Comparison of the Diagnostic Values of Leukocytes, Neutrophils, Neutrophil-to-Lymphocyte Ratio and Platelet-to-Lymphocyte Ratio in Distinguishing between Acute Appendicitis and Right Ureterolithiasis.

BACKGROUND: To compare the diagnostic values of leukocytes, neutrophils, neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in distinguishing between acute appendicitis (AA) and right ureterolithiasis (RU). METHODS: In this retrospective study, 106 patients diagnosed with AA (Appendicitis group) and 33 cases with RU (Ureterolithiasis group) were enrolled due to acute right lower abdominal pain. The levels of peripheral blood leukocyte counts (leukocytes), neutrophil counts (neutrophils), lymphocyte counts (lymphocytes), platelet counts (platelets), NLR and PLR were recorded and compared between the two groups. Student's t-test for independent samples was adopted for comparing the mean between the two groups. Model discrimination was evaluated using the area under the receiver operating characteristic curve (AUC). Comparison of AUC was performed using the Z-test. RESULTS: The levels of leukocytes, neutrophils, NLR, and PLR were significantly increased in AA compared with RU (all p < 0.01), while there were no significant statistical differences of lymphocytes and platelets (all p > 0.05); moreover, AUC in distinguishing AA from RU was 0.797 (95% confidence interval (CI), 0.721 to 0.861) for leukocytes, 0.814 (95% CI, 0.740 to 0.875) for neutrophils, 0.770 (95% CI, 0.691 to 0.837) for NLR, and 0.608 (95% CI, 0.522 to 0.690) for PLR, and significant differences were observed between PLR and any of the three other parameters (all p < 0.01), while there were no significant statistical differences after pairwise comparison between leukocytes, neutrophils and NLR (all p > 0.05). Finally, the cutoff values were 13.1 × 109/L in distinguishing between AA and RU (specificity 87.88%, sensitivity 63.21%, and Youden index 0.511) for leukocytes, 7.4 x 109/L (specificity 69.70%, sensitivity 83.02%, and Youden index 0.527) for neutrophils, 5.57 (specificity 81.82%, sensitivity 68.87%, and Youden index 0.507) for NLR, and 182.5 (specificity 84.85%, sensitivity 37.74%, and Youden index 0.226) for PLR. CONCLUSIONS: Leukocytes, neutrophils, and NLR can demonstrate more accurate and reliable diagnostic values than PLR, suggesting that they are useful and potential biomarkers in distinguishing between AA and RU.

The "old" 15 mm renal stone size limit for RIRS remains a clinically significant threshold size.

PURPOSE: To investigate the performance of retrograde intrarenal surgery (RIRS) for the 1-2 cm renal stone size range in comparison to smaller stones. MATERIALS AND METHODS: From a data base of 3000 ureteroscopies between 2004 and 2014, 635 consecutive patients underwent RIRS for renal stones. Patients were divided to three groups according to their renal stone size (<10, 10-15, 15-20 mm). Preoperative, operative, stone free rate (SFR) and follow-up data were analyzed and compared. RESULTS: The SFR for the three groups was 94.1, 90.1 and 85%, respectively. Patients with renal stone size above 15 mm had a statistically significantly lower SFR. The efficiency quotient calculated for stones larger and smaller than 15 mm was 83.9 vs. 91.8%, respectively (p < 0.01). The mean operative time and hospital stay were longer for patients with renal stones larger than 15 mm (73.6 ± 29.9 vs. 53 ± 19.4 min, p < 0.01 and 2.2 ± 2 vs. 1.8 ± 1.8 days, p = 0.031, respectively). Moreover, the complication rate was almost two times higher (10 vs 5.4%, p = 0.08). Concomitant ureteral stones and older age were independent predictors of failure in the large stone group. CONCLUSIONS: While the overall SFR following RIRS for renal stones up to 2 cm is generally high, the SFR for 15-20 mm stones is significantly lower, with a longer operating time and hospital stay, and a higher complication rate.

Influence of acetylsalicylic acid and low-molecular weight heparins on the formation of renal hematoma after shock wave lithotripsy.

