitation bubbles induce impulsive forces on surrounding substrates, particles, or surfaces. Even though cavitation is a traditional topic in fluid mechanics, current understanding and studies do not capture the effect of cavitation on suspended objects in fluids. In the present work, the dynamics of a spherical particle due to a cavitation bubble is experimentally characterized and compared with an analytical model. Three phases are observed: the growth of the bubble where the particle is pushed away, its collapse where the particle approaches the bubble, and a longer time scale postcollapse where the particle continues to move toward the collapsed bubble. The particle motion in the longer time scale presumably results from the asymmetric cavitation evolution at an earlier time. Our theory considering the asymmetric bubble dynamics shows that the particle velocity strongly depends on the distance from the bubble as an inverse-fourth-power law, which is in good agreement with our experimentation. This study sheds light on how small free particles respond to cavitation bubbles in fluids.

Is flexible ureterorenoscopy and laser lithotripsy the new gold standard for lower pole renal stones when compared to shock wave lithotripsy: Comparative outcomes from a University hospital over similar time period

Introduction

Renal lower pole stones pose difficulty in management due to anatomical variation, stone size, hardness and patient demographics. Flexible ureterorenoscopy and laser lithotripsy (FURSL) and shock wave lithotripsy (SWL) are preferred for stones 1-2 cm in size. We wanted to compare the outcomes of FURSL and SWL for lower pole stones during the same time period.

Material and methods

All patients who were treated for lower pole stones with FURSL and SWL during a 19-month period were included. The stone free rate (SFR) was defined as ≤3 mm fragments on follow-up imaging or stone free endoscopically. Data was recorded in an excel spreadsheet with SPSS version 21 used for statistical analysis.

Results

A total of 161 lower pole procedures were done (93 SWL and 63 FURSL). The mean stone size for SWL (7.4 mm; range: 4-16 mm) was significantly smaller than for FURSL (13.4 mm; 4-53 mm). The mean operating time and hospital stay for FURSL was 65 minutes (range: 30-160 minutes) and 0.5 days (range: 0-7 days) respectively.

The SFR was significantly better (p <0.001) for FURSL (n = 63, 93%) compared to SWL (n = 23, 25%). There were 4 (6%) complications (3 Clavien II and 1 Clavien I) in the FURSL group (2 urosepsis, 1 UTI and 1 stent pain). Three patients in the SWL group (Clavien I) were readmitted with renal colic but there were no other complications.

Conclusions

FURSL for lower pole stones seems to be a much better alternative than SWL with a high SFR even for larger stones and seems to be the new gold standard for lower pole stone management.

Suppressing bubble shielding effect in shock wave lithotripsy by low intensity pulsed ultrasound

Extracorporeal shock wave lithotripsy (ESWL) has been used as an effective modality to fragment kidney calculi. Because of the bubble shielding effect in the pre-focal region, the acoustic energy delivered to the focus is reduced. Low pulse repetition frequency (PRF) will be applied to dissolve these bubbles for better stone comminution efficiency. In this study, low intensity pulsed ultrasound (LIPUS) beam was aligned perpendicular to the axis of a shock wave (SW) lithotripter at its focus. The light transmission was used to evaluate the compressive wave and cavitation induced by SWs without or with a combination of LIPUS for continuous sonication. It is found that bubble shielding effect becomes dominated with the SW exposure and has a greater significant effect on cavitation than compressive wave. Using the combined wave scheme, the improvement began at the 5th pulse and gradually increased. Suppression effect on bubble shielding is independent on the trigger delay, but increases with the acoustic intensity and pulse duration of LIPUS. The peak negative and integral area of light transmission signal, which present the compressive wave and cavitation respectively, using our strategy at PRF of 1 Hz are comparable to those using SW alone at PRF of 0.1 Hz. In addition, high-speed photography confirmed the bubble activities in both free field and close to a stone surface. Bubble motion in response to the acoustic radiation force by LIPUS was found to be the major mechanism of suppressing bubble shielding effect. There is a 2.6-fold increase in stone fragmentation efficiency after 1000 SWs at PRF of 1 Hz in combination with LIPUS. In summary, combination of SWs and LIPUS is an effective way of suppressing bubble shielding effect and, subsequently, improving cavitation at the focus for a better outcome.

