Adjuvant chemotherapy after radical cystectomy: Do all patients who need chemotherapy after surgery actually receive it?

Background: Compliance with the guideline recommendations for neoadjuvant chemotherapy in patients with muscle-invasive bladder cancer is incomplete. The adjuvant chemotherapy approach has the advantage of pathology-based decision-making, allowing for patient selection. In addition, radical surgery is not delayed and treatment-related toxicity does not impair surgical fitness. The proportion of patients who completed chemotherapy after cystectomy among those who were fit and in need of treatment were evaluated. The reasons for not completing adjuvant chemotherapy were determined. Materials and methods: We retrospectively evaluated all patients who had undergone radical cystectomy at our center over the last 7 years. Indications for adjuvant chemotherapy included pathological T > 2, any node+, or surgical margin involvement. Only patients who were fit for chemotherapy before surgery were included in the study. Results: Of the 52 patients with muscle-invasive bladder cancer, 14 received neoadjuvant chemotherapy or unfit for chemotherapy were excluded. Of the remaining 38 patients, 14 (37%) had bladder-confined cancers and did not require additional chemotherapy. Of the 24 patients who needed chemotherapy and were fit to receive it, 8 patients completed treatment (33%), and 3 discontinued treatment due to toxicity. Twelve patients (50%) declined chemotherapy, whereas 1 patient became unfit for chemotherapy after surgery. Conclusions: While the adjuvant chemotherapy approach could save unnecessary treatment in 37% of patients, two-thirds of those who needed chemotherapy did not complete it. Patient refusal was the primary reason for not receiving treatment.

The Impact of Radiographic, Metabolic and Demographic Characteristics on Kidney Stone Recurrence.

Urolithiasis is a frequent disease with cited rates of recurrence after initial diagnosis that vary widely and range between 35% and 50%. We assessed the radiographic recurrence rate in patients with urinary stones and its risk factors. We retrospectively identified patients who were diagnosed with urinary stones on non-contrast computed tomography from 2010 to 2011, and underwent another imaging examination at least six months afterwards. We collected patient demographic, clinical, laboratory and radiologic data and compared patients with and without urinary stone recurrence. Ultimately, 237 patients were included in the study; the mean follow-up was 6.7 years; 88 patients (37.1%) had recurrence based on our recurrence criteria. On univariate analysis, the significant parameters for recurrence were baseline serum calcium and uric acid, stone location in the kidney, surgical intervention and stone burden volume. On multivariate analysis, surgical intervention (OR 3.07, p = 0.001), baseline calcium (OR 2.56, p = 0.011), baseline uric acid (OR 1.30, p = 0.021) and stone location in the kidney (OR 2.16, p = 0.012) were associated with higher risk of recurrence. These findings may guide personalized follow-up protocols for patients with urolithiasis based on their risk factors.

Potential Markers to Reduce Non-Contrast Computed Tomography Use for Symptomatic Patients with Suspected Ureterolithiasis.

Most patients with ureterolithiasis are managed successfully with conservative treatment. In this context, delineation of clinical risk factors that identify patients with low risk for surgical intervention may reduce use of Non-Contrast Computed Tomography (NCCT). Here, emergency department patient files from a 14-month period were reviewed retrospectively, to identify patients who underwent NCCT and showed a ureteral stone. Demographic, clinical and laboratory information was collected. Patients were grouped to either requiring surgical intervention (Group 1) or having successful conservative management (Group 2). The cohort included 368 patients; 36.1% ultimately required surgical intervention (Group 1) and 63.9% were successfully treated conservatively (Group 2). On univariate analysis, patients who required surgical intervention were older, had longer duration of symptoms, had history of urolithiasis and surgical intervention for urolithiasis and had higher serum creatinine levels. Multivariate analysis identified the following risk factors associated with surgical intervention: creatinine >1.5 mg/dL, duration of symptoms ≥ 1.5 days and age > 45 years. Patients with 0, 1, 2 or 3 of the identified risk factors had 19%, 32%, 53% and 73% likelihood, respectively, of surgical intervention. Incorporating these data may reduce the use of NCCT scans in patients who are likely to pass a stone via conservative management.

