What is the role of the renal pelvis?

The renal pelvis is a funnel-shaped structure located at the upper end of the ureter that serves as a collection point for urine within the kidney. It receives urine from the calyces—cavities where urine collects after being produced—and facilitates its passage into the ureter and toward the urinary bladder.12

The walls of the renal pelvis contain smooth muscle fibers that undergo peristaltic movements, which are rhythmic contractions that actively push urine out of the kidney. The lining of the pelvis is impermeable to substances found in urine, ensuring that fluids are not reabsorbed into the body.1

In the context of renal system disease, the renal pelvis is highly susceptible to complications. For example, urinary tract obstruction can cause the pelvis to become distended, potentially leading to severe kidney damage or renal failure. Additionally, the renal pelvis can become a site of pyelonephritis, an infection and inflammation that can lead to the destruction of vital kidney tissue.34