Venesection

Venesection, also known as venous bloodletting, is the withdrawal of blood from a vein. In modern medical usage, phlebotomy is more common for routine diagnostic blood draws, while venesection is used to describe therapeutic blood removal. The procedure targets peripheral veins, typically in the arm, and is performed with sterile technique using a needle or cannula and evacuated collection tubes.

Indications include therapeutic phlebotomy for iron overload (hereditary hemochromatosis) and conditions with elevated hematocrit such as polycythemia vera, as well as other hyperviscosity syndromes. It may also be used to reduce blood volume before certain procedures. Diagnostic venipuncture for laboratory tests is related but not intended to alter total blood volume.

Technique: after consent and assessment, a tourniquet is applied to engorge a suitable vein, usually in the antecubital fossa. The skin is cleaned with antiseptic, and a sterile needle or cannula is inserted. Blood is drawn into appropriate tubes; the tourniquet is released as soon as flow begins; after collection, pressure is applied and a bandage used. The procedure is performed by trained personnel under sterile conditions, with monitoring for adverse reactions.

Risks include vasovagal reactions, bleeding, hematoma, infection, or nerve or vascular injury. Repeated procedures can contribute to iron deficiency. Contraindications include active infection at the puncture site, significant coagulopathy, thrombocytopenia, severe dehydration, or when venous access is poor or anticoagulation raises bleeding risk.

History and status: Venesection has a long historical role in medicine. Today, therapeutic phlebotomy remains standard of care for selected diseases, while diagnostic venipuncture is routine for laboratory testing.