How to Start an IV with an Ultrasound Machine: Transverse Mode

Are you tired of dreading the act of starting an IV on a patient? Does it seem like every patient you get is a “hard stick?” If any of these conditions are true, learning to use an ultrasound machine for peripheral IV placements is for you. Let’s begin. Specialties Critical Knowledge


How to Start an IV with an Ultrasound Machine: Transverse Mode

This article does not apply to central lines, nor does it go into the theory of ultrasound technology. For in-depth knowledge of ultrasound technology refer to ultrasound textbooks.

Do not be afraid of an ultrasound machine. Yes, it has many knobs, buttons, and probes. It looks intimidating, but once you learn the controls, it's fairly straightforward. Every ultrasound machine has a few different probes. The only probe you need to become familiar with is the linear probe. The linear probe is the "flat" or "straight" probe. Most ultrasound machines have an attached card that describes the probes, buttons, and knobs on that specific machine. Read the card. Several manufacturers make ultrasound machines, it would be impossible to describe each one in this article.

Gather Supplies

Gather your supplies: bedside table, towel, washcloth, ultrasound gel, ultrasound machine, IV start supplies, and a chair. While you are getting set up, explain to the patient what you are doing. Explanations go a long way in helping calm the fears of patients.

Step 1. Power Up

Learn where the power switch is. Press it. Let the machine boot up. Also, always keep the ultrasound machine plugged into a power outlet. Not everyone plugs the machine back in after use and this causes the battery to discharge. You do not want to be mid-insertion and have the machine power off.

Step 2. Clean the Probe and the Patient

While the machine is powering up, clean the linear probe with whatever cleaner your facility has available for the probes. Always clean the probe, but do not clean the ultrasound screen with the same cleaner. Ultrasound screens have special cleaners. Clean the patient's skin as you would for any IV insertion.

Step 3. Configure the Machine

Select the "B" mode on the ultrasound machine. The "B" mode is the brightness mode. When the ultrasound machine is in brightness mode, what you are really seeing on the screen is a two-dimensional gray-scale image of a patient's forearm when you have the probe touching the patient's forearm. You can "brighten" the image by adjusting the "gain" knob. No perfect brightness level exists. It is ultrasound-user dependent.

Step 3A. Select the Highest Frequency

If the linear probe has frequency adjustments, select the highest frequency possible. This allows for the sharpest image possible. Not all ultrasound machines have a linear probe that is frequency adjustable. Either way, even the best images are not that sharp, but you want the sharpest images possible and that means the highest frequency possible on the linear probe.

Step 4. Position the Patient

Position the patient. If your facility has bedside tables for the patient's rooms, use them. Clean the table's top and place the towel over the table. The towel serves three purposes: it keeps the patient's arm off the cold surface, it absorbs any blood that drips onto the surface, and it serves as a quick way to dispose of all your trash when you are done.

If you do not have a bedside table, have the patient adjust themselves in bed so they can place their arm on the bed. If this is the case, place the towel folded long-ways under their arm. When you are finished, any blood that is lost does not remain in bed with the patient.

Step 5. Position the Ultrasound Machine

Place the ultrasound machine directly in front of you so that you can easily view the screen and the patient without contorting your body. You need to be comfortable when placing the IV catheter. If your body is contorted to see the screen and the patient, you are setting yourself up for failure. Do not put the machine on the other side of the bed. Ultrasound screens are just not that large, and you will miss subtle clues that appear on the screen.

Step 6. Sit Down

Starting an ultrasound-guided IV requires coordination and some finesse. You cannot control the probe and the catheter while you are standing with any measure of accuracy. Sit down and allow your body to relax. Imagine trying to lift weights and thread a sewing needle simultaneously. It's almost impossible to do. Your accuracy with the ultrasound machine will exponentially increase when you sit. The one exception is in a code blue situation. In a code blue situation, have someone hold the arm and do your best.