Design of a fully intraureteral stent and proof-of-concept in vivo evaluation.

Background: Ureteral stents are employed regularly to facilitate urine drainage and ureteral healing in a wide variety of endourological procedures, associated mainly with ureteral stone obstruction. However, stent use frequently impairs patient quality of life, which is generally attributed to the presence of anchoring stent curls in the bladder and/or kidney. The purpose of this study was to examine the potential effectiveness and safety of a newly designed, fully intraureteral stent, in an initial proof-of-concept in vivo evaluation. Methods: "Yoticurl" stents were synthesized from copolymeric, commercially-available ureteral stents. A first test to confirm the intended expansion of the spiral curls in a ureter was performed on a pig cadaver. Subsequently, a preliminary in vivo evaluation in a single pig model was completed to test stent viability, over a period of 25 days. Two stents were inserted to fully intraureteral positions into the two ureters, by standard human endourological procedure. Daily observational checks of the pig, and regular radiographic analyses were performed; the animal was then euthanized and examined by explorative laparotomy, followed by histological analysis of kidney, ureter and bladder tissue samples. Results: The pig displayed normal activity, appetite and sleep patterns, and radiography indicated free flow of urine, and no significant stent migration nor anatomical abnormalities. Subsequent histology found only mild inflammation in the ureter. Conclusions: The innovative stent design tested here, if ultimately proven safe and effective for human use, may offer an alternative to currently available stents for multiple indications.

Magnetic resonance imaging of in vitro urine flow in single and tandem stented ureters subject to extrinsic ureteral obstruction.

OBJECTIVE: To quantify the relative volumetric flows in stent and ureter lumina, as a function of stent size and configuration, in both unobstructed and externally obstructed stented ureters. METHODS: Magnetic resonance imaging was used to measure flow in stented ureters using a phantom kidney model. Volumetric flow in the stent and ureter lumina were determined along the stented ureters, for each of four single stent sizes (4.8F, 6F, 7F, and 8F), and for tandem (6F and 7F) configurations. Measurements were made in the presence of a fully encircling extrinsic ureteral obstruction as well as in benchmark cases with no extrinsic ureteral obstruction. RESULTS: Under no obstruction, the relative contribution of urine flow in single stents is 1-10%, while the relative contributions to flow are ~6 and ~28% for tandem 6F and 7F, respectively. In the presence of an extrinsic ureteral obstruction and single stents, all urine passes within the stent lumen near the extrinsic ureteral obstruction. For tandem 6F and 7F stents under extrinsic ureteral obstruction, relative volumetric flows in the two stent lumina are ~73% and ~81%, respectively, with the remainder passing through the ureter lumen. CONCLUSIONS: Magnetic resonance imaging demonstrates that with no extrinsic ureteral obstruction, minimal urine flow occurs within a stent. Stent lumen flow is significant in the presence of extrinsic ureteral obstruction, in the vicinity of the extrinsic ureteral obstruction. For tandem stents subjected to extrinsic ureteral obstruction, urine flow also occurs in the ureter lumen between the stents, which can reduce the likelihood of kidney failure even in the case of both stent lumina being occluded.

Drainage of infected kidneys with ureteral stents: does size matter?