Hounsfield density of renal papillae in stone formers: analysis based on stone composition

PURPOSE

We examined renal papillary Hounsfield density in stone formers with all common stone subtypes to further understand the pathophysiology of stone formation.

MATERIALS AND METHODS

Using computerized tomography we measured the Hounsfield density of a 0.2 cm(2) renal papillary area in patients with a single renal calyceal stone. Results were compared with those in patients without a nephrolithiasis history who served as controls. Stone composition was determined by stone passage or extraction during endoscopic procedures using infrared spectroscopy and polarized microscopy. We measured the Hounsfield density of the stone bearing calyx and of a single calyx from the upper, middle and lower poles of each kidney.

RESULTS

Mean ± SD renal papillary Hounsfield density in controls was 36.2 ± 4.0 HU. In patients with stones Hounsfield density was significantly greater than in controls in stone bearing calyces, nonstone bearing calyces in the affected kidney and calyces in the contralateral nonstone bearing kidney for all stone composition subtypes (range 48.4 to 61.3 HU, each p <0.001).

CONCLUSIONS

Patients with kidney stones regardless of composition showed the unique radiographic characteristic of increased renal papillary Hounsfield density. This was true for all calyces and for each kidney in all stone formers with a single renal calyceal stone. This radiographic evidence supports the role of renal papillary deposits or plaques in the pathophysiology of stone formation.

Comparison of diagnostic performance between single- and multiphasic contrast-enhanced abdominopelvic computed tomography in patients admitted to the emergency department with abdominal pain: potential radiation dose reduction

OBJECTIVES

To evaluate feasibility of radiation dose reduction by optimal phase selection of computed tomography (CT) in patients who visited the emergency department (ED) for abdominal pain.

METHODS

We included 253 patients who visited the ED for abdominal pain. They underwent multiphasic CT including precontrast, late arterial phase (LAP), and hepatic venous phase (HVP). Three image sets (HVP, precontrast + HVP, and precontrast + LAP + HVP) were reviewed. Two reviewers determined the most appropriate diagnosis with five-point confidence scale. Diagnostic performances were compared among image sets by weighted-least-squares method or DeLong's method. Linear mixed model was used to assess changes of diagnostic confidence and radiation dose.

RESULTS

There was no difference in diagnostic performance among three image sets, although diagnostic confidence level was significantly improved after review of triphasic images compared with both HVP images only or HVP with precontrast images (confidence scale, 4.64 ± 0.05, 4.66 ± 0.05, and 4.76 ± 0.04 in the order of the sets; overall P = 0.0008). Similar trends were observed in the subgroup analysis for diagnosis of pelvic inflammatory disease and cholecystitis.

CONCLUSIONS

There is no difference between HVP-CT alone and multiphasic CT for the diagnosis of causes of abdominal pain in patients admitted to the ED without prior chronic disease or neoplasia.

KEY POINTS

• There was no difference in diagnostic performance of HVP CT and multiphasic CT. • The diagnostic confidence level was improved after review of the LAP images. • HVP CT can achieve diagnostic performance similar to that of multiphasic CT, while minimizing radiation.

Usefulness of hounsfield unit and density in the assessment and treatment of urinary stones

Computed tomography (CT) is widely used to examine stones in the urinary system. In addition to the size and location of the stone and the overall health of the kidney, CT can also assess the density of the stone in Hounsfield units (HU). The HU, or Hounsfield density, measured by CT, is related to the density of the tissue or stone. A number of studies have assessed the use of HU in urology. HUs have been used to predict the type and opacity of stones during diagnosis, and the efficacy has been assessed using methods including extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), ureterorenoscopic ureterolithotripsy (URSL), and medical expulsive treatment (MET). Previous studies have focused on the success rate of HU for predicting the type of stone and of ESWL treatment. Understanding the composition of the stone plays a key role in determining the most appropriate treatment modality. The most recent reports have suggested that the HU value and its variants facilitate prediction of stone composition. However, the inclusion of data regarding urine, such as pH and presence of crystals, increases the predictive accuracy. HUs, which now form part of the clinical guidelines, allow us to predict the success of ESWL; therefore, they should be taken into account when ESWL is considered as a treatment option. However, there are currently insufficient data available regarding the value of HU for assessing the efficacy of PCNL, URSL, and MET. Studies performed to date suggest that these values would make a significant contribution to the diagnosis and treatment of urinary system stones. However, more data are required to assess this further.