Hematuria and Microhematuria: Blood in Urine
Definition of Hematuria and Microhematuria
Hematuria is defined as visible blood in urine; microhematuria is defined with more than 5 erythrocytes per high power field. More than 20 erythrocytes per high power field is a strong microhematuria. Medical history and urine analysis are cornerstones for planing rational further imaging and endoscopic diagnosis:
Differential Diagnosis of Hematuria and Microhematuria
Abnormal Urine Color
Abnormal urine color can simulate hematuria, microscopic examination of the urine shows no blood cells.
- Food: beetroot ("beeturia"), blueberry, blackberry
- Chronic lead poisoning
- Medication with rifampicin
Examination of the urine shows deformed (dysmorphic) red blood cells, red blood cell casts and proteinuria.
- IgA nephropathy
- Various forms of glomerulonephritis
- Alport's syndrome
- Systemic lupus erythematosus
- Subacute bacterial endocarditis
Examination of the urine shows circular red blood cells and frequently proteinuria (especially in systemic diseases and medical renal diseases). Initial hematuria is a sign for diseases of the urethra or prostate. Terminal hematuria is often caused by diseases of the bladder trigone.
- Systemic diseases:
- Disseminated intravascular coagulation
- Kidney diseases:
- Lower urinary tract:
Diagnostic Work-up of Hematuria
Basic Work-up of Hematuria
- Urine analysis with microscopic examination
- Labatory tests: blood count, coagulation tests (PTT, PT) and creatinine
- Ultrasound imaging of kidneys and full urinary bladder
- Intravenous urography or computer tomography of the abdomen (CT urography)
Further studies in Hematuria
- CT Urography: indicated for suspected tumors or with pathologic intravenous urography. Best imaging of the kidney is achieved with a multislice CT scanner and dynamic multiphase scans.
- Urine cytology: indicated in persisting hematuria and a basic work-up with no pathologic findings
- MRI Urography: indicated as an alternative to CT Urography, e.g. due allergy to iodinated contrast medium or for children.
- Retrograde pyelography and ureteroscopy: indicated in suspected diseases of the ureter or renal pelvis.
- Angiography: to identify suspected arteriovenous fistula or diseases of the renal artery or vein
- Renal biopsy: indicated in suspected medical renal diseases (e.g. glomerulonephritis).
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