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.

Usefulness of urinalysis in following patients with distal ureterolithiasis.

PURPOSE: The determine the usefulness of urinalysis in monitoring patients with distal ureterolithiasis. MATERIALS AND METHODS: Patients with microhematuria who were found to have a distal ureteral stone and who were candidates for conservative management were enrolled in the study. Patients were typically seen in clinic at 1 to 2 weeks after initial diagnosis and reassessed. A urinalysis, including office dipstick and automated laboratory analysis using the IQ 200 IRIS analyzer, were performed. The absence or presence of microhematuria was determined and compared with results of repeated unenhanced helical CT of the abdomen and pelvis to determine the sensitivity, specificity, and positive and negative predictive values of urinalysis. RESULTS: Twenty-nine patients were enrolled in this prospective study. The mean age of the patients was 43.5 years. The sex distribution was predominantly male, with 72% men and 28% women. Ultimately, 18 patients are included in our analysis with the remainder either lost to follow-up or excluded because of protocol violation. Average distal stone size was 4.1 mm (range 2.0-6.5 mm). Stones were evenly distributed between the right and the left ureters, with 50% on either side. Mean time to follow-up was 18 days with a range of 2 to 63 days. The sensitivity of urinalysis was determined to be 40% (8%-72%) while the specificity was 63% (28%-98%). The predictive value of a positive test was 57% (19%-95%) and the predictive value of a negative test was 55 % (25%-85%). The confidence interval for each of these parameters is inclusive of the value of 50%, indicating that urinalysis is no better than randomness in predicting presence or absence of a stone by CT. CONCLUSIONS: The absence or presence of microhematuria does not accurately predict whether a distal ureteral stone has passed or is still present. In those patients who need or want to know whether a stone is still present, unless a stone is strained, we suggest repeated CT imaging.