The Utility of the Kidneys-ureters-bladder Radiograph as the Sole Imaging Modality and Its Combination With Ultrasonography for the Detection of Renal Stones

International Alliance of Urolithiasis (IAU) consensus on miniaturized percutaneous nephrolithotomy

Over the past three decades, there has been increasing interest in miniaturized percutaneous nephrolithotomy (mPCNL) techniques featuring smaller tracts as they offer potential solutions to mitigate complications associated with standard PCNL (sPCNL). However, despite this growing acceptance and recognition of its benefits, unresolved controversies and acknowledged limitations continue to impede widespread adoption due to a lack of consensus on optimal perioperative management strategies and procedural tips and tricks. In response to these challenges, an international panel comprising experts from the International Alliance of Urolithiasis (IAU) took on the task of compiling an expert consensus document on mPCNL procedures aimed at providing urologists with a comprehensive clinical framework for practice. This endeavor involved conducting a systematic literature review to identify research gaps (RGs), which formed the foundation for developing a structured questionnaire survey. Subsequently, a two-round modified Delphi survey was implemented, culminating in a group meeting to generate final evidence-based comments. All 64 experts completed the second-round survey, resulting in a response rate of 100.0%. Fifty-eight key questions were raised focusing on mPCNLs within 4 main domains, including general information (13 questions), preoperative work-up (13 questions), procedural tips and tricks (19 questions), and postoperative evaluation and follow-up (13 questions). Additionally, 9 questions evaluated the experts' experience with PCNLs. Consensus was reached on 30 questions after the second-round survey, while professional statements for the remaining 28 key questions were provided after discussion in an online panel meeting. mPCNL, characterized by a tract smaller than 18 Fr and an innovative lithotripsy technique, has firmly established itself as a viable and effective approach for managing upper urinary tract stones in both adults and pediatrics. It offers several advantages over sPCNL including reduced bleeding, fewer requirements for nephrostomy tubes, decreased pain, and shorter hospital stays. The series of detailed techniques presented here serve as a comprehensive guide for urologists, aiming to improve their procedural understanding and optimize patient outcomes.

Determining the Stone Free Rate of Retrograde Intrarenal Surgery. Which Radiological Technique? RIRSearch Study Group

OBJECTIVE

To evaluate the sensitivity and specificity of ultrasonography (USG) and kidney ureter bladder radiography (KUB) for the determination of stone-free status of retrograde intrarenal surgery (RIRS) according to different stone-free status definitions.

MATERIALS AND METHODS

The patients who underwent RIRS between September 2021 and September 2022 were prospectively included in the study. All patients underwent a KUB radiography, urinary system USG and noncontrast abdominal tomography at the postoperative first month of the surgery. The sensitivity, specificity, negative predictive factor, and positive predictive factor of USG and KUB on evaluating the stone-free rate were analyzed according to different stone-free status definitions.

RESULTS

A total of 178 patients were included in the study. The stone-free rates according to stone-free definitions as; residual stone <4 mm, <2 mm and no residual stone were 79.2%, 64.0%, and 56.7%, respectively. According to its definition as a residual stone <4 mm, the sensitivity and specificity of USG were 64.9% and 84.3%, respectively. The sensitivity of USG was 57.1% and 52.5% as the definitions were residual stone <2 mm and no residual stone, respectively. Addition of KUB to USG slightly increased the sensitivity but did not change the specificity.

CONCLUSION

USG had high specificity but low sensitivity for evaluating stone-free status after RIRS and addition of KUB did not increase the diagnostic efficacy. Although USG may be used in daily practice, it may overestimate the stone-free status and noncontrast abdominal tomography must be used during the clinical trials to document the exact stone-free rates of RIRS.

Effect of preoperative ureteral stenting on the surgical outcomes of patients with 1-2 cm renal stones managed by retrograde intrarenal surgery using a ureteral access sheath

OBJECTIVE

To assess the surgical results of patients who underwent retrograde intrarenal surgery (RIRS) using a ureteral access sheath (UAS) for management of renal stones sized 1-2 cm compared between patients who did and did not undergo preoperative ureteral stenting.