PURPOSE: The purpose of our study was to evaluate the ability of ureteral stents with different diameters to drain pus that accumulates in an obstructed kidney using an in vitro model. METHODS: We developed an in vitro model of an obstructed kidney filled with pus. The model included a silicon kidney unit based on computed tomography (CT) data, a 3D printed ureteral stone based on a real extracted ureteral stone, a latex ureter model, a bladder vessel, and a fluid with qualities resembling pus. Identical printed stones were inserted into four ureter models containing stents with varying diameters (4.8F, 6F, 7F, 8F), each of which was connected to the kidney unit and the bladder vessel. The kidney unit was filled with artificial pus to pressures of 30 cmH2O to simulate an infected and obstructed kidney. The obstruction was relieved with stents in place, while artificial urine was pumped into the kidney; pressure in the kidney and remaining pus were measured continuously. RESULTS: The rate of pressure drop and the final pressure measured in the kidney were unaffected by the diameter of the stent. For all stent diameters, the pressure reached non-obstructed levels within 30 s, final pressure was reached within 90-120 s, and minimal amounts of pus remained in the kidney after 120 min. CONCLUSIONS: In vitro experiments demonstrate that all stent diameters drain pus-filled, obstructed kidneys with the same efficacy. The common perception that larger diameter tubes are more effective under such circumstances should be re-examined.

When should we give up on expectant management for patients with proximal ureteral stones?

Background: Proximal ureteral stones (PUS) have relatively low rates of spontaneous expulsion. However, some patients do well on expectant management. Our aim was to compare risk factors for surgical intervention in patients with PUS who underwent primary intervention to those subjected to expectant management. Materials and methods: We retrospectively reviewed the medical charts of patients presented to the emergency room with symptoms of renal colic and underwent computerized tomography between August 2016 and August 2017. A total of 97 consecutive patients were identified with up to 10mm PUS. We collected patient demographics, clinical, and imaging data, and performed binary regression analysis for risk of intervention. Results: The average age was 49years (range 17-97) and average stone size was 7.1mm (range 3-10). Forty-one patients underwent immediate intervention while the remaining 56 patients were treated conservatively. Of the 56 patients treated conservatively, 26 underwent delayed intervention while 30 reported spontaneous stone expulsion. On univariate analysis of all 97 patients, statistically significant risk factors for intervention were found based on stone size, age, serum lymphocyte, platelet counts, and stone density. Of these risk factors, stone size ≥ 7mm (p = 0.012, odds ratio = 5.4) and platelet count ≤ 230K/µL (p = 0.027, odds ratio = 4.9) remained statistically significant on multivariate analysis. Conclusion: Stone size and platelet count were found to be risk factors for surgical intervention in patients with up to 10mm PUS. These findings may assist in identifying patients who are more suitable for conservative approach.

Imaging and Chemical Analysis of External and Internal Ureteral Stent Encrustation.

Introduction: Ureteral stents are effective in alleviating flow disruptions in the urinary tract, whether due to ureteral stones, strictures or extrinsic ureteral obstruction. However, significant stent encrustation on the external and/or internal stent lumen walls can occur, which may interfere with stent functioning and/or removal. Currently, there is only limited, generally qualitative, information on the distribution, mineral structure, and chemical content of these deposits, particularly in terms of stent lumen encrustation. Objective: To quantify, in an initial investigation, external and internal encrustation in representative, intact ureteral stents. The study investigates possible correlations between patterns of external and internal encrustation, determines mineral structure and chemical composition, and examines the potential for stent lumen obstruction even in the absence of external stent wall encrustation. Study Design: High-resolution, laboratory micro-computed tomography (micro-CT) was used to non-destructively image external and internal stent encrustation in four representative stents. X-ray diffractometry (XRD) and scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS) enabled parallel analysis of mineral structure and chemical content of samples collected from external and internal encrusted material along the distal, proximal and mid-ureteral stent regions. Results: Extensive stent lumen encrustation can occur within any region of a stent, with only incidental or minor external encrustation, along the entire length of the stent. External and internal encrusted materials in a given stent are generally similar, consisting of a combination of amorphous (mostly organic) and crystalline mineral deposits. Conclusion: Micro-CT demonstrates that significant stent lumen encrustation can occur, which can lead to partial or full stent lumen occlusion, even when the exterior stent wall is essentially free of encrusted material.

