What Is an IV Catheter?

An IV catheter (short for intravenous catheter, and sometimes called a peripheral IV or an IV cannula) is a short, flexible plastic tube inserted into a vein to give a clinician or researcher direct access to the bloodstream. Once placed, it stays in the vein — usually in the hand or forearm — and lets fluids, medications, or blood draws happen through the same access point without a new needle stick each time.

Where to source this: CASRAI’s sister medical-supply business, LAC, stocks IV catheters for both bulk facility ordering and smaller individual orders. Browse LAC’s IV catheters category to see current stock across gauges and pack sizes.

What an IV Catheter Actually Is

The device itself is a two-part system during insertion: a thin, hollow steel needle inside a slightly longer plastic tube (the catheter itself). The clinician inserts both together through the skin and into a vein. Once blood return confirms the tip is correctly positioned inside the vein, the needle is withdrawn and discarded into a sharps container, leaving only the soft plastic catheter sitting in the vein. That plastic-only design is the point — a flexible tube can stay in place for hours or days without the puncture risk a rigid needle would carry if left in a moving patient.

The exposed end of the catheter has a small hub that connects to IV tubing, a saline lock, or a syringe. From there, clinicians can run continuous fluids, push medications, or draw blood — all through the one access point, secured to the skin with a transparent dressing so the site stays visible for infection monitoring.

What Problem It Solves

Before catheter-over-needle designs became standard, repeated venous access meant repeated needle sticks — more trauma to the vein, more pain, and more puncture-site risk with every draw or dose. A peripheral IV catheter solves that by establishing one stable access point that can be used repeatedly: fluids can run for hours, multiple medications can be given without re-puncturing the skin, and blood can be sampled through the same line when appropriate. It’s why an IV catheter is one of the first things placed for almost any patient who is going to need ongoing medication, fluids, or monitoring — from a same-day outpatient infusion to an inpatient surgical stay.

Who Uses IV Catheters

Peripheral IV catheters are used across essentially every setting where a vein needs to be accessed for more than a single draw: emergency departments, surgical and pre-operative units, infusion and oncology centers, inpatient wards, outpatient clinics, and clinical research settings running trials that require repeated dosing or serial blood sampling. Nurses and other trained clinical staff place the large majority of peripheral IVs; the skill is a core competency taught early in nursing and paramedic training precisely because it’s used so often.

How an IV Catheter Differs From Related Devices

A few adjacent devices get confused with a standard peripheral IV catheter, and the distinctions matter for anyone specifying or procuring supplies:

• Butterfly needle (winged infusion set) — a short steel needle with flexible plastic “wings” for grip, used for a single blood draw or brief IV access. Unlike an IV catheter, the needle itself stays in the vein for the duration of use rather than being withdrawn, so it isn’t left in place for extended infusions. See What Is a Butterfly Needle? for the full comparison.
• Midline catheter and central venous catheter (central line) — both are longer catheters threaded further into the venous system (a midline into a larger upper-arm vein, a central line into a large central vein near the heart), used when therapy will run longer or requires medications too irritating for a peripheral vein. A standard IV catheter is shorter and sits in a smaller peripheral vein, and is not interchangeable with either for that reason.
• Urinary catheter — a completely different device and body system: it drains urine from the bladder rather than accessing a vein. The two share the word “catheter” but nothing else functionally. See Urinary Catheter Types and Selection if that’s the device you’re actually looking for.

Gauge Sizing, Briefly

IV catheters come in a range of gauge sizes, and the numbering is inverted from what feels intuitive: a lower gauge number (like 14G) means a larger-diameter catheter, and a higher number (like 24G) means a smaller one. Larger-bore catheters support faster flow rates and are used for rapid fluid resuscitation or blood transfusion; smaller-bore catheters are gentler on the vein and easier to place in fragile or small veins, at the cost of a slower maximum flow rate. Color-coded hubs (following ISO 6009) make gauge identifiable at a glance without reading the print on the catheter itself.

This page covers the concept at a general level. For the full gauge-by-gauge breakdown — flow rates, color codes, and which gauge fits which clinical scenario — see IV Catheter Gauge Selection: A Procurement Reference for Clinical Staff.

Insertion Site Care and Related Supplies

Because the catheter stays in the vein between uses, the insertion site itself becomes something to manage: it’s cleaned with an antiseptic before insertion, secured with a transparent film or gauze dressing so the site stays visible for signs of infiltration or infection, and checked on a regular schedule for as long as it remains in place. Aseptic insertion technique — including gloved hands throughout — is standard practice specifically because an indwelling catheter creates an open pathway into the bloodstream for as long as it’s in. See What Is a Nitrile Glove? and What Is a Wound Dressing? for more on the PPE and dressing side of that picture.

Why This Matters for Research Administration and Procurement

For anyone managing supplies rather than placing the device themselves — a clinical trial coordinator setting up sample-collection logistics, a lab or clinic manager building a par-level formulary, or a procurement officer sourcing consumables — the practical questions are usually about gauge mix, pack sizing, and vendor sourcing rather than insertion technique itself. A trial protocol that specifies serial blood draws, for instance, typically dictates a minimum gauge for sample integrity, which is a procurement input as much as a clinical one. Knowing the basic vocabulary (catheter vs. needle, gauge, indwelling vs. single-use) is what makes those specification conversations go smoothly between clinical and purchasing staff.

Frequently Asked Questions

Is an IV catheter the same as an IV cannula?

Yes — “IV cannula” and “peripheral IV catheter” refer to the same device. “Cannula” is more common in UK/international usage; “IV catheter” is more common in US clinical settings. Both describe the flexible plastic tube left in the vein after the insertion needle is withdrawn.

How long can an IV catheter stay in place?

It varies by institutional policy and the catheter’s condition rather than a single fixed number, and current infection-prevention guidance has moved away from a mandatory routine-replacement calendar toward replacing a peripheral IV when clinically indicated (signs of infiltration, phlebitis, or infection) rather than on a fixed schedule alone. Site assessment on a regular basis is the constant across settings, whatever the specific interval a facility’s policy uses.

Does an IV catheter hurt more than a regular needle stick?

Insertion involves a single needle stick, similar to a blood draw. The advantage is that it’s typically the only stick needed for the duration of treatment, rather than a new puncture for every dose or draw.

What gauge IV catheter is used for a blood transfusion?

Blood transfusion generally calls for a larger-bore catheter than routine fluids, since blood is more viscous and a larger lumen reduces the risk of damaging red blood cells during infusion. Exact institutional minimums vary; see the gauge selection guide linked above for the general size-to-use relationship.