An intravenous (IV) site delivers fluids, medications, and nutrients directly into the bloodstream. Although the procedure is routine, complications can arise at the insertion point where a small catheter is placed into a vein. Localized swelling around an IV site is a common sign that something has gone wrong, requiring immediate assessment to determine the cause and prevent further injury.
The Most Common Cause: Infiltration and Extravasation
The most frequent reason for swelling at an IV site is a mechanical failure: the catheter slips out of the vein, causing the infusing fluid to leak into the surrounding subcutaneous tissue. This complication is categorized as either infiltration or extravasation, depending on the fluid type. Infiltration occurs when a non-vesicant solution (one that is not irritating or damaging to tissue) escapes the vein and accumulates in the nearby space, causing puffiness.
Signs of infiltration include the area becoming cool to the touch and appearing pale or blanched because the fluid compresses local blood vessels. The skin around the site may feel taut, and the infusion rate often slows down or stops completely. This leakage is a mechanical problem, usually occurring when the catheter tip punctures the vein wall or becomes dislodged.
Extravasation follows the same mechanical process as infiltration but involves the leakage of a vesicant solution. Vesicants are medications or fluids known to cause blistering, severe tissue damage, or necrosis if they contact soft tissue. Examples include certain chemotherapy agents, high-concentration electrolytes, or vasopressor medications.
Due to the irritating nature of the fluid, extravasation presents with much more severe symptoms than infiltration. While swelling is present, the patient typically reports intense pain, burning, or stinging at the site. The skin may show early signs of damage, such as blistering, ulceration, or dark discoloration indicating tissue death. Extravasation is a medical emergency requiring prompt recognition and specialized treatment to minimize long-term damage.
Inflammation of the Vein Wall: Phlebitis and Thrombophlebitis
Swelling can also result from phlebitis, which is inflammation of the vein wall itself, distinct from the fluid leakage of infiltration. Phlebitis is the inflammation of the tunica intima (the innermost lining of the vein wall) and can be triggered by mechanical, chemical, or infectious factors. Mechanical irritation occurs when the catheter, especially if too large, causes friction or trauma to the lining as the arm moves.
Chemical phlebitis is caused by the properties of the infused solution, such as a medication with a very high or low pH, or a solution with high osmolarity that irritates the vein wall. This irritation causes an inflammatory response, leading to localized pain, tenderness, and swelling. Unlike infiltration, the area affected by phlebitis is typically warm to the touch and may exhibit a visible red streak along the path of the vein.
Thrombophlebitis is a more serious form of inflammation that includes the formation of a thrombus (blood clot) within the inflamed vein. The clot obstructs blood flow, intensifying the inflammatory signs. When a clot is present, the affected vein may feel like a hard, rope-like cord upon palpation.
The presence of a clot can increase the risk of infectious phlebitis if microorganisms colonize the thrombus or the catheter site. While mechanical and chemical causes are common, prolonged catheter use or a break in sterile technique can introduce bacteria. This infectious process requires immediate attention and can escalate rapidly.
Localized Bleeding and Bruising (Hematoma)
Another cause of localized swelling is a hematoma, which is a bruise that forms when blood leaks out of the vein and pools in the surrounding tissue. This swelling results from vascular trauma, most commonly occurring during catheter insertion or immediately following its removal. During insertion, the needle or catheter may pass entirely through the vein wall, creating an exit site through which blood escapes before the vein can seal.
A hematoma can also form if inadequate pressure is applied to the site after catheter removal, allowing blood to seep into the subcutaneous space. The swelling associated with a hematoma is typically contained, firm to the touch, and accompanied by immediate discoloration. The skin rapidly turns purple, blue, or black as the blood spreads beneath the surface.
While often transient and less complex than infiltration or phlebitis, a hematoma can cause pain and tenderness at the site. This swelling is usually contained immediately around the puncture, distinguishing it from the generalized puffiness of infiltration. The body naturally reabsorbs the pooled blood over time, causing the bruise to change color and fade.
Recognizing Severe Complications and Immediate Action Steps
Recognizing that swelling may indicate a severe complication, such as a localized infection, is crucial for patient safety. A serious infection, like cellulitis or an abscess, is often indicated by signs that spread beyond the immediate site. These include pain that radiates outward, increasing redness and warmth, and the presence of purulent drainage or pus at the insertion point.
Systemic symptoms, such as fever or chills, indicate that the infection may have entered the bloodstream, potentially leading to sepsis. Another serious, though rare, complication is compartment syndrome, which can occur after severe extravasation when excessive swelling compresses muscles and nerves.
If swelling or other signs of distress are noticed at an IV site, the action plan requires immediate attention from healthcare staff. The first step is to never attempt to remove the IV catheter yourself, as this can cause further injury or bleeding. If the infusion is running, it must be stopped immediately to prevent more fluid or medication from leaking into the tissue.
The most important action is to notify a nurse or doctor right away so they can assess the site and determine the underlying cause. If infiltration is suspected, elevating the limb helps reduce swelling by promoting the reabsorption of leaked fluid. Quick communication ensures the infusion can be restarted in a new location and that necessary treatments, such as an antidote for extravasation or antibiotics for infection, are administered without delay.