Biological samples are collected through various methods depending on the type of sample and the purpose of the collection. A common method for blood collection involves venipuncture.
Here's a breakdown focusing on blood sample collection, based on the provided reference:
Blood Sample Collection via Venipuncture
Venipuncture is a procedure used to obtain blood samples from a vein, typically in the arm. The standard process involves the following steps:
- Patient Positioning: The subject is seated in a semi-upright position. It's crucial to record the exact position for consistency.
- Equipment Preparation: Vacutainers (evacuated tubes) are prepared. These tubes contain specific additives depending on the type of blood sample needed (e.g., anticoagulant for plasma, clot activator for serum).
- Vein Selection & Preparation: A healthcare professional selects a suitable vein (often in the antecubital fossa - the inner elbow). The area is cleaned with an antiseptic solution (e.g., alcohol).
- Venipuncture: A tourniquet is applied to the upper arm to make the veins more prominent. A needle attached to a vacutainer holder is inserted into the selected vein.
- Blood Collection: The vacutainer is pushed into the holder, puncturing the tube stopper and allowing blood to flow into the tube via vacuum. Two 10 mL tubes are typically collected:
- One tube for plasma and buffy coat analysis (contains an anticoagulant like EDTA or heparin).
- One tube for serum analysis (contains a clot activator).
- Needle Removal & Bandaging: The tourniquet is released, and the needle is carefully removed. Pressure is applied to the puncture site with a sterile gauze pad until bleeding stops. A bandage is then applied.
- Sample Processing & Storage: The collected blood samples are labeled appropriately and processed according to the study protocol. This may involve centrifugation to separate plasma/serum from cells. Samples are then stored at appropriate temperatures (e.g., -80°C) until analysis.
Other Biological Sample Collection Methods
Besides blood, other common biological samples and their collection methods include:
- Urine: Collected via urination into a sterile container. Specific collection methods (e.g., midstream clean catch) may be used depending on the test requirements.
- Saliva: Collected by spitting into a collection tube or using a swab to absorb saliva.
- Tissue Biopsies: Obtained through surgical procedures (e.g., needle biopsy, excisional biopsy) where a small piece of tissue is removed for microscopic examination.
- Fecal Samples: Collected in a sterile container, following specific instructions to avoid contamination.
- Swabs (Nasal, Throat, Skin): Collected by gently swabbing the target area to collect cells and microorganisms.
