What is microscopic haematuria?
This is defined as presence of red blood cells in the urine. This red blood cells are not visible to the naked eye. When it is visible to the naked eye, it is termed as gross haematuria.
It is most commonly an incidental finding during your routine medical examination. Your GP might also be able to identify them using the urine dipstick.
Urine needs to be examine under high magnification to confirm the presence of red blood cells (RBC).
The source of blood can come from anywhere within the urinary system. Since the blood is collected in a container, it is usually difficult to localise the site and source of bleeding just by examining it under microscopy. The blood could arise from the kidneys, ureter, Urinary bladder, prostate (males) and urethra. The blood could also be secondary to contamination from neighbouring structures example during menstrual cycle in females.
The causes of this must be investigated by your urologist. The evaluation could include repeating the urine analysis, urine cytology, urine culture sensitivity and phase contrast study. Depending on the results, he might proceed to do further radiological and invasive test.
The radiological investigation could either be a CT scan (contrasted) or ultrasound followed by a flexible cystoscopy. A flexible cystoscopy is a small camera which is inserted through your urinary passage under local anaesthetic to visualise the bladder. This test can be performed as outpatient.
Depending on all these results, your urologist will advise you on further assessment if required or might decide to refer you to a nephrologists.
With this evaluation strategy, nearly 80% of the cases are usually identified and 20% of patients with asymptomatic microscopic haematuria are discovered to have urological cancers. Patients with persistent haematuria after the negative evaluation require regular follow-up and repeat valuation sometime in 2 to 3 years time. This is done since days 3% chance that they will be subsequently diagnosed with a urological malignancy.
References:
Asymptomatic Microscopic Hematuria in Adults: Summary of the AUA Best Practice Policy Recommendations, Grossfeld GD, Wolf JS,
Litwin MS, Hricak H, Shuler CL, Agerter DC, Carroll PR, American Family Physician, 2001, 63 (6) accessed May 7,
2011: http://www.aafp.org/afp/2001/0315/p1145.html
Evaluation of the patient with hematuria, Yun EJ, Meng MV, Carroll PR, Medical Clinics of North America, 2004, 88 (2)
Evaluation of hematuria in adults, Rose BD, Fletcher RH, UpToDate, 2007
Campbell-Walsh Urology, 9 th edition, WB Saunders; 2007, pages 97-100