venipunctures

Venipuncture is the puncture of a vein to obtain a blood sample or to administer intravenous medications or fluids. It is one of the most common medical procedures and is typically performed by phlebotomists, nurses, or physicians using aseptic technique and standard safety practices.

Common sites include veins in the antecubital fossa such as the median cubital vein, cephalic vein, and basilic vein, which are preferred for ease of access and sample quality. When these are unsuitable, veins on the dorsum of the hand, forearm, or, in infants, scalp veins may be used. The choice depends on vein visibility, palpability, patient factors, and the purpose of the collection.

Procedure and equipment involve preparing the patient and setting, using gloves, a tourniquet, antiseptic for skin preparation, a suitable needle (typically 21-23 gauge), evacuated collection tubes, and gauze or an adhesive bandage. The collection sequence may follow guidelines to prevent cross-contamination of additives. The vein is palpated and anchored; the needle is inserted at a shallow angle with the bevel up, blood is drawn into the tubes, the tourniquet is released before needle removal, and the needle is withdrawn with direct pressure applied to the puncture site.

Post-procedure steps include labeling and transporting specimens to the laboratory, ensuring sample integrity, and monitoring for immediate complications. Potential complications are usually rare but can include hematoma, infection, prolonged bleeding, nerve or arterial injury, vascular injury, or vasovagal syncope.

Special considerations include pediatric and elderly patients, difficult venous access, dehydration, and allergies to antiseptics or latex. Alternatives such as capillary sampling may be used when venipuncture is not feasible.