PURPOSE: To investigate the risk of renal hematoma (RHT) after shock wave lithotripsy (SWL) among patients on acetylsalicylic acid (ASA) or low-molecular-weight heparin (LMWH). PATIENTS AND METHODS: Retrospective analysis of 434 patients treated with SWL for nephrolithiasis and ureterolithiasis of the proximal ureter. Primary endpoint was detection of RHT by ultrasound the day after SWL. Secondary outcome variables included transfusion of erythrocyte concentrate(s), interventions, hospital readmission or death due to RHT within 30 days of SWL. Binary logistic regression analysis was used including a post hoc one-way analysis. RESULTS: Of 434 patients, 33 (7.6%) and 67 (15.4%) patients were medicated with ASA and LMWH, respectively. RHT was detected in 20 of 434 (4.6%) patients. Of those, 3 (20%) were on ASA, 6 (35%) were on LMWH, 1 (5%) was on ASA and LMWH, and 10 (50%) had no anticoagulation. Univariate analysis showed a statistically significant higher risk for RHT among patients on ASA (p = 0.04) and LWMH (p = 0.02) with an untreated urinary tract infection (UTI) (p = 0.008) and history of cardiovascular disease (p = 0.028). On multivariate analysis, ASA medication, untreated UTI (OR 4.4, 95% CI 1.31-14.75, p = 0.016 and OR 5.79, 95% CI 1.65-20.32, p = 0.03) and a therapeutic dose of LMWH (OR 10.4, 95% CI 1.74-62.27, p = 0.01) were independent predictors for RHT. CONCLUSIONS: Before SWL, a patient risk profile should be evaluated. If feasible, LMWH in therapeutic dosing should be avoided, and ASA should be discontinued. UTI should be treated before SWL in any case. TRIAL REGISTRATION: http://www.clinicaltrials.gov ; Identifier NCT02875717.

The efficacy and safety of silodosin for the treatment of ureteral stones: a systematic review and meta-analysis.

BACKGROUND: To evaluate the efficacy and safety of silodosin as a medical expulsive therapy for ureteral stones by means of a systematic review and meta-analysis. METHODS: We searched MEDLINE, EMBASE and the Cochrane Controlled Trials Register to identify randomized controlled trials (RCTs) of silodosin in the treatment of ureteral stones. The reference lists of retrieved studies were also investigated. RESULTS: Six RCTs, including 916 participants and comparing silodosin with controls, were used in the meta-analysis. Silodosin was superior to controls in terms of stone expulsion rate, the primary efficacy end point in all six RCTs (odds ratio [OR] for expulsion 2.16, 95 % confidence interval [CI] 1.62 to 2.86, p <0.00001). Silodosin was also more effective for secondary efficacy end points; the stone expulsion time (standardized mean difference [SMD] -3.66, 95 % CI -6.61 to -0.71; p =0.01) and analgesic requirements (SMD -0.89, 95 % CI -1.19 to -0.60; p < 0.00001) were significantly reduced compared with those of controls. Other than the incidence of abnormal ejaculation, which was higher in the silodosin groups (OR 2.84, 95 % CI 1.56 to 5.16, p =0.0006), few adverse effects were observed. CONCLUSION: This meta-analysis indicates silodosin is an effective and safe treatment option for ureteral stones with a low occurrence of side effects.

Validity of STONE scores in younger patients presenting with suspected uncomplicated renal colic.

OBJECTIVES: Recent studies have cast doubt on the routine need for emergent computed tomographic (CT) scan in patients with suspected renal colic. A clinical prediction rule, the STONE score, was recently published with the goal of helping clinicians predict obstructive kidney stones in noninfected flank pain patients before CT scan. We sought to examine the validity of this score in younger, noninfected flank pain patients. METHODS: A secondary analysis of a retrospective cohort study was performed to determine the validity of STONE scores for predicting the outcome of obstructive kidney stone in patients age 18 to 50 years presenting with flank pain suggestive of uncomplicated ureterolithiasis. Validity was measured by calculation of the area under the curve of the receiver operating characteristic curve. Sensitivity, specificity, negative predictive value, positive predictive value, and ±likelihood ratios were calculated for various cutoff values. RESULTS: Of 134 patients who met inclusion criteria, 56.7% were female, average age was 37 years, and 52% had an obstructing kidney stone by CT scan. The receiver operating characteristic curve for the STONE score had an area under the curve of 0.87 (95% confidence interval, 0.80-0.93) and indicated that a cutoff of greater than or equal to 8 would have a sensitivity of 78.6%, specificity of 84.4%, negative predictive value of 78.3%, positive predictive value of 84.6%, and +likelihood ratio of 4.9. CONCLUSIONS: This analysis suggests that the STONE score is valid in younger populations. It can aid in determining pretest probability and help inform conversations about the likelihood of the diagnosis of renal colic before imaging, which may be useful for decision making.

