Medically Reviewed By William C. Lloyd III, MD, FACS

What is dialysis?

Dialysis is a treatment for kidney failure. Kidney failure, also called renal failure, is a life-threatening condition. Healthy kidneys produce urine by filtering waste from your blood and controlling water levels in the body. Diseases or injury can damage your kidneys so they no longer perform these critical functions. 

Kidney failure leads to a buildup of waste and fluid in the body. Dialysis substitutes for damaged kidneys by filtering waste products from the blood and regulating the amount of fluid in the body.  

Chronic kidney failure occurs over a long period of time and can lead to permanent kidney damage and end-stage kidney failure. Treatment for end-stage kidney failure is life-long dialysis or a kidney transplant. 

Acute kidney failure occurs suddenly. Acute kidney failure may go away after treating the cause. In this case, dialysis is a temporary treatment used until the kidneys heal.

Types of dialysis

There are two general types of dialysis. Discuss all of your dialysis options with your doctor to understand which option is right for you. The types of dialysis include:

  • Hemodialysis is a procedure in which your blood flows from your body to a machine called a hemodialyzer. The hemodialyzer removes wastes, extra fluid, and other harmful substances from your blood. It then returns the blood to your body. A specialized hemodialysis team often performs hemodialysis in a hospital or outpatient dialysis center. Some patients are trained to perform hemodialysis in the home.

  • Peritoneal dialysis is a procedure that you perform at home. It involves filling the space in your abdomen with a dialyzing solution through a small tube called a catheter. The catheter is surgically implanted in your abdomen and comes out below your belly button. The dialyzing solution draws wastes and extra water out of your blood through the small blood vessels in your abdomen. The solution, wastes, and extra body water then drain out of your abdomen through the catheter into a bag. There are two types of peritoneal dialysis. Continuous ambulatory peritoneal dialysis (CAPD) is a treatment you perform several times throughout the day without a machine. Ambulatory means that CAPD is adapted for staying mobile. You can take part in various activities with the solution in your abdomen. Continuous cycling peritoneal dialysis (CCPD) is a treatment in which a machine performs multiple cycles of dialysis during the night while you sleep.

Why is dialysis performed?

Your doctor may recommend dialysis to treat kidney failure. Kidney diseases, injury and other conditions can lead to kidney damage, poor kidney function, and possibly kidney failure. Doctors generally recommend dialysis when 85% to 90% of kidney function is lost.

Conditions that can lead to kidney failure include:

  • Autoimmune diseases that attack the kidneys, such as lupus (systemic lupus erythematosus, or SLE). Autoimmune diseases occur when the body’s immune system attacks its own healthy cells and tissues.

  • Diabetes, which can damage the kidneys over time if blood sugar is not properly controlled

  • High blood pressure, which can damage the kidneys over time when not properly controlled

  • Infections, such as repeated bladder, kidney or blood infections

  • Kidney cancer, which can damage the kidneys

  • Medications, such as intravenous (IV) drug abuse, overdose of certain drugs, or long term-use of certain medications, such as nonsteroidal anti-inflammatory drugs

  • Nephritis and glomerulonephritis and other diseases that cause kidney inflammation and damage

  • Polycystic kidney disease, an inherited disease that causes formation of large cysts in the kidneys

  • Reduced blood flow to the kidneys due to shock or renal artery stenosis, which is a narrowing of the renal arteries

  • Trauma or injury that affects the kidneys or the arteries that supply blood to the kidneys

  • Urinary tract obstruction due to a kidney stone, tumor, congenital deformity, or enlarged prostate gland

Who performs dialysis?

A specialized dialysis team performs dialysis. A nephrologist leads the dialysis team. A nephrologist is a doctor who specializes in kidney diseases. Critical care medicine doctors (intensivists) also prescribe dialysis. These doctors specialize in caring for acute, life-threatening illnesses or injuries. 

Dialysis teams also include specialized nurses and certified hemodialysis technologists. Some patients may be trained to perform their own hemodialysis at home with the support of a trained partner and a home care dialysis team.

How is dialysis performed?

Dialysis procedures vary depending on the type of dialysis. 

How hemodialysis is performed

The frequency and length of hemodialysis sessions vary depending on your condition. Hemodialysis often takes three to five hours, three times a week. Some people may have hemodialysis for a shorter period every day. 

Weeks to months before starting hemodialysis, your surgeon will create a vascular access. This is a minor surgical procedure. A vascular access is the place where your dialysis team will insert the dialysis needles. Dialysis needles allow blood to flow out to the hemodialyzer machine and return back to your body after filtering. 

The best long-term vascular access is an arteriovenous (AV) fistula. Your surgeon makes an AV fistula by connecting an artery to a vein, usually in the forearm. Sometimes, a piece of synthetic material called a graft is needed to construct the connection between the artery and vein.