Influence of Single Stent Size and Tandem Stents Subject to Extrinsic Ureteral Obstruction and Stent Occlusion on Stent Failure.

Background and Purpose: Drainage of obstructed kidney attributable to extrinsic ureteral obstruction (EUO), required to prevent renal damage, is often achieved using Double-J ureteral stents. However, these stents fail frequently, and there is considerable debate regarding what stent size, type, and configuration offer the best option for sustained drainage. In this study, we examine the impact of stent diameter and choice of single/tandem configuration, subject to EUO and various degrees of stent occlusion, on stent failure. Materials and Methods: Computational fluid dynamics simulations and an in vitro ureter-stent experiment enabled quantification of flow behavior in stented ureters subject to EUO and stent occlusions. Various single and tandem stents under EUO were considered. In each simulation and experiment, changes in renal pressure were monitored for different degrees of stent lumen occlusion, and onset of stent failure as well as simulated distributions of fluid flow between stent and ureter lumina were determined. Results: For an encircling EUO that completely obstructs the ureter lumen, with or without partial stent occlusion, the choice of stent size/configuration has little effect on renal pressure. The pressure increases significantly for ∼90% stent lumen occlusion, with failure at >95% occlusion, independent of stent diameter or a tandem configuration, and with little influence of occlusion length along the stent. Conclusions: Stent failure rate is independent of stent diameter or single/tandem configuration, for the same percentage of stent lumen occlusion, in this model. Stent failure incidence may decrease for larger diameter stents and tandem configurations, because of the larger luminal area.

Surgical Outcomes in High-risk Prostate Cancer and Salvage Radical Prostatectomy.

BACKGROUND: Patients with high-risk prostate cancer are at higher risk of treatment failure, development of metastatic disease, and mortality. There is no consensus on the treatment of choice for these patients, and either radical prostatectomy (RP) or external beam radiation therapy (EBRT) is recommended. Surgery is less common as the initial treatment for high-risk patients, possibly reflecting the concerns regarding morbidity as well as oncological and functional outcomes. Another high-risk group includes patients with failure of previous EBRT or focal treatment. For these patients, salvage radical prostatectomy (SRP) can be offered. OBJECTIVES: To describe our experience with surgery of high-risk patients and SRP. METHODS: This cohort included all high-risk patients undergoing RP or SRP at our institution between January 2012 and December 2019. We reviewed the electronic medical charts and collected pathological, functional, and oncological outcomes. RESULTS: Our cohort included 39 patients; average age was 67.8 years, and average follow-up duration was 40.9 months. The most common postoperative morbidity was transfusion of packed cells. There were no life-threatening events or postoperative mortality. Continence was preserved (zero to one pad) in 76% of the patients. Twenty-three patients (59%) had undetectable prostate specific antigen levels following the surgery, 11 (30%) were treated with either adjuvant or salvage EBRT, and 12 patients (31%) were found with no evidence of disease and no additional treatment was needed. CONCLUSIONS: Radical prostatectomy and SRP are safe options for patients presenting with high-risk prostate cancer, with good functional and oncological outcomes.

Radical Cystectomy after Previous Radiation or Pelvic Surgery: Is It Associated with Increased Morbidity?

BACKGROUND: Radical cystectomy is a complicated surgery with significant risks. Complications of Clavien-Dindo grade 3-4 range from 25% to 40% while risk of mortality is 2%. Pelvic surgery or radiotherapy prior to radical cystectomy increases the challenges of this surgery. OBJECTIVES: To assess whether radical cystectomy performed in patients with prior history of pelvic surgery or radiation was associated with increased frequency of Clavien-Dindo grade 3 or higher complications compared to patients without prior pelvic intervention. METHODS: We retrospectively evaluated all patients who underwent radical cystectomy at our center over a 7-year period. All patients with pelvic radiation or surgery prior to radical cystectomy comprised group 1, while group 2 included the remaining patients. RESULTS: In our study, 65 patients required radical cystectomy at our institution during the study period. Group 1 was comprised of 17 patients and group 2 included 48 patients. Four patients from group 2 received orthotopic neobladder, while an ileal conduit procedure was performed in the remaining patients. Estimated blood loss and the amount of blood transfusions given was the only variable found to be statistically different between the two groups. One patient from group 1 had four pelvic interventions prior to surgery, and her cystectomy was aborted. CONCLUSIONS: Radical cystectomy may be safely performed in patients with a history of pelvic radiotherapy or surgery, with complication rates similar to those of non-irradiated or operated pelvises.