MATERIALS AND METHODS

This prospective study included 83 patients (aged ≥ 20 years) who underwent RIRS from July 2021 to January 2023. All patients had renal calculi (stone size: 1-2 cm) located within the pelvicalyceal system. 43 and 40 patients were allocated to the non-prestent (group A) and prestent (group B), respectively. Patient baseline characteristics, renal stone details, operative data, stone-free rate (SFR) at 4 weeks and 6 months, and perioperative complications were compared between groups.

RESULTS

The baseline characteristics of all patients were comparable across the groups. Four weeks after surgery, the overall stone-free rate (SFR) stood at 62.65%. In the non-prestent and prestent groups, the SFRs were 58.12% and 67.5%, respectively (p = 0.89). By the sixth month post-surgery, the overall SFR rose to 80.72%. In the non-prestent and prestent groups, the SFRs were 76.74% and 85%, respectively (p = 0.081). No notable differences emerged in other variables, including perioperative complications, between the two groups.

CONCLUSIONS

The SFR showed no significant difference between the prestenting and non-prestenting groups at the 4-week and 6-month postoperative marks. Additionally, there were no substantial differences in complications during surgery and recovery between the groups. Notably, the SFR increased from 4 weeks to 6 months without any additional procedures in either group.

ACR Appropriateness Criteria® Acute Onset Flank Pain-Suspicion of Stone Disease (Urolithiasis)

Noncontrast CT (NCCT) is the imaging study of choice for initial evaluation of patients with acute onset of flank pain and suspicion of stone disease without known prior stone disease. NCCT can reliably characterize the location and size of an offending ureteral calculus, identify complications, and diagnose alternative etiologies of abdominal pain. Although less sensitive in the detection of stones, ultrasound may have a role in evaluating for signs of obstruction. Radiography potentially has a role, although has been shown to be less sensitive than NCCT. For patients with known disease and recurrent symptoms of urolithiasis, NCCT remains the test of choice for evaluation. In pregnancy, given radiation concerns, ultrasound is recommended as the initial modality of choice with potential role for noncontrast MRI. In scenarios where stone disease suspected and initial NCCT is inconclusive, contrast-enhanced imaging, either with MRI or CT/CT urogram may be appropriate. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Surgical outcomes of patients who underwent retrograde intrarenal surgery using a ureteral access sheath to manage kidney stones sized 1-2 cm compared between patients who did and did not undergo preoperative ureteral stenting

Objective

To investigate the surgical outcomes of patients who underwent retrograde intrarenal surgery (RIRS) using a ureteral access sheath (UAS) to manage kidney stones sized 1-2 cm compared between patients who did and did not undergo preoperative ureteral prestenting.

Materials and methods

This retrospective cohort study included 166 patients (aged ≥18 years) who underwent RIRS at Siriraj Hospital (Bangkok, Thailand) during February 2015-February 2020. All patients had renal calculi (stone size: 1-2 cm) located within the pelvicalyceal system. 80 and 86 patients were allocated to the prestent and non-prestent groups, respectively. Patient baseline characteristics, renal stone details, operative equipment, stone-free rate (SFR) at 2 weeks and 6 months, and perioperative complications were compared between groups.

Results

All patient baseline characteristics were similar between groups. At 2 weeks after surgery, the overall SFR was 65.1%, and the SFRs in the prestent and non-prestent groups were 73.4% and 59.5%, respectively (p = 0.09). At 6 months after surgery, the overall SFR was 80.1%, and the SFRs in the prestent and non-prestent groups were 90.7% and 79.3%, respectively (p = 0.08). The incidence of perioperative complications was not significantly different between groups.

Conclusions

There was no significant difference in the SFR between the presenting and non-prestenting groups at both the 2-week and 6-month postoperative time points. There was also no significant difference in intraoperative and postoperative complications between groups. The SFR was higher at 6 months than at 2 weeks in both groups with no additional procedure.

