Do you know your blood type? Rhesus disease in pregnancy
Unless you are a blood donor or have had an operation in the past, most commonly women don’t know their blood type until they are first pregnant.
As well as blood type, the ABO system, there are lots of different markers on the surface of our red blood cells. The system in pregnancy that we are interested in is the Rhesus system and the effect it can have on your baby.
[00:00:36] All right, everyone, well, welcome to Episode 29. And today we're going to cover. "Do you know your blood type? Rhesus disease in pregnancy.
Brigid [00:02:13] So we are going to talk about blood type. And for me, blood type was I always knew my blood type was A negative. Yeah. A Rhesus negative. So, Paddy, can you just tell us, what are the different blood types?
Patrick [00:02:45] Yes. So there's some blood type. We know we all have a blood type, there are some markers on the surface of our red blood cells which determine that blood type. And there are lots and lots of different ones. But there are only a few blood type systems that are what we call clinically relevant. So typically that's the ABO system. People, you know, blood group A, B, AB or O. And the Rhesus system, which is a set of markers that you've either got or you don't. Yes.
Brigid [00:03:23] They can make you A negative or. Yeah.
Patrick [00:03:25] So when we talk about A negative we mean in the ABO system. I'm A. Yeah. And in the Rhesus system I'm negative. Yeah. And these two systems of markers on our red blood cell surface are clinically significant because they're relevant to pregnancy. And also for example, if we need a blood transfusion, they're the ones they have to get. Right. Yeah. So if I'm A positive. And if I was gonna get a blood transfusion, it would have to be just from someone who matched my A group. Yeah.
Brigid [00:04:03] Or O-negative. That's the universal donor. Yeah, that's right. Yeah. That have got none of the markers. Yeah. But there are some more obscure blood markers that nobody knows about and the reason no one knows about them is that they're not relevant to be matched for a transfusion.
Brigid [00:04:18] Right. And so when we're talking about blood groups in pregnancy, a lot of women only find out their blood group when they are pregnant, don't they?
Patrick [00:04:25] Yes, it's interesting. Sometimes people say to me, can you if I'm seeing them for gynae problem "can you sort out by group for me? I'm interested". And mostly we don't do that because it all costs money, you know, to to do a pathology test. So people tend to only have known their blood group by the time they're up to having a baby if they've been a blood donor. Yes. Or have received blood for some reason or have been about to receive blood for some reason, like an operation.
Brigid [00:04:53] Or your mum's a kook, a bit like mine. And she went through this phase where we all had to eat right for our blood type. So we all found out what our blood types were.
Patrick [00:05:01] I think there might be an evidence deficit behind that. Yes. Anyway, so.
Patrick [00:05:12] So it is definitely relevant in pregnancy and it's all about a problem called Rhesus disease.
Brigid [00:05:18] And I just wanted to talk about Rhesus well, just the markers to begin with, cause I'm pretty fascinated with how it all works. So let's just say you are positive Rhesus positive. I'm rhesus negative. What are the chances? What will our baby be?
Patrick [00:05:34] Well, it could be either. And we say that positive trumps negative, but somebody who's Rhesus positive will have two genes determining their Rhesus status. And if one of my genes is positive and the other is negative, then I'm going to be Rhesus positive because my positive gene trumps my negative gene. But I may make a sperm with a negative. One of my negatives goes into matches up with your eggs, which are all negative and and we could have a negative baby.
Brigid [00:06:15] Okay. All right. So you can't really use it to test paternity.
Patrick [00:06:21] Well no. Not completely. You might be. It can occasionally exclude some things, but it's not enough. And so we just always need to assume that that rhesus negative women are at some risk.
Brigid [00:06:41] Yes. So they're the ones that you will test the baby afterwards to save that baby is Rhesus positive.
Patrick [00:06:46] Exactly. So the Rhesus disease as a disease works like this. A woman who's Rhesus negative has a pregnancy and the baby, the Fetus has positive is has Rhesus positive blood cells. At some point during the pregnancy, some blood escapes from the pregnancy into the woman's system. And the times when that might happen might be a big bleed during the pregnancy. An abruption, which is a bleed behind the placenta. Trauma like a car accident or something or something really bleedy like a cesarean section. Yeah. Right. And some of those Rhesus blood cells get into the woman's system. She recognizes them as foreign and develops an immune response against rhesus positive cells. Now, for the rest of that pregnancy, the immune response is immature and it's unlikely to be strong enough to trouble that baby much. But by the time the woman's pregnant again, she may have developed a very powerful and mature immune response to positive cells. And if the next baby is also rhesus positive, then the mother's immune system will attack that baby's red blood cells.