Comparative study of renal drainage with different ureteral stents subject to extrinsic ureteral obstruction using an in vitro ureter-stent model.

BACKGROUND: To compare the efficacy of different ureteral stents subject to extrinsic ureteral obstruction (EUO), in a controlled in vitro stented ureter experiment. METHODS: We employ an in vitro ureter-stent experimental set-up, with latex tubing simulating flexible ureters attached to vessels simulating renal units and bladders. The flow behavior of five ureteral stents-polymeric 8F, tandem 6F, tandem 7F, endopyelotomy and metal-was tested under a ureteral deformation configuration of 40°, with 2000 g external force over a 3.5 cm length of the ureter. A constant fluid flow was applied through the ureter-stent configurations, and pressure fluctuations in the renal unit were monitored. We considered a renal unit pressure of 10 cmH2O or flow discontinuation in the bladder as stent failure. Urine containing debris was mimicked by use of a colloidal solution. RESULTS: Of all assessed ureteral stents, under EUO conditions, only the single 8F stents remained patent throughout the length of the experiment. All other stents-tandem 6F and 7F, single 7F, metal and endopyelotomy-displayed limitations. CONCLUSIONS: Tandem and metal stents show no superiority over large luminal polymeric stents for EUO treatment in this in vitro model. Larger luminal stents offer excellent resistance to external pressure and allow adequate colloidal flow. The need for frequent exchange and bladder irritation should also be considered in the choice of stent configuration for treatment of kidney drainage under EUO.

Do organic substances act as a degradable binding matrix in calcium oxalate kidney stones?

BACKGROUND: Calcium oxalate (CaOx) stones are considered to be highly resistant to chemolysis. While significant organic matter has been identified within these stones, which is presumed to bind (inorganic) CaOx particles and aggregates, most chemolysis efforts have focused on methods to attack the CaOx components of a stone. We examine the feasibility of inducing chemolysis of CaOx kidney stones, within hours, by specifically attacking the organic matrix present in these stones. METHODS: In contrast to previous studies, we focused on the possible "brick and mortar" stone configuration. We systematically tested, via in vitro experiments, the ability of an extensive range of 26 potential chemolysis agents to induce relatively fast disintegration (and/or dissolution) of a large set of natural CaOx stone fragments, extracted during endourological procedures, without regard to immediate clinical application. Each stone fragment was monitored for reduction in weight and other changes over 72 h. RESULTS: We find that agents known to attack organic material have little, if any, effect on stone chemolysis. Similarly, protein and enzymatic agents, and oral additive medical treatments, have little immediate effect. CONCLUSIONS: These findings suggest that the organic and inorganic constituents present in CaOx stones are not structured as "brick and mortar" configurations in terms of inorganic and organic components.

Do patients with ureterolithiasis treated conservatively return to follow up?