Subcapsular hematoma after ureteroscopy and laser lithotripsy.

Subcapsular hematoma is an uncommon complication after ureteroscopy and laser lithotripsy. We report on a 38-year-old male with an 8 mm lower pole stone who underwent a left ureteroscopy and laser lithotripsy. The stone was successfully fragmented. Several hours after being discharged home, the patient returned complaining of back pain and hematuria. He was hemodynamically stable. Laboratory exams were normal. A CT study showed a crescent renal subcapsular hematoma surrounding the left kidney. The patient was admitted to the ward for conservative treatment. No additional intervention was necessary. Most subcapsular hematomas tend to resolve spontaneously.

Comparison of ureteroscopic laser lithotripsy with laparoscopic ureterolithotomy for large proximal and mid-ureter stones.

OBJECTIVES: To compare the effectiveness and complications of ureteroscopic laser lithotripsy with laparoscopic ureter laparoscopic ureterolithotomy in mid- or proximal portion of large ureteral stones. MATERIAL AND METHODS: We reviewed patients with large (>15 mm) ureteral stone and those who underwent ureteroscopic laser lithotripsy (URS group) or laparoscopic ureterolithotomy (LU group). The first attempt was considered successful in patients who had residual fragments smaller than 2 mm and no conversion of the primary procedure to another. RESULTS: Sixty patients (URS group 29, LU group 31) met inclusion criteria. FURS was used as an adjunctive procedure in one patient for URS group and in two patients for LU group in the same season. LU had a higher success rate and the first-day stone-free rate when compared with URS. Number of procedures was also significantly higher in URS group. There was no difference in stone-free rates at the first and third months, and length of hospitalization and operation were higher in the LU group. Only two patients in the LU group and one patient in the URS group had major complications. CONCLUSIONS: Laparoscopy is an effective option of large proximal and mid-ureter stone treatment; however, URS provides similar stone-free rates at three months as a minimal invasive procedure.

Comparing of different methods for prevention stone migration during ureteroscopic lithotripsy.

AIM: To compare the effectiveness of Stone Cone™, PercSys and lidocaine jelly instillation to prevent stone migration during ureterorenoscopy (URS). MATERIALS AND METHODS: One hundred patients who underwent URS for proximal ureteral stones between 2007 and 2012 were evaluated prospectively. The patients were divided into four groups consecutively. The control group (Group I) consisted of the 25 consecutive patients, in whom no device or method was used to prevent stone migration. Group II consisted of 25 patients treated with the Stone Cone, group III consisted of 25 patients treated with PercSys, and group IV consisted of 25 patients treated with lidocaine jelly instillation. RESULTS: The migration rates were 4.5% in group II, 8.7% in group III, 21.7% in group IV, and 31.8% in group I. The migration rate was found to be statistically significantly lower in the groups treated with the Stone Cone and PercSys compared to the control group (p = 0.014, p = 0.048). However, there was no statistically significant difference between the lidocaine jelly group and the control group in terms of migration rates (p = 0.444). CONCLUSIONS: Our results suggested that the Stone Cone and PercSys were the most successful methods with significantly low migration rates (4.5 and 8.7%, respectively).

Recent finding and new technologies in nephrolitiasis: a review of the recent literature.

This review summarizes recent literature on advances regarding renal and ureteral calculi, with particular focus in areas of recent advances in the overall field of urolithiasis. Clinical management in everyday practice requires a complete understanding of the issues regarding metabolic evaluation and subgrouping of stone-forming patients, diagnostic procedures, effective treatment regime in acute stone colic, medical expulsive therapy, and active stone removal. In this review we focus on new perspectives in managing nephrolitihiasis and discuss recentadvances, including medical expulsive therapy, new technologies, and refinements of classical therapy such as shock wave lithotripsy, give a fundamental modification of nephrolithiasis management. Overall, this field appears to be the most promising, capable of new developments in ureterorenoscopy and percutaneous approaches. Further improvements are expected from robotic-assisted procedures, such as flexible robotics in ureterorenoscopy.

[Management of adult's renal and ureteral stones. Update of the Lithiasis Committee of the French Association of Urology (CLAFU). General considerations]. / Prise en charge urologique des calculs rénaux et urétéraux de l'adulte. Mise au point du Comité Lithiase de l'Association Française d'Urologie (CLAFU). Aspects généraux.

