SAMPLE COLLECTION

how to take a sample collection

1. Overview on sample collection Types of samples, techniques of collection.

2. Introduction There are several types of samples that can be collected and analyzed in a diagnostic laboratory, depending on the specific diagnostic test being performed and the suspected medical condition.

3. Types Blood samples: Blood samples can be collected through venipuncture or fingerstick , and are commonly used for various diagnostic tests such as complete blood count (CBC), blood glucose, electrolyte levels, liver function tests, lipid profile, and infectious disease testing.

4. Types Urine samples: Urine samples can be collected through a clean catch, mid-stream collection or catheterization, and are commonly used for urinalysis, pregnancy testing, drug screening, and testing for urinary tract infections.

5. Types Stool samples: Stool samples can be collected in a sterile container, and are commonly used for fecal occult blood testing, stool culture for infectious agents, and testing for parasites.

6. Types Tissue samples: Tissue samples can be collected through biopsy, surgical excision, or autopsy, and are commonly used for histopathological analysis, cancer diagnosis, and identification of infectious agents

7. Types Body fluid samples: Other body fluids such as cerebrospinal fluid (CSF), pleural fluid, ascitic fluid, and pericardial fluid can be collected through aspiration or drainage, and are commonly used for diagnostic tests such as cell counts, glucose and protein levels, and infectious disease testing.

8. Blood sampling Wash your hands with soap and water or use an alcohol-based hand sanitizer to prevent the spread of infection. Assemble the required equipment, including a sterile needle, a sterile syringe or vacutainer , alcohol swabs, gauze pads, and a tourniquet. Position the patient's arm with the antecubital vein visible and palpable. Apply the tourniquet about 3-4 inches above the venipuncture site to make the vein more visible and accessible. Ask the patient to make a fist or repeatedly squeeze a stress ball to promote venous distention and blood flow. Clean the venipuncture site with an alcohol swab, starting at the center and moving outward in a circular motion, allowing the area to air dry completely. Once the site is dry, stabilize the vein by gently pulling the skin taut below the puncture site using your non-dominant hand.

9. Blood sampling Insert the sterile needle into the vein at a 15 to 30-degree angle, bevel up. The bevel is the slanted tip of the needle, and it should face up towards the surface of the skin. Once the needle is inserted, remove the tourniquet and slowly pull back on the plunger of the syringe or vacutainer to collect the blood sample. Once the required amount of blood is collected, remove the needle and apply pressure to the venipuncture site with a gauze pad to promote clotting and reduce bleeding. Dispose of the used equipment in a biohazard container and apply a bandage to the puncture site. Label the collected sample with the patient's name, date of birth, and other necessary information, and send it to the laboratory for analysis .

10. Vacuutainers Serum Separator Tube (SST) - Yellow : This tube contains a gel that separates the blood cells from the serum after centrifugation. It is used for chemistry tests, including glucose, cholesterol, and liver function tests. Plain Tube - Red: This tube does not contain any additives and is used for routine blood tests, such as blood typing and cross-matching. Heparin Tube - Green: This tube contains sodium heparin, an anticoagulant that prevents blood clotting by inhibiting thrombin formation. It is used for tests that require plasma, such as electrolyte and hormone testing.

11. Vacuutainers EDTA Tube - Lavender or Pink: This tube contains EDTA ( ethylenediaminetetraacetic acid), which chelates calcium ions and prevents blood clotting by binding with the clotting factors. It is used for hematology tests, including complete blood count (CBC) and blood smear examination, Hba1c. Citrate Tube - Blue: This tube contains sodium citrate, which binds calcium ions and prevents blood clotting by inhibiting coagulation factors. It is used for coagulation tests, including prothrombin time (PT) and activated partial thromboplastin time (APTT). Fluoride Tube - Gray: This tube contains potassium oxalate and sodium fluoride, which prevent glycolysis by inhibiting the enzymes that break down glucose. It is used for glucose testing and alcohol level.

12. Tissue processing The aim of tissue processing is to embed the tissue in a solid medium firm enough to support the tissue and give it sufficient rigidity to enable thin sections to be cut, and yet soft enough not to damage the knife or tissue.

13. Gross examination of tissue specimens Gross examination of tissue specimens is an important step in the pathology process that involves visual examination of the tissue with the naked eye. It is performed by a pathologist or a trained laboratory technician/technologist.

14. Steps involved Specimen receipt and accessioning: The tissue specimen is received by the laboratory, and the accessioning process begins. This involves assigning a unique identifier to the specimen and recording relevant information such as the patient's name, date of birth, and medical history. Examination of the specimen container: The container is inspected for any leaks or damage, and the labeling is checked to ensure that it matches the patient's identification. Inspection of the external features of the tissue: The tissue is examined for its size, shape, color, texture, and consistency. The pathologist may also take note of any gross abnormalities or lesions.

15. Tissue dissection: The tissue is dissected or sectioned into smaller pieces to allow for more detailed examination. The pathologist may use a scalpel, scissors, or other instruments to cut the tissue specimen. Sampling: Tissue samples are taken for further processing, such as histological or molecular analysis. The pathologist selects areas of the tissue that appear abnormal or representative of the lesion and cuts them into smaller pieces for processing. Tissue fixation: The tissue specimens are then fixed in formalin, which preserves the tissue and prevents degradation. Macroscopic description: The pathologist provides a macroscopic description of the tissue specimen, which includes details such as the size, shape, color, texture, and any gross abnormalities. This description is included in the pathology report and is used to guide further testing.

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