Venipuncture, the process of accessing a vein with a needle, is one of the most common invasive procedures in healthcare. It is routinely used for drawing blood samples (phlebotomy) or for administering intravenous (IV) fluids and medications. While generally safe, the procedure requires precision to avoid damaging the delicate vessel walls. When the needle passes entirely through the vein, this complication has a specific technical name describing the mechanics of the accident.
The Terminology: Transfixing the Vein
The technical name for a needle passing completely through a blood vessel is “transfixion” or a “through-and-through puncture.” This describes the mechanical failure where the needle penetrates the vein’s anterior wall, enters the central channel (lumen), and then exits through the posterior wall. Patients and staff sometimes refer to this event less accurately as a “blown vein.” Transfixion occurs when the angle of insertion is too steep or excessive force is used. This double puncture means the needle is partially or entirely outside the vessel, compromising the vein’s integrity and leading to leakage.
The Immediate Result: Extravasation and Infiltration
Once the vein wall is transfixed, the immediate consequence is the leakage of fluid into the surrounding soft tissues. This leakage is categorized based on the substance involved, depending on whether the procedure was a blood draw or an IV infusion.
Infiltration and Extravasation
If the needle is used for an IV infusion, non-irritating fluid (such as saline solution) leaking out is called “infiltration.” This occurs because the fluid seeps into the subcutaneous space instead of traveling through the vein. “Extravasation” is the leakage of an irritant solution, such as certain chemotherapy drugs. These substances are more concerning as they can cause severe pain, blistering, and tissue necrosis.
Hematoma and Symptoms
During a blood draw, the primary result of transfixion is a “hematoma,” a localized collection of blood outside the vessel. The blood escapes through the posterior puncture site and pools under the skin. Symptoms of leakage include sudden localized swelling and pain or a stinging sensation. The most visible sign is the rapid formation of bruising (ecchymosis).
Contributing Factors to Vein Transfixion
Several patient-specific and procedural factors increase the likelihood of vein transfixion during a needle stick.
Patient Factors
Some individuals have veins that are naturally small, deep, or fragile, making them susceptible to damage. Veins in older adults or those who have received frequent IV treatments often lose elasticity and become brittle, increasing the risk of the needle passing through both walls. “Rolling veins” are not well-anchored and move laterally during needle entry. If a vein rolls, the clinician may inadvertently push the needle deeper while attempting to follow it, resulting in a posterior wall puncture.
Procedural Factors
Technical errors also contribute significantly to transfixion. These include using an insertion angle that is too steep, often exceeding the recommended 15 to 30 degrees. Furthermore, a lack of proper stabilization prevents the healthcare provider from holding the vessel securely against the underlying tissue, increasing the chance of a through-and-through injury.
Management and Prevention Techniques
When transfixion is suspected, management begins by immediately stopping the procedure to prevent further leakage. If the needle tip is thought to be just past the posterior wall, the provider may attempt to slowly withdraw the needle slightly to pull the tip back into the lumen. However, if swelling is apparent or blood flow is lost, the needle must be removed entirely to avoid causing a larger hematoma. After removal, firm, continuous pressure must be applied for several minutes to minimize bleeding. Applying an ice pack later helps reduce swelling and discomfort.
To prevent transfixion, healthcare providers use proper vein anchoring techniques. They pull the skin taut below the puncture site to stabilize the vein and prevent it from rolling. They also use the shallowest possible angle of insertion, typically between 15 and 30 degrees, ensuring the needle enters the anterior wall and rests safely within the lumen without puncturing the back wall.