Step 7. Orient the Probe Correctly

On the screen and on the probe will be some style of marker so that when they are lined up the probe is oriented correctly in relation to the screen (both markers on your left or right side). Usually in a corner of the screen will be a triangle, dash, or circle and the probe will have the same style of marker. You want to make sure the marker on the probe is on the same side as the marker on the screen (I.e., if the screen marker is on the left side of the screen, the mark on the probe should be on your left as you hold the probe). When you line the screen and probe up in this manner, you have the probe in the correct orientation. Sometimes the markers can be difficult to determine. A simpler way to make sure the probe is oriented correctly is to slide the probe across the patient's forearm to your left, if the screen images move off to the right of the screen, you have the probe oriented correctly.

Step 8. Be a Painter

Apply a tourniquet. Place just a dab of ultrasound gel on the patient's forearm. The ultrasound probe needs the tiniest amount of gel to transmit ultrasound waves through. The more gel you add, the more you must remove, and the more slippery the probe becomes. You will find your optimal amount the more you use the ultrasound machine. A perfect amount does not exist. You want to move up and down the patient's forearm with the probe. Imagine being a painter and painting the patient's arm with gel. The probe must have gel under it to see into the patient's forearm. While you are "painting" with gel, you are looking for veins on the screen and how the paths of those veins change as you move up the patient's forearm. Knowing how a patient's veins change before you advance the needle and catheter will help you have a successful cannulation.

Step 9. Find a Vein

What does a vein or artery look like on the screen? They both look like black circles. (see Figure 1). As you can see in Figure 1, the image even with a 14MHz linear probe is not great. Most older ultrasounds machines only have a 10MHz linear probe. Don't get caught up in technology. A 10 MHz probe will work just fine for peripheral IV cannulations.

How do you distinguish an artery from a vein? Press the probe into the patient's forearm and hold it against the patient. A vein collapses and will remain collapsed, and an artery will pulsate. It's as simple as that, but with one caveat. Patients with extremely weak pulses can fool you. Watch the screen closely for a few seconds to determine if the black circle is pulsating.

Learning how to apply the probe to a limb requires some practice to get both the positioning and the downforce correct at the same time. You cannot just press the probe into a patient's forearm while looking for veins or while inserting the IV. If you press too strongly, you will obscure the veins. You will know you have the probe correctly against a patient's skin when you see a complete image on the screen (I.e., no large solid black areas) and the veins and arteries are circles. If the veins and arteries are not circles, you have too much pressure on the probe. (see Figure 2). Optimal holding of the probe takes time to learn. Practice often. It pays off in the long run.

Step 10. Insert the Catheter

On the screen will be numbers that increase as they go down the screen. Those numbers represent the depth in centimeters into the patient's forearm. The top of the screen represents the skin of the patient's forearm. When you have located the vein you want to cannulate, look over at the depth gauge to find out how deep the vein is in the patient's forearm. Use the center of the vein as a reference point. As an example, let's say the vein's center is one centimeter down from the top of the patient's forearm. Your insertion point for the catheter will be one centimeter back from the probe.

But how do you know where to insert the needle? This is where skill and practice come into play.

In the middle of the screen will be some type of marker. It may be a simple triangle pointed down or a line of dots in the center of the screen. You carefully position the probe so that the image of the vein you want to cannulate is centered on the screen marker. On the side of the probe will be a marker that corresponds to the center of the probe. The mark on the probe matches the center marker on the screen, When the center marker on the screen is exactly over the center of the vein image, the mark on the probe is exactly over the center of the vein. Come back from the probe as far as the vein is deep in the patient's forearm, angle the catheter at a 45 ° angle to the patient's forearm, and insert the catheter in line with the mark on the probe. Make sure you are in line with the probe's marker and the patient's forearm and not angled to one side. It truly is a finesse operation. In time, it will become second nature. Believe it or not.

Never take your eyes off the screen once you are lined up and ready to insert. Taking your eyes off the screen to look down at the insertion site is the biggest mistake new ultrasound users make. No information is gained by taking your eyes off the screen, but much information is lost. When you are using an ultrasound machine to insert an IV, all the information that you need to insert an IV is on the screen. Once you look down at the insertion site and then back up on the screen, you have missed. It is almost impossible to reacquire the needle on the screen when you have taken your eyes away from the screen as a new user. Train yourself to not take your eyes from the screen.