Brigid [00:07:59] And what happens when someone's immune system attacks that baby's red blood cells?
Patrick [00:08:04] Well, untreated, it's serious. And that's and that's what rhesus disease is. And it used to be a thing like so it used to be something that everybody knew about. And big hospitals used to have rhesus clinics that would deal with this problem. Right. And so the more the fetus's red blood cells got attacked by the maternal immune system, the baby, those red cells of blood cells in the Fetus would break open and and the baby would become anaemic and sick and not growing well and develop fluid where there shouldn't be fluid. And in a worst case scenario would lead to, you know, fetal loss, stillbirth. So in the 1960s, along comes the AntiD, which was the injection we use today. Yes. And what that does is if there are any positive, rhesus positive blood cells floating around inside the mother's bloodstream, the AntiD injection will find them and neutralize them right before the maternal immune system has a chance to build up a powerful response.
Brigid [00:09:07] And you said that you have to have, AntiD after a bleed during your pregnancy. What are we talking? What sort of bleed?
Patrick [00:09:14] We tend to give them after sort of any event that we think might result in what we call a sensitising event. Enough of a bleed for this to happen.
Brigid [00:09:24] So not spotting?
Patrick [00:09:24] Well, the spottings, spottings rarely relevant because there isn't much blood in a in a Fetus. You know, that's some six, seven, eight weeks. And so that's thought to be a relatively low risk event, although we can give some AntiD. for first trimester bleed. They make it in a low dose. And then but if there's been something really significant, like a big bleed in the third trimester or something, then we give them the full dose and we might give multiple doses, multiple injections.
Brigid [00:09:59] And are there routine? There are routine ones, I should say.
Patrick [00:10:04] So the routine ones are because there was still people getting this even know we were giving it to anyone who'd had a bleed. And so it became obvious, I guess, with time that some were sneaking through the system. And that there might have been some people with bleeds that we didn't know about. Yeah. Yeah. Sneaky ones where there were some blood obviously crossed from the pregnancy to the woman, but nothing was revealed vaginally. So we didn't know what had happened. Right. So typically we'll give some preventative doses at 28 and 34 weeks.
Brigid [00:10:35] And so say I'm in the public system. What happens, I've just I have an appointment booked anyway at 28 and 32.
Patrick [00:10:43] So you be going to the engine you on those days anyway and a negative group women will be shuffled off to have an injection as well.
Brigid [00:10:48] And to be honest, I can't remember their gauge needle. Is it a fine gauge needle?
Patrick [00:10:52] Yeah, it hurts, people say it hurts a bit. Okay, but it gets a small needle. But it's a needle nevertheless.
Brigid [00:11:00] Where is my brain. I can't remember. Is it in your arm or your leg or where he gave you. Yeah.
Patrick [00:11:06] So. And then the other dose of course is is after the birth because procedure of vaginally it's going to be some bleeding and bleeding can also be a sensitising event. So but of course we'd have to give everyone more after the birth. Only the only the babies, only the mothers of the babies that have a positive group. Yeah. And of course that's easy to find out once the baby's out.
Brigid [00:11:32] When does the baby have the blood test?
Patrick [00:11:34] We get from the cord? Oh, okay. So you don't have to drain blood from the baby's take from the cord, because that's foetal blood in the cord. Yeah. And so you do a blood group on the cord blood. Yes. And if that's Rhesus positive then you give mum some more.
Brigid [00:11:49] Right. But if that baby's Rhesus negative, the mum doesn't need it. There's no risk. Yeah. Yeah. Okay. So what does what happens to a baby that, you know, has survived the pregnancy but has Rhesus disease?
Patrick [00:12:02] Yes. So let's say this has all happened and we'd pick and despite the use of Anti D, there was a degree of risk of Rhesus disease happening. Then during the pregnancy, that baby would have been very closely monitored. You know, there are ways of measuring anaemia in the Fetus. And if it's severe enough that you can give her a Fetus, an intrauterine blood transfusion.
Brigid [00:12:27] Really, like laparoscopically?
