Definition of Haematuria
Haematuria is the presence of blood in the urine. Haematuria can be classified into 2 types:
- Microscopic haematuria -where the blood is not visible and present only on testing of the urine.
- Macroscopic haematuria- where there is visible blood in the urine causing it to be discoloured pink, red, brownish-red or tea-coloured. Gross haematuria is another term for visible blood in 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 always be confirmed with microscopic examination on an MSU or mid-stream urine testing.
Although seeing blood in the urine with visible or macroscopic haematuria can be frightening, most of the time blood in the urine is not life threatening. The important thing is not to ignore the symptoms of haematuria and to have it investigated because it can sometimes be caused by a serious condition in the urinary tract.
Blood in the urine can originate from any part of the urinary tract ranging from the kidneys, collecting system (ureters and bladder) as well as from the urethra (waterpipe) taking urine from the bladder.
Urine testing for haematuria should only be done for identifiable clinical reasons rather than as a form of population health screening.
Classification of Haematuria
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)
- Dysuria - burning or pain on urination
- Abdominal or flank pain
- Asymptomatic – occurring without symptoms
How often does 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 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.
What is the significance of Haematuria?
Not all haematuria is caused by significant problems in the urinary tract.
Studies have shown that even with extensive investigation, a specific cause for the haematuria is not found in up to 70% of patients with microscopic haematuria and up to 50% of patients with macroscopic haematuria.
Haematuria requires investigation to exclude significant or worrying pathology in the urinary tract.
Macroscopic or visible haematuria is more concerning than microscopic (invisible) haematuria. Cases of macroscopic haematuria (including even one episode of visible blood in the urine) require thorough investigation because of the significant rate of urinary tract cancers found in people with visible blood in the urine. The prevalence of urinary tract cancers in people presenting with the symptom of visible blood in the urine ranges between 3 to 6% but has been reported to be as high as 19% in some studies.
Risk factors for Urinary Tract Cancers
Risk factors for urinary tract cancers (or malignancy) include:
- Increasing age especially > 40 years
- History of smoking (both current and past)
- Occupational exposure to dyes in the print and clothing industries, benzenes
- Exposure to medications such as cyclophosphamide and phenacetin
- Previous pelvic radiation
- History of macroscopic or visible haematuria
- Significant bladder symptoms in the absence of a urinary infection such as urgency, frequency, pain or discomfort on urination