As the needle tip pierces the vein, you will see the vein tent down then a white dot or white angular image will appear inside the vein (see Figure 3). At this point, you have pierced the vein; but again, do not look away from the screen, you still must advance the needle and catheter into the vein. Slightly move the probe forward until the image inside the vein almost disappears. It changes color from bright white to dull gray as the probe moves away from the needle tip, then hold the probe stationary and slightly advance the needle and catheter forward, making whatever adjustments it takes with the needle to keep the needle image in the center of the vein. Repeat this procedure of moving the probe slightly then the needle slightly until you feel confident you can advance the catheter the rest of the way in. You can absolutely insert the needle completely into the vein using this procedure. Once you feel confident you can insert the catheter all the way in, do so.

To verify you have a solid insertion, occlude the vein above the catheter, remove the needle and just ever so slightly release pressure and you will see blood back up into the catheter hub. Then re-occlude the vein, attach the pigtail or hub, and use the washcloth to clean all the excess gel from the patient's skin while you hold the catheter. Next, use alcohol swabs or chlorapreps around the cannulation site to ensure you reduce the bacterial load as much as possible. At this point, dress the IV site as you would any new IV. Don't forget to take the tourniquet off.

Things to Think About

New ultrasound users should practice inserting the needle and catheter all the way in before removing the needle. Nothing is worse than removing the needle too soon and then not being able to advance the catheter. Practice, Practice, Practice. Your technique will improve.

Practice using the ultrasound on patients that do not require an ultrasound-guided IV. Being able to see a patient's vein when you are learning the ultrasound technique is invaluable. Attempting to learn the ultrasound-guided technique on a patient that truly needs the technique is a recipe for disaster. You need to practice on patients with easily located veins first, to develop your targeting skills.

You can cannulate much smaller veins than you think you can. Become proficient in the ultrasound-guided technique and your days of not being able to acquire IV access almost go away, but you must practice and practice often. If you enjoy the feeling of helping patients; wait until you can gain access on almost any patient with one attempt.

People who claim to be "hard sticks" usually have veins that do not follow a straight path. Using the needle to insert the catheter completely makes hard sticks easy sticks.

Rarely will you need to use anything but an 18G catheter when using the ultrasound technique. This at first may seem bizarre or even insane, but if you examine a 22G or 20G catheter, they are just not that much smaller than an 18G. With the ultrasound machine, you can see how big the vein is and you will feel more confident using the 18G catheter. Using an 18G catheter ensures the patient can get any radiologic studies they need as well as blood transfusions or fluid resuscitations.

Longer catheters are your friend. The longer the catheter, the less chance the catheter will dislodge.

Patients with large arms with loose skin need to be reminded to keep their arms still. Catheters are secured to the skin, but nothing keeps the catheter in the vein while the skin is moving. Even long catheters will dislodge.

The more you practice with an ultrasound machine the better you will become. Hard sticks become fun challenges when you master the transverse ultrasound technique. YouTube has great videos on ultrasound IV insertions. Do not give up on yourself if you miss the first few times. Your brain is learning a new skill. It takes time to master, but it is so worth it in the end. Good Luck.

Figure 1


Figure 2


Figure 3


My name is Damon McGill ([email protected]). I have been an ICU and ED nurse for almost 15 years. For twelve of the fifteen years, I have been a travel nurse. Using the ultrasound machine to start difficult IVs is a game-changer for patient care.

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Specializes in Critical Care.

Please note: refer to state BON and facility policies before performing skill, some locations require additional education and/or supervised insertions prior to using this skill. 

Specializes in Emergency Room and ICU.

Always sage advice.

Specializes in Freelance Writer, Utilization Review RN Consultant.

Well-written.  I work in oncology and vein access for those patients without a port can be quite difficult.  Thank you. 

Specializes in ICU RN.

This is awesome! Thanks for this great info!

Thanks for the rundown. I’ve been interested in learning the techniques with ultrasound IV insertion, but limited with the policies on my unit.

Specializes in Education.

Very awesome, and thorough step-by-step guide. Thanks 

Specializes in New Critical care NP, Critical care, Med-surg, LTC.

Very well presented! I am much better at placing IVs with a ultrasound than by feel, it's just not a skill I developed. But being able to see the length of the catheter within the vein is a great confirmation. 

I've also used the ultrasound to figure out whether an IV already in place has infiltrated when patients are edematous and difficult to visually assess.