The Lithiasis Committee of the French Association of Urology (CLAFU) aimed to update the current knowledge about urolithiasis. This update will be divided into four parts: 1) general considerations; 2) the management of ureteral stones; 3) the management of kidney stones; 4) metabolic assessment and medical treatment of urolithiasis. Recent technicals advances helped the urologists to improve stones management: new extracorporeal shockwave lithotripsy (ESWL) devices, new flexible ureterorenoscopes, development of laser fragmentation. ESWL, semi-rigid and flexible ureteroscopy and the percutaneous nephrolithotomy (PCNL) remain currently the main therapeutic options. The first part of this update deals with the description and classification of stones, preoperative assessment, post-operative management and clinical follow-up. Main criteria of therapeutic choices are stone location, stone composition and stone size. Stone composition is assessed with infrared spectrophotometry analysis and its hardness is correlated with U.H. density on CT scan assessment. Preoperative assessment consists in urinary cytobacteriological examine, urinary PH, blood creatininemia, hemostasis. Low-dose CT scan is recommended before urological treatment. The result of the treatment must be done 1 or 3 months later with plain abdominal film and ultrasonography. Medical management of urolithiasis will be based on stone composition, metabolic and nutritional evaluation. Treatment success is definited by absence of residual fragments. Annual follow-up is recommended and based either on plain abdominal film and ultrasonography or low-dose CT scan.

Risk factors for concomitant positive midstream urine culture in patients presenting with symptomatic ureterolithiasis.

In patients with symptomatic ureterolithiasis, immediate treatment of concomitant urinary tract infection (UTI) may prevent sepsis. However, urine cultures require at least 24 h to confirm or exclude UTI, and therefore, clinical variables may help to identify patients who require immediate empirical broad-spectrum antibiotics and surgical intervention. Therefore, we divided a consecutive cohort of 705 patients diagnosed with symptomatic ureterolithiasis at a single institution between 2011 and 2017 into a training (80%) and a testing cohort (20%). A machine-learning-based variable selection approach was used for the fitting of a multivariable prognostic logistic regression model. The discriminatory ability of the model was quantified by the area under the curve (AUC) of receiver-operating curves (ROC). After validation and calibration of the model, a nomogram was created, and decision curve analysis (DCA) was used to evaluate the clinical net-benefit. UTI was observed in 40 patients (6%). LASSO regression selected the variables elevated serum CRP, positive nitrite, and positive leukocyte esterase for fitting of the model with the highest discriminatory ability. In the testing cohort, model performance evaluation for prediction of UTI showed an AUC of 82 (95% CI 71.5-95.7%). Model calibration plots showed excellent calibration. DCA showed a clinically meaningful net-benefit between a threshold probability of 0 and 80% for the novel model, which was superior to the net-benefit provided by either one of its singular components. In conclusion, we developed and internally validated a logistic regression model and a corresponding highly accurate nomogram for prediction of concomitant positive midstream urine culture in patients presenting with symptomatic ureterolithiasis.

Ureterolithiasis in Adolescents: A Case Report.

A 13-year-old patient presented to the emergency department with a history of abdominal pain and right flank pain. Two days before, she was evaluated at her pediatrician's office and was diagnosed with acute gastroenteritis and sent home. In the emergency department, the patient was diagnosed with ureterolithiasis after a physical examination, laboratory work, and imaging findings. She was treated successfully with conservative medical management. Symptomatic presentation of ureterolithiasis can include abdominal pain, flank pain, hematuria, dysuria, urgency, nausea, and vomiting. Nurse practitioners need to recognize nonspecific symptoms of ureterolithiasis for accurate diagnosis and treatment. Risk factors, signs and symptoms, prevention, and treatment options for ureterolithiasis are discussed.

Retrocaval ureter with stone in the retrocaval segment of the ureter.

Retrocaval ureter is abnormal looping of the proximal ureter behind the inferior vena cava. The aberrant anatomy results in the compression of the ureter causing hydronephrosis. This is a very infrequent cause of hydronephrosis in children. Association of retrocaval ureter with a stone in the looping segment of the ureter is extremely rare. We report one such pediatric case which was diagnosed preoperatively with a review of pediatric-only cases reported in last 5 years.

Narcotic Pain Control for Ureterolithiasis Is Associated With Unnecessary Repeat Imaging in the Emergency Department.

