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