INTRODUCTION Distal ureteral stones (DUS) are common in patients presenting to the emergency department (ED) with renal colic. The majority of DUS will pass spontaneously and therefore conservative care is common. Follow up is imperative as some of these stones might not pass and potentially lead to complications. The aim of our study was to evaluate the rate of compliance with follow up and to find predictive variables for it. MATERIALS AND METHODS: We retrospectively surveyed the medical records of all patients who had a non-contrast computed tomography (NCCT) at our ED between 01/03/16 and 31/5/17. We included patients with a DUS smaller than 10 mm that were treated conservatively. We obtained demographic, clinical, laboratory and imaging data. Compliance to follow up was evaluated by surveying the medical records and by calling the patients. We then compared the characteristics of patients who returned for follow up to those who did not. RESULTS: A total of 230 consecutive patients were included in our cohort: 194 (84%) patients were male and the average age was 46 y (21-82); 138 patients (60%) returned for a follow up visit while 92 patients (40%) did not. Univariate analysis revealed stone size and admission to hospital to be predictive of compliance to follow up while multivariate analysis revealed only hospital admission to be predictive of compliance. CONCLUSIONS: Only 60% of the patients with DUS treated conservatively return for a follow up visit. Hospital admission, which likely reflects appropriate patients counseling by a urologist and adequate follow up scheduling, was found to be associated with increased compliance with follow up.

Failure of ureteral stents subject to extrinsic ureteral obstruction and stent occlusions.

PURPOSE: To quantify the occurrence of stent failure and the dynamic behavior of urine flow in ureter-stent systems, including the relative flow in the ureter and stent lumina, subject to various degrees of ureter and stent blockage. METHODS: Numerical simulations based on computational fluid dynamics (CFD) were used to quantify urine flow behavior in stented ureters, in the presence of extrinsic ureteral obstruction (EUO) and stent occlusions. Two stented ureter configurations were considered, one with circumferential occlusion of the ureter and the second with pressure on one side of the ureter wall. The pressure within the renal unit for different degrees of ureter closure and stent lumen occlusion was determined systematically. Onset of stent failure and the distribution of urine flow between stent and ureter lumina were determined. RESULTS: In the case of EUO completely encircling the ureter, causing 100% obstruction of the ureter lumen, pressure in the renal unit is essentially unaffected until the stent lumen reaches ~ 90% occlusion, and fails only with > 95% occlusion. Occlusions of 50% in stent side holes in the vicinity of the EUO only alter local flow patterns but have no significant influence on renal unit pressure. For EUO deforming and compressing the ureter from one side, with ~ 50% reduction in ureter lumen, urine drainage proceeds with negligible increase in renal pressure even with 100% occlusion in the stent lumen. CONCLUSION: CFD simulations show that stent failure under EUO tends to occur suddenly, only when both ureter and stent lumina become almost fully blocked.

Impact of Colloidal Fluid on Stent Failure Under Extrinsic Ureteral Obstruction: An In Vitro Experimental Study.

Background and Purpose: Drainage of an obstructed kidney due to extrinsic ureteral obstruction (EUO) is imperative. Ureteral stents, commonly employed to facilitate drainage, often fail under EUO; this is usually attributed to external pressure over the ureter that occludes the stent lumen. We showed previously that external pressure and deformation of the ureter, alone, cannot explain frequent stent failure and speculated that colloids present in urine may play a critical synergetic role. In this study, we evaluate the role of colloidal fluid in ureteral obstruction under extrinsic compression. Materials and Methods: An in vitro ureter-stent model was employed using a latex tube to simulate a flexible ureter connecting simulated glass kidney and bladder units. The ureter was placed in deformed configuration of 40° with external pressure of 2000 g exerted over the deformed region of the stented ureter, representing extrinsic pressure. Four different ureteral stents were tested-4.8F, 6F, 7F, and 8F. Colloidal solution based on chicken albumin was injected through the simulated kidney into the stented ureter. Four replicates were performed for each stent diameter and straight stented ureters with no external pressure were used as controls. Stent failure was defined as kidney unit pressure over 10 cmH2O or complete obstruction of fluid flow; time to stent failure was measured. Results: Average failure time in 4.8F and 6F stents was 44 and 66 hours, respectively. The 7F ureteral stent failed in two replicates, after an average time of 75 hours, and continued to drain in the other two replicates. The 8F and control stents showed no change in kidney unit pressure in any of the replicates. Conclusions: Large-diameter stents are more effective in ureteral drainage under EUO in the presence of colloidal material in the fluid. Colloidal fluid may have a role in stent failure under EUO.

