I
Introduction to Cannulation
- A.Definition - placing a short plastic catheter into a peripheral vein for fluids, medication, or blood draws.
- B.A foundational procedural skill, built through repetition rather than a single explanation.
The skill behind every IV line, blood draw, and emergency drug route - placed correctly, first attempt, without blowing the vein.
This page is educational, not clinical protocol. Peripheral IV cannulation is an invasive skill that requires supervised, hands-on practice before it's performed on a real patient. This page doesn't replace that training.
Peripheral IV cannulation is the placement of a short plastic catheter into a vein, giving the team direct access for fluids, medications, and blood draws. It looks simple once someone's good at it, and that's exactly the problem: the technique that makes it look easy is a specific sequence of site selection, angle, and control that has to be practiced, not guessed. CARDIG-Jerusalem's Cannulation Workshop builds that sequence on real arm models until it's automatic.
Not every visible vein is a good target. These four sites cover the vast majority of successful adult cannulations, roughly in the order you should consider them.
Hover or tap each point to see where it sits on the arm.
Visible, accessible, and easy to secure. The default first choice when the veins are usable.
Try firstRuns along the outer forearm. Straight, stable, and comfortable for the patient once placed.
Try firstLarger and deeper, on the inner forearm. Useful when hand veins are poor, but rolls more easily.
Backup optionLarge and easy to hit at the elbow crease, but flexes with the joint - reserve it for urgent access.
Reserve siteEight steps, done in order, with control at every stage - rushing the insertion is the single most common reason for a failed attempt.
Too Flat (<15°)
Skates along under the skin, past the vein
Correct (15-30°)
Clean entry, reliable flashback
Too Steep (>30°)
Risks puncturing through the back wall
Gather supplies within reach, explain the procedure, and choose a site working distal to proximal - starting at the hand keeps options open higher up if it fails.
Tie it 10-15 cm above the intended site, tight enough to distend the vein without cutting off the arterial pulse.
Disinfect with an alcohol or chlorhexidine swab in a single outward spiral, and let it air-dry fully before touching the site again.
Stretch the skin taut below the insertion point with your non-dominant hand so the vein can't roll away from the needle.
Enter bevel-up at 15-30 degrees to the skin, watching for the flashback of blood in the catheter's chamber that confirms you're in the vein.
Once you see flashback, lower the angle, advance a few more millimeters, then slide the plastic catheter forward off the needle while holding the needle still.
Release the tourniquet, apply pressure above the catheter tip to control bleeding, remove the needle, connect the line, and flush to confirm patency.
Apply a transparent dressing so the site stays visible for monitoring, label it with the date, and dispose of the needle directly into a sharps container.
Flashback isn't the finish line. A weak or delayed flashback often means the needle tip is only partially in the vein - advance carefully and confirm free flow before you commit to threading the catheter.
Bigger isn't automatically better - the gauge should match the vein and the reason for the line, not just what's on top of the tray.
| Gauge | Color Code | Typical Use | Flow Rate |
|---|---|---|---|
| 14G | Orange | Trauma, rapid transfusion | Fastest |
| 16G | Grey | Blood products, major surgery | Very fast |
| 18G | Green | Standard adult IV access | Fast |
| 20G | Pink | Most common general-purpose line | Moderate |
| 22G | Blue | Pediatric or fragile veins | Lower |
| 24G | Yellow | Neonatal or very fragile veins | Lowest |
Color coding follows the widely taught convention, though exact shades vary slightly by manufacturer - always confirm gauge from the printed label, not color alone.
Most complications trace back to a specific, preventable step in the sequence above.
The Infusion Nurses Society's 0-4 scales are the shared language for documenting a site's condition on every check.
Vein wall inflammation
Fluid leaking into surrounding tissue
A perfect insertion with poor asepsis still causes harm - these five standards are checked at every station.
Wash or sanitize hands before gloving and again after the line is secured.
Let the antiseptic fully air-dry before puncture - wiping it off cancels the effect.
Don't touch the cleaned site again unless you're re-gloved and re-cleaning.
A sterile, see-through dressing keeps the site both protected and visible for checks.
Check the site every shift and remove or replace the line per local policy, not on a fixed guess.
Short teaching blocks feed directly into hands-on stations on realistic arm models, so every concept gets rehearsed within minutes of being taught.
Identifying and ranking usable veins by feel and visibility, not just what looks biggest.
Gloving, skin prep, and set-up sequencing, drilled until it's automatic.
Angle, anchoring, and flashback recognition, repeated on realistic arm models.
Connecting the line, flushing, and applying a dressing that stays put and stays visible.
What a weak flashback, a rolling vein, or a blown attempt actually looks like, and what to do next.
A timed return demonstration of the full sequence, with direct instructor feedback.
The questions we actually get about the workshop.
No. This workshop is built for medical students with no prior needle-based skills experience - everything starts from anatomy and site selection.
No. Every attempt happens on realistic silicone arm models with simulated veins - this workshop builds the technique before anyone touches a real patient under supervision.
That's exactly what Station 3 and Station 5 are for. Instructors work one-on-one on angle and anchoring technique until the flashback becomes consistent.
Yes - CARDIG-Jerusalem issues a CARDIG Certification to everyone who completes the workshop and passes the skills check-off, verifiable through our Verify Certificate portal.
Mostly 18G and 20G, since those cover the majority of routine adult access - the gauge table above is covered at Station 1 so you understand the full range.
Against the same sequence taught throughout the workshop: site selection, aseptic technique, angle and control on insertion, and a properly secured, dressed line.
This page explains peripheral IV cannulation for learning purposes - it is not a substitute for supervised, hands-on clinical skills training. Vein access is an invasive procedure that carries real risk to the patient and requires direct instructor oversight before independent practice.
CARDIG-Jerusalem runs hands-on clinical skills training for Al-Quds medical students and members - this page is the starting point, not the endpoint.
Explore Membership →A condensed, section-by-section reference. For the full explanation of each point, see the Workshop overview above.
Want the full explanation behind each point? The Workshop overview above walks through every section here in detail, including the reasoning behind each guideline.