A urine dipstick is positive with approximately 5 to 20 red blood cells per mL of urine. All positive dipsticks should be followed by microscopy. False-positive results can occur with the presence of myoglobin, porphyrins, free hemoglobin (as opposed to intact RBCs) due to hemolysis, and povidone-iodine. Catheterization usually does not cause an abnormal result. False-negative results can be seen with very high specific gravity. Differential diagnostic considerations are numerous. Consider the patients' age, sex, demographic characteristics, habits, potential risk factors for urologic malignancy, comorbidities, or any history of recent urinary tract instrumentation. The most common causes of hematuria are UTI, nephrolithiasis, neoplasms, benign prostatic hypertrophy, glomerulonephritis, and schistosomiasis (most common cause worldwide). In the ED, consider strenuous exercise, poststreptococcal infection (in younger patients) and life threats including malignant hypertension, eroding abdominal aortic aneurysm, coagulopathy, foreign body, immune-mediated disease (Henoch-Schönlein purpura, pulmonary-renal syndromes), sickle cell disease complications, and renal vein thrombosis.