A 47-year-old woman presents to the office with severe right flank pain that does not radiate. Dipstick urinalysis shows hematuria, and microscopic examination confirms the presence of many red blood cells per high-power field (Figure 69-1). There is no pyuria or bacteriuria. The physician gives her some pain medication and sends her to get a non-contrast helical computed tomography (CT). The CT scan shows a stone in the right ureter and some mild hydronephrosis. Fortunately for the patient, she passes the stone when urinating after the imaging study is complete.
Red blood cells (RBCs) seen in the urine of a woman passing a kidney stone. Some of the RBCs are crenated and there is one epithelial cell visible. (Reproduced with permission from Richard P. Usatine, MD.)
Examination of the urinary sediment is a test frequently done for evaluation of patients with suspected genetic/intrinsic (e.g., systemic lupus nephritis, renal sarcoidosis, sickle cell disease, glomerulonephritis, interstitial nephritis), anatomic (e.g., arteriovenous malformation), obstructive (e.g., kidney or bladder stones, benign prostatic hypertrophy), infectious, metabolic (e.g., coagulopathy), traumatic, or neoplastic disease of the urinary tract. Potential findings of red or white blood cells, casts, bacteria, or neoplastic cells help in directing further evaluation of a patient's problem.
A finding of microscopic hematuria (defined by the American Urological Association [AUA] as ≥3 red blood cells [RBCs]/high-power field [HPF]) on a single microscopic urinalysis in an asymptomatic person is common and most often a result of menses, allergy, exercise, viral illness, or mild trauma.1,2
One study of servicemen, conducted for a period of 10 years, found an incidence of 38%.1
In one UK population study, first episode of hematuria resulted in a noncancer or cancer diagnosis within 90 days in 17.5% of women (95% confidence interval [CI], 16.4% to 18.6%) and 18.3% of men (95% CI, 17.4% to 19.3%).3
Persistent (>3 RBCs/HPF over 3 specimens) and significant hematuria (>100 RBCs/HPF or gross hematuria) was associated with significant lesions in 9.1% of more than 1000 patients.1
In a review of hematuria, approximately 5% of patients with significant microscopic hematuria (>3 RBCs/HPF on 2 of 3 properly collected specimens during a 2- to 3-week period)3 and up to 40% of patients with gross hematuria had a neoplasm.4
Isolated pyuria (>2 to 10 white blood cells per high-power field [WBCs/HPF]) is uncommon, as inflammatory processes in the urinary tract are usually associated with hematuria.1
Glomerulonephritides, although rare, account for about 20% of cases of chronic kidney disease and present with variable amounts of proteinuria and hematuria.5 Annual incidence for IgA nephropathy is estimated as 2.5 cases per 100,000 adults, 1.2 per 100,000 for membranous glomerulonephritis, 0.6–0.8 per 100,000 for minimal change ...