Question: How does an organ transplant work?

Alex Haragan answered on 12 Jun 2018:

It does vary from which organ is being transplanted – but broadly speaking the idea is that when someone has an organ that no longer works, it is replaced with someone else’s that does work.
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Lets take kidneys as an example. Most people are born with two – and kidney failure can be very slow, often over decades, or very fast, sometimes in hours, depending on the cause.
If you’re kidneys are not working, one thing we can do in hospital is use something called dialysis, which is where we do the job of the kidney using a machine.
Unfortunately this is time consuming, bulky, and far from perfect.
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An alternative then is to give the person with a failed kidney a working one. Now because most people have two, someone might decide to donate one whilst they are still living. In other cases, you might have to wait until someone has died (for example, we only have one liver).
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We will only remove the damaged kidney if we have to, but its a difficult area to operate, so transplanted kidneys are normally put in the front of the abdomen at the lower part. (rather than at the back and high end where kidneys naturally sit).
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Its worth remembering that you also have to have a “match”. For blood donation you must have your type checked (A, B, AB or O) along with rhesus status (+ve or -ve). There are 8 types of blood, and some can be given to others (O -ve can be given to everyone).
Organs require far more of these groups to be the same – so its much harder to find someone with the same “type” of kidney. This means people are often on waiting lists for years, and many sadly die because no match is ever found.
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On an aside – I think everyone should be aware of this, and sign up to have their organs donated if they die because if you’ve died you don’t need them – but you could save a life (or even several lives!)
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Once the working organ has been surgically placed into the patient, they will need lifelong checks to make sure it is working, that it isn’t being attacked by the patient’s immune or system (or its own immune functions attacking the patient), and be on various drugs to help this. It means a transplanted organ is never as good as the original – but it can give someone a new lease of life so they are fantastic things!