Hematuria



The presence of red blood cells in the urine, either microscopic or macroscopic, should be re­garded as a significant finding. Hematuria is a sign of genitourinary tract inflammation and occurs in a number of disorders, including glomeruloneph­ritis, acute and chronic renal failure, urinary tract infection, urinary tract obstruction, and neopla­sia. Although the source of bleeding cannot be de­fined on the basis of the presenting signs and symptoms or the urinalysis, certain specific find­ings are helpful. The presence of red blood cell casts and associated proteinuria is good evidence for a glomerular inflammatory lesion. Smoke-col­ored urine is also considered a sign of glomerular bleeding, since the contact time of the red blood cells with the urine is prolonged and allows for the formation of methemoglobin. The passage of gross clots in the urine is suggestive of bleeding distal to the renal tubule.
The evaluation of the patient with hematuria will often require anatomical imaging of the uri­nary tract to exclude a neoplastic lesion or renal stone. Cystoscopy may be indicated to exclude an inflammatory lesion of the bladder. A urine cul­ture should be obtained to rule out the possibility of hemorrhagic bacterial cystitis. If the bleeding is of glomerular or tubular origin and a specific diagnosis cannot be made by other means, a renal biopsy may be helpful.