Specializes in CEN, Firefighter/Paramedic.

Excellent post, I do want to offer my own thoughts if I may.  

My own single biggest tip - When I first started ultrasound I was really terrible at it.  I made one quick change to my technique and have been crushing it ever since - find the tip of the needle as soon as you insert.  I know that sounds obvious, but I was inserting about 1/2" distal to the probe and then waiting on the tip to come into view.  By the time I found it, I was already in a bad position.  Either insert closer or bring the probe towards the catheter immediately after insertion.  From there, it's 1-2mm movements at a time - move the probe, then the catheter, follow it all the way into the vein.  Once you enter the vein, flatten your angle out just like a superficial IV, advance 2-3 more times while ensuring the bright glowy part is in the middle of the dark circle.  ***Never lose your tip.  If you do, stop moving the catheter around until you find it again***

I disagree with you on one point, which is not to look away from the screen prior to insertion.  I'm not sure how else you would verify that your insertion point is lined up with the centerline triangle on the probe and your angio is oriented correctly if not for a quick peek right before insertion.  I've found that if I make solid connection between my probe hand, the probe, and their arm, I can make a quick peek for insertion and then come right back up to the screen without moving a beat.

As for angio size, I honestly use 20 longs more than anything.  They're just more comfortable for the patient and more than adequate for 99% of the things we do with IVs.  Admittedly, we do have a few machines at work that 18s are much easier to see than 20s, but I always make sure the machine I like is stocked, charged, and nearby.

One final pearl of wisdom I've picked up - dealing with hardened veins.  Every now and again you'll encounter hardened veins (happens at all depths).  On the US, you'll swear you're in the vein but you won't have any blood return and the catheter won't advance, you'll probably even feel the entire angio pushing back at you when you're trying to advance it.  You can punch through with a little 1-2mm swift poke with higher pressure to push through those calcifications.

Overall, I've been starting IV's for 20 years out of the hospital setting but only about 6 months with ultrasound.  My ultrasound technique has come to the point now where if a person even mentions they're a hard stick, I'll take a quick look without the machine, but if I don't see anything I'll just go grab it.  It can be extremely slow and tedious at first, but now I can drop an US line in pretty quickly.


Great article, I love placing ultrasound guided IV's. That said, I do feel there are a couple things I've learned over the years that differ from the information above. 

1. Learn how to place ultrasound IV's standing up. Sitting down is great in theory, but sometimes you need an ultrasound IV in a hurry ( a few examples I've run into include, coding patients, patients who need pressers with no IV access waiting for an attending to come place a central line, patients who blew their four other PIV's and are hyperthermic (47+ degrees celsius, and posturing/close to seizure), and seizure patients who blow access and need the availability for medications), just to name a few. Knowing how to place these under pressure, and under less than ideal circumstances is a must. The hospital I was at had only 2-3 nurses trained on the machine, so I could be doing anywhere from 5-15 IV's a day in the PICU, ED, ICU, or floor. So, trust me it's important. 

2. Always watch the insertion of the needle, make sure that the second you break skin, you turn your attention to the monitor, but making sure you are lined up is crucial. The biggest mistake I see is nurses lining their needle and probe up on the patient, looking at the screen, then moving the probe/needle without noticing and inserting without actually being lined up. Then, we spend 5 minutes trying to locate the needle tip because we were so far off, and now we are not in line with the vessel. Once in the skin though, do not look at the insertion site.

3. As stated above, you can almost ALWAYS cannulate a vessel with a bigger IV than you think. While I love 18g for fluid resuscitation, blood, or pressor needs in a pinch. I also love a 20g for lab draws in a bigger vessel. 

Ultimately, I know that a lot of hospitals tend to "gate keep" this skill. I know I bothered my house supervisor about it until she finally let me sign up for the class, and eventually I was teaching the skill to nurses in the hospital. I was a firm believer that every nurse in critical areas (ED, ICU) needs to know this skill. 

Specializes in Ultrasound-guided Peripheral IV Insertion.

