Venipuncture refers to drawing of blood from a person's vein for testing. Usually venipuncture is conducted from the inside of the person's elbow. Typically a tourniquet or elastic band is tied around the upper arm so as to swell the vein and ease the venipuncture process. The blood is then sent to a laboratory for testing.
Blood transfusion is one of the important procedures administered in healthcare centers to meet surgical and trauma needs. This procedure is categorized under transfusion medicine section. Blood transfusion is a high-risk procedure as it involves multiple protocols and guidelines for safe and effective transfusion.
Guidelines and Procedure
Transfusion medicine has high significance as it involves the transfusion of blood and blood products depending upon the patient needs. Blood required for the transfusion is obtained from blood banks, which are established either by the government or privately following NCCLS standards for the blood banks. The standards are evaluated by organizations such as WHO to set a uniform and global protocol for safe transfusion. Blood transfusion is predominantly done to increase the percentage of hemoglobin in anemic patients and also to replace vital components such as platelets and serum proteins in some medical conditions. Other reasons for blood transfusion is to replace the amount of blood lost during surgery or trauma. Patients suffering thrombocytopenia (any disorder in which there is an abnormally low amount of platelets) might be in need of platelet transfusion.
Blood banks are authorized by the government to collect blood of different groups. Some of the rare groups include B negative, O negative and Bombay blood group. In these situations, the names and the address of these respective rare blood types are noted to ensure timely availability in case of a transfusion request. Cancer patients also require transfusion in case of conditions such as leukemia and malignant carcinomas associated with spleen or bone marrow. Leukocyte reduction procedure is followed in some transfusion centers in order to minimize the incidence of transfusion-associated allergic reactions. All donors are checked for a three-month gap before the subsequent transfusion to facilitate fresh blood collection from the donors containing viable red blood cells.
Different types of Blood transfusions:
Fresh Whole Blood: This is mostly needed during cardiac surgery or massive hemorrhage. Fresh Whole blood has RBC, plasma and fresh platelets.
Packed RBC: This is mostly needed to raise the hematocrit (the proportion of total blood volume that is composed of red blood cells).
Frozen packed RBC: Stored for nearly 3 years, frozen packed RBC is sparingly used. It is often used for rare blood groups. Patients suffering severe leukoagglutinin reactions or anaphylactic reactions might need this.
Leukocyte-Poor Blood: Patients who suffer severe leukoagglutinin reactions might need this. It is an expensive process as WBC are removed by centrifugation.
Precautions and risks
Transfusion is a very important procedure and hence primary analysis of the donor blood is done in order to avoid blood borne sepsis, transfusion allergies and organ damage. The donor blood is always cross-matched with the recipient's in order to check the compatibility of the blood. All procedures are documented to ensure safety and tracking of a transfusion procedure, as it is associated with medico-legal protocols. The A and B antigens are the first check before transfusion. In emergencies, type O/Rh-negative blood can be given to any recipient and usually packed cells are given. The Rh factor has also to be tested. Blood from the donor is also investigated for infections such as HIV 1&2, HBV, HCV, and VDRL to ensure safe transfusion.
Blood is collected from the healthy donor in a blood bank by administering venipuncture procedure from the brachial region. The obtained blood is transported for immediate need in surgeries or stored for few days in case of a scheduled surgery having the requirement for the particular blood group. The transfusion requirement is clearly stated in the surgical form and the blood bank technicians provide number of units required on the given date. Some of the common side effects associated with blood transfusions are infections of both viral and bacterial origin obtained from an infected donor. Receipt of blood contaminated with gram-negative bacteria often causes septic shock, Disseminated intravascular coagulation or DIA (a large amount of procoagulant enters the blood stream over a short period of time, overwhelming the body’s ability to replenish coagulation factors and causing bleeding) and acute kidney injury. Receipt of blood with gram-positive bacteria causes fever and Bacteremia (presence of bacteria in blood) but rarely causes sepsis.
Complete Blood Count
A Complete Blood Count test CBC is a diagnostic test to measure the following in blood - the number of red blood cells, the number of white blood cells, Platelets and the total amount of hemoglobin in blood. Hematocrit (HCT) is the fraction of blood composed of red blood cells.
