A&P II: 18.6 Blood Typing

What is the main purpose of blood typing?

To determine blood-group antigens and help ensure donor-recipient compatibility before transfusion.

What are the major blood-group systems emphasized

The ABO blood-group system and the Rh blood-group system.

What are blood-group antigens?

Molecules on red blood cell membranes that can be recognized by the immune system.

What are antibodies?

Proteins, also called immunoglobulins, made by plasma cells that bind specific antigens.

Where are blood-group antigens found during RBC transfusion?

On the donor red blood cell membrane.

Where are the antibodies relevant to RBC transfusion found?

In the recipient's plasma.

Why are incompatible RBC transfusions dangerous?

Recipient antibodies can bind antigens on donor RBCs, causing agglutination and hemolysis.

What is agglutination?

Clumping of red blood cells caused by antibody binding to RBC antigens.

What is hemolysis?

Rupture or destruction of red blood cells.

What can agglutination cause in an incompatible transfusion?

Clumps can obstruct small blood vessels and impair blood flow to tissues.

What can hemolysis cause in a severe transfusion reaction?

Released cellular contents can contribute to kidney injury, shock, or death.

What is the key rule for RBC transfusion compatibility?

The recipient must not receive donor RBC antigens that the recipient's plasma antibodies will attack.

What determines the ABO blood group?

The presence or absence of A antigen, B antigen, both antigens, or neither antigen on RBC membranes.

Is ABO blood type genetically determined?

Yes.

What type of molecules are A and B antigens?

Glycoproteins on erythrocyte plasma membranes.

When do ABO antibodies generally develop?

Early in life, after exposure to environmental antigens similar to A and B antigens.

Does a person need a prior blood transfusion to develop ABO antibodies?

No. ABO antibodies are generally naturally present early in life.

What RBC antigen is present in blood type A?

A antigen.

What antibodies are present in the plasma of a person with blood type A?

Anti-B antibodies.

What RBC antigen is present in blood type B?

B antigen.

What antibodies are present in the plasma of a person with blood type B?

Anti-A antibodies.

What RBC antigens are present in blood type AB?

Both A and B antigens.

What antibodies are present in the plasma of a person with blood type AB?

Neither anti-A nor anti-B antibodies.

What RBC antigens are present in blood type O?

Neither A nor B antigen.

What antibodies are present in the plasma of a person with blood type O?

Both anti-A and anti-B antibodies.

Which ABO blood types can a type A recipient receive as RBCs?

Type A or type O RBCs.

Which ABO blood types can a type A donor give RBCs to?

Type A or type AB recipients.

Which ABO blood types can a type B recipient receive as RBCs?

Type B or type O RBCs.

Which ABO blood types can a type B donor give RBCs to?

Type B or type AB recipients.

Which ABO blood types can a type AB recipient receive as RBCs?

Type A, B, AB, or O RBCs.

Which ABO blood types can a type AB donor give RBCs to?

Type AB recipients only.

Which ABO blood types can a type O recipient receive as RBCs?

Type O RBCs only.

Which ABO blood types can a type O donor give RBCs to?

Type A, B, AB, or O recipients.

Why can type O RBCs be donated across ABO groups?

They lack both A and B antigens, so recipient anti-A or anti-B antibodies have no A/B donor antigen to attack.

Why can type AB recipients receive RBCs from all ABO groups?

They have neither anti-A nor anti-B antibodies in their plasma.

Why can type O recipients receive only type O RBCs?

They have both anti-A and anti-B antibodies, which would attack A, B, or AB donor RBCs.

Why can type A recipients not receive type B or AB RBCs?

Their anti-B antibodies would attack donor RBCs carrying B antigen.

Why can type B recipients not receive type A or AB RBCs?

Their anti-A antibodies would attack donor RBCs carrying A antigen.

What is the Rh blood-group system based mainly on?

The presence or absence of the Rh D antigen on RBCs.

What does Rh positive mean?

The Rh D antigen is present on RBCs.

What does Rh negative mean?

The Rh D antigen is absent from RBCs.

What is the most clinically important Rh antigen?

The Rh D antigen.

Can ABO type and Rh type be combined in one blood type?

Yes. Examples include A+, O−, AB+, and B−.

Is Rh status independent of ABO type?

Yes.

About what percentage of Americans are Rh positive according to the notes?

About 85%.

Are anti-Rh antibodies naturally present in Rh-negative people?

No. They usually develop only after exposure to Rh-positive blood.

What is Rh sensitization?

The development of anti-Rh antibodies after an Rh-negative person is exposed to Rh-positive blood.

How can an Rh-negative person become sensitized?

By receiving Rh-positive blood or, in an Rh-negative mother, by exposure to fetal Rh-positive blood during pregnancy-related events.

What can happen if a sensitized Rh-negative person is later exposed to Rh-positive RBCs?

Anti-Rh antibodies can cause agglutination and hemolysis of the Rh-positive RBCs.

What RBCs should an Rh-negative recipient receive whenever possible?