Your post was very educational and informative. I'm not a nurse or clinician, by the way. I was trained on how to insert IVs with US guidance in the Navy as a hospital corpsman. When I got out and started working as a PCT at George Washington University Hospital in D.C. I had the opportunity to perform this skill and became quite proficient at it. In a very short time, the hospital leadership allowed me to start training other PCTs, RNs, and even doctors. I dedicated a lot of my time both on-the-job and on my days off training people on how to insert USGPIVs. GWUH did not have an IV team. It was quite upsetting really. On top of my PCT duties, trying to juggle the 15 patients that were assigned to me, I was also called to insert USGPIVs throughout the hospital, even in the ED where they already had ER Techs and RNs who were trained to do them. It was very stressful but I truly loved it. On my days off I would come in and volunteer my VAD services. I would insert over 30 USGPIVs in a day sometimes. Unfortunately, I had to quit because of school. I work at the NIH Clinical Center now working in an outpatient medical oncology clinic as a PCT. Sadly, only RNs are allowed to insert USGPIVs here. Regardless of my training and background I'm not allowed to use an US machine to insert PIVs. I'm very good at conventional PIVs too. However, I have a greater passion for USGPIVs. I even bought my own Butterfly ultrasound probe that cost me over $3,000, out-of-pocket so that I could do my own insertions for my own patients, without my leadership knowing. I know it's wrong. However, our VAD/PICC team is always short staffed and the wait time varies from 20 minutes to 3 hours just a simple USGPIV. These patients need blood work, radiological studies, and chemotherapy all throughout the day. Waiting 3 hours is so wrong. So when I know that there's a wait time of over 1 hour I do the USGPIV myself. There is no greater reward when the patient is grateful and happy that there day doesn't have to end at 10PM. 

After I read your post I noticed some concerns and I addressed them below. I do hope I didn't offend you. Because I'm so passionate about US-guided PIV insertion, I have to help clarify somethings. For others reading this I hope this helps.

"If your body is contorted to see the screen and the patient, you are setting yourself up for failure. Do not put the machine on the other side of the bed. Ultrasound screens are just not that large, and you will miss subtle clues that appear on the screen.”

  • Although I might agree that some US screens are small, there are options on most US machines to zoom in on your target area of visualization. However, I do not agree with not putting the US machine on the other side of the bed. The ultimate goal is to keep your head and neck in a neutral and comfortable position. This is also dependent on the position of the patient's arm. You want to position your body to be in line with patient's arm, and more importantly, their vein. This helps to reduce awkward angles of insertion. If you place the US machine next to you on the same side of the bed that you are in, it is important to position the patient's arm to be in line with the machine as best as possible. Turning your neck even 10-15 degrees or more can cause discomfort if cannulation takes longer than expected. Neck strain is a major distraction and it could potentially jeopardize the success of the procedure.

"As an example, let's say the vein's center is one centimeter down from the top of the patient's forearm. Your insertion point for the catheter will be one centimeter back from the probe.”

