Do I Need To Worry?
This is what is usually called a “false-positive” test result. The test was positive in a case where it seems that it should have been negative. Any medical test has a certain false-positive rate (usually very low). The problem with a false-positive result with urine cytology is that there is no way to guarantee the absence of cancer. It is always possible that the cancer is there, but we have not been able to find it yet. Sometimes it can hide in places such as the ureters or kidney where we cannot see as well.
Other times, especially with carcinoma in situ, the diseased areas look normal through the cystoscope but actually harbor serious disease. Because of this, one should never ignore a positive cytology result. Close to 80% of patients with a positive cytology but a negative evaluation will eventually be found to have a urologic malignancy. The current recommendation for patients with a positive urine cytology and a negative initial evaluation is to repeat the urine cytology 6 to 8 weeks later. Those patients with a negative cytology on the follow-up test do not need further evaluation.
If the follow-up cytology is positive, however, careful evaluation should be undertaken, as most of these patients will eventually be found to have a malignancy. Your urologist may recommend multiple small biopsies of the bladder to look for carcinoma in situ, a condition that is often associated with positive cytology. Washings may also be obtained from each ureter separately to screen for cancer above the bladder. Finally, you may need to be evaluated for a malignancy in an adjacent organ, such as the colon or uterus, as these tumors can occasionally be the source of an abnormal cytology.