Urology - Haematuria
Haematuria - a patient's guide
Dr Michael Mackey - Urologist
What is it?
The term "haematuria" refers to the presence of red blood cells in the urine. Haematuria should be defined as either "macroscopic" (visible blood in the urine) or "microscopic" (only detected by chemical reagent strip testing or urine microscopy).
Microscopic haematuria has a reported prevalence of 2-5% in most community-based studies. It is normal to lose several million red blood cells in the urine per day, but generally this is not enough to show up in the common tests. There is no universally accepted "normal" amount of red blood cells in the urine, but the often-quoted lower limit is 10x10 red blood cells per litre.
Red urine does not necessarily mean blood in the urine. Beetroot and blackberries can discolour the urine red due to their anthrocyanin pigment, as can various medications, including phenothiazines, prefantacin, and haemoglobinuria and myoglobinuria (filtered breakdown products of blood and muscle).
There are various dip strip tests for haemaglobin in the urine, and these should only be used to screen for haematuria, with microscopic analysis of the urinary sediment used for confirmation. The reason being, free haemoglobin or myoglobin in the urine may give a positive reading, and ascorbic acid (vitamin C) in the urine can inhibit the dip strip and give a false negative result. Also, dilute urine can break red blood cells, and thus provide a positive dip strip reading for haemoglobin, but no visible red cells on microscopic analysis.
If blood is detected on a reagent strip, a microscopic analysis of the urine is required. Further microscopy of the urine may reveal white cells in the urine, which may indicate urinary infection. In addition, urine should be sent for urine culture.
Urine cytology involves microscopic examination of the urine, in an endeavour to detect any abnormal cells. The lining of the urinary tract continually sheds cells. If a cancer is present, particularly an aggressive cancer, or carcinoma in situ of the bladder, these cells may be detectable in the specific urine cytology examination. Urine cytology is not very sensitive in detecting "well-differentiated" (less aggressive) tumours, as the cells in these tumours vary very little from the normal lining cells of the urinary tract, but is reasonably sensitive at detecting poorly differentiated (aggressive) tumours.
In adults approximately 20% of patients who have painless haematuria have an underlying urinary tract cancer, whereas only about 2-3% of patients with microscopic haematuria have an underlying malignancy.
Macroscopic haematuria often causes considerable concern, and just a few mils of blood can turn a whole bladder full of urine quite dark red. Sometimes the site of bleeding can be localised within the urinary tract by determining whether the bleeding is
"initial" - i.e. at the beginning of the stream only,
"terminal" - i.e. at the end of the stream only,
or "complete" - i.e. throughout the entire stream.
Initial haematuria generally indicates bleeding from the urethra that is flushed out by the first passage of urine through the urethra.
Terminal haematuria can arise from the posterior urethra, bladder neck or trigone (base of the bladder), and is noticed at the end of urination, when the bladder compresses these areas.
Total haematuria indicates that the bleeding occurs at the level of the bladder or higher in the urinary tract, so that all of the urine is mixed with the blood, and the entire stream is therefore bloody.
Pain that occurs in association with a urinary tract infection or passage of a stone may indicate that the bleeding is from a benign cause.
Painless haematuria is generally regarded as secondary to a urinary tract cancer, until proven otherwise.
However, all bleeding warrants investigation, to be certain that there is not an associated cancer, besides the more obvious causes for painful bleeding.
There are multiple causes of haematuria, which include the following:
Following a careful history and physical examination, generally with a kidney dye test called an IVU or IVP is performed. Recently this has been superseded by a contrast CT Scan (CT Urogram). This involves an injection of contrast, which is outlined by the kidneys and ureter tubes, and collects in the bladder. The IVU is very sensitive at detecting causes of bleeding. An alternative to the IVU is an ultrasound which is also sensitive at detecting causes of bleeding from the kidney, but does not clearly visualise the ureter tube from the kidney to the bladder, and therefore can miss lesions in the ureter (apart from stones, causes of bleeding in the ureter are very rare).
A combination of an ultrasound and IVU is sometimes used.
If an abnormality in an IVU or ultrasound is present, a CT scan of the urinary tract may be required.
The radiological investigations above are very sensitive at detecting causes of bleeding in the upper renal tract, but can miss causes in the bladder. Small bladder tumours may be missed, so in addition a cystoscopy is usually also necessary.
A cystoscopy involves inserting a telescope through the urethra tube into the bladder. This can be done with local anaesthetic jelly inserted into the urethra, or with a general anaesthetic. The modern flexible telescopes are very small, and this procedure can be done with installation of local anaesthetic jelly in the urethra with very little discomfort, as a relatively minor office procedure. If an abnormality is detected in the bladder that requires biopsying or removal, a general or spinal anaesthetic will be required, as larger instruments will be needed to help remove the lesion and biopsy the region for laboratory testing.
Currently there is controversy regarding screening for haematuria, because the incidence of serious underlying conditions is relatively low. However, if haematuria is detected, it is very important that patients are thoroughly evaluated, as this is the presenting symptom of many of the urological cancer malignancies, which do not necessarily cause any other symptoms until they are relatively advanced and possibly metastatic (have spread).