The efficacy of ultrasonography for the detection of upper tract urothelial carcinoma

PURPOSE

Ultrasonography and computed tomography urography are two commonly used modalities to image the upper tracts for the evaluation of hematuria. This study evaluated the efficacy of ultrasonography for the detection of upper tract urothelial carcinoma compared to computed tomography urography as a standard reference.

METHODS

This retrospective study included patients with urothelial carcinoma of the renal pelvis and/or ureter who were diagnosed using computed tomography urography and underwent surgical treatment. We calculated the sensitivity of ultrasonography in upper tract urothelial carcinoma diagnosis, further classified the degree of hydronephrosis on ultrasonography, and analyzed the relationship between the sensitivity and the degree of hydronephrosis and tumor location. Additionally, the usefulness of the combination of the screening ultrasonography findings, the presence of gross hematuria, and/or urine cytology was analyzed.

RESULTS

This study included 136 patients with upper urothelial carcinoma. Ultrasonography in the diagnosis had 45.6% sensitivity, and ultrasonography findings, including the detection of hydronephrosis, were present in 72.8%. The presence of hydronephrosis and tumor location were associated with detection by ultrasonography. The tumor was identified in a total of 134 (98.5%) patients by combining tumor detection and hydronephrosis using ultrasonography with gross hematuria and positive urine cytology as screening.

CONCLUSION

Ultrasonography showed acceptable sensitivity for upper tract urothelial carcinoma diagnosis. Considering the hydronephrosis findings, ultrasonography is a useful screening tool for upper tract urothelial carcinoma. Additionally, excessive computed tomography examinations can be reduced by adding gross hematuria and positive urine cytology.

Safety and efficacy of ureteroscopy for urolithiasis in octogenarians

OBJECTIVE

To examine the safety and efficacy of ureteroscopy (URS) for urolithiasis in octogenarians, and identify preoperative risk factors for the incidence of postoperative complications.

METHODS

The patients who underwent URS for urolithiasis were divided into octogenarians and younger patients (age: <80 years), and the groups were compared regarding their clinical characteristics, intraoperative and postoperative complications, and stone-free rate. The predictors of postoperative complications were evaluated using logistic regression models.

RESULTS

A total of 1207 patients were included, 166 in the octogenarian patient group and 1041 in the younger patient group. The proportion of female patients (p < 0.001), American Society of Anesthesiologists (ASA) score (p < 0.001), rate of preoperative pyelonephritis (p < 0.001), and diabetes mellitus (p = 0.003) were higher in the octogenarian group. No statistically significant differences were found between the two groups regarding stone size, location, and intraoperative complications. Postoperative complications, which reached a significant difference, were observed in 34 (20.5%) octogenarians and 117 (11.2%) younger patients (p = 0.002). However, age itself was not significantly associated with postoperative fever, the most frequent postoperative complication, in multivariate analysis. Female sex, ASA score of ≥3, history of diabetes mellitus, and prolonged operative time (≥120 min) were the significant predictors of fever. The stone-free rate in the octogenarian group was superior to that in the younger patient group (80.1% vs. 70.6%, respectively; p = 0.035).

CONCLUSION

Our results suggest that URS for urolithiasis can be safely and effectively applied to octogenarians in selected cases.

Can plain film radiography improve the emergency department detection of clinically important urinary stones?

OBJECTIVE

Physicians frequently use ultrasound to assess hydronephrosis in patients with suspected renal colic, but ultrasound has limited diagnostic sensitivity and rarely clarifies stone size or location. Consequently, up to 80% of emergency department (ED) renal colic patients undergo confirmatory CT imaging. Our goal was to estimate x-ray sensitivity for urinary stones and determine whether x-ray substantially improves stone detection (sensitivity) compared to hydronephrosis assessment alone.

METHODS

We reviewed imaging reports from all renal colic patients who underwent x-ray and CT at four EDs. For each patient, we documented stone size, location and hydronephrosis severity on CT and whether stones were identified on x-ray. We considered moderate and severe hydronephrosis (MS-Hydro) as significant positive findings, then calculated the sensitivity (detection rate) of MS-Hydro and x-ray for large stones ≥5 mm and for stones likely to require intervention (all ureteral stones >7 mm and proximal or middle stones >5 mm). We then tested a diagnostic algorithm adding x-ray to hydronephrosis assessment.

