What does haemodialysis mean?
Haemodialysis is a medical treatment in which a patient's blood is passed through a filtering machine outside the body. The filter, or dialyser, removes waste products, excess fluid, and abnormal levels of electrolytes, while the blood is then returned to the patient. It is most commonly used for people with severe kidney failure, although it may also be needed temporarily for certain other serious medical conditions. A typical course of treatment involves several sessions each week, with each session lasting several hours. The term is principally associated with British and international medical usage; US publications often spell it "hemodialysis". In everyday conversation, people may simply say that someone "is on dialysis". Haemodialysis is distinct from peritoneal dialysis, which uses the lining of the abdomen as a filtering membrane rather than an external machine. The word is worth knowing because it identifies one of the central treatments used to support people whose kidneys can no longer adequately remove waste and regulate the body's fluid balance.
nounHaemodialysis is a form of dialysis in which a patient's blood is circulated through a filtering machine outside the body to remove waste products and excess fluid. It is chiefly used to treat severe kidney failure and other serious disorders of fluid or electrolyte balance.
- medical: the process of purifying a patient's blood by passing it through an external filtering machine, used primarily in the treatment of severe kidney failure.
"The patient undergoes haemodialysis three times a week at the renal unit."
"Her haemodialysis treatment takes four hours each session."
"The clinical guidelines recommend that patients preparing for haemodialysis receive clear information about the procedure and its risks."
The plural is used when referring to separate treatment sessions or procedures.
"The renal unit schedules three haemodialyses each week for the patient."
The word names a treatment that does something deceptively simple: it filters a patient's blood through a machine, removing waste and excess water without removing the blood itself.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does haemodialysis come from?
The British form combines haemato-, from Greek haima meaning "blood", with -dialysis, from Greek dialusis, referring to separating or dissolving. The related forms haematology, haemoglobin, haemophilia, and haemolysis likewise derive from the Greek element for blood. The spelling with initial "haem-" is traditional British usage, whereas the form with "hem-" is standard in US English.
How haemodialysis is actually used
This is a formal medical term. British English commonly uses the spelling "haemodialysis", while US medical literature generally uses "hemodialysis". In non-specialist contexts, "dialysis" may be used more broadly.
Easily confused with haemodialysis
Haemodialysis filters blood through a machine outside the body, whereas peritoneal dialysis uses the lining of the abdomen as a natural filter.
Haemolysis is the breakdown or destruction of red blood cells, while haemodialysis is a treatment that filters waste and excess fluid from the blood.