IU School of Medicine, Terre Haute, CHD

As part of biomedical laboratory training, IUSM-TH students learn phlebotomy procedures. Please note that all medical students at IUSM receive annual safety training in the handling of potential bloodborne pathogens during the Fall orientation. Students also observe a phlebotomy procedure video. Later, the students have a general introduction from a trained phlebotomist and observe a live demonstration. In the lab, students practice drawing synthetic blood pumping through a latex arm model's vein. Students spend their wait time between activities completing a quiz about blood facts.

Answers to the Blood Facts Quiz are now available here. (The file is a Adobe Acrobat pdf Document).

When students feel ready, they each have a chance to practice venipuncture on another student from their learning group. Blood is collected in anticoagulent tubes. Blood smears are prepared by all students, using their own blood samples. It is a fairly relaxed atmosphere (mostly) in which students learn or practice venipuncture.

BLOOD TYPING During a different lab session, each student tests their hematocrit and blood type, runs a serum protein gel electrophoresis, stains the blood smears and performs a differential blood cell count. The stations are supervised by Dr. Johnson, Dr. Nindl, Ms. Seaward, and Ms. Hughes.
Blood typing is performed using typical anti-A, anti-B, and anti-D (Rh factor) typing antisera.
The procedure (shown above) involves mixing a drop of anti-coagulated blood with a drop of each of the typing reagents. If a clumping reaction occurs, the result is positive.	An example of each of the clumping reactions is shown below (also shown is the double negative result shown on the far left, for type O blood).  Anti-D serum typing would show Rh factor type. Below, there are two pie charts of blood typing data. The chart on the left is a composite of student blood samples. The chart on the right is the normal distribution for blood types in the U.S. general population. Below them is a map showing distribution of the "B" allele worldwide.

BLOOD FACTS:
A person with type O blood can donate to anyone (universal donor), but can receive blood from a person with type O blood only.

A person with type AB blood can receive blood from anyone (universal recipient), but can donate blood only for others who have type AB blood.

A person with type A blood can donate blood for people with type A or type AB blood. A person with type A blood can receive blood from a person with type A or type O.

A person with type B blood can receive blood from a person with type B or type O. A person with type B blood can donate blood for persons with either type B or type AB blood.

Actually, blood banking is more complicated than this simple description, with test run for other minor compatibility antigens (like the MN antigen system) before transfusions are given.

Each student uses his/her own blood sample to determine hematocrit value (above). Hematocrit determinations are performed by filling microhematocrit tubes with blood obtained by finger prick or filled from venipuncture tubes. Once the blood has been collected into anticoagulant vacutainer tubes, a sample can be removed for hematocrit determination. This is performed by removing the vacutainer cap and withdrawing blood by dipping a microhematocrit tube into the blood until the volume of blood withdrawn reaches the red mark. Hematocrit tubes are sealed at the bottom with Critoseal clay by holding a finger over the top of the microhematocrit tube and pushing the bottom into the clay in the Critoseal tray. The capillary tubes are then centrifuged in a clinical centrifuge making sure that the positions are balanced by tubes being placed opposite one another in the rotor. Tubes should be centrifuged for 5 minutes at 2000 rpm. The packed red blood cell volume is determined by comparison with a standard scale on a microhematocrit reader. Typically, all hematocrit values fall within the normal range each year, which means that we rarely have anemic students.

Once the heatocrit tubes are prepared, the laboratory staff will separate the plasma for use in the Serum Protein Electorphoresis exercise.

Basophils can increase in cases of leukemia, chronic inflammation, the presence of a hypersensitivity reaction to food, or radiation therapy. Decreased basophil levels can indicate acute infection, a response to an overactive thyroid gland, and stress.

Eosinophils can increase in response to allergic disorders, inflammation of the skin, and parasitic infections. They can also occur in response to some infections or to various bone marrow malignancies. Decreased levels of eosinophils can occur as a result of infection.

Monocyte levels can increase in response to infection of all kinds as well as to inflammatory disorders. Decreased monocyte levels can indicate bone marrow injury or failure and some forms of leukemia.

Lymphocytes can increase in cases of bacterial or viral infection, leukemia, cancer of the bone marrow, or radiation therapy. Decreased lymphocyte levels can indicate diseases that affect the immune system, such as lupus, and the later stages of HIV infection.

Polymorphonuclear neutrophils (PMNs) can increase in response to bacterial infection or inflammatory disease. Severe elevations in neutrophils may be caused by various bone marrow malignancies, such as chronic myelogenous leukemia. Decreased neutrophil levels may be the result of severe infection or other conditions, such as responses to various medications.

Class results shown above follow the basic ESR interpretation guidelines: male values are on average lower than female values (p<0.075). All student ESR values were in the normal range.

The ESR is a measurement of the increased rate of settling of erythrocytes and is an important laboratory test in evaluation of disease activity in patients with connective-tissue diseases, certain infections, and neoplastic diseases.

Increased ESR:
- infection, inflammatory conditions, cancer, lymphoma, multiple myeloma, and pregnancy (third month to 1-month post partum);
- a useful measure to follow the course of previously diagnosed specific illnesses;
- in routine orthopedic procedures, a maximum of 25 to 100 mm/hr is reached at 4 days; this gradually decreases to normal over 1-2 weeks;
- with more extensive surgery like total hip replacement, there might be mild ESR elevation that can perist for up to a year

Decreased ESR:
- rate may be "falsely low" in conditions where RBCs do not undergo rouleaux formation (like sickle cell anemia)

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