Phlebotomy is a technique in which a needle is temporarily inserted into a vein to provide venous access for venous blood sampling. [1, 2, 3] Veins have a three-layered wall composed of an internal endothelium surrounded by a thin layer of muscle fibers, which in turn is surrounded by a layer of connective tissue.
Identification of the optimal site for venous access (see Technical Considerations) involves both visual and tactile evaluation. After applying a venous tourniquet, the physician should inspect and palpate potential sites, starting with the nondominant extremity. On palpation, the vein should be soft and bouncy, it should refill after being depressed, and it ideally should be well supported by the surrounding tissue.
Phlebotomy is commonly performed with either an evacuated tube system (eg, Vacutainer; BD, Franklin Lakes, NJ) or a syringe and needle or winged butterfly needle device (see Technique).
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Indications
Indications for phlebotomy include the following:
Blood sampling
Short-term infusion (via butterfly needle)
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Contraindications
Contraindications for phlebotomy include the following:
Evidence of cellulitis or abscess
Venous fibrosis on palpation
Presence of a hematoma
Presence of a vascular shunt or graft
Presence of a vascular access device
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Technical Considerations
Anatomy
The superficial veins of the upper extremities, particularly those in the antecubital fossa, are the ones most commonly selected for phlebotomy because they are usually readily visible and easily palpable. The antecubital fossa contains four veins (see the images below). Of these, the median cubital vein is usually the vein of choice for phlebotomy: It is typically more stable (less likely to roll), it lies more superficially, and the skin overlying it is less sensitive than the skin overlying the other veins.
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In many cases, the metacarpal veins are easily visualized and palpated (see the image below). However, obtaining needle access on the dorsal hand is more painful, and the metacarpal veins are more likely to roll and collapse on vacuum application than the antecubital veins are.
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It appears that the device used to collect blood is the strongest independent predictor of hemolysis in blood samples drawn in the emergency department (ED). An ED study suggested that the most effective strategy to reduce the rate of hemolysis in the ED is to use butterfly needles for phlebotomy rather than intravenous catheters. [4]
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Periprocedure
References
Lavery I, Ingram P. Venepuncture: best practice. Nurs Stand. 2005 Aug 17-23. 19 (49):55-65; quiz 66. [QxMD MEDLINE Link].
Phlebotomy. WebPath. Available at //library.med.utah.edu/WebPath/TUTORIAL/PHLEB/PHLEB.html. Accessed: April 12, 2021.
Ernst DJ. Flawless phlebotomy: becoming a great collector. Nursing. 1995 Oct. 25 (10):54-7. [QxMD MEDLINE Link]. [Full Text].
Wollowitz A, Bijur PE, Esses D, John Gallagher E. Use of butterfly needles to draw blood is independently associated with marked reduction in hemolysis compared to intravenous catheter. Acad Emerg Med. 2013 Nov. 20 (11):1151-5. [QxMD MEDLINE Link].
Media Gallery
Antecubital veins, left arm.
Antecubital veins, right arm. Note variable anatomy; median cubital vein is not visible.
Metacarpal veins.
Phlebotomy equipment.
Blood collection tubes.
Vacutainer(R) needle and adapter.
Pediatric blood collection tubes.
Phlebotomy. Tourniquet application.
Phlebotomy. Vein palpation.
Phlebotomy. Antiseptic solution application.
Phlebotomy. Assembly of Vacutainer(R) device.
Phlebotomy. Application of traction.
Phlebotomy. Insertion of needle (bevel up).
Phlebotomy. Insertion of winged butterfly device.
Phlebotomy. Insertion of winged butterfly device, flashback of blood.
Phlebotomy. Holding device in place and filling tubes.
Phlebotomy. Blood sample tube inversion.
Phlebotomy. Removal of needle.
Phlebotomy. Application of pressure on straight arm for 5 minutes.
Phlebotomy. Transfer of blood from syringe to vacuum tube.
Phlebotomy. Vacutainer(R).
Phlebotomy. Butterfly needle.
Antecubital veins, right arm.
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Contributor Information and Disclosures
Author
Gil Z Shlamovitz, MD, FACEP Associate Professor of Clinical Emergency Medicine, Keck School of Medicine of the University of Southern California; Chief Medical Information Officer, Keck Medicine of USC
Gil Z Shlamovitz, MD, FACEP is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association
Disclosure: Nothing to disclose.
Chief Editor
Vincent Lopez Rowe, MD Professor of Surgery, Program Director, Integrated Vascular Surgery Residency and Fellowship, Department of Surgery, Division of Vascular Surgery and Endovascular Therapy, Keck School of Medicine of the University of Southern California
Vincent Lopez Rowe, MD is a member of the following medical societies: American College of Surgeons, American Surgical Association, Pacific Coast Surgical Association, Society for Clinical Vascular Surgery, Society for Vascular Surgery, Western Vascular Society
Disclosure: Nothing to disclose.
Acknowledgements
Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference