Urine cytology is a test where a urine sample is sent to the pathology lab to look out for cancer cells.
Bladder cancers are usually transitional cell cancers arising from the urothelium which is the inner lining of the bladder, majority of the urethra (the urine tube where urine exits from the bladder), the ureters (tubes that join the 2 kidneys to the bladder) and the collecting system of the kidneys.
When there is a cancerous growth arising from the urothelium, the cells are shed into the urine and these cells are abnormal and would be detected and the appearance would make the pathologist suspect cancer. However, only the high grade cancers and carcinoma-in-situ cancers of the bladder would shed cells. The low grade bladder cancers usually do not shed cells.
Hence, urine cytology being positive for cancer cells (usually reported as "presence of carcinoma cells") would suggest that there is a cancerous growth in the urinary system arising from the inner lining (urothelium).
But if the urine cytology is negative for cancer cells, this test does not rule out cancer as low grade cancers may not have a positive urine cytology.
If you are unsure what your urine cytology report says, you should show it to a friendly urologist.
