Blood Collection: Terminology and Procedures
Introduction
Blood collection, also known as phlebotomy, is a critical diagnostic procedure in modern healthcare. It involves drawing blood from patients for laboratory testing, transfusion, or research purposes. Proper blood collection techniques ensure accurate test results, patient safety, and minimize complications. This guide outlines the essential terminology and procedures related to blood collection.
Blood Collection Equipment
Modern blood collection utilizes several specialized pieces of equipment designed to improve efficiency, safety, and specimen quality:
- Butterfly needle: A small, winged needle attached to a flexible tubing, ideal for patients with difficult veins or for pediatric use.
- Vacutainer: A blood collection system that uses a vacuum-sealed tube with a double-pointed needle, allowing for the automatic filling of blood collection tubes.
- Syringes: Used for manual blood collection, particularly when veins are fragile or difficult to access.
- Tourniquet: A constricting band placed around the patient's arm to make veins more visible and prominent.
- Alcohol swabs: Used to clean and disinfect the venipuncture site.
- Gauze and bandages: Applied to the venipuncture site after blood collection to control bleeding.
Common Blood Collection Terminology
Venipuncture
The process of puncturing a vein to access the bloodstream for blood collection. This is the most common method of blood collection and is typically performed in the antecubital fossa (the inner elbow area).
Arterial Puncture
A more specialized procedure that involves drawing blood from an artery, typically the radial artery in the wrist. Arterial blood is primarily used for blood gas analysis to evaluate respiratory function.
Capillary Collection
Also known as fingerstick or heelstick (in infants), this method involves collecting blood from capillaries rather than veins. It's used when only a small amount of blood is needed or when venipuncture is difficult.
Hemolysis
The breakdown of red blood cells, which can alter test results and render specimens unsuitable for certain tests. Proper collection techniques can minimize hemolysis.
Anticoagulants
Substances added to blood collection tubes to prevent clotting. Different tests require different anticoagulants, including EDTA, heparin, and sodium citrate.
Fasting Specimen
Blood collected after the patient has fasted (no food or drink except water) for a specified period, typically 8-12 hours. Fasting specimens are required for certain tests to establish baseline values.
Blood Collection Procedures
Venipuncture Procedure
- Verify patient identity using two patient identifiers (name and date of birth).
- Review the test requisition to determine the appropriate collection tubes and order of draw.
- Gather supplies and explain the procedure to the patient.
- Wash hands and don gloves.
- Apply tourniquet 3-4 inches above the venipuncture site.
- Select the appropriate vein; palpate to assess its size, depth, and resilience.
- Clean the venipuncture site with alcohol swab in a circular motion, moving outward from the center.
- Allow the site to dry completely.
- Perform venipuncture with collected equipment at a 15-30 degree angle.
- Fill the blood collection tubes in the correct order.
- Release the tourniquet before removing the needle (or after no more than 1 minute).
- Activate needle safety device and dispose of it properly.
- Apply gentle pressure to the venipuncture site with clean gauze.
- Label all specimens with patient information at the bedside.
- Check the patient for adverse reactions and verify hemostasis.
- Properly transport specimens to the laboratory.
Order of Draw
The "order of draw" refers to the sequence in which blood collection tubes should be filled to prevent cross-contamination of additives between tubes. The standard order of draw is:
- Blood culture bottles
- Light blue top (sodium citrate) for coagulation studies
- Serum tubes with or without clot activator
- Green top (heparin)
- Lavender/purple top (EDTA)
- Pink top (EDTA, for blood bank)
- Gray top (oxalate/fluoride)
Arterial Puncture Procedure
- Verify patient identity and review the test requisition.
- Explain the procedure to the patient.
- Gather supplies including arterial blood gas syringe with heparin.
- Wash hands and don gloves.
- Perform Allen's test to assess collateral circulation (for radial artery puncture).
- Prepare the puncture site with alcohol and allow it to dry.
- Palpate the arterial pulse with your non-dominant hand.
- Insert the needle at a 30-45 degree angle, aiming for the pulsating artery.
- Allow blood to fill the syringe spontaneously without suction.
- Withdraw needle and apply continuous pressure for at least 5 minutes.
- Immediately cap the syringe and gently mix to prevent clotting.
- Label the specimen and transport to the laboratory immediately.
Capillary Collection Procedure
- Verify patient identity and review the test requisition.
- Explain the procedure to the patient or parent/guardian.
- Gather supplies including lancet, alcohol wipes, gauze, and collection tubes.
- Wash hands and don gloves.
- Select the puncture site (fingertips for adults, heel for infants).
- Warm the site if necessary to increase blood flow.
- Clean the site with alcohol and allow it to dry.
- Perform a quick, firm puncture with the lancet.
- Wipe away the first drop of blood with gauze.
- Collect subsequent drops into the appropriate container by touching the container to the blood drop (not the skin).
- Gently squeeze the finger or heel to encourage blood flow if needed.
- Apply pressure to the site with gauze until bleeding stops.
- Label the specimen properly.
Safety Measures
Proper safety measures are essential during blood collection to protect both healthcare workers and patients:
- Hand hygiene: Wash hands before and after each patient contact, and always before and after gloving.
- PPE: Wear gloves, and consider face shields, gowns, or eye protection when there's a risk of splashes.
- Needle safety: Use safety-engineered devices and immediately dispose of needles in sharps containers.
- Biohazard disposal: Properly dispose of all blood-contaminated materials in biohazard containers.
- Patient identification: Use at least two patient identifiers before collecting specimens.
- Infection control: Clean the venipuncture site according to established protocols.
- Avoid recapping: Never recap used needles by hand.
Special Considerations
Certain patient populations require special approaches to blood collection:
- Pediatric patients: Use smaller needles, proper restraint techniques, and consider distraction methods.
- Elderly patients: Veins may be fragile; use smaller gauge needles and gentle handling.
- Patients with difficult veins: Consider using a blood pressure cuff (instead of tourniquet) or warm compresses to help distend veins.
- Patients with bleeding disorders or on anticoagulants: Apply pressure for longer periods after venipuncture.
- Patients with edema: Avoid areas of swelling when selecting veins.
Best Practices
Following best practices ensures quality specimen collection and improves patient experience:
- Continuously assess your technique and look for areas of improvement.
- Maintain professional communication with patients throughout the procedure.
- Stay updated on new guidelines, equipment, and techniques.
- Document any difficulties or complications during the procedure.
- Properly label specimens at the point of collection.
- Handle specimens gently to prevent hemolysis.
- Follow proper transport and storage guidelines for different specimen types.
- Participate in ongoing education and quality improvement programs.
Conclusion
Blood collection is a fundamental skill in healthcare that requires both technical knowledge and empathy. Understanding the terminology and mastering the procedures ensures accurate diagnostic information while prioritizing patient comfort and safety. Regular practice, adherence to established protocols, and continuous education are essential for healthcare professionals involved in blood collection.
As laboratory technology advances, so too do the techniques and equipment for blood collection. Staying current with these developments, while firmly grounded in the fundamental principles outlined in this guide, will enable healthcare professionals to provide the highest quality care to their patients.
Blood Collection Terminology And Procedures and Reference File Download Link
Blood Bank Organization And Blood Component Processing and Reference File Download Link
Arterial Blood Gas Collection And Analysis and Reference File Download Link