The peritoneal membrane is a sac around the abdominal organs.

Peritoneal dialysis is another method of removing waste products and excess fluid from the body. Here, the process of removal of waste products and excess fluid takes place within the patients own body, in the peritoneal or abdominal cavity, rather than outside the body in an artificial kidney as happens with hemodialysis. The potential problem with peritoneal dialysis is peritonitis which is an infection of the peritoneal membrane. Therefore, the process of introducing dialysis fluid into peritoneal cavity and removing it from the cavity must be done under strict aseptic conditions.

The patient has a plastic tube called a peritoneal catheter surgically implanted into the belly. He or she slowly empties about two quarts of dialysate fluid through the catheter into the abdomen. As the patient’s blood gets exposed to the dialysate through the peritoneal membrane, impurities in the blood are drawn through the membrane walls and into the dialysate. The patient drains out the dialysate after three or four hours and pours in fresh fluid. The draining takes about half an hour and must be repeated about five times a day. This is called Continuous Ambulatory Peritoneal Dialysis (CAPD).

The main benefit of Continuous Ambulatory Peritoneal Dialysis is freedom – the patient doesn’t have to stay at a dialysis clinic several hours a day, three times a week. The dialysate can be exchanged in any well–lit, clean place, and the process is not painful. The drawback to this treatment is that some people get an infection of their peritoneal lining, and the process may not work well enough on very large people.

Children often do a similar type of dialysis called Continuous Cycling Peritoneal Dialysis (CCPD). Their treatments can be done at night while they sleep. A machine warms and meters dialysate in and out of their abdomens for 10 hours continuously. Then they are free from treatments during the day.