Rh d type positive means

Rhesus disease - Causes - NHS

Rhesus disease is caused by a specific mix of blood types between a pregnant mother and her unborn baby.

It can only occur where all of the following happen, where the:

• mother has a rhesus negative (RhD negative) blood type
• baby has a rhesus positive (RhD positive) blood type
• mother has previously been exposed to RhD positive blood and has developed an immune response to it (known as sensitisation)

Blood types

There are several different types of human blood, known as blood groups, with the 4 main ones being A, B, AB and O. Each of these blood groups can either be RhD positive or negative.

Whether someone is RhD positive or RhD negative is determined by the presence of the rhesus D (RhD) antigen. This is a molecule found on the surface of red blood cells.

People who have the RhD antigen are RhD positive, and those without it are RhD negative. In the UK, around 85% of the population are RhD positive.

How blood types are inherited

Your blood type depends on the genes you inherit from your parents. Whether you're RhD positive or negative depends on how many copies of the RhD antigen you've inherited. You can inherit one copy of the RhD antigen from your mother or father, a copy from both of them, or none at all.

You'll only have RhD negative blood if you don't inherit any copies of the RhD antigen from your parents.

A woman with RhD negative blood can have an RhD positive baby if her partner's blood type is RhD positive. If the father has two copies of the RhD antigen, every baby will have RhD positive blood. If the father only has one copy of the RhD antigen, there's a 50% chance of the baby being RhD positive.

Sensitisation

An RhD positive baby will only have rhesus disease if their RhD negative mother has been sensitised to RhD positive blood. Sensitisation occurs when the mother is exposed to RhD positive blood for the first time and develops an immune response to it.

During the immune response, the woman's body recognises that the RhD positive blood cells are foreign and creates antibodies to destroy them.

In most cases, these antibodies aren't produced quickly enough to harm a baby during the mother's first pregnancy. Instead, any RhD positive babies the mother has in the future are most at risk.

How does sensitisation occur?

During pregnancy, sensitisation can happen if:

• small numbers of foetal blood cells cross into the mother's blood
• the mother is exposed to her baby's blood during delivery
• there's been bleeding during the pregnancy
• an invasive procedure has been necessary during pregnancy – such as amniocentesis, or chorionic villus sampling (CVS)
• the mother injures her abdomen (tummy)

Sensitisation can also occur after a previous miscarriage or ectopic pregnancy, or if a RhD negative woman has received a transfusion of RhD positive blood by mistake (although this is extremely rare).

How sensitisation leads to rhesus disease

If sensitisation occurs, the next time the woman is exposed to RhD positive blood her body will produce antibodies immediately.

If she's pregnant with an RhD positive baby, the antibodies can lead to rhesus disease when they cross the placenta and start attacking the baby's red blood cells.

Page last reviewed: 16 November 2021
Next review due: 16 November 2024

Rh factor blood test - Mayo Clinic

Overview

Rh factor is an inherited protein found on the surface of red blood cells. If your blood has the protein, you're Rh positive. If your blood doesn't have the protein, you're Rh negative. The "+" or "–" you might see after your blood type refers to Rh positive or Rh negative.

Rh positive is much more common than Rh negative. Having an Rh negative blood type is not an illness, and it usually does not affect your health. But it can affect pregnancy. Your pregnancy needs special care if you're Rh negative and your baby is Rh positive. That's called Rh incompatibility. A baby can inherit the Rh factor from either parent.

Your health care provider will advise that you have a blood type and Rh factor screening test during your first prenatal visit. This will show whether you are Rh positive or Rh negative.

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Why it's done

During pregnancy, problems can happen if you're Rh negative and your baby is Rh positive. Usually, your blood doesn't mix with your baby's blood during pregnancy. However, a small amount of your baby's blood could come in contact with your blood when the baby is born. It can also happen if you have bleeding or trauma to your abdomen during pregnancy.

If you're Rh negative and your baby is Rh positive, your body might produce proteins called Rh antibodies if your blood and the baby's blood mix. Those antibodies aren't a problem during the first pregnancy. But problems can happen if you become pregnant again.

If your next baby is Rh positive, the Rh antibodies can cross the placenta and damage the baby's red blood cells. This could lead to life-threatening anemia, a condition in which red blood cells are destroyed faster than the baby's body can replace them. Red blood cells are needed to carry oxygen throughout the body.

If you're Rh negative, you might need to have another blood test — called an antibody screen — several times: during your first trimester, during week 28 of pregnancy and when your baby is born. Some people need the test more often.

That test is used to detect antibodies to Rh positive blood. If you haven't started to produce Rh antibodies, you'll likely need a shot (injection) of a blood product called Rh immune globulin. This prevents your body from producing Rh antibodies during your pregnancy.

If your baby is born Rh negative, you don't need any other treatment. If your baby is born Rh positive, you'll need another injection shortly after delivery.

If you're Rh negative and your baby might be or is Rh positive, your health care provider may recommend an Rh immune globulin injection after situations in which your blood could come into contact with the baby's blood, including:

• Miscarriage
• Ectopic pregnancy — when a fertilized eggs implants somewhere outside the uterus, usually in a fallopian tube
• Abortion
• Removal of a molar pregnancy — a noncancerous (benign) tumor that develops in the uterus
• Amniocentesis — a prenatal test in which a sample of the fluid that surrounds and protects a baby in the uterus (amniotic fluid) is removed for testing or treatment
• Chorionic villus sampling — a prenatal test in which a sample of the wispy projections that make up most of the placenta (chorionic villi) is removed for testing
• Cordocentesis — a prenatal test in which a sample of the baby's blood is removed from the umbilical cord for testing
• Bleeding during pregnancy
• Injury or other trauma to your abdomen during pregnancy
• The external manual rotation of a baby in a breech position — such as buttocks first — before labor
• Delivery

If the antibody screen shows that you're already producing antibodies, an injection of Rh immune globulin won't help. Your baby will be carefully monitored during your pregnancy. The baby might be given a blood transfusion through the umbilical cord during pregnancy or immediately after delivery if necessary.