RESULTS

Among 1026 patients with 1527 stones, MS-Hydro sensitivity was 39% for large stones and 60% for interventional stones. X-ray sensitivity was 46% for large stones and 52% for interventional stones. Adding x-ray to hydronephrosis assessment increased sensitivity in all stone categories, specifically from 39% to 68% for large stones (gain = 29%; 95%CI, 23% to 35%) and from 60% to 82% for interventional stones (gain = 22%; 95%CI, 13% to 30%). Because CT and ultrasound show strong agreement for MS-Hydro identification, physicians who depend on ultrasound-based hydronephrosis assessment could achieve similar gains by adding x-ray.

CONCLUSIONS

Adding x-ray to hydronephrosis assessment substantially improves diagnostic sensitivity, enabling the detection of nearly 70% of large stones and over 80% of interventional stones. This level of sensitivity may be sufficient to reassure physicians about a renal colic diagnosis without CT imaging for many patients.

Predictors of Repeat Surgery and Stone-related Events After Flexible Ureteroscopy for Renal Stones

OBJECTIVES

To evaluate the risk of repeat surgery and stone-related events after flexible ureteroscopy (fURS) for renal stones, and to identify their predictive factors.

PATIENTS AND METHODS

This was a single-center, retrospective cohort study of patients (n = 664) who underwent fURS for renal stones with or without concomitant ureteral stones between January 2012 and December 2019. The primary outcomes were time to ipsilateral stone-related surgical intervention and any stone-related event (including ipsilateral renal colic, symptomatic ureteral calculi, obstructive urinary tract infection, and surgical intervention).

RESULTS

During median follow-up of 31.1 months, 103 (15.5%) and 135 (20.3%) patients experienced surgical intervention and any stone-related event, respectively. The estimated 2-year intervention-free survival and stone-event-free survival was 86.9% and 81.6%, respectively. On Cox multivariate analysis, younger age (hazard ratio [HR] 0.96), history of stone surgery (HR 2.17), larger preoperative stone burden (HR 1.03), and larger residual fragment (HR 1.09) showed an association with future intervention. Use of the four identified risk factors (age ≤60, history of stone surgery, stone burden ≥20 mm, and residual fragment ≥4 mm) allowed stratification of patients based on the risk of future intervention (low [score: 0-1], intermediate [2], and high [3-4] risk). The estimated 2-year intervention-free survival rates in low-, intermediate-, and high-risk groups were 96.2%, 86.4%, and 71.3%, respectively.

CONCLUSION

Patients undergoing fURS are at risk of future ipsilateral surgical intervention and stone-related events. Our simple predictive tool can facilitate treatment decision-making by identifying patients who are at high risk of recurrence.

The future of CT: deep learning reconstruction

There have been substantial advances in computed tomography (CT) technology since its introduction in the 1970s. More recently, these advances have focused on image reconstruction. Deep learning reconstruction (DLR) is the latest complex reconstruction algorithm to be introduced, which harnesses advances in artificial intelligence (AI) and affordable supercomputer technology to achieve the previously elusive triad of high image quality, low radiation dose, and fast reconstruction speeds. The dose reductions achieved with DLR are redefining ultra-low-dose into the realm of plain radiographs whilst maintaining image quality. This review aims to demonstrate the advantages of DLR over other reconstruction methods in terms of dose reduction and image quality in addition to being able to tailor protocols to specific clinical situations. DLR is the future of CT technology and should be considered when procuring new scanners.

Do low dose CT-KUBs really expose patients to more radiation than plain abdominal radiographs?

BACKGROUND

Urolithiasis patients often require frequent urinary tract imaging, leading to high radiation exposure. CT Kidney-Ureter-Bladder (CT-KUB) is the gold standard in urolithiasis detection, however it is thought to harbour significant radiation load. Urologists have therefore utilised abdominal radiographs (XR-KUB) as an alternative, though with markedly lower sensitivity and specificity. We present the first contemporary UK study comparing the effective doses of XR-KUBs with low dose CT-KUBs.

