The peritoneum lines the walls of the abdomen and covers the internal organs. It has similar attributes to the artificial filter used in hemodialysis: its pores allow the passage of certain substances while retaining others. Peritoneal dialysis uses this naturally filtering organ.

A cleansing liquid (dialysis solution) is introduced through a catheter placed in the abdominal wall that ends in the pelvis behind the bladder. The metabolic toxins are brought to the abdominal wall in hair-thin blood vessels and pass through the pores into the cleansing liquid. Dextrose in the dialysis solution also pulls water from the body with the help of osmotic mechanisms. The used cleansing liquid is removed from the body through the catheter, along with the toxins and excess water. As with hemodialysis, the peritoneal dialysis can be performed at home or in a clinic.