What you can expect

An Rh factor test is a basic blood test. The blood sample usually is taken during the first prenatal visit and sent to a lab for testing. No special preparation is necessary.

Results

If you're Rh positive, you don't need to do anything.

If you're Rh negative and your baby is Rh positive, your body could make antibodies that might be harmful during another pregnancy. Take these steps:

• If you have vaginal bleeding any time during pregnancy, contact your health care provider right away.
• Talk with your health care provider about scheduling an Rh immune globulin injection during your pregnancy.
• Remind your health care team during labor that you're Rh negative.

By Mayo Clinic Staff

Related

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About Blood Types - Blood Center

When a doctor talks about your blood type, he usually means two things: your ABO blood type and your Rh (rhesus factor).

A person's blood group is determined by antigens found on his red blood cells. An antigen is a structure on the surface of a cell. If it is foreign to the body, then the human defense system will react to it. Therefore, it is necessary to take into account blood groups when transfusing: the donor's blood group is determined at the Blood Center, and the patient's blood group is determined before transfusion. nine0003

The most important is the ABO blood group system, according to which blood is divided into groups A, B, O and AB. It is determined by two antigens located on the surface of red blood cells:

• group A - only antigen A is present on the surface of erythrocytes
• group B - only antigen B is present on the surface of erythrocytes
• group AB - both A and B antigens are present on the surface of erythrocytes
• group O - on the surface of erythrocytes there is neither antigen A nor antigen B.

If a person has blood type A, B or 0, then in his blood plasma there are also antibodies that destroy those antigens that the person himself does not have. Examples: If you have type A blood, then you cannot be transfused with type B blood, because in this case there are antibodies in your blood that fight against B antigens. If you have blood type 0, then your blood contains antibodies that fight like against antigens A and against antigens B.

If a person has blood type AB, then he does not have such antibodies, so he can be transfused with blood of any group. Therefore, the carrier of the AB blood group can be called universal patient.

A carrier of blood type 0 with a negative Rh factor, in turn, is called a universal donor, , since his red blood cells are suitable for all patients.

Rh factor (Rh) can be positive (+) and negative (-). It depends on the presence of the D antigen on the surface of the red blood cells. If the D antigen is present, the person is considered Rh-positive, and if the D antigen is absent, then the person is Rh-negative. nine0003

If a person is Rh negative, contact with Rh positive blood (for example, during pregnancy or blood transfusion) may form antibodies. These antibodies can cause pregnancy problems in an Rh-negative woman if she is carrying an Rh-positive baby.

In addition to the ABO and Rh systems, about thirty more blood group systems have been discovered to date. Clinically, the most important of these are the Kell, Kidd and Duffy systems. According to the Kell system, donor blood is also examined. nine0003

To determine the blood type, it is mixed with a reagent containing known antibodies.

Three drops of blood taken from one person are applied to the base: the anti-A test reagent is added to one drop, the anti-B test reagent to the other, and the anti-D test reagent to the third, i.e. Rh test reagent. If blood clots form in the first drop, i.e. erythrocytes stick together (agglutination), then the person has antigen A. If erythrocytes do not stick together in another drop, therefore the person does not have antigen B; and if agglutination occurs in the third drop, then this indicates a positive Rh factor. In this example, the donor has blood type A and is Rh positive. nine0003

Donor and recipient blood group compatibility is extremely important, otherwise the recipient may have dangerous reactions to the blood transfusion.

A person inherits from his father and from his mother to the same extent. Therefore, the hereditary substance has a double structure: one part from the mother and the other from the father. Speaking about the inheritance of blood groups, it must be borne in mind that:

• Most of our genes exist in two copies
• Each parent gives (based on a random selection) one of these copies to their children
• Genes occur in different versions (alleles)
• Some versions of the gene are stronger than others

ABO system	System Rh
In the AB0 system, antigens are presented in three versions A, B and 0. Given that the hereditary substance consists of two parts, six different combinations can occur: nine0072
Genes
AA
A0
AB
B0
BB
00

The stronger part appears, both equally or a combination. In the AB0 system, genes A and B are stronger than 0, which affects the formation of the blood group as follows:

Example: The mother has a combination of A0 genes in hereditary substance, and her blood type is A (at the same time, she is a carrier of the blood type 0 gene, and there is a possibility that she will pass it on to her child). The father's blood type has the designation 0, and in his hereditary substance there is a combination of genes 00. Accordingly, he can only pass 0 to the child, i.e. absence of antigens. Thus, their child may have an A (A0) or 0 (00) blood type. nine0003

Example: if the mother has Rh positive blood, and there is a hidden negative version, that is, the allele (+/-), and the father has exactly the same combination, and they both pass the negative allele, then two Rh-positive parents can have a child with a negative Rh factor.

Rh factor

Rh factor is a protein that can be found on the surface of human red blood cells. It is of great importance in the management of pregnancy and blood transfusion.

Synonyms Russian

Rh-affiliation, Rh.

English synonyms

Rh, Rh type, Rh typing, Rh-factor, rhesus factor.

Research method

Agglutination test.

What biomaterial can be used for research? nine0008