Rh-negative RBCs.

What Rh blood can an Rh-positive recipient generally receive when ABO-compatible?

Rh-positive or Rh-negative RBCs.

What is best practice for RBC transfusion when possible?

Use fully ABO- and Rh-type-matched blood with appropriate crossmatching.

Why is O-negative called the universal RBC donor?

O-negative RBCs lack A, B, and Rh D antigens.

Why is AB-positive called the universal RBC recipient?

AB-positive recipients have A, B, and Rh D antigens and typically lack anti-A, anti-B, and anti-Rh antibodies.

Why are the labels universal donor and universal recipient simplifications?

They apply to RBC transfusion, especially emergencies; routine transfusions still require exact matching and crossmatching for other antigens.

What is hemolytic disease of the newborn (HDN)?

A condition in which maternal antibodies cross the placenta and destroy fetal RBCs, classically involving Rh incompatibility.

What maternal-fetal combination creates the classic risk for Rh-related HDN?

An Rh-negative mother carrying an Rh-positive fetus.

How can an Rh-negative mother become sensitized during pregnancy?

Fetal Rh-positive blood can enter maternal circulation, often during childbirth or another pregnancy-related event.

Why is the first Rh-positive pregnancy often less affected by HDN?

Sensitization commonly occurs late in pregnancy or during delivery, so substantial maternal anti-Rh antibodies are more likely to affect a later Rh-positive pregnancy.

What happens in a later Rh-positive pregnancy after an Rh-negative mother has been sensitized?

Maternal anti-Rh antibodies cross the placenta and attack fetal Rh-positive RBCs.

What are possible consequences of hemolytic disease of the newborn?

Fetal RBC agglutination and hemolysis, anemia, jaundice, severe illness, or death.

Why can HDN cause jaundice?

Hemolysis increases RBC breakdown and bilirubin production.

What is RhoGAM?

Rh immune globulin given to an Rh-negative mother when indicated to prevent sensitization to Rh D antigen.

How does RhoGAM prevent hemolytic disease of the newborn in later pregnancies?

It prevents the Rh-negative mother from developing anti-Rh antibodies after exposure to Rh-positive fetal blood.

When is RhoGAM administered?

During and after pregnancy-related care when indicated for an Rh-negative mother.

What are antisera?

Laboratory solutions containing known antibodies used to test whether specific RBC antigens are present.

How is ABO blood typing performed?

A blood sample is mixed separately with anti-A and anti-B antisera and observed for agglutination.

What does agglutination with anti-A antiserum indicate?

A antigen is present on the RBCs.

What does agglutination with anti-B antiserum indicate?

B antigen is present on the RBCs.

What does agglutination with anti-A antiserum only indicate?

Blood type A.

What does agglutination with anti-B antiserum only indicate?

Blood type B.

What does agglutination with both anti-A and anti-B antisera indicate?

Blood type AB.

What does no agglutination with either anti-A or anti-B antiserum indicate?

Blood type O.

How is Rh typing performed?

The blood sample is mixed with anti-Rh antiserum and checked for agglutination.

What does agglutination with anti-Rh antiserum indicate?

Rh-positive blood; Rh D antigen is present.

What does no agglutination with anti-Rh antiserum indicate?

Rh-negative blood; Rh D antigen is absent.

What is crossmatching?

Testing donor and recipient blood together before transfusion to check for incompatibility.

What is mixed during an RBC crossmatch?

Recipient plasma and donor RBCs.

What indicates incompatible blood during crossmatching?

Agglutination or hemolysis.

Why is crossmatching still important when ABO and Rh types appear compatible?

Other minor RBC antigens can still cause transfusion reactions.

What type of transfusion do ABO/Rh compatibility tables usually describe?

Red blood cell transfusion.

Why do plasma transfusions use different compatibility rules?

Plasma contains antibodies, so compatibility depends on avoiding donor plasma antibodies that could attack recipient RBC antigens.

When may O-negative RBCs be used?

In a life-threatening emergency when the recipient's blood type is unknown.

Why is exact matching still preferred over universal-donor RBCs when possible?

Exact matching and crossmatching reduce the risk of reactions caused by other blood-group antigens.

What is an antigen in blood typing?

A surface marker on an RBC membrane that can be recognized by antibodies.

What is an antibody in blood typing?

A plasma protein that binds a specific RBC antigen.

What is agglutination in blood typing?

RBC clumping caused by antibody-antigen binding.

What is hemolysis in blood typing?

RBC rupture or destruction after an immune reaction.

What are the ABO antigens and antibodies for type A blood?

A antigen on RBCs and anti-B antibodies in plasma.

What are the ABO antigens and antibodies for type B blood?

B antigen on RBCs and anti-A antibodies in plasma.

What are the ABO antigens and antibodies for type AB blood?

A and B antigens on RBCs and neither anti-A nor anti-B antibody in plasma.

What are the ABO antigens and antibodies for type O blood?

No A or B antigens on RBCs and both anti-A and anti-B antibodies in plasma.