  • This recommendation is not correct and inaccurate. The art of USGIV insertion involves math, specifically basic geometry. I'll use your example of the vein depth of 1cm. If you determine that the center of the vessel lumen is 1cm then you need to consider a few other important things that are crucial to ensuring swift cannulation after you puncture the skin: 
  1. What is your angle of insertion? This is dependent on two things: the depth of the vein and the length of the IV catheter you decide to use. For example, if your vein depth is 1cm, it's ideal to use a catheter needle that is at least 1.75in in length. To be honest, any vein that is 0.8cm (8mm) to 1.1cm deep, you need to use a catheter needle that is greater than or equal to 1.75in. Why? I'm sure you're familiar with the 45/50 rule for inserting PIVs. The ideal angle of insertion is 45 degrees. This will ensure that you get the optimal length of the catheter in the vein within a shorter distance. This is where the "50" part comes in. If you insert the catheter needle at about 45 degrees, then you should have 50% of the catheter remaining to be cannulated once you have reached the center of the vein lumen. This is only the end-result if you follow that 45/50 rule. The next important thing to consider is next.
  2. How far away from the edge of the probe do I insert the needle? You stated that if the vein is 1cm deep then you should insert the needle 1cm away from the probe. That is incorrect. It should be 0.5cm away from the probe. Why? You have to take into consideration that the image on the US screen is not being projected from the edge of the probe surface closest to you. In reality it's coming from the center of the probe surface. If you look at the probe surface on most US probes, the width is about 1cm. So, if the image is coming from the center of the probe which is 0.5cm from the edge of the probe closest to you, then that means you need to insert the needle 0.5cm away from the probe. I can guarantee that once you insert the needle at a 45 degree angle, and advance it slowly, you will see the needle tip start to tent the anterior side of the vein and eventually puncture the vein wall without moving the probe. I know what you may be thinking but it's true. However, this technique and mastery comes with a lot of practice. It took make at least 20 attempts (on a vein block) to ensure that my approximations were relatively accurate. However, this only applies if you're using a 45 degree angle of insertion. What about a 30 degree angle of insertion? Does the rule still apply? This brings up the next point.
  3. When is it appropriate to use an angle less than 45 degrees? In some cases, using a 45 degree angle may be disadvantageous. If the vein is actually shallow (<0.7 cm deep) then you run the risk of the catheter potentially "kinking"because the angle is too steep. I've noticed so many instances where after an USGPIV catheter had just been placed by someone earlier had, all of sudden, lost its patency and the RN could not flush it anymore or draw back blood. Over a few times after I would remove the PIV I would notice the actual kink in the catheter. When you remove a catheter you can tell a story of how it was inserted just by observing the way it's contorted. Catheters don't revert to their original state after you remove them from the patient's arm. They actually remain in the state they were in while in the patient's arm. What's impressive is you can tell the angle of insertion used and how much of the catheter was in the vein. No one is perfect. You cannot accurately insert a catheter needle at exactly 45 degrees unless you had a protractor or some needle guide that some US probes have as attachments to assist you. Some people who are proficient in USGPIV insertion with many years of experience are guilty of inserting catheters at "45 degrees" or even more without even realizing it. So this brings me to my point: what is the appropriate angle of insertion? Generally speaking, when using US guidance and cannulating veins that are deep enough to where conventional methods of insertion no longer work, the angle of insertion is quite relative and even dependent on the length of the catheter needle. My rule is never insert at an angle less than 30 degrees. This presents the next thing to consider.
  4. What's the best length of catheter to use to guarantee a successful cannulation and longer dwell time? As I mentioned earlier in #1 above, if the vein depth is 0.8cm to 1.1cm deep you need to use a catheter at least 1.75in in length or greater. The concepts above mentioned in #2 and #3 are based on the "Right Angle Method.” If you are not familiar with it the look it up on Google. This is the basic geometry I mentioned before. So, in the case of inserting a catheter at a 45 degree angle at a vein depth of 1cm, you need to insert 1cm away from the center of US probe surface. However, if you're inserting at a 30 degree angle, then you need to insert the catheter needle approximately 1.75cm away from the center of the US probe. This might seem odd especially if you haven't taken geometry in like 24 years like me. However, the numbers don't lie. The reason why this is important is because once you start to lower your angle of insertion before you insert the needle this will dictate the length of both time and catheter before you reach the center of the lumen. The more shallow the angle, the more catheter is "wasted" before reaching to vessel lumen. This is why it's extremely important to use a catheter that is long enough to be able to reach the vessel lumen (whether it's a 30 or 45 degree angle) and have at least 50% of its length within the vein. Once you go beyond 1.2cm in depth, you are limited on what angle you insert with and the length of catheter you can get away with. Some RNs (and even PCTs/LPNs/EMTs) overestimate the length of the catheter. When you think of how deep a vein actually is using US (especially using metrics) you tend to misjudge the catheter thinking it's long enough because we are so used to inches. I've seen some RNs that I have trained and who have been signed off on this skill to use a catheter that at the time they thought was long enough but it turned out to become dislodged. How though? Here's a good scenario: The patient is a 75 year old female with poor skin integrity. The vein is approximately 1cm (0.4in) deep and you only have a 1.25in catheter. Well, at first glance that seems perfect considering the parameters. So you insert the catheter at 45 degrees, as is customary. This means you need to insert 1cm away from the center of the probe based on the right angle method. You successfully cannulate the catheter, get amazing blood return in the catheter hub, and it flushes flawlessly. You dress it up, write the date and time of insertion on the dressing, and document. The patient decides to use the restroom after you're done and returns to her bed. The assigned RN comes into the room to start IV fluids. When she goes to flush the PIV before attaching the primary tubing she is met with resistance. She attempts all methods of troubleshooting the PIV and nothing works. What happened in a matter of 30 minutes after you just inserted the catheter using a fool proof method of using US guidance? You are called back and are told that the IV you inserted is no longer patent. Why? If you actually did the math you would realize that based on the parameters (45 degrees, 1cm depth, 1cm insertion from the center of the probe, and a 1.25in needle) you forgot one detail: the 50% rule. If you're using a 45 degree angle to insert for a vessel depth of 1cm, that means that you would have to "double" that depth in order to determine the length of catheter that is "wasted" before you even puncture the anterior wall of the vessel. So if the depth was 1cm, then that means you are going to waste 2cm (0.8in) of catheter before you enter the vein. If you do the math that means you only have about  36% of the total length of the 1.25in catheter within the vein which leaves 0.45in of catheter available. Had the patient never moved, literally catatonic, this scenario would be null. However, for most patients who require US guidance for IV insertion, you can guarantee that they are not your typical patient with ideal vasculature or great surrounding tissue integrity. The surrounding connective tissue around the vein you cannulated is not as it used to be when the patient was young. It's loose and shifty. This patient is ambulatory and has full ROM in her UEs. Again, no one is perfect. Let's say you thought your angle was 45 degrees but in all reality it was 40 degrees. Not a huge difference but with regard to catheter length it is quite significant. That means that less than 36% of the catheter was cannulated. This increases the risk of dislodgment and extravasation, as well as reducing dwell time. The catheter length is crucial to a successful cannulation!