METHOD

Fifty-three patients were retrospectively identified in a single centre who underwent both a XR-KUB and a CT-KUB in 2018. Effective-Dose was measured by converting the recorded 'Dose Area/Length Product' via the International Commission on Radiological Protection formula.

RESULTS

The average effective dose of XR-KUBs and low dose CT-KUBs were 5.10 mSv and 5.31 mSv respectively. Thirty-four percent (18/53) of patients had a XR-KUBs with a higher effective dose than their low dose CT-KUB. Patients with higher Weight, BMI and AP diameter had higher effective doses for both their XR and low dose CT-KUBs. All patients in our study weighing over 92 kg or with a BMI greater than 32 had a XR-KUBs with a higher effective dose than their low dose CT-KUB.

CONCLUSION

This data supports moving away from XR-KUBs for the investigation of urolithiasis, particularly in patients with a high BMI.

Extremely-slow, half-number shockwave lithotripsy for asymptomatic renal stones <20 mm

PURPOSE

To compare the treatment success rate and safety of reduced (30 shocks/min, 1,200 shocks/session) versus standard (60 shocks/min, 2,400 shocks/session) extracorporeal shockwave lithotripsy for the management of renal stones.

MATERIALS AND METHODS

We retrospectively analyzed 404 patients who underwent extracorporeal shockwave lithotripsy for 5-20-mm renal stones between April 2011 and March 2019. Patients selected the reduced or standard protocol (group R and S) after explaining the potential benefits and disadvantages. The primary outcome was treatment success within 12 weeks, which was defined as no residual fragment or fragments <4 mm on ultrasonography and plain radiograph.

RESULTS

In total, 94 and 310 patients underwent shockwave lithotripsy with a reduced and standard protocol, respectively. The background characteristics of the participants did not significantly differ. The treatment success within 12 weeks was achieved in 78 (83.0%) patients in group R and 259 (83.5%) in group S (p=0.88). The median number of the session was 3 (interquartile range, 2-4) in both groups (p=0.53). The total complication rates were 5.4% in group R and 6.1% in group S. Three (1.0%) patients in group S experienced perirenal hematoma, which was conservatively treated. The reduced protocol was not associated with treatment success in the multivariate analysis adjusted for potential confounders (odds ratio, 0.91; 95% confidence interval, 0.46-1.80; p=0.78).

CONCLUSIONS

The new treatment amendment with a slower delivery rate successfully reduced the total number of shocks need to fragment renal stones <20 mm without compromising the stone-free rate.

Fragmentation and propulsive effect of shock wave lithotripsy in treatment of small renal calculi

Background

Small renal calculi are frequently observed in clinical practice, and chemo-lytic therapy has limited effects. The purpose of the study is to evaluate the effectiveness of extracorporeal shock wave lithotripsy (ESWL) in the treatment of small renal calculi.

Methods

We studied 60 patients with small renal stones from March 2017 to March 2019. After excluding eight patients with incomplete data, the remaining 52 patients were evaluated. Patients with symptomatic single or multiple stones of 6–8 mm in diameter or asymptomatic on ultrasound and kidney-ureter-bladder radiograph were eligible for inclusion. Small stones were treated by ESWL. The data were analyzed using the Statistical Packages for Social Sciences - version 25 (IBM Corporation).

Results

The mean age of the 52 patients was 34.5 ± 9.5 years. Forty-one (78.8%) patients were symptomatic, while 11 (21.2%) were asymptomatic. Forty-seven (90.4%) had single small renal stones, while four patients had two stones (7.7%) and only one patient had three stones (1.9%). Forty-five stones were successfully treated by ESWL, while 13 stones failed to respond.

Conclusion

ESWL is a useful tool for treating small renal calculi; it works either by fragmenting the stones or by acting as a pushing force. However, further large prospective studies are needed to corroborate the above conclusions.

