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Dialysis (Vascular) Access

Hemodialysis access, or vascular access, is a way to reach the blood for hemodialysis.  The access allows blood to travel through soft tubes to the dialysis machine where it is cleaned as it passes through a special filter, called a dialyzer. An access is placed by a minor surgery.


Dialysis is a treatment that can take over the job of your kidneys. It is done during regular visits to a clinic. Your blood passes from your body to a machine. The machine will clean the blood then return it to your body. You may be on dialysis for a short time, or you may need it for the rest of your life.

There are two types of dialysis. This fact sheet will focus on hemodialysis.

Reasons for Procedure

The kidneys have many important jobs. They clear toxins out of your blood and help balance salt levels. Dialysis may be needed if the kidneys are not able to work well. It may be started when the kidneys have lost more than 90% of their function.

The main functions of hemodialysis are to:

  • Remove waste and excess fluid from your blood
  • Control blood pressure
  • Keep a safe level of salts in the body, such as potassium, sodium, and chloride

Dialysis may be used short term to allow your kidneys to rest and heal. If the kidney damage is permanent, dialysis will be needed for the rest of your life. It can improve quality and length of life in people with severe kidney disease.

It may also be done to treat a poisoning or drug overdose. Dialysis can quickly remove toxins from the bloodstream.

Possible Complications

Problems from the procedure are rare, but all procedures have some risk. Your doctor will review potential problems, like:

  • A drop in blood pressure during hemodialysis
  • Problems with heart rhythm
  • Muscle cramps
  • Nausea, vomiting
  • Headaches
  • Infection
  • Feeling hot, sweaty, weak, and/or lightheaded
  • Disruption of calcium and phosphorus balance, resulting in weakened bones

If you have heart problems, this may increase your risk of complications from hemodialysis.

What to Expect

Prior to Procedure

A fistula may be needed for long term dialysis. It allows better access to blood flow during dialysis. A surgery is needed to make the fistula. It will take 4-6 months before it can be used. Your care team will connect directly to blood vessels until it is ready.

Before your hemodialysis, you will:

  • Have your weight, blood pressure, and temperature taken
  • Be given heparin—to prevent blood clotting


A medicine may be placed over the area the needle is placed. This will help to numb the skin.

Description of the Procedure

Hemodialysis is done at a dialysis center or hospital. It may be done at home with assistance. They will need to gain access to your blood flow. This may be through a large IV in one of the major veins of the neck. It may also use a fistula if one is available.

Blood will pass through one needle, into a tube to a machine. The machine will filter and clean the blood. It will then be passed out through a tube and back into your body.

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How Long Will It Take?

Hemodialysis is usually done 3 times a week. Each treatment can last 3 to 4 hours. The specific time needed depends on:

  • How much kidney function remains
  • How much fluid weight gain has occurred since the last treatment
  • The amount of waste in the body
  • Body size
  • The level of salts in your body, such as sodium, potassium, and chloride

Will It Hurt?

You will not feel the blood exchange. There may be some discomfort when the needle is placed.

Post-procedure Care

Your blood pressure will be checked. Some may have a decrease in blood pressure. It can cause nausea, headache, or cramps. This may happen less often in later treatment.

Once blood pressure is stable, you will be able to leave. Most will be able to return to normal activities.

You may need a special diet. This will help your overall health. It can also decrease stress on your kidneys. Ask your doctor about your diet.

Call Your Doctor

It is important to monitor your recovery. Alert your doctor to any problems. If any of the following occur, call your doctor:

  • Signs of infection, including fever and chills
  • Redness, swelling, warmth, increasing pain, excessive bleeding, or discharge at the catheter or tube insertion site
  • Nausea or vomiting
  • Abdominal pain
  • Lightheadedness or weakness

If you think you have an emergency, call for emergency medical services right away.


  • Hemodialysis. National Kidney Foundation website. Available at: https://www.kidney.org/atoz/content/hemodialysis. Accessed January 29, 2021.
  • Dialysis for end-stage renal disease. EBSCO DynaMed website. Available at: http://www.dynamed.com/topics/dmp~AN~T900075/Dialysis-for-end-stage-renal-disease . Accessed January 29, 2021.
  • Hemodialysis. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: https://www.niddk.nih.gov/health-information/kidney-disease/kidney-failure/hemodialysis. Accessed January 29, 2021.