Hematology 105
Disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, and
hemolytic uremic syndrome (look for schistocytes and red blood cell fragments on smear
and other appropriate findings)
Other hemoglobinopathies (the hemoglobin C and E varieties are fairly common)
Paroxysmal nocturnal or cold hemoglobinuria;
Clostridium perfringens infection, malaria, and babesiosis (cause intravascular hemolysis
and fever)
Hypersplenism (associated with splenomegaly and often with low platelets and white
blood cells).
Thrombotic thrombocytopenic purpura
(TTP). Widespread confluent and necrotic
ecchymoses of the facial skin are seen in
this man with severe TTP. (From Hoff-
brand AV, Pettit JE: Color Atlas of Clini-
cal Hematology, 3rd ed. St. Louis,
Mosby, 2000, p 215, with permission.)
39. When is transfusion indicated for anemia (at what hemoglobin level)?
Always transfuse on clinical grounds; observe the symptoms. In other words, treat the
patient, not the lab value. There is no such thing as a "trigger value" for transfusion. Having said
this, hemoglobin levels < 7 or 8 gm/dl in the acute setting make most clinicians nervous.
40. What are the indications for the use of various blood products?
Whole blood: used only for rapid, massive blood loss or exchange transfusions (poisoning,
thrombotic thrombocytopenic purpura).
Packed red blood cells: used for routine transfusions.
Washed red blood cells: free of traces of plasma, white cells, and platelets; good for IgA
deficiency as well as allergic or previously sensitized patients.
Platelets: given for symptomatic thrombocytopenia (usually < 10,000/ul).
Granulocytes: used on rare occasions for neutropenia.
Fresh frozen plasma (FFP): contains all clotting factors; used for bleeding diathesis when
you cannot wait for vitamin K to take effect (e.g., disseminated intravascular coagulation, severe
warfarin poisoning) or when vitamin K will not work (liver failure).
Cryoprecipitate: contains fibrinogen and factor 8; used in hemophilia, von Willebrand's
disease, and disseminated intravascular coagulation.
41. What is the most common cause of a blood transfusion reaction? What blood type can
be given in an emergency to avoid a reaction?
The most common cause of a blood transfusion reaction is lab error. Type O negative blood
can be used to avoid a reaction when you cannot wait for blood typing or when the blood bank
does not have the patient's blood type.
42. Describe the signs and symptoms of a blood transfusion reaction.
Look for febrile reaction (e.g., chills, fever, headache, back pain) from antibodies to white
blood cells; hemolytic reaction (e.g., anxiety or discomfort, dyspnea, chest pain, shock, jaun-
dice) from antibodies to red blood cells; or allergic reaction (e.g., urticaria, edema, dizziness,
dyspnea, wheezing, anaphylaxis) to an unknown component in donor serum. Oliguria may be an
associated finding.