A Complete Blood Count normally includes the following components:
A CBC test provides information on measurements such as average red blood cell size or MCV, Hemoglobin per blood cell or Mean Corpuscular Hemoglobin MCH, hemoglobin concentration or the amount of hemoglobin relative to the size of the cell, per red blood cell or MCHC and platelet count.
Why Complete Blood Count test?
This is a complete lab test and is used to detect or monitor different health conditions. A doctor may require this test for various reasons: As a routine check up
If the patient exhibits symptoms such as fatigue, weight loss, fever or any other signs of infection, weakness, bruising, bleeding or signs of cancer
Blood count results may change if you are receiving treatment for medicines and radiation
To monitor any chronic health problem that can change your blood count results such as chronic kidney disease.
Results of CBC
Though blood count may vary with altitude, in general the normal ranges are given below. But it should be noted that these ranges may vary slightly from one laboratory to another. Various laboratories use varied measurements or test different samples. It is best to have it interpreted by a health care provider.
Red blood cell indices:
MCV (Mean Corpuscular Volume): 80 to 95 femtoliter
MCH (Mean Corpuscular Hemoglobin): 27 to 31 pg/cell
MCHC (Mean Corpuscular Hemoglobin Concentration): 32 to 36 gm/dL
RBC (erythrocyte) count:
Male: 4.7 to 6.1 million cells/mcL
Female: 4.2 to 5.4 million cells/mcL
WBC (leukocyte) count:
4,500 to 10,800 cells/mcL
Male: 40.7 to 50.3%
Female: 36.1 to 44.3%
Male: 13.8 to 17.2 gm/dL
Female: 12.1 to 15.1 gm/dL
Platelet (thrombocyte) count:
150,000 to 450,000/dL
What abnormal results mean?
An abnormal result means elevated RBC, hemoglobin or Hematocrit. These may be due to various factors including lack of adequate water and fluids due to severe diarrhea, excessive sweating or if diuretics are used to treat hypertension.
Low RBC, hemoglobin or hematocrit is also a sign of which result due to blood loss on account of heavy menstrual periods over long periods of time, bone marrow failure from radiation, infection or tumor, Hemolysis or breakdown of red blood cells, chronic kidney disease, ulcerative colitis or rheumatoid arthritis, leukemia, multiple myeloma, long term infections such as hepatitis, poor diet and nutritional deficiencies of iron, Vitamin B6, Vitamin B12 and folate.
High levels of Hematocrit can be the result of dehydration, diarrhea, erythrocytosis or myeloproliferative disorders such as Polycythemia Vera.
Lower than normal white blood cell count, or Leukopenia (Leucopenia), can be the result of alcohol abuse and liver damage, autoimmune diseases, bone marrow failure due to infection, tumor, radiation or fibrosis, chemotherapy medicines, disease of liver or spleen, enlarged spleen, infections caused by viruses such as AIDS or medications.
High WBC count is called leukocytosis which can result from certain medicines such as corticosteroids, infections, diseases such as rheumatoid arthritis or allergy, leukemia and severe emotional and physical stress, tissue damage
High platelet count may be due to bleeding - diseases such as cancer, iron deficiency, problems with the bone marrow.
Low platelet count may be due to anemia, disorders where platelets are destroyed during pregnancy, enlarged spleen, bone marrow failure (for example, due to infection, tumor, radiation, or fibrosis), Chemotherapy medicines used to treat cancer.
Disease of the platelets is known as Thrombocytopathy, which could be due to lower Platelet counts (a condition called as Thrombocytopenia or Thrombopenia), or due to a decrease in function (called as Thrombasthenia) or an increase in the number of platelet (addressed as Thrombocytosis). Normal platelet counts do not necessarily indicate normal functioning. In some cases the platelet counts may appear normal but the platelets themselves are dysfunctional. Aspirin inhibits cyclooxygenase-1 (COX1) which results in the disruption of platelet function affecting coagulation. Normal platelet function will be restored only when the affected platelets have been replaced which can take a week.
Precaution : At the time of drawing the blood, it is necessary to clean the venipuncture site with alcohol.
Bibliography / Reference
Collection of Pages - Last revised Date: January 22, 2019