Hematuria

Hematuria can be classified according to visibility, anatomical origin, and timing of blood during urination. • In terms of visibility, hematuria can be visible to the naked eye (termed "gross hematuria") and may appear red or brown (sometimes referred to as tea-colored), or it can be microscopic (i.e. not visible but detected with a microscope or laboratory test). • In terms of the anatomical origin, blood or red blood cells can enter and mix with urine at multiple anatomical sites within the urinary system, including the kidney, ureter, urinary bladder, and urethra, and in men, the prostate. Non-glomerular causes can be further subdivided into the upper urinary tract and lower urinary tract causes. Normally, red blood cells should never pass from the glomerular capillary into the renal tubule, and this is always a pathological process. Glomerular causes include: • IgA nephropathy • Nephrotic syndrome Non-glomerular hematuria Visible blood clots in the urine indicate a non-glomerular cause. False positive urine dipstick A urine dipstick may be falsely positive for hematuria due to other substances in the urine. Thus, a positive dipstick test does not necessarily indicate hematuria; rather, microscopy of the urine showing three of more red blood cells per high power field confirms hematuria. Menstruation In women, menstruation may cause the appearance of hematuria and may result in a urine dipstick test positive for hematuria. Menstruation can be ruled out as a cause of hematuria by inquiring about menstruation history and ensuring the urine specimen is collected without menstrual blood. == In children ==

Common causes of hematuria in children are: • Fever • Strenuous exercise • Acute nephritis • Congenital abnormalities: • Non-vascular: ureteropelvic junction obstruction, posterior urethral valves, urethral prolapse, urethral diverticulum and multicystic dysplastic kidney • Vascular: arteriovenous malformations, hereditary hemorrhagic telangiectasias, renal vein thrombosis in newborns. • Urinary stones. • Coagulation disorders. • Mechanical trauma: masturbation, foreign body. • Nephritic syndrome: IgA nephropathy, Post-streptococcal glomerulonephritis, Benign familial hematuria, Alport syndrome. • Sickle cell trait or disease. == Evaluation ==

The evaluation of hematuria is dependent upon the visibility of the blood in the urine (i.e. visible/gross vs microscopic hematuria). It is important to obtain a detailed history from the patient (i.e. recreational, occupational, and medication exposures) as this information can be helpful in suggesting a cause of hematuria. The physical exam can also be helpful in identifying a cause of the hematuria as certain signs found on the physical exam can suggest specific causes of the hematuria. Benign causes include urinary tract infection, viral illness, kidney stone, recent intense exercise, menses, recent trauma, or recent urological procedure. To be in the low risk category, one must satisfy all of the following criteria: Has never smoked tobacco or smoked less than 10 pack-years; is a female less than 50 years old or a male less than 40 years old; has 3–10 red blood cells per high power field; has not had microscopic hematuria before; and has no other risk factors for urothelial cancer. To be in the intermediate risk category, one must satisfy any of the following criteria: Has smoked 10–30 pack-years; is a female 50–59 years old or a male aged 40–59 years old; has 11–25 red blood cells per high power field; or was previously a low-risk patient with persistent microscopic hematuria and has 3–25 red blood cells per high power field. To be in the high risk category, one must satisfy any of the following criteria: Has smoked more than 30 pack-years; is older than 60 years of age; or has above 25 red blood cells per high power field on any urinalysis. For the low risk category, the next step is to either repeat a urinalysis with urine microscopy in 6 months or perform a cystoscopy and renal ultrasound. For the intermediate risk category, the next step is to perform a cystoscopy and renal ultrasound. For the high risk category, the next step is to perform a cystoscopy and CT urogram. If an underlying cause for hematuria is discovered, it should be managed appropriately. However, if no underlying cause is discovered, the hematuria should be re-evaluated with urinalysis and urine microscopy within 12 months. Additionally, for all risk categories, if a nephrologic origin is suspected, consultation of a nephrologist should be made. == Pathophysiology ==

The pathophysiology of hematuria can often be explained by damage to the structures of the urinary system, including the kidney, ureter, urinary bladder, and urethra, and in men, the prostate. Common mechanisms include structural disruption to the glomerular basement membrane and mechanical or chemical erosion of the mucosal surfaces of the genitourinary tract. == Management ==

Medical emergency: acute clot retention Acute clot retention is one of three emergencies that can occur with hematuria. The other two are anemia and shock. Urosepsis is the result of a systemic inflammatory response to infection and can be identified by numerous signs and symptoms (e.g. fever, hypothermia, tachycardia, and leukocytosis). Signs and symptoms that indicate a urogential tract infection is the source of the sepsis may include, but are not limited to, flank pain, costovertebral angle tenderness, pain with micturition, urinary retention, and scrotal pain. In terms of the visibility, hematuria can be visible to the naked eye (termed "gross hematuria") and may appear red or brown (sometimes referred to as tea-colored), or it can be microscopic (i.e. not visible to the eye but detected of urosepsis. In addition to imaging tests, patients may be treated with antibiotics to relieve the infection and intravenous fluids to maintain cardiovascular and renal perfusion. Acute management of hemodynamic status, in the event intravenous fluids are unsuccessful, may include the use of vasopressor medications and the placement of a central venous line. == Epidemiology ==

In the United States, microscopic hematuria has a prevalence of somewhere between 2% and 31%. Risks factor include older age and female gender. About 5% of individuals with microscopic hematuria receive a cancer diagnosis. 40% of individuals with macroscopic hematuria (blood easily visible in the urine) receive a cancer diagnosis. == References ==