Dialysis is a medical treatment that is used to remove waste products and excess fluid from the blood when the kidneys are not functioning properly. In a dialysis department, patients with kidney failure or other conditions that affect the kidneys' ability to filter the blood are treated.

During dialysis, a patient's blood is circulated through a machine called a dialysis machine, which contains a semipermeable membrane. This membrane is designed to allow small molecules, such as waste products and excess fluid, to pass through it, while larger molecules, such as blood cells and proteins, are unable to pass through.

The blood is removed from the patient's body and circulated through the dialysis machine using a sterile tubing system. The dialysis machine is connected to the patient's bloodstream through a surgical puncture in the patient's arm or leg, or through a surgically created access point in the patient's abdomen.