Patrick [00:12:28] Or an ultrasound guidance, pass a needle through the belly, mum's belly and cannulate the cord? Yeah, right near where it goes into the baby and run some and run some donated blood in it.
Brigid [00:12:43] And have you ever done that or have you ever seen that done?
Patrick [00:12:46] Well, it's hardly ever done anymore because they fixed it with Anti D. Yeah, but that's what these clinic clinics used to do. And you know, the old boys who can remember the Rhesus clinics said that women were coming with absent foetal movements because the babies were too anaemic to kick. And then they'd give the transfusion in the woman go, yep, that's worked, because a baby kinda comes straight back to life. And then and then three weeks later, they come back anaemia in her again. Oh, my God.
Brigid [00:13:10] So it's all they can't be turned around in utero, but they can't get to the point where the Rhesus diseases isn’t a problem.
Patrick [00:13:17] No it would keep on happening.
Patrick [00:13:19] And so they would potentially need recurrent transfusions. And then, of course, they would get to a point where delivery was safer. Yes. So they would just be delivered. Yeah. So let's say it all happened despite everything that we do these days. Then the baby's born with mismatch. Jaundiced and potentially need transfusions, transfusions and the yellow lights. Yeah. So. So it might be beyond. So the yellow lights have mild jaundice. And then there's something called an exchange transfusion. You can't just pump a lot of extra blood into a baby. So you take a bit out and put some put some in. And that's again, that's something that's just done less and less often.
Patrick [00:14:04] Yeah. As we've got a better handle on this and in particular with Rhesus. It can be entirely prevented with the AntiD injections.
Brigid [00:14:13] And we actually were asked by journalists to provide some information about this that ended up being on the MamaMia website. And the journalist was sort of fearful of having Rhesus negative blood.
Patrick [00:14:29] Yes, she was negative herself. Yeah. And I think she'd found that quite, quite anxiety provoking when she was first pregnant.
Brigid [00:14:38] Yeah. But I think what we're trying to say here is that the solution is pretty easy. Again, it's another real win for modern obstetrics, isn't it?
Patrick [00:14:49] I think looking back, this must have been at the time one of the massive wins. Yeah. Yeah. So that and of course it changed it all around from something that used to be a big deal to something that really is hardly ever seen.
Brigid [00:15:01] So like how special am I? Like how common is rhesus negative.
Patrick [00:15:08] That's about 15 percent of the community have a negative blood group. Yeah. Yeah. So you know, it's less than a positive group, but it's not rare. No, that's right. So. So this is a everyday thing to deal with on a on a obstetric unit practices. Is establishing people's blood groups. And man putting in a plan to make sure they're adequately covered.
Brigid [00:15:34] Just because we've recently done our miscarriage podcast. It just does remind me, say someone has had a miscarriage at six weeks. Would it be just routine that their GP or, you know, if they've sort of managed it themselves and they've let that miscarriage happen naturally. What if they aren't advised. Oh, I'm I'm sure that they would be advised to have an AntiD. Injection.
Patrick [00:15:59] Yeah. If someone knows that or I think part of the sort of workup of her first trimester miscarriage should involve a blood group and Antibody screen. Yeah, for that reason. Yeah. And that's why it's part of that first blood test you have when you're pregnant. So, I think the blood group and antibody screen is definitely worth knowing because you might give some AntiD even in what appeared to be a routine first trimester miscarriage. And also, there are some other rare markers on the surface of the red blood cells that would turn up in a blood group and antibody screen that aren't Rhesus but are dangerous for pregnancy. And they've all got names named after the people who discovered them. There's Kelle and Duffie and all these other antibodies. And those are definitely relevant as well in rare cases and potentially could be a cause of recurrent pregnancy loss.
Brigid [00:16:50] Yeah, right. Okay. Well, that's good to know, too.
Brigid [00:16:53] So that's why they do a full screen, not just an ABO and Rhesus.
Patrick [00:16:56] Yeah. Okay. All right. Well, I think we've covered everything about Rhesus negative and Rhesus disease.
Brigid [00:17:05] Thanks, everyone, for listening.
Brigid [00:17:06] We really do appreciate your comments and we really do appreciate if you take the time just to give us a five star rating on our Apple i-Tunes podcast app. And also, if you've got even more time to give us a little review, that would be wonderful.
Patrick [00:17:24] Thanks for listening, everybody. Thank you. Bye now.