Hematology

RBC parameters

Hemoglobin (Hb)

  • g/L

Red Blood Cell Count (RBC) expressed as n x 10

  • cells/L

Mean Cellular/Corpuscle Volume (MCV)

  • Average cell size
  • L/cell

Red Blood Cell Distribution Width (RDW)

Dimensionless quantity

Standard deviation of red blood cell vol. divided by mean vol

Variation in cell size in population of RBC

Hematocrit (Hct) L/L, %
= RBC x MCV

Mean Cell Hemoglobin (MCH) pg/cell
= Hb/RBC

mean Cell Hemoglobin Concentration (MCHC) g/dL
= Hb/Hct

Reticulocytes

Increase in reticulocytes in peripheral blood reflects an increase in red cell output by bone marrow

Retic count is index of production of mature RBC by bone marrow

Has to be corrected for the no. of RBC in peripheral blood

= RETIC x (Hct(patient)/Hct(normal, approx 40))

Blood film prep

Take from zone of morphology, just above the tail

Storage

RBC

4 degrees C. 35 days

Check for ABO match

Pooled platelets

22 degrees C, 5 days, constant soft aggitation

Fresh Frozen Plasma

-30 degrees C, 24 months

Blood fractions

55% Plasma

<1% WBC and platelets

45% RBC

Slow spin (less force)

Packed RBC

Platelet rich plasma

Hard spin

PRBC

FFP

Cryosupernatant

Cryopercipitate

each unit of FFP (200-250ml) will raise plasma clotting factors by 3-5%

Cross matching not required but ABO-compatible plasma should be selected

Blood Grouping Test

Red Cell Testing

Reaction of red cells (of patient) with antibodies

e.g. for blood group A, red cell will react with anti A and Anti-A,B antibodies

Serum testing

Reaction of patient serum (no clotting factors) with test red cells

e.g. serum from patients (blood group A) will react with test B cells

Very impt to keep checking blood products

Blood transfusion

Signs and symptoms of a transfusion reaction can occur as quickly as 5-10mls of transfused blood

Blood that cannot be transfused immediately should be returned to the blood bank

at Hb> 10g/dL, transfusion is rarely indicated

Symptoms of transfusion reaction include

Fever

Low BP

Generalized oozing from the wounds or puncture site

Flushing

Agitation

Pain at cannula site, abdomen or chest

Platelet counts

<50000 increase risk of hemorrhage with trauma or operations

10000-15000 may cause spontanous bleeding

< 10000 can be fatal

RBC Morphology

Acanthocyte

Cell with irregular, long, asymmetrical projections

Damaged

Anisocytosis

Variation in size of RBC

Basophilic Stippling

Small aggregates of RNA seen as blue dots in the RBC

Fine stippling: reticulocytes

Coarse stippling: toxic marrow damage, thalassemias

Burr cell

Short, evenly spaced projections

Cabot Ring (?)

Long thin ring in RBC

Elliptocyte

Elongated, elliptical cell

Heinz Body

Precipitated Hgb seens as perimembranous blue dot only after supravital staining

Howell-Jolly body

Small, round deeply basophilic nuclear REMNANT

Hypochromia

Cells with decrease MCH (mean cell Hb), typical iron deficiency (less coloured)

Macrocytosis

Cells with increase MCV (mean cell volume)

Microcytosis

Cells with decreased MCV

Pappenheimer body

Multiply, tiny iron containing granular blue dots

Poikilocytosis

Variation in shape of RBC

Polychromasia

Bluish tint to young RBC with high RNA content

Reticulocyte

Young RBCs with increased RNA content

Rouleaux

Linear aggregation of RBC that resembles a stack of coins

Sideroblast

Nucleated RBC with stainable iron

Spherocyte

Small, round dense cell without central pallor

Schistocyte

Fragmented, irregularly shaped

Sickle cell

Curved, banana-shaped cell

Stomatocyte

Cell with slit-like central pallor

target Cell

cell with central and peripheral staining (like a target)

Tear drop cell

Cell pinched at one end

In organ transplant, ABO antigens are the most important

Rh(D) -ve when giving birth to a Rh(D) +ve will start to develop antibodies to Rh(D) +ve due to exposure to the fetus' blood.

In subsequent pregnancies, this AB could cross to the baby and result in reactions -> bad for the baby

Administer Rh immune globulin to mother after first pregnancy for it to react with the Rh(D) +ve antibodies so that in subsequent pregnancies, no reactions will occur