The Impact of Ureteral Deformation and External Ureteral Pressure on Stent Failure in Extrinsic Ureteral Obstruction: An In Vitro Experimental Study.

Background and Purpose: Extrinsic ureteral obstruction is caused frequently by pelvic malignancies or metastatic lymphadenopathy, necessitating renal drainage with ureteral stents to prevent renal failure and kidney damage. Understanding the nature of stent behavior under deformation and realistic external pressures may assist in evaluation of stent performance. Few published studies have investigated the flow and mechanical properties of stents within ureters, and none has considered the effects of deformation and compression on flow in realistic, in vitro, ureter-stent systems. The purpose of this work was to determine whether or not stent failure is due only to stent compression and deformation in the presence of extrinsic obstruction. Methods: We developed an in vitro ureter-stent experimental setup, using latex tubing to simulate a flexible ureter connecting a renal unit and a bladder side. We examined flow behavior in three stents (4.8F, 6F, 7F). The ureter-stent configuration was varied, simulating four levels of deformation (0°, 20°, 40°, 60°) and then simulating different external compressive forces on a stented ureter with 40° deformation. A constant, realistic fluid flow was applied through the ureter-stent configurations, and pressure fluctuations in the renal unit were monitored. Results: Deformation alone on four different levels (0°, 20°, 40°, 60°) has essentially no influence on fluid flow and renal pressure variation. Under increasing external compressive forces of 500, 1000, 2000, and up to 5000 g at 40° deformation, no effect on fluid flow and pressure within the renal unit was noted for the 6F and 7F stents. The only exception was for the 4.8F stent, which demonstrated complete failure at compressive forces near 4000 g. Conclusions: Neither realistic extrinsic ureteral compression forces nor ureteral deformation explain the high frequency of stent failure in extrinsic ureteral obstruction. Other factors such as urine composition may be a major contributor to stent failure.

Prediction of Surgical Intervention for Distal Ureteral Stones.

Introduction and Objective: Eighty percent of patients with distal ureteral stones <10 mm will ultimately pass the stone under conservative care. Nonetheless, some may experience related morbidity before surgical intervention is performed. Our study aims to find predictive variables for surgical intervention. Methods: We retrospectively surveyed medical records of patients found to have distal ureteral stone up to 10 mm by noncontrast computed tomography (NCCT) done between March 1, 2016 and May 31, 2017. Demographic, clinical, laboratory, and radiologic data were obtained. We compared characteristics of patients who underwent surgical intervention (ureteroscopy/renal drainage) with those treated conservatively. Results: A total of 268 consecutive patients were included: 226 (84%) were male and the average age was 46 years (18-82). Of these patients, 60 patients (22%) underwent surgical intervention (group 1) and 208 patients (78%) were treated expectantly (group 2). No significant differences were observed with respect to demographic data or proportion of patients treated with medical expulsive therapy between the groups. Univariate analysis found stone diameter, stone-to-ureterovesical junction (UVJ) distance, stone density, presence of a "rim sign" on NCCT, and pain duration at presentation to be significantly different between the groups. Multivariate analysis showed stone diameter, stone-to-UVJ distance, and pain duration at presentation to be independently predictive for intervention. Receiver operating characteristics curve analysis identified stone size >4 mm, stone-to-UVJ distance >4 mm, and pain duration >4 days to be the most significant cutoff points for patient risk stratification-"Rule of 4's." Further analysis showed that the prevalence of intervention among patients with 0, 1, 2, and 3 risk factors was 4.3%, 22.1%, 45%, and 66.7%, respectively. Conclusions: Stone size, stone distance from the UVJ, and pain duration play a significant role in predicting surgical intervention. "Rule of 4's" may aid in early recognition of patients who will ultimately undergo intervention and omit the burden of nonfavorable expectant management.