Hello and welcome to the Zero to Finals podcast. My name is Tom and in this episode I'm going to be talking to you about Reesus incompatibility.

And you can find written notes on this topic at zero to finals.com slash resus, spelt R-H-E-S-U-S-U-S, or in the Antinatal Care section of the Zero to

finals, Obstetrics and Gynaecology book. So let's jump straight in. The term resus

refers to various types of resus antigens on the surface of red blood cells.

The antigens on the red blood cells vary between individuals.

The recess antigens are separate to the ABO blood group system that you may be aware of.

Within the recess group, many different types of antigens can be present or absent

depending on the person's blood type. The most relevant antigen within the recess blood group

system is the resus D antigen. When we refer to somebody's recess status in relation to

pregnancy, for example saying she's

recess negative, we're usually referring to whether they have the recess D antigen present on their

red blood cell surface.

So let's talk about recess incompatibility in pregnancy.

Women that are recess D positive do not need any additional treatment during pregnancy. Women that are recess D positive do not need any additional treatment during pregnancy.

When a woman that is recess D negative becomes pregnant, we have to consider the possibility that

her child will be recess positive. It's likely at some point in the pregnancy, for example at childbirth, that the blood

from the baby will find a way into the mother's bloodstream. When this happens, the baby's red

blood cells display the resus deantigen. The mother's immune system will recognize this

resus deantogen as foreign and produce

antibodies to this antigen. The mother has then become sensitized to the resust de antigens,

meaning that she produces antibodies to those antigens.

Usually this sensitization process does not cause problems during the first pregnancy.

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