"Taking your eyes off the screen to look down at the insertion site is the biggest mistake new ultrasound users make. No information is gained by taking your eyes off the screen, but much information is lost.”

  • I have to disagree with you on this to a degree. Yes, you should always keep your eyes on the US screen once you have punctured the skin wall. For most beginners, they have the tendency of gliding their probe a little too far from the insertion site. They don't tend to realize just how small of a distance it is when you're working with an US machine when trying to cannulate a vein. They're not familiar with the different techniques you can use when trying to capture the needle tip on the screen if they're lost. This leads them to take their eyes off the screen almost every time to gauge where they are at on the patient's arm. It's not necessarily a mistake but it can potentially cause confusion. However, by looking back at the insertion site, even for seasoned practitioners of US guidance, it's actually advantageous to do so because, if you're in doubt of where your needle tip is, it's imperative to reposition yourself and go back to where you started which requires you to look away from the screen. I have observed so many new US users that, for the life of them, cannot find the needle tip and fail to realize that they're literally 2-4 inches away from the insertion. Although in their training I tell them to not take their eyes off the screen, they can look at what they're doing to get themselves back in starting position if they are struggling to find the needle tip. With more experience you don't need to do that anymore since you know and feel that you've only gone a few centimeters away from the insertion site and, if necessary, you can put the probe literally up to the needle itself and start to glide the probe forward to find the tip, all without looking away from the screen. In some cases, which can happen to the best of us, we are so consumed with trying to search for the needle tip and don't realize that the probe is no longer perpendicular to the catheter itself. In the attempt to follow the pathway of the vein, we lose track of where we're initially at in the beginning. This inevitably requires both new and veteran US users to take their eyes off the screen to reposition themselves. Also, with new US users, they tend to advance too much of the needle not realizing that they've almost inserted the entire needle, having gone through the vein completely, and are even deeper than they anticipated. In this instance, they have to look away from the screen to see that. In contrast, some new US users are so conservative that the advance very little of the needle and they're nowhere near the vessel they're trying to cannulate. I have to tell my students to pause from the screen and look down. The last issue that requires you look away from the screen is the angle of insertion. For superficial veins (<0.5cm deep) you can get away with a shallow angle like 30 degrees. However, as you go deeper (>1.5 cm) the angle of insertion must remain constant if you intend to cannulate successfully within a reasonable amount of time. But this is not always the case. I have done hundreds of USGPIVs and I have caught myself lowering my initial angle of insertion due to fatigue and extended time. I remember I wasted over 30 minutes trying to find my needle tip and didn't realize that my angle had changed drastically. It wasn't until I look away from the screen to determine where I made the mistake. Much information would have been lost had I not looked away from the US screen.

