How Do Doctors Check If a Kidney Will Match the Patient?

Finding a willing kidney donor is an important step, but it does not automatically mean the transplant can go ahead.

Doctors need to check whether the kidney will match the patient safely. Kidney transplant matching involves several blood tests that show how likely the patient’s body is to accept the donated kidney.

First, doctors check the blood group

The first step in kidney transplant matching is usually blood group testing.

The main blood groups are A, B, AB and O.

Some blood groups can donate to certain other blood groups more easily than others. For example, a patient does not always need a donor with exactly the same blood group, but the groups should normally be compatible.

Blood group is usually checked more than once before a living donor transplant.

If the blood groups are not normally compatible, it does not always mean the transplant is impossible. Selected patients may be able to undergo an ABO incompatible kidney transplant after special treatment.

There may also be an option called kidney swap transplantation for some families.

What is tissue matching?

Blood group is only one part of the process.

Doctors also perform a test called tissue typing.

You may hear the term HLA during this test. HLA means human leukocyte antigen. These are markers found on cells in the body.

You do not need to remember the medical name.

A simple way to understand HLA testing is that doctors are comparing certain biological markers between the donor and patient.

A closer tissue match can be helpful, especially between family members, but a perfect match is not required for every kidney transplant.

Modern transplant medicines allow many people to receive kidneys even when their tissue types are not identical.

So families should not assume that a brother or sister is automatically suitable, or that a spouse cannot donate because they are not related by blood.

The actual test results matter more.

What is a crossmatch test?

One of the most important kidney transplant matching tests is called a crossmatch.

This test checks whether the patient already has antibodies that strongly react against the donor.

Antibodies are part of the body’s immune system. They normally help protect us from infections. But some antibodies can also attack a transplanted kidney if they recognise it as foreign.

In a crossmatch test, the laboratory checks how the patient’s blood reacts to cells from the donor.

A negative crossmatch is usually a good sign. It means doctors have not found the type of strong reaction they are looking for.

A positive crossmatch means the patient may have antibodies against that donor.

That does not always mean transplantation is impossible. In selected situations, specialist treatment may be used to reduce these antibodies. The risk and benefit have to be considered carefully.

Why do some patients have more antibodies?

Some patients already have antibodies before they ever meet their kidney donor.

This can happen after previous blood transfusions, pregnancy or an earlier organ transplant.

Doctors may therefore perform additional antibody tests to understand how sensitive the patient’s immune system is.

For someone with many antibodies, finding a suitable kidney may take more planning.

This is one reason two patients with the same blood group can have very different matching results.

Kidney transplant matching is not simply about asking, “Are both people B positive?” There is much more information that needs to be checked.

Matching is only one part of donor approval

Even if the kidney matches well, doctors still have to make sure the donor is healthy enough to donate.

Kidney function, blood pressure, blood sugar, infections, heart health and kidney anatomy are checked.

The patient is also evaluated to make sure they are fit for transplant surgery.

Only after the complete donor and patient assessment is finished can the transplant team decide whether it is safe to proceed.

For families in Gadag and surrounding North Karnataka areas, these tests can be discussed with a kidney transplant team without automatically travelling to a metro city for the first opinion.

Dr. Avinash Udugar and his team in Gadag can guide patients and donors through blood group testing, tissue typing, crossmatch testing and the other steps needed before transplantation.

A donor does not have to be a “perfect match.” What matters is finding a donor who is medically safe to donate and whose kidney can be transplanted with an acceptable level of risk.