Blood in Urine

The most common causes differ somewhat by the person's age but overall are

• Bladder infection (cystitis)

• Prostate infection (prostatitis)

• Urinary tract stones (in adults)

• Kidney and urinary tract birth defects

Less common causes include

• Cancer (of the kidneys, bladder, or prostate)

• Noncancerous enlargement of the prostate (benign prostatic hyperplasia)

• Disorders of the small blood vessels of the kidneys (called kidney filtering disorders or glomerular disorders)

• Cysts in the kidneys (polycystic kidney disease)

• Narrowing scars (called strictures) or other abnormalities of the ureters

Cancer and benign prostatic hyperplasia may cause blood in the urine. These disorders are a concern mainly in people over 50, although younger people with risk factors (smoking, family history, or chemical exposures) may develop cancer.

Disorders of the microscopic blood vessels of the kidneys (glomeruli) can be a cause at any age.

Kidney filtering disorders (glomerular disorders) may be part of a kidney disorder or may occur as a result of a disorder elsewhere in the body. These disorders are more likely if the urine has protein, clumps of red blood cells (called red blood cell casts), or malformed red blood cells. Such disorders include infections (such as a heart valve infection), connective tissue disorders (such as systemic lupus erythematosus) and vasculitis, blood disorders (such as serum sickness), or certain chronic disorders (such as diabetes). Also, almost any kind of kidney damage may cause small amounts of blood in the urine.

Severe injuries, such as from a fall or a motor vehicle crash, can injure the kidneys or bladder and cause bleeding. Various procedures and surgeries (for example, inserting a catheter or doing a prostate or kidney biopsy) can also cause bleeding.

Schistosoma haematobium is a parasitic worm that causes a disease called schistosomiasis in Africa and, to a lesser extent, in India and parts of the Middle East. This worm can invade the urinary tract, causing blood in the urine. Doctors consider schistosomiasis only if people have spent time in areas where the worm is found. Tuberculosis may cause blood in the urine.

Other causes of blood in the urine include bladder inflammation from radiation therapy of the pelvic region, certain drugs, and blood vessel disorders of the kidney.

In people with blood in the urine, certain symptoms and characteristics are cause for concern. They include

• Large amount of blood in the urine

• Age over 50

• Swelling of the feet or legs, plus high blood pressure

People who notice blood in their urine should see their doctor within a day or two. However, people who are passing a large amount of blood, who are unable to urinate, or who have severe pain should see a doctor right away.

Doctors first ask questions about the person's symptoms and medical history and then do a physical examination. What they find during the history and physical examination often suggests a cause of the blood in the urine and the tests that may need to be done (see table Some Causes and Features of Blood in the Urine).

Doctors ask how long blood has been present and whether there have been any previous bleeding episodes. They ask about fever, weight loss, or symptoms of urinary blockage, such as difficulty starting urination or inability to completely empty the bladder. Pain or discomfort is an important finding. Burning during urination or dull pain in the lower abdomen just above the pubic bone suggests a bladder infection. In men, mild to moderate pain in the lower back or pelvis is often the result of a prostate infection. Extremely severe pain is usually due to a stone or a blood clot blocking the flow of urine.

Doctors then do a physical examination. Usually, a pelvic examination is necessary in women. If women have blood in the vagina, a catheter may need to be inserted into the bladder to see whether the source of blood is the bladder or the vagina. In men, doctors usually do a digital rectal examination to check the prostate.

Sometimes doctors can make a diagnosis based on the person's symptoms and the results of the physical examination. More often, because symptoms of many disorders overlap, testing is needed to determine the cause (or sometimes the presence) of blood in the urine. Urinalysis is the first test done. Urinalysis can detect blood (confirming that the red color of the urine is caused by blood) and may show evidence of a kidney filtering disorder. If infection is suspected, urine culture is usually done.

In all people over 50 and in people who have risk factors for cancer, doctors typically use a flexible viewing tube to look inside the bladder (cystoscopy) to determine the cause of bleeding.

People of any age who do not have an infection or a kidney filtering disorder as the cause of visibly bloody urine typically have imaging studies, such as computed tomography (CT), ultrasonography, or magnetic resonance imaging (MRI) of the abdomen and pelvis. For people under 50 who have only microscopic hematuria and no other abnormalities detected during the physical examination, blood tests, or urinalysis, doctors may simply repeat the urinalysis in 6 or 12 months. If blood is still present, they will do further tests.

If doctors suspect a kidney filtering disorder (based of the results of urinalysis), they usually do blood tests to evaluate kidney function and sometimes a kidney biopsy. Blood tests for sickle cell disease may be needed in people of African or Mediterranean descent who are not known to have the disease.

In men who are 50 or older, doctors usually measure the level of prostate-specific antigen (PSA) in the blood.