Another type of vascular access is a tube (catheter) inserted into a large neck vein, called a vasc-cath or perma-cath. This type of access is often temporary. The dialysis team uses it only until an AV fistula or other permanent access is ready.   

Your hemodialysis will be performed in a hospital or outpatient dialysis center. The procedure generally includes these steps:

  1. The dialysis team checks your vital signs and weight.

  2. The dialysis team cleans your vascular access site and may apply an anesthetic cream or spray to numb your skin.

  3. The dialysis team inserts one or two needles through the skin into your vascular access point. The needles are attached to tubes that carry your blood to the dialyzer machine and back to your body.

  4. You can relax, read, watch TV, text, use your laptop, or nap during the treatment.

  5. Your dialysis team will check your vital signs throughout the procedure.

  6. Your dialysis team removes the needles, applies a dressing, and rechecks your weight.

How peritoneal dialysis is performed

A surgeon will perform a surgery to insert a small soft tube (catheter) into the abdomen before your first peritoneal dialysis treatment. The tube has a port outside your body located near the belly button. The catheter stays in your abdomen between dialysis sessions. Peritoneal dialysis can begin as soon as the catheter is in place. You may begin with a partial schedule of sessions until the site is fully healed.

Continuous ambulatory peritoneal dialysis (CAPD) generally involves these steps:

  1. You wear a surgical mask and wash your hands, catheter site, and other equipment as directed to prevent infection. You should perform the procedure in a clean, dry place.

  2. You connect your catheter to a tube and bag containing dialysis fluid.

  3. You fill your abdomen with the dialysis fluid. The fluid flows into your abdomen by gravity.

  4. You disconnect the tube and allow the fluid to stay (dwell) in your abdomen for a certain period of time, generally four to six hours. Your doctor will tell you what dwell time period is appropriate for you. You can perform certain activities with the solution in your abdomen.

  5. You connect a tube to your abdominal catheter and allow the fluid to drain out by gravity. The fluid now contains wastes and extra water that your body doesn’t need.

  6. You repeat this procedure, usually several times a day. Your doctor will tell you how many times a day to do this.

Continuous cycling-assisted peritoneal dialysis (CCPD) generally involves these steps:

  1. You wear a surgical mask and wash your hands, catheter site, and other equipment as directed to prevent infection. You should perform the procedure in a clean, dry place.

  2. At bedtime, you connect your catheter to a tube attached to your automated cycler machine. 

  3. As you sleep, the automated cycler fills your abdomen with dialysis fluid and allows it to dwell. It then drains the fluid at the right time. The automated cycler will generally perform this about three to five times a night for a total of 10 to 12 hours. Your doctor will tell you how many cycles you need each night and the best dwell time for you.

  4. In the morning, your automated cycler fills your abdomen with dialysis fluid, but you disconnect your catheter from the machine before draining the fluid.

  5. You allow this cycle of fluid to dwell in your abdomen for a prescribed amount of time during the day. Your doctor will tell you how long your daytime dwelling should last. After the dwell time, you reconnect your catheter to the machine to drain the used fluid.

  6. You repeat this procedure every night.

Your doctor will customize your dialysis time based on how you feel, your activity and lifestyle, and other factors. Some people find that they feel best with a combination of cycler-assisted and ambulatory peritoneal dialysis.

Will I feel pain?

Your comfort and relaxation is important to you and your care team. Dialysis itself is not painful. You may feel a pinch or pin prick pain during the placement of the dialysis needles for hemodialysis. Many people say that they quickly become accustomed to this. Your care team can also use an anesthetic spray or cream to numb your skin before inserting the dialysis needle. 

You may feel a bit bloated when the dialysis solution is in your abdomen during peritoneal dialysis. You should not feel pain. Tell your dialysis team if you are uncomfortable in any way. 

What are the risks and potential complications of dialysis?  

Dialysis involves risks and potential complications. Complications may become serious in some cases. In addition, dialysis does not replace all the functions of healthy kidneys. Some complications of kidney failure will need ongoing monitoring and treatment.

Complications of dialysis and kidney failure include: 

  • Anemia, a low number of red blood cells. Healthy kidneys produce the hormone erythropoietin, (EPO). EPO stimulates your body to make red blood cells. Diseased kidneys often don't make enough EPO. Dialysis patients may need to take synthetic EPO.

  • Blood clot that develops in the vascular access, requiring surgical revision.

  • Dialysis-related amyloidosis (DRA), a complication where proteins in the blood build up on joints and tendons. This causes pain, stiffness, and fluid in the joints. Dialysis is less effective in filtering out these harmful proteins than healthy kidneys. It is common in people who need dialysis for more than five years.

  • Infection, including peritonitis (an infection of the abdomen). Peritonitis is a risk of peritoneal dialysis.

