What is dialysis?

Dialysis is one of the treatments that are available when kidneys have almost stopped working. Other options include kidney transplant and conservative management. Dialysis does not do everything that healthy kidneys normally do, but it cleans the blood and filters out harmful wastes and excess fluids. Most people who start dialysis remain on dialysis for the rest of their lives, or until they receive a kidney transplant.

What are the most common types of dialysis?

This website focuses on the two types of dialysis that are used by the majority of patients with kidney failure: in-center HD and PD. Since these treatments are very different, we want to help you understand how each might fit your preferences and lifestyle.

What is in-center hemodialysis (HD)?

In-center HD is a treatment that uses a machine to take blood out of the body, filter out wastes and excess fluid, and put the clean blood back into the body.

Where is it done?

We focus on in-center HD that is done in a specialized clinic, called a dialysis center. In some cases, when a person is very ill, HD is done at the hospital. HD can also be done at home. For more information on home hemodialysis, see Home Hemodialysis.

Who is involved?

Dialysis nurses and patient care technicians (PCT) are responsible for performing dialysis treatment, following a doctor's prescription.

Experiences & StoriesSuppose something goes wrong, or I don't do anything. I'm not an expert at doing dialysis. I get it at the center, where I know I'll get professional treatment. If anything goes wrong, they're there.


How is it done?

To take blood out of the body and put it back in, an access site to the blood stream is needed. There are two types of accesses:

1. Fistula or Graft: Connects a vein to an artery, causing strong blood flow that is needed for HD. Fistulas/grafts are placed during outpatient surgery, usually in one arm. It takes some time (usually weeks, sometimes months) for a fistula/graft to get strong enough for dialysis. With time, the large amount of blood causes the vein to bulge. Fistulas/grafts are the preferred access because there are lower chances of infection.

Hemodialysis fistula on a patient's arm; a nurse is inserting needles that will be connected to tubing delivering blood to the dialysis machine.

2. Catheter: A plastic tube is inserted into a large vein to take blood in and out of the body. It is placed during outpatient surgery, most often in the chest or neck. Catheters increase the risk of getting very serious infections, which is why they are usually only a temporary option.

Central venous catheter in a patient's chest, connected to dialysis tubing; a nurse is changing the dressing at the point the catheter enters the skin.

HD treatment

Here is what you can expect from the in-center HD session:

  • Patient washes hands and fistula/graft (if present) with soap and water.
  • Patient sits in a reclining chair in a room with other patients on HD.
  • Blood pressure, temperature, and weight are measured.
  • PCT or nurse sets up access site:
    • Fistula/graft: Skin is disinfected, and two large needles are inserted.
    • Catheter: Tubing from the machine is connected to the catheter.
  • At regular intervals, the PCT or nurse will check in to see how the patient is doing.
  • During dialysis, patients may:
    • Sleep
    • Use electronics
    • Watch TV
    • Listen to music
    • Read
    • Socialize with other patients
  • TVs and WIFI internet connection are often offered at dialysis centers.
  • Patients often feel cold during HD.
  • Some patients experience low blood pressure and leg cramping.
  • The PCT or nurse disconnects the patient from the dialysis machine.
  • Patients with grafts or fistulas hold gauze over the needle holes until they stop bleeding, which sometimes can take up to 10 minutes.
  • Blood pressure, temperature, and weight are measured again.
  • The PCT or nurse checks in to make sure the patient is OK to leave the dialysis center.

What is peritoneal dialysis (PD)?

PD uses the membrane that lines the inside of the belly (peritoneum) to clean the blood. A sterile fluid ("dialysate") is put into the belly, pulls wastes and excess fluid from the blood through the peritoneum, and is then removed from the belly. This process is called "PD exchange."


Where is it done?

PD is usually done at home, but it can also be performed in other places (e.g. your workplace, in a hotel room).

Experiences & StoriesI wanted to maintain my lifestyle as much as possible, and being on PD doesn't disrupt that too much. I know that I have to cycle for 10 hours at night, but then I can get up and go to work, and go about my normal routine.


Who is involved?

If you choose PD, you will be responsible for performing your own treatment every day. Before starting PD you will receive extensive training until you are proficient with the entire treatment process. A member of your health care team will always be available by phone, and you will go to the clinic for appointments, usually once or twice a month.

How is PD done?

PD catheter

For the dialysate fluid to go in and out of the belly, a plastic tube ("PD catheter") is placed through surgery. One end of the catheter is inserted under the skin into the peritoneum, while the other end sticks out from the skin, usually below the belly button. Since the catheter is directly connected to the belly, there is a risk of getting very serious infections if the catheter is not properly cared for.

There are two types of PD: continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD). In CAPD, the catheter is connected to a bag of dialysate and a bag for drainage. In APD, a machine (called a cycler) is connected to the bags, fills the belly with dialysate, and then drains it out.

Continuous Ambulatory Peritoneal Dialysis


Automated Peritoneal Dialysis


CAPD or APD may be better for a specific person, depending on physical condition and personal characteristics. If you choose PD, your doctor will indicate what modality is best for you.

PD treatment

Here is what you can expect from the PD treatment:

  • Patient washes hands with soap and water.
  • Patient cleans all surface areas where s/he will put PD supplies..
  • Patient sets up PD supplies.
  • Patient sets up PD cycler, if s/he uses it.
  • Patient measures and records blood pressure and weight.
  • CAPD
    • Patient connects the PD catheter to the PD tubing.
    • Fluid is drained out of the belly.
    • Patient fills the belly with the amount of dialysate fluid needed.
  • APD
    • Patient connects to the cycler and turns it on.
  • Patient disconnects the tubing from the catheter.
  • Patient measures and records blood pressure and weight again.
  • Patient records information about dialysate fluid drainage.

As with hemodialysis (HD), there isn't an exact timeline. Events may take place at different times for each person.

Here is a comparison of HD and PD:


In-center Hemodialysis (HD)

Peritoneal Dialysis (PD)

What is it?

Uses a machine to clean the blood

Uses the peritoneum to clean the blood

Where is it done?

In a specialized dialysis center

At home or wherever the patient is (example: workplace, vacation)

Who is involved?

Health care team does the treatment

Patient does the treatment

How is it done?

With a machine that pumps blood in and out of the body through an access site

With dialysate fluid that is put into and out of the belly through a tube

Research described on this web site was partially funded through a Patient-Centered Outcomes Research Institute (PCORI) Award (1109). The statements and views presented here are solely the responsibility of the authors and do not necessarily represent the views of the Patient-Centered Outcomes Research Institute (PCORI), its Board of Governors or Methodology Committee.