BLOOD FILM MORPHOLOGY

A test is performed in other to determine the structure, shape, color and pattern appearances of the different blood cells present in the blood. i.e red cells, white cell, platelets.

BLOOD FILM?
Is a thin layer of blood smeared on a microscopic slide and then stained in such a way to allow the various blood cells to be examined microscopically.
FIXING

When completely dry, fix a blood film with absolute methanol.
Place the film on a staining rack and add 1-2 drops of moisture free methy alcohol and allow to dry on the film.

STAINING THE BLOOD FILM

In district laboratories, thin blood films are usually stained manually using leishman or wright’s stain.
These stains are example of alcohol containing romanowsky stains which stain blood cells differently, making it possible for the scientist to differentiate and identify the various blood cells.

USING LEISHMAN STAIN

Cover the blood film with undiluted stain but do not flood the slide.
Add twice the volume of PH 6.8 buffered water. Ensure the water is mixed with the stain.
Wash off the stain with tap water
Wipe the back of the slide clean and stand it in a draining rack to dry or place it horizontally on a hotplate.

VALUE OF BLOOD FILMS
Examination of thin blood films is important in the investigation and management of anemia, infections and other conditions which produce changes in the appearance of blood cells and differential white blood cells count.

Making, fixing and staining blood films

Thin blood film can be made from free-flowing capillary blood or well mixed EDTA anticoagulated blood
NOTE: It is important to make blood films from EDTA anticoagulated blood with as little delay as possible.
MAKING
Examine the slide, if one end of the slide is frosted; use the non-frosted side.
Label the slide with patient name.
Place a drop of blood on the end of the dry slide.
Using a clean smooth edged spreader draw the spreader back to the touch of the blood and allow the blood to extend along the edge of the spreader, at an angle of about 30 degrees spread the drop of the blood to make a film about 40-50mm in length.
Wipe the edge of the spreader.
Immediately air dry the film by waving the slide back and forth.

Morphology of normal blood cells with their clinical significance

Neutrophils 12-15micrometre . Lobed nucleus with 3-5 lobes .separated by chromatin thread. Pale staining and containing small neutrophilic mauve staining granules.

Small lymphocyte 10-12micrometre , dark mauve, compact with clumped chromatin . Thin rim of blue cytoplasm surrounds the nucleus.

Monocyte 15-20 micrometre , round, indented, or folded .stain mauve with delicate chromatin pattern Clear grey-blue cytoplasm containing fine granules and sometimes vacuoles.

Eosinophils 12-17micrometre. Lobed nucleus, usually 2 lobes, staining dark mauve. Pale staining cytoplasm containing orange-red granules.

Basophils 10-12micrometre,bilobed(but usually obscured granules) Contain large darkly staining blue-violet granules.

Large lymphocyte 12-16micrometre. round or oval, sometimes indented More cytoplasm than small lymphocyte, pale blue, often containing small granules.

White Cell Abnormalities

Left shift of neutrophil, toxic granulation Immature neutrophil and precursor cells seen e.g bands cells, metamylelocytes and sometimes myelocytes. Cells may contain darkly staining coarse granules(toxic granulaton) and sometimes vacoules Commonly seen in acute bacterial infections and inflammatory conditions.

Hypersegmentation of neutrophils: Nucleus of more than 5% of neutrophils has 5 or more distinct lobes More frequently seen in megaloblastic anemia.

Hyper-segmented neutrophil:

Reactive lymphocyte:

Irregularly shaped larger than normal lymphocytes with a less dense nucleus. abundant blue cytoplasm, often appearing dark blue and folded at periphery of cell Typically seen in acute malaria, infectious mononucleosis, cytomegalovirus infection and other viral infections.

Malaria pigment

Brown black pigment often seen in monocytes and occasionally neutrophils. Well established falciparum malaria

Abnormal red cells

Hypochromic cells: Pale staining red cells with increased area of pallor Iron deficiency anemia, thalassaemia, of chronic diesease, sideroblastic anemia(rare).

Polychromasia: Blue-grey or blue mauve staining of immature cells(reticulocytes) which are larger in size than normal red cells Post haemorrhage and haemolytic anemias with effective bone marrow response and following treatment for anemia.

Dimorphic appearance: Presence of two different population of red cells e.g hypochromic cells with normal cells, or hypochromic cells with macrocytic cells Commonly seen following treatment for anemia and post blood transfusion.

Polychromasia

Dimorphic appearance

Microcytosis: Smaller than normal red cells, having a diameter usually less than 6.5micrometre Iron dfeficiency, anemia of chronic disease, thalassaemia syndrones, secondary sideroblastic anemia

Macrocytosis: Larger than normal red cellshaving a diameter greater than 8micrometre Folate and vitamin b12 deficiencies (oval macrocyte), liver disease and alcoholism (round macrocyte).

Spherocytosis: Small densely staining spherical red cells with no central pallor Haemolytic anemia due to warm autoantibody drugs, snake venom, infection with C.perfringens .also heriditary spherocytosis, bartonellosis, ABO haemolytic disease of the newborn

Cigar cells