With this method, instead of being cleaned by an artificial membrane outside the body, the blood is cleaned inside the body, through the Peritoneum. This is the thin membrane that surrounds the outside of the organs in the abdomen.
The peritoneum allows waste products to pass through it and is very rich in small blood vessels. By running a dialysis fluid into the peritoneal cavity, through a tube called a Tenckhoff Catheter - and then out again - waste can be filtered from the blood.