A PIV device, short for peripheral intravenous catheter, is the small flexible tube placed into a vein in your hand or arm to deliver fluids, medications, or blood products directly into your bloodstream. It’s the most common invasive medical device used in hospitals. If you’ve ever had an IV during a hospital stay, emergency visit, or outpatient procedure, you almost certainly had a PIV.
How a PIV Works
A PIV consists of a short, flexible plastic tube (the cannula) that sits inside your vein, a small hub that remains outside your skin, and a connector where tubing or syringes attach. During insertion, a needle guides the cannula into the vein. Once the plastic tube is in place, the needle is withdrawn and discarded, leaving only the soft, flexible catheter behind. A flash of blood visible in a small chamber confirms the needle entered the vein correctly.
The hub is then secured to your skin with a transparent adhesive dressing, which lets nurses monitor the site for any redness or swelling without removing the bandage. From there, IV tubing connects to the hub, allowing a continuous or intermittent flow of whatever your body needs.
Where It Gets Placed
The most common location is a vein on the back of your hand or along the forearm of your nondominant arm. Using the nondominant side keeps your dominant hand free and reduces the chance the catheter gets bumped or pulled loose. Nurses look for veins that feel soft and spongy to the touch, are relatively straight, and sit away from branching points where valves can interfere with insertion.
The inner elbow (antecubital fossa) is another frequent site, especially when a larger catheter is needed quickly. Veins on the top of the foot or lower leg are occasionally used when arm veins aren’t accessible, though this is less common in adults. For newborns and infants, scalp veins are sometimes used when other sites aren’t viable.
Finding a suitable vein can be harder in certain situations: people with obesity, those who are pregnant, patients in shock, children, and anyone whose veins have been affected by chemotherapy or repeated needle sticks. When standard methods fail, ultrasound-guided insertion can help. Trained providers using ultrasound achieve first-attempt success rates up to 90%, significantly higher than the traditional feel-and-look approach in difficult cases.
Gauge Sizes and What They Mean
PIV catheters come in different diameters, measured by gauge. The gauge system works counterintuitively: a lower number means a larger catheter. Each size is color-coded at the hub so healthcare providers can quickly identify what’s in place.
- 14 gauge (orange): The largest standard size, used for rapid fluid resuscitation or major trauma when large volumes need to flow fast.
- 16 gauge (grey): Common for surgery and blood transfusions.
- 18 gauge (green): A versatile mid-range size used for blood products, contrast dye for CT scans, and moderate fluid delivery.
- 20 gauge (pink): The workhorse for most adult patients needing standard IV medications and fluids.
- 22 gauge (blue): Often chosen for older adults or anyone with smaller, more fragile veins.
- 24 gauge (yellow): Typically reserved for pediatric patients or very delicate veins.
The larger the catheter, the faster fluid can flow through it, but a bigger catheter also requires a bigger vein and can be more uncomfortable. Your nurse will choose the smallest gauge that still meets your treatment needs.
How It’s Maintained
Between uses, your PIV needs periodic flushing with saline to keep blood from clotting inside the catheter and blocking it. The standard flush for a peripheral catheter is about 5 mL of normal saline before and after each medication. After blood transfusions or thicker infusions like nutrition formulas, a larger 20 mL flush is typical because blood components are more likely to stick to the catheter walls.
The transparent dressing over the site should stay clean and dry. If it becomes damp, peels up at the edges, or gets visibly dirty, it needs to be replaced. Otherwise, the dressing stays in place until the catheter is removed or routinely changed.
Potential Complications to Watch For
PIVs are generally safe, but problems can develop, especially the longer one stays in place. The most common complications include:
Phlebitis is inflammation of the vein wall. It’s graded on a scale from 0 to 4. At the mild end (grade 1), you might notice some redness around the insertion site with or without tenderness. At the severe end (grade 4), there are signs of actual infection: pain, redness extending along the vein in a cord-like pattern, swelling, warmth, and sometimes pus at the site. If you notice increasing redness or pain tracking up your arm from the IV site, let a nurse know right away.
Infiltration happens when the catheter slips out of the vein or pokes through the vein wall, causing IV fluid to leak into the surrounding tissue. You’ll notice swelling around the site, pain, and the area may look slightly puffy compared to the other arm. The IV may also feel like it’s not flowing well. Infiltration is uncomfortable but usually resolves on its own once the catheter is removed.
Extravasation is a more serious version of the same problem, occurring when the leaking fluid is a medication that can damage tissue. Signs include marked swelling, skin that turns white (blanching) and stays that way, coolness to the touch, and slow capillary refill in your fingers. In severe cases, skin breakdown can occur. This is why nurses check your IV site regularly and why you should speak up if something feels different.
How Long a PIV Can Stay In
Current practice favors removing a PIV when it’s no longer needed or when signs of a complication appear, rather than replacing it on a fixed schedule. Older guidelines recommended routine replacement every 72 to 96 hours, but more recent evidence supports a “clinically indicated” approach: leave a functioning, complication-free catheter in place and remove it at the first sign of trouble or when treatment is complete.
That said, PIVs don’t last forever. The longer a catheter remains in a vein, the higher the risk of phlebitis and infection. If your PIV stops flushing easily, the area becomes painful or swollen, or redness develops around the insertion site, those are signs the catheter needs to come out. Removal itself is quick and painless: the dressing is peeled off, the catheter is gently slid out, and a small bandage goes over the site.