A subset of patients with ureteral stones who present to the emergency department (ED) will return with recurring symptoms and will receive unnecessary repeat imaging. We retrospectively identified 112 patients from 2012 to 2016 diagnosed with at least one ureteral stone on computerized tomography (CT) at our institution who returned to the ED within 30 days. Patients were stratified based on the presence or absence of repeat CT scan imaging. Mean values were compared with independent t-test and proportions with chi-square analysis. Multivariate logistic regression was performed to determine independent predictors of repeat imaging. Sixty-eight patients (60.7%) underwent repeat CT scan imaging upon representation to the ED within 30 days of being diagnosed with ureterolithiasis. Ureteral stone position changed in 34 patients (30.4%) who underwent repeat imaging. On univariate analysis, younger age, nondiabetics, narcotics prescribed on discharge from first ED visit, and longer mean time between ED visits were associated with repeat CT scan imaging being performed (p < .05). Only prescription of narcotic pain medications was an independent predictor of repeat CT scan imaging (odds ratio: 3.18, 95% confidence interval: 1.22-8.28; p = .018). Nonsteroidal anti-inflammatory drugs or nonnarcotic pain medications, therefore, should primarily be used for pain control in these patients to avoid unnecessary testing.

Cost-effectiveness analysis (CEA) of intravenous urography (IVU) and unenhanced multidetector computed tomography (MDCT) for initial investigation of suspected acute ureterolithiasis.

BACKGROUND: It is important to compare the cost and effectiveness of multidetector computed tomography (MDCT) and intravenous urography (IVU) to determine the most cost-effective alternative for the initial investigation of acute ureterolithiasis. PURPOSE: To analyze the task-specific variable costs combined with the diagnostic effect of MDCT and IVU for patients with acute flank pain, and to determine which is most cost effective. MATERIAL AND METHODS: 119 patients with acute flank pain suggestive of stone disease (ureterolithiasis) were examined by both MDCT and IVU. Variable costs related to medical equipment, consumption material, equipment control, and personnel were calculated. The diagnostic effect was assessed. RESULTS: The variable costs of MDCT versus IVU were EUR 32 and EUR 117, respectively. This significant difference was mainly due to savings in examination time, higher annual examination frequency, lower material costs, and no use of contrast media. As for diagnostic effect, MDCT proved considerably more accurate in the diagnosis of stone disease than IVU and markedly more accurate concerning differential diagnoses. CONCLUSION: MDCT had lower differential costs and a higher capacity to determine correctly stone disease and differential diagnoses, as compared to IVU, in patients with acute flank pain. Consequently, MDCT is a dominant alternative to IVU when evaluated exclusively from a cost-effective perspective.

Bilateral ureterolithiasis: A true positive and false negative PoCUS exam in a patient with renal colic.

Acute flank pain from suspected urolithiasis is a common presenting complaint in the Emergency Department. Multiple computed tomography (CT) has traditionally been the standard imaging modality used to diagnose obstructive kidney stones, however point of care ultrasound (PoCUS) can play an important role in the diagnostic algorithm and risk stratification of acute flank pain. Here, we present the case of a 29-year-old female with suspected urolithiasis, who underwent PoCUS that revealed right-sided hydronephrosis and normal left kidney, bladder, and aorta. A subsequent KUB was negative. As the clinical course failed to improve with therapy, an abdominal and pelvic CT was ordered revealing a 5 mm distal obstructing ureteric calculus at the right vesico-ureteric junction and another 5 mm left mid ureteric calculus. To the best of our knowledge, this is the first case in which a patient presenting with acute right-sided flank pain demonstrated unilateral hydronephrosis on PoCUS, but had clinically significant bilateral ureteric stones on CT. Emergency physicians who employ PoCUS for evaluation of flank pain must be aware of its benefits and drawbacks and how they apply to each patient. As such, we have developed a script emergency physicians can use for shared decision-making with renal colic patients when deciding on the appropriate imaging modality.

Bilateral same session ureteroscopy: safety and efficacy.