  • Low blood pressure, which generally goes away after you get used to dialysis treatments

  • Renal osteodystrophy, which causes bones to become thin and weak or form incorrectly

Reducing your risk of complications

You can reduce the risk of certain complications by following your treatment plan and: 

  • Following activity, dietary and lifestyle restrictions and recommendations before your procedure and during recovery

  • Notifying your doctor or care team immediately of any concerns, such as fever, pain, weakness, dizziness, or changes in the way you feel

  • Performing or going to your dialysis treatments as often and as long as recommended

  • Taking your medications exactly as directed

  • Using proper clean technique when performing peritoneal dialysis

How do I prepare for dialysis?

You are an important member of your own healthcare team. The steps you take before beginning dialysis can improve your comfort and overall health. This includes answering all questions about your medical history and medications you take. Medications include prescriptions and over-the-counter drugs, herbal treatments, and vitamins. It is a good idea to carry a current list of your medical conditions, medications, and allergies at all times.

Questions to ask your doctor

Facing dialysis is stressful. Dialysis requires a big change in your lifestyle. It requires a large time commitment and you will also have dietary restrictions. However, many people who need dialysis live active lives and continue to work and participate in many favorite activities. 

You will likely have many questions about living with dialysis. It is common for patients to forget some of their concerns during a brief doctor’s office visit. You may also think of other questions after your appointment. Contact your doctor with concerns and questions before dialysis and between appointments. 

It is also a good idea to bring a list of questions to your appointment. Questions can include:

  • Why do I need dialysis? Are there any other options for diagnosing or treating my condition, such as a kidney transplant?

  • How long will dialysis take? How often will I need to go to dialysis or perform it myself?

  • What restrictions will I have with dialysis?  What can I eat and drink?

  • Can I return to work and other activities?

  • What kind of assistance will I need at home?

  • How should I take my medications?

  • What other tests, procedures or surgeries might I need?

  • When should I follow up with you?

  • How should I contact you and my dialysis team? Ask for numbers to call during and after regular hours.

What can I expect after dialysis?

Dialysis is a life-saving treatment for severe chronic kidney failure, but it is not a cure. The only cure for end-stage chronic kidney failure is a kidney transplant. You will need life-long, regular medical care and dialysis treatments for chronic kidney failure. With good care, many people on dialysis live full, active lives. This includes doing many types of work, travel and other activities.

You will have dietary restrictions and recommendations to keep you as healthy as possible. Your doctor will tell you what diet is best for you. A registered dietician will help you understand and stick to your diet while enjoying a wide variety of foods. Common dietary recommendations include:

  • Avoiding foods that are high in phosphorus, which can be harmful to the bones of a person on dialysis. Foods high in phosphorus include dairy products, legumes (such as soybeans), and nuts.

  • Avoiding foods that are high in potassium, such as oranges, bananas, tomatoes, potatoes, and dried fruits. Too much potassium can be harmful to the heart of a person on dialysis.

  • Eating a low salt diet. Salt (sodium) causes increased fluid retention and can lead to high blood pressure and heart failure.

  • Monitoring and possibly restricting fluids

  • You may need to adjust the amount of protein in your diet.

  • You may need to eat a healthy diet with extra calories if you are underweight.

How will I feel after dialysis?

Your blood pressure may get lower after dialysis. This can lead to nausea, vomiting, and headache. This problem generally goes away after you get used to your dialysis treatments. You may also feel tired after your dialysis session. 

People on dialysis may also experience itchy skin, restless legs, or problems sleeping. Tell your doctor or dialysis team if you have any of these problems. Treatments are available to help you live and sleep comfortably. 

When can I go home?

Patients generally go home right after dialysis treatments, as long as heart rate, blood pressure, and other vital signs are stable.

When should I call my doctor?

It is important to keep your follow-up appointments.  Contact your doctor for questions and concerns between appointments.

Call your doctor right away or seek immediate medical care if you have:

  • Catheter that is dislodged

  • Fever

  • Nausea or vomiting

  • Redness, swelling or pain around your catheter or vascular access

  • Unusual bloating or swelling

  • Unusual color or cloudiness in the used peritoneal dialysis solution

  • Vision problems

Was this helpful?
  1. Dialysis. National Kidney Foundation. http://www.kidney.org/atoz/content/dialysisinfo.cfm. http://kidney.niddk.nih.gov/KUDiseases/pubs/vascularaccess/index.aspx
  2. Vascular Access for Hemodialysis. National Kidney & Urologic Diseases Information Clearinghouse (NKUDIC). http://kidney.niddk.nih.gov/KUDiseases/pubs/vascularaccess/index.aspx
  3. Treatment Methods for Kidney Failure: Hemodialysis. National Institute of Diabetes and digestive and Kidney Diseases. http://kidney.niddk.nih.gov/KUDiseases/pubs/hemodialysis/index.aspx
  4. Treatment Methods for Kidney Failure: Peritoneal Dialysis. National Institute of Diabetes and digestive and Kidney Diseases. http://kidney.niddk.nih.gov/KUDiseases/pubs/peritoneal/index.aspx
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 24
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