Starting a peripheral IV follows a consistent sequence: prepare your supplies, select a vein, clean the site, insert the catheter at a shallow angle until you see a flash of blood, thread the catheter forward, and secure it with a transparent dressing. Whether you’re a nursing student looking for a printable reference or a new clinician building confidence, this guide walks through every step with the specific details that matter at the bedside.
Supplies You Need Before You Start
Gathering everything before you approach the patient saves time and prevents contamination mid-procedure. Here’s the standard supply list:
- Clean (nonsterile) gloves
- Single-use tourniquet
- Peripheral IV catheter in the appropriate gauge size
- Antiseptic pad, typically chlorhexidine-based, povidone-iodine, or 70% alcohol (check for patient allergies)
- Needleless cap or extension tubing set
- Prefilled 10 mL syringe with preservative-free normal saline
- Transparent semipermeable dressing
- Securement device (adhesive stabilizer, subcutaneous anchor, or tissue adhesive)
- IV pole
- Sharps disposal container within arm’s reach
- Label for the dressing (date, time, gauge, your initials)
If the patient will receive fluids or medication immediately, the IV solution should already be attached to a primed administration set before you begin the insertion.
Choosing the Right Catheter Size
Peripheral IV catheters range from 14 gauge (the largest) to 24 gauge (the smallest). The lower the gauge number, the wider the catheter and the faster fluid can flow through it. Most clinical settings stock 16, 18, 20, and 22 gauge catheters. Here’s how to choose:
- 20 gauge: The most commonly used size. Suitable for most adult patients receiving standard IV fluids, medications, or contrast dye for imaging.
- 18 gauge: Used when rapid fluid delivery is expected, such as in surgical patients or those who may need blood transfusions.
- 16 gauge (or 14 gauge): Reserved for trauma or major surgery where large volumes of fluid need to flow quickly.
- 22 or 24 gauge: Best for pediatric patients, elderly patients, or anyone with small, fragile veins. A 22 gauge catheter has a maximum gravity flow rate of about 35 mL per minute, which limits its use for rapid infusions.
When in doubt, choose the smallest gauge that will meet the patient’s treatment needs. A smaller catheter causes less discomfort and is less likely to damage the vein.
Selecting the Best Vein
Start by looking at the hand and forearm of the patient’s nondominant arm. You want a vein that feels bouncy and springy when you press it, not one that rolls away from your fingertip or feels hard and cord-like. Straight segments of vein work best because they’re easier to thread a catheter through.
Avoid veins near joints (like the bend of the elbow if possible, since movement increases the risk of the catheter shifting), areas with bruising or previous puncture sites, and any arm on the side of a mastectomy, dialysis fistula, or existing injury. If the patient has had a topical numbing cream applied, wipe it off before you clean the skin.
Apply the tourniquet about 5 to 10 centimeters above your intended puncture site. It should be tight enough to make the veins swell and become visible, but not so tight that you can’t feel a pulse at the wrist. Having the patient open and close their fist a few times, or dangling the arm downward for a moment, can help veins fill and become more prominent.
Step-by-Step Insertion
1. Prepare and Clean
Perform hand hygiene and put on your gloves. Clean the insertion site with your antiseptic pad using a back-and-forth friction scrub. Allow the antiseptic to dry completely before inserting the needle. For chlorhexidine, a minimum of two minutes of contact time produces the most significant reduction in bacteria on the skin. Skipping the drying step is one of the most common mistakes and increases infection risk.
2. Stabilize the Vein
With your nondominant hand, place your thumb below the intended puncture site and pull the skin downward (toward the patient’s fingers). This anchors the vein in place and stretches the skin taut, which makes the needle entry smoother and prevents the vein from rolling away.
3. Insert the Needle
Hold the catheter with your dominant hand, gripping the hub between your forefinger and thumb. Point the bevel (the angled opening of the needle) upward. Insert the needle into the skin at a shallow angle, less than 45 degrees, and advance it slowly toward the vein.
Watch the flash chamber on the catheter. When the needle enters the vein, you’ll see a small burst of blood appear in the chamber. This is called the “flash,” and it confirms you’re in the right place. If you only see a tiny drop of blood, the needle tip may be only partially inside the vein. In that case, flatten the angle slightly and advance 1 to 2 millimeters more until you see steady blood flow.
4. Thread the Catheter
Once you have a good flash, hold the needle still and use your other hand to slide the plastic catheter forward over the needle, threading it into the vein until the hub sits flush against the skin. You should see a second flash of blood inside the catheter itself as it advances into the vein. This confirms the catheter (not just the needle) is properly seated.
5. Remove the Needle and Connect
Release the tourniquet. Apply gentle pressure over the vein just above the catheter tip (this prevents blood from flowing back out), then withdraw the needle and immediately dispose of it in the sharps container. Connect the extension tubing or needleless cap to the catheter hub.
6. Flush and Confirm
Attach the prefilled saline syringe to the extension set and slowly flush. The flush should flow easily without resistance. Watch the skin around the insertion site. If you see swelling, the patient reports burning, or the skin feels tight, the catheter may not be in the vein. If the flush runs smoothly and the patient has no complaints, you have a working IV line.
Securing the Catheter
A properly secured IV line is less likely to shift, fall out, or cause irritation. Apply a transparent semipermeable dressing over the insertion site so you can visually monitor the area without removing the dressing. Use a sutureless securement device to stabilize the catheter hub, which reduces both movement and infection risk compared to tape alone.
Label the dressing with the date and time of insertion, the catheter gauge, and your initials. Transparent dressings should be replaced at least every seven days. If you’re using gauze instead (for patients who are sweating heavily or have oozing at the site), change it at least every two days. Replace any dressing immediately if it becomes damp, loosened, or visibly soiled.
What to Document
After the procedure, chart the date and time of insertion, the catheter gauge and type, the anatomical site you used, how many attempts it took, the condition of the skin at the insertion site, how the patient tolerated the procedure, and whether the flush confirmed patency. Accurate documentation protects both you and the patient, especially if the line later needs to be evaluated for complications.
Recognizing Complications Early
Peripheral IV complications are common and usually mild when caught quickly. Check the site regularly, either visually through the transparent dressing or by gently pressing around it.
Infiltration happens when the catheter slips out of the vein and fluid leaks into the surrounding tissue. Signs include swelling around the site, skin that feels cool and tight, pain, and a slowing or stopping IV flow. If you notice these, stop the infusion and remove the catheter.
Extravasation is similar to infiltration but involves caustic medications. It produces the same swelling and pain, plus burning, stinging, redness, or blistering. This requires immediate action: stop the infusion and follow your facility’s protocol for the specific medication involved.
Phlebitis is inflammation of the vein. Look for redness, warmth, pain, and swelling that tracks along the path of the vein. You may feel a hard, cord-like vein under the skin. If there’s pus at the site, infection is likely and the catheter should be removed and cultured.
Tips for Difficult Veins
Some patients, particularly those who are dehydrated, elderly, or receiving frequent IV therapy, have veins that are hard to find or tend to collapse. A few techniques improve your odds. Applying a warm compress to the area for several minutes before attempting access helps veins dilate and become more visible. Letting the arm hang below the level of the heart uses gravity to fill the veins. Palpation matters more than appearance: a vein you can feel but can’t see is often a better target than one that looks prominent but is thin-walled and fragile.
If the forearm veins aren’t cooperating, try the back of the hand or the outer forearm. Ultrasound guidance is increasingly available in clinical settings and significantly improves first-attempt success rates in patients with difficult access, reducing the need for multiple painful sticks. Many facilities now have specialized IV access teams equipped with portable ultrasound for exactly these situations.