Blood in the urine may be visible (gross or macroscopic) or not visible to the naked eye (microscopic).

In visible bleeding in the urine, the urine is colored red. This may range from a brownish red to pink. In severe cases, there may be blood clots.

In microscopic hematuria, a test strip coated with chemicals detects the blood in the urine. This can be confirmed by examining the urine sample under a microscope for red blood cells. This is called urinalysis or urine FEME (full examination including microscopic examination).

Microscopic hematuria is a common condition. Most of its causes are benign. However, it may be a warning of something more ominous in some patients.

Gross blood in the urine or visible hematuria, especially with blood clots, needs urgent attention. Although the cause may be something simple like infection, it is important to diagnose more serious causes such as cancer and stone disease.

Possible causes of blood in the urine range from minor, incidental findings that do not require treatment to highly significant lesions that may be a threat to the patient’s wellbeing and life.

• Urinary tract infections.
  Urinary tract infections are particularly common in women, though men also get them. Associated symptoms can include frequent urge to urinate, pain and burning with urination, and strong-smelling urine.
  
  Kidney infections (pyelonephritis) can occur when bacteria enter the kidneys from the bloodstream or move from up from the bladder to the kidney. Signs and symptoms are often similar to bladder infections, though kidney infections are more likely to cause fever and flank pain.
  
  
• A bladder or kidney stone.
  The minerals in concentrated urine sometimes precipitate out, forming crystals on the walls of your kidneys or bladder. Over time, the crystals can turn into small, hard stones. The stones are generally painless, unless they cause a blockage or are being passed. Kidney stones can cause excruciating pain. They can also cause both gross and microscopic bleeding.
  
  
• Enlarged prostate.
  This is one of the leading causes of visible blood in the urine in men older than 50. The prostate gland located just below the bladder, and surrounding the urethra, often begins growing as men approach middle age. When the gland enlarges, it compresses the urethra, partially blocking urine flow. Symptoms of an enlarged prostate (benign prostatic hypertrophy or BPH) include difficulty urinating, an urgent or persistent need to urinate, and either gross or microscopic bleeding. Please read more in the Prostate Clinic section. Infection of the prostate (prostatitis) can cause the same signs and symptoms.
  
  
• Kidney disease/ kidney inflammation (Glomerulonephritis)
  Microscopic urinary bleeding is a common symptom of inflammation of the kidneys known as glomerulonephritis. Glomerulonephritis may be part of the effect of diseases such as diabetes, or it can occur on its own. Viral or bacterial infections, blood vessel inflammation (vasculitis), and immune diseases such as IgA nephropathy, which affects the small capillaries that filter blood in the kidneys (glomeruli), can trigger it.
  
  
• Cancer.
  Visible urinary bleeding may be the first sign of kidney cancer, bladder cancer, ureteric cancer or prostate cancer. In the early stages, there may not be any pain in the affected organs.
  
  
• Inherited disorders.
  Sickle cell anemia and Alport Syndrome are examples of inherited disorders that can cause blood in urine, both gross and microscopic hematuria. 
  
  
• Kidney injury.
  A blow or a knock on the kidneys from an accident or contact sports can cause gross blood in the urine. The force is usually fairly great to cause blood in the urine, especially gross hematuria. If the force is slight but there is gross hematuria, there may be an abnormality in the kidneys such as an obstructed kidney.
  
  
• Medications.
  Common drugs that can cause visible urinary blood include aspirin, penicillin, blood thinners such as warfarin and heparin, and the anti-cancer drug cyclophosphamide (Cytoxan).
  
  
• Strenuous exercise.
  This is likely due to dehydration. Breakdown of red blood cells very rarely occurs with sustained aerobic exercise. Any athlete can develop visible urinary bleeding after an intense workout.

Any evidence of blood in the urine, both gross and microscopic, warrants a visit to the doctor for an examination and investigation of possible life-threatening causes.

A good medical history and physical exam may help find the cause of urinary bleeding. Urine and blood tests may be requested as needed.

This is followed by tests, including:

1. Imaging tests.
   This might be a computerized tomography (CT) scan, which uses radiation and a computer to create cross-sectional images of the urinary system. The urinary system may also be visualized with x-rays with intravenous contrast injected called intravenous urogram.
   
   
2. Cystoscopy.
   If there is gross blood in the urine or in cases where bladder pathology such as cancer is strongly suspected, the bladder can be examined with a pencil-thin flexible telescope passed gently through the natural urinary passage into the bladder.

This examination is done under local anesthesia and does not require hospital stay. It usually takes only a few minutes and the patient go home just after the procedure.

The immediate treatment is determining the underlying cause and institute appropriate treatment to stop the bleeding. Blood thinners such as Aspirin, Plavix, warfarin and Persantin should be stopped.

Blood clots may accumulate in the bladder causing retention of urine. This will require a catheter to be passed into the bladder to drain the bladder. In severe bleeding, the bladder may need to be flushed continuously till the bleeding stops.