Transitional Cells

Transitional cells (also called urothelial cells) are cells that line the wall of the kidney renal (part of the kidney that connects the kidney tubules to the ureters), the ureters (connecting the renal pelvis to the bladder) and the bladder itself. A small number are found in normal urine and are observed more frequently in the elderly. Any damage that results in a separation (desquamation) of the surface cells of the renal pelvis, ureters, bladder or first segments of the urethra will lead to a high number of transitional cells in the urine specimen (urothelial polyp, tumour or cancer, usually of the bladder). A cytological examination of the urine can help characterize the nature of the transitional cells that are observed during the routine urine test.