"New ultrasound users should practice inserting the needle and catheter all the way in before removing the needle.”

  • This is not good practice, at all. Inserting the needle with the catheter all the way before removing the catheter is not realistic in most situations. We all know that veins never run completely straight. They can be torturous, bifurcate, narrow, or even end up in a valve. If you're using a short catheter (<1.25in) and you know the vein that you plan to cannulate is fairly straight with no twists or bifurcations then it's okay to advance the needle the entire way (if the angle of insertion permits it). However, 90% of cases are not like this. It's crucial that new US users are trained to inspect the entire length of the vessel they are considering before they cannulate. That should be a given in their training and practice. Once they do puncture the anterior vessel wall and see the needle tip within the lumen, I usually instruct my students to advance the catheter needle about 4-5mm before threading the catheter. The golden rule in this situation is to not remove or even move the position of the needle when threading the catheter, this also includes the angle of the needle. Once they feel that while threading the catheter there is no resistance and the entire catheter is advanced, it is save to remove the needle. One more caveat : check for blood return in the catheter hub before you even remove the needle. If, for instance, they thread the catheter but feel resistance, it is imperative that they not change the angle or position of their needle. This could lead the needle to puncture the catheter when the US user tries to retract the catheter over the needle. This only happens when the angle of the needle is changed and raised a slight bit. If you do want to advance the needle more than 5mm, then it's best to advance the needle and the probe together so that there is no doubt as to why the catheter didn't cannulate appropriately, but not the entire needle. That's not possible especially with deeper vessels.

"You can cannulate much smaller veins than you think you can.”

  • This is both true and false. What do you mean by "smaller" veins? I tell my students that if a vein is smaller than 0.3cm (3mm) in diameter do not attempt to cannulate unless you have a 24Ga catheter. There are not many manufacturers that make such a catheter for deep vein access. I only know of the Braun Introcan Safety Glide 24Ga x 2.5in catheter. Even trying to insert a 22Ga catheter in a vein with a diameter of less than 0.3cm is possible, however, you run the risk of thrombophlebitis. You have to remember that when you're visualizing the vessels on the US screen, they are all distended due to the tourniquet being on. Once you remove the tourniquet the vessels revert to their even smaller state. If you cannulate a smaller vein with a 22Ga you could risk the vessel integrity if you don't assess the vessel diameter appropriately. Research dictates that you use a catheter that is 1/3 the diameter of the vessel you plan to cannulate. So if the vessel is 0.3cm in diameter, then the catheter needs to be less than 0.1cm (1mm) in diameter. A 22Ga catheter's outer diameter (O.D.) is about 0.9mm. Now this may seem appropriate enough since 0.9mm is smaller than 1mm. However, this could lead to thrombophlebitis which is very painful for the patient. Please be very careful when you decide to cannulate "smaller" veins. Assess all veins thoroughly before you decide on a specific catheter gauge. I tell my students that if the vessel diameter is less than 0.45cm it is safe to use a 20Ga or smaller. If it is greater than 0.45cm then you can use a 18Ga or smaller. If you need a large bore catheter greater than an 18Ga, the vessel diameter must be greater than 0.7cm to prevent occlusion or thrombophlebitis. 

"Rarely will you need to use anything but an 18G catheter when using the ultrasound technique. This at first may seem bizarre or even insane, but if you examine a 22G or 20G catheter, they are just not that much smaller than an 18G.”

  • For years I only used 18Ga catheters for deeper veins since, in the major of "healthy" patients, their veins are much larger as you go deeper and more proximal to the axillary vein. This was before I knew about 1/3 rule. An 18Ga catheter's O.D. is about 1.3mm, a 20Ga is ~1.1mm, 22Ga is ~0.9mm, and a 24Ga is ~0.7mm. Unless you know the exact diameter of vessel using the measuring tools on some US machines, it is safer to cannulate using a smaller bore unless the vessel is obviously 1cm in diameter just by visualizing it on the screen. If you're attempting to stick an athlete with amazing deep veins with the diameter of a #2 pencil, then use caution and be conservative in your discernment. Patients with cancer, ESRD, or sickle cell crisis don't have