Microscopic haematuria (microhaematuria) is the presence of unseen but significantly high numbers of red blood cells in the urine.It is normal for urine to have very small amounts of blood (<3 red blood cells per high power field). However if it exceeds 3 red cells, and remains high on repeat testing, it may indicate a significant problem in the urinary system.
Many people have microhaematuria for many years and yet do not have kidney or urinary tract disease. In fact, many seem to be related to physical exercise or vigorous sports (called stress microhaematuria) or hypertension. However, before concluding that such persistent microhaematuria is benign in nature, it is important to exclude any significant urological disease. In order of importance, they are:
- tumours and cancers in kidney or bladder [Fig 1]
- kidney parenchymal disease (glomerulonephritis)
- urinary stones
- prostatic bleeding in men and
- urethral caruncle in women
Microhaematuria can only be regarded as idiopathic after the following investigations have been done:
- urine tests eg. phase contrast study to determine if the blood is coming from glomerular disease or urinary tract lining, urine cytology to look for cancers of the urinary tract lining
- ultrasound and xrays, eg. IVU or CT scan
- endoscopy, eg. flexible cystoscopy [Fig 2] which is easily done in the clinic under local anaesthesia and regarded as the most reliable way of excluding any small tumours / cancer in the bladder. In men, the prostate can also be evaluated to see if this is the likely source of bleed
Microhematuria can indicate an absolutely harmless occurrence or a serious disease. Even if no apparent cause is found after extensive investigations, it is recommended that urine analysis still be done at least on a yearly basis. This is because there is still be a chance a disease that may later show up, especially if the red cell count continues to increase or when one is above 50 years of age.