Decreased Recurrence of Urolithiasis After Simultaneous Ureteroscopic Surgery for Ureter and Ipsilateral Renal Calculi: Comparison to Shockwave Lithotripsy for Ureter Calculi Alone

OBJECTIVE

To compare follow-up outcomes of ureteroscopy (URS) and shockwave lithotripsy (SWL) for ureter calculi in the setting of asymptomatic renal calculi <15 mm.

METHODS

This study included 789 patients who underwent URS (n = 301) or SWL (n = 488) as primary treatment for ureter calculi and who had ipsilateral renal calculi <15 mm between January 2012 and December 2019. For the URS group, all renal calculi were simultaneously treated unless contraindicated. One-to-one matching was performed using the propensity score (PS).

RESULTS

After PS matching, analysis included 262 matched pairs of URS and SWL patients. The stone-free rate for ureter calculi without auxiliary procedure was 97.3% in the URS group and 93.9% in the SWL group. Any complication rates were 11.0% and 9.2% in the URS and SWL group, respectively; 1.1% of the URS patients experienced complications classified as Clavien-Dindo ≥IIIb. The estimated 2-year intervention-free survival was 88.1% in the URS group and 84.2% in the SWL group (P = 0.045). The estimated 2-year stone-event-free survival was 80.1% in the URS group and 71.0% in the SWL group (P = 0.009). Cox multivariate analysis showed that the hazard ratios of URS were 0.62 (P = 0.025) for surgical interventions and 0.64 (P = 0.008) for stone-related events after adjusting for baseline variables.

CONCLUSION

For patients with symptomatic ureter calculi and asymptomatic renal calculi <15 mm, URS with active treatment for renal calculi reduces future ipsilateral surgical intervention and stone-related events compared with SWL for ureter calculi.

Imaging Modalities in Genitourinary Emergencies

Emergency physicians rely on a multitude of different imaging modalities in the diagnosis of genitourinary emergencies. There are many considerations to be taken into account when deciding which imaging modality should be used first, as oftentimes several diagnostic tools can be used for the same pathologic condition. These factors include radiation exposure, sensitivity, specificity, age of patient, availability of resources, cost, and timeliness of completion. In this review, the strengths and weaknesses of different imaging tools in the evaluation of genitourinary emergencies are discussed.

Symptomatic and Radiographic Manifestations of Kidney Stone Recurrence and Their Prediction by Risk Factors: A Prospective Cohort Study

BACKGROUND

Meaningful interpretation of changes in radiographic kidney stone burden requires understanding how radiographic recurrence relates to symptomatic recurrence and how established risk factors predict these different manifestations of recurrence.

METHODS

We recruited first-time symptomatic stone formers from the general community in Minnesota and Florida. Baseline and 5-year follow-up study visits included computed tomography scans, surveys, and medical record review. We noted symptomatic recurrence detected by clinical care (through chart review) or self-report, and radiographic recurrence of any new stone, stone growth, or stone passage (comparing baseline and follow-up scans). To assess the prediction of different manifestations of recurrence, we used the Recurrence of Kidney Stone (ROKS) score, which sums multiple baseline risk factors.

RESULTS

Among 175 stone formers, 19% had symptomatic recurrence detected by clinical care and 25% detected by self-report; radiographic recurrence manifested as a new stone in 35%, stone growth in 24%, and stone passage in 27%. Among those with a baseline asymptomatic stone (54%), at 5 years, 51% had radiographic evidence of stone passage (accompanied by symptoms in only 52%). Imaging evidence of a new stone or stone passage more strongly associated with symptomatic recurrence detected by clinical care than by self-report. The ROKS score weakly predicted one manifestation-symptomatic recurrence resulting in clinical care (c-statistic, 0.63; 95% confidence interval, 0.52 to 0.73)-but strongly predicted any manifestation of symptomatic or radiographic recurrence (5-year rate, 67%; c-statistic, 0.79; 95% confidence interval, 0.72 to 0.86).

CONCLUSIONS

Recurrence after the first stone episode is both more common and more predictable when all manifestations of recurrence (symptomatic and radiographic) are considered.