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Microscopic or invisible haematuria

What is Microscopic Haematuria?

Haematuria is the presence of blood in the urine. Microscopic haematuria is where the blood is not visible and is present only on testing of the urine.

In Australia microscopic haematuria is defined as greater than 10 red blood cells visible on a high-powered microscopic examination of urine. The definition of microscopic haematuria varies from more than 3 to 10 red blood cells in different countries. Microscopic haematuria is usually discovered when urine is tested with a dipstick test. As the results of urine testing with a dipstick are not always accurate, the finding of microscopic haematuria should be confirmed with microscopic examination on an MSU or mid-stream urine testing.

Apart from the main classification into microscopic (invisible) haematuria and macroscopic (visible) haematuria, haematuria can be classified into:

  • Symptomatic – associated with voiding symptoms such as
    • Hesitancy (slow urination)
    • Frequency
    • Urgency
    • Dysuria - burning or pain on urination 
    • Abdominal or flank pain
  • Asymptomatic – occurring without symptoms

How often does Microscopic Haematuria occur?

The prevalence of asymptomatic microscopic haematuria (i.e. invisible blood in the urine without urinary symptoms) ranges from 2 to up to 31% of the population with higher rates occurring in the older population, men and those with a history of smoking.

What is the significance of Microscopic Haematuria?

Not all haematuria is caused by significant problems in the urinary tract.

Studies have shown that even with extensive investigation, that a specific cause for the haematuria is not found in up to 70% of patients with microscopic haematuria.

What are the common causes of Haematuria?

Urinary tract infection (UTI) is one of the most common causes of haematuria. Stones within the urinary tract (kidney or ureteric) can also cause blood in the urine. Urinary tract cancers such as kidney cancer and cancers of the bladder (TCC - transitional cell cancer of the lining of the urinary tract) are also important causes of haematuria.

Haematuria requires investigation to exclude significant or worrying pathology in the urinary tract.