Bleeding DisordersThe most common

causes of abnormal bleeding are:

1. Platelet deficiency Known as

thrombocytopenia

2. Deficits of some of the clotting factors

Might result from impaired liver function or certain genetic disorders

ThrombocytopeniaThrombocytopenia – Results from an

insufficient number of circulating platelets.Even normal movements cause

spontaneous bleeding from small blood vessels. This is evidenced by many small purplish

blotches called petechiae on the skin.Can arise from any condition that

suppresses myeloid tissue such as: Bone marrow cancer Radiation Certain drugs

Impaired Liver FunctionWhen the liver is unable to synthesize its usual

supply of clotting factors, abnormal and often severe bleeding episodes occur.If vitamin K (needed by the liver to produce clotting

factors) is deficient, the problem is easily corrected with supplements.

When liver function is severely impaired (as in hepatitis and cirrhosis) only whole blood transfusions are helpful.

HemophiliaHemophilia – The term applies to several

different hereditary bleeding disorders that result from a lack of any of the factors needed for clotting. Commonly called “bleeder’s disease.”

Hemophilia: Signs and SymptomsHemophilias have similar signs

and symptoms that begin early in life:Minor tissue trauma results in

prolonged bleeding and can be life threatening.

Repeated bleeding into joints causes them to become disabled and painful.

Hemophilia: TreatmentWhen a bleeding episode

occurs hemophiliacs are given either:A transfusion of fresh plasmaInjections of the purified

clotting factor they lackHemophiliacs are completely

dependent on these therapies.

Loss of Blood VolumeThe body can compensate for a loss of blood

volume up to a certain limit.Losses of 15-30% lead to pallor and weakness.Losses of over 30% cause severe shock, which

can be fatal.

Blood TransfusionsAre routinely given to replace substantial blood

loss and to treat severe anemia and thrombocytopenia.Blood banks mix the

collected blood with an anticoagulant to prevent blood clotting.

The treated blood can be stored for about 35 days until needed.

Human Blood GroupsPeople have different blood groups and

transfusing incompatible or mismatched blood can be fatal.

The plasma membranes of RBCs bear genetically determined proteins (antigens), which identify each person as unique. An antigen is a substance that the body

recognizes as foreign. Antigens stimulates the immune

system to release antibodies or use other means to mount a defense against it.

Most antigens are viruses or bacteria.

Human Blood GroupsEach of us tolerates our own

antigens.One person’s RBC proteins

will be recognized as foreign if transfused into another person with different RBC antigens.Antibodies are “recognizers.”

Present in the plasma Attach to RBCs bearing surface

antigens different from those on the patient’s (blood recipient’s) RBCs.

AgglutinationBinding of the antibodies causes

the RBCs to clump, a phenomenon called agglutination.Leads to the clogging of small

blood vessels throughout the body.

During the next few hours, the foreign RBCs are lysed (ruptured) and their hemoglobin is released into the bloodstream.

Transfusion ReactionsMost Devastating Consequence:

The freed hemoglobin molecules may block the kidney tubules and cause kidney failure.If kidney shutdown does not occur,

then the reaction will probably not be fatal.

The transfused blood is unable to deliver the increased oxygen-carrying capacity hoped for.

Can cause fever, chills, nausea, and vomiting.

Treatment of Transfusion ReactionsTreatment is aimed at

preventing kidney damage by:

1. Infusing alkaline fluids to dilute and dissolve the hemoglobin

2. Diuretics to flush it out of the body in urine

RBC AntigensThere are over 30 RBC antigens in humans,

allowing each person’s blood cells to be classified into different blood groups. However, it is the antigens of the ABO and Rh

blood groups that cause the most vigorous transfusion reactions.

ABO Blood GroupsABO Blood Groups – Based on which of two

antigens, type A or type B, the person inherits.Type O Blood: Absence of both antigens.Type AB Blood: Presence of both antigens.Type A Blood: Presence of

type A antigen.Type B Blood: Presence of

type B antigen.

ABO Blood GroupsAntibodies are formed during infancy

against the ABO antigens NOT present on your own RBCs.A baby with neither the A nor the B

antigen (group O) forms both anti-A and anti-B antibodies.

A baby with type A antigens (Group A) forms anti-B antibodies and so on…

Rh Blood GroupsNamed because one of the eight Rh antigens

was originally identified in Rhesus monkeys.Later the same antigen was discovered in

human beings. Most Americans are Rh+ (Rh positive),

meaning that their RBCs carry the Rh antigen.

Rh Blood GroupsAnti-Rh antibodies are NOT

automatically formed and present in the blood of Rh- . If an Rh- person receives Rh+ blood, shortly after

the transfusion his/her immune system becomes sensitized and begins producing anti-Rh+ antibodies against the foreign blood type. Hemolysis (rupture of RBCs) does not occur with the

first transfusion because it takes time for the body to react and start making antibodies.

But the second and every time thereafter, a typical transfusion reaction occurs.

Rh-Related Problem in PregnancyAn important Rh-related problem occurs in

pregnant Rh- women who are carrying Rh+ babies. The first such pregnancy usually results in the

delivery of a healthy baby.

Rh-Related Problem in PregnancyBecause the mother is

sensitized by Rh+ antigens that have passed through her bloodstream, she will form anti-Rh+ antibodies unless treated with RhoGAM shortly after giving birth.RhoGAM is an immune

serum that prevents this sensitization and her subsequent immune response.

Rh-Related Problem in PregnancyIf the Rh- mother is not treated with

RhoGAM and becomes pregnant a second time with a Rh+ baby, her antibodies will cross through the placenta and destroy the baby’s RBCs.The baby will be anemic and

becomes hypoxic.Brain damage and even death may

occur unless fetal transfusions are done before birth to provide more RBCs for O2 transport.

Blood TypingThe importance of

determining the blood group of both the donor and the recipient BEFORE blood is transfused is glaringly obvious.

Blood typing involves testing the blood by mixing it with two different types of immune serum-

1. Anti-A2. Anti-B

Typing for Rh factors is done in the same manner as ABO blood typing.

Blood TypingType A Blood:

Agglutination occurs only when mixed with the anti-A serum

Type B Blood:Agglutination occurs only when mixed with anti-B

serumType AB Blood:

Agglutination occurs when mixed with both the anti-A serum and the anti-B serum.

Type O Blood: No agglutination occurs when mixed with either serum.

Blood TypingSince it is critical that blood groups be

compatible, crossmatching is done.Cross matching involves testing for agglutination

of donor RBCs by the recipient serum, and of the recipient’s RBCs by the donor serum.

Type AB: Can receive any type of blood

Type O: Universal donor