BLOOD TESTS

The primary duty of the phlebotomist is to collect blood specimens for laboratory testing, this task is also performed by nurses and doctors.

Blood tests are performed for diagnostic purposes and monitor treatment, they are collected by several methods, including arterial puncture, capillary puncture and venipuncture.

Clinical laboratory services:

-Hematology: performs laboratory tests that identify diseases associated with blood and the blood-forming tissues.

-Coagulation: is the study of the ability of blood to form and dissolve clots.

-Chemistry: performs most laboratory tests and often has subsections such as toxicology and radioimmunoassay.

-Serology or Immunology:serology tests deal with the body´s response to the presence of bacterial, viral, fungal or parasitic diseases stimulating antigen-antibody reactions.

-Urinalysis: physical and chemical evaluation of urine specimens.

-Microbiology: analyzes body fluids and tissues for the presence of microorganisms, primarily by means of culture and sensitivity.

-Blood bank or Immunohematology: prepares blood products to be used for patient transfusions.

Venipuncture

Venipuncture is the process of collecting or "drawing" blood from a vein and the most common way to collect blood specimens for laboratory testing.

Common test status designations:

-Stat: immediately (from Latin statim).

-Med Emerg: medical emergency (replaces stat).

-Timed: collect at a specific time.

-ASAP: as soon as possible.

-Fasting: no food or drink except water for 8-12 hours prior to specimen collection.

-NBM, NPO: nil by mouth (from Latin nil per os).

-Preop: before an operation.

-Postop: after an operation.

-Routine: relating to established procedure.

Order of draw refers to the order in which tubes are collected during a multiple-tube draw or are filled from a syringe. CLSI (Clinical and Laboratory Standards Institute)* recommends the following order of draw for both ETS (evacuated tube system) collection and in filling tubes with a syringe:

1. Sterile tube (blood culture).

2. Blue-top coagulation tube.

3. Serum tube with or without clot activator, with or without gel.

4. Heparin tube with or without gel plasma separator.

5. EDTA tube.

6. Glycolytic inhibitor tube.

Capillary puncture

Capillary puncture can be an appropiate choice for adults and older children under the following circumstances:

-available veins are fragile or must be saved for other procedures such as chemotherapy,

-several unsuccessful venipunctures have been performed and the requested test can be collected by capillary puncture,

-the patient has thrombotic or clot-forming tendencies,

-the patient is apprehensive or has an intense fear of needles,

-there are no accessible veins,

-to obtain blood for POCT (Point-Of-Care Testing) procedures such as glucose monitoring.

Capillary puncture is the preferred method of obtaining blood from infants and very young children. The heel is the recommended site for collection of capillary puncture specimens on infants less than 1 year of age.

The CLSI order of draw for capillary specimens is as follows:

1. Blood gas specimens (CBGs)

2. EDTA specimens

3. Other additive specimens

4. Serum specimens.

Arterial puncture

Arterial puncture is technically difficult and potentially more painful and hazardous than venipuncture. The primary reason for arterial puncture is to obtain blood for arterial blood gas (ABG) tests, which evaluate respiratory function.

ABG evaluation is used in the diagnosis and management of respiratory disorders such as lung disease to provide information about a patient´s oxygenation, ventilation, acid-base balance and in the management of electrolyte and acid-base balance in patients with diabetes and other metabolic disorders.

Laboratory tests

Laboratory Tests

Leer más publicaciones en Calaméo

*Organizations similar to CLSI but in the United Kingdom and another clinical laboratory information site:

-http://www.acb.org.uk/whatweare.aspx

-http://labtestsonline.org.uk/

Source:
-Phlebotomy Essential, 5th Edition, Ruth E. McCall, Cathee M. Tankersley, Wolters Kluwer/ Lippincott Williams & Wilkins, 2012.
-http://clsi.org/.
-http://www.healthaw.com/userfiles/image/Blood%20Collection.jpg
-http://i.ytimg.com/vi/YuFK22n-tvI/hqdefault.jpg