Actually ureteroscopy represents the therapy of choice for the treatment of ureteric stones. In the case of bilateral synchronous ureteric calculi the options are between a staged or a synchronous procedure; the last would potentially reduce costs and the need for a second anesthetic in comparison with a staged procedure. We reviewed our experience with bilateral same session ureteroscopy and compared with staged bilateral or unilateral procedure in the same series. The size and site of the stones were similar in all groups with a mean of 8.5 x 6.51 mm (15-7 x 10-5 mm). Symptoms were compared between the groups both before and after surgery, like painful urination, flank pain, urgency, nocturia, frequency, lower abdominal pain and urinary incontinence were assessed. A slight prevalence in the presence of hematuria was present in the bilateral same session URS group, probably due to the presence of the DJ stent. Urinary discomfort was more common in this group without reaching statistical significance (p>0.05). In no case differences between groups were statistically significant. No statistically significant differences were reported between the groups regarding postoperative pain (p>0.5). In our series, bilateral synchronous ureteroscopy is a safe procedure, with high stone free rate even compared with staged bilateral and monolateral treatment. It has the advantage of saving multiple procedures and the need of a second anesthesia and hospitalization. It can be performed safely with minimal risks. The positioning of a DJ stent at the end of the procedure adds little time, preventing post-operative complications with little discomfort for the patient.

Glomerular filtration rate determination by computed tomography in two pet rabbits with renal disease.

CASE DESCRIPTION A 3-year-old and a 7-year-old spayed female rabbit (Oryctolagus cuniculus) were evaluated because of digestive stasis associated with renal asymmetry. CLINICAL FINDINGS Neoplasia of the right kidney was diagnosed via cytologic analysis in the 3-year-old rabbit. Ureterolithiasis of the left kidney was diagnosed via abdominal ultrasonography in the 7-year-old rabbit. To evaluate whether unilateral nephrectomy was indicated, evaluation of glomerular filtration rate by dynamic CT (CT-GFR) was performed on both rabbits. On the basis of the functional and morphological CT-GFR results, radical nephrectomy was recommended for the rabbit with renal neoplasia whereas a more conservative approach was recommended for the other rabbit. TREATMENT AND OUTCOME The rabbit with renal neoplasia underwent radical nephrectomy without complication. The rabbit with ureterolithiasis underwent ureteral stent placement, and the renal pelvic dilatation resolved. Both rabbits maintained unremarkable serum urea and creatinine concentrations after surgery. CLINICAL RELEVANCE GFR is a highly useful and reliable variable for the evaluation of renal function but is difficult to assess with routine clinical laboratory tests. The CT-GFR technique described here was quickly performed, was technically suitable for rabbits, and provided clinically relevant information. Studies are required to establish reference values for CT-GFR in rabbits.

A Comparison of Urolithiasis in the Presence and Absence of Microscopic Hematuria in the Emergency Department.

INTRODUCTION: Urolithiasis is a common medical condition that accounts for a large number of emergency department (ED) visits each year and contributes significantly to annual healthcare costs. Urinalysis is an important screening test for patients presenting with symptoms suspicious for urolithiasis. At present there is a paucity of medical literature examining the characteristics of ureteral stones in patients who have microscopic hematuria on urinalysis versus those who do not. The purpose of this study was to examine mean ureteral stone size and its relationship to the incidence of clinically significant hydronephrosis in patients with and without microscopic hematuria. METHODS: This is a retrospective chart review of patient visits to a single, tertiary academic medical center ED between July 1, 2008, and August 1, 2013, of patients who underwent non-contrast computed tomography of the abdomen and pelvis and urinalysis. For patient visits meeting inclusion criteria, we compared mean stone size and the rate of moderate-to-severe hydronephrosis found on imaging in patients with and without microscopic hematuria on urinalysis. RESULTS: Out of a total of 2,370 patient visits 393 (16.6%) met inclusion criteria. Of those, 321 (82%) had microscopic hematuria present on urinalysis. Patient visits without microscopic hematuria had a higher rate of moderate-to-severe hydronephrosis (42%), when compared to patients with microscopic hematuria present (25%, p=.005). Mean ureteral stone size among patient visits without microscopic hematuria was 5.7 mm; it was 4.7 mm for those patients with microscopic hematuria (p=.09). For ureteral stones 5 mm or larger, the incidence of moderate-to-severe hydronephrosis was 49%, whereas for ureteral calculi less than 5 mm in size, the incidence of moderate-to-severe hydronephrosis was 14% (p < 0.0001). CONCLUSION: Patients visiting the ED with single-stone ureterolithiasis without microscopic hematuria on urinalysis could be at increased risk of having moderate-to-severe hydronephrosis compared to similar patients presenting with microscopic hematuria on urinalysis. Although the presence of hematuria on urinalysis is a moderately sensitive screening test for urolithiasis, these results suggest patients without hematuria tend to have more clinically significant ureteral calculi, making their detection more important. Clinicians should maintain a high index of suspicion for urolithiasis, even in the absence of hematuria, since ureteral stones in these patients were found to be associated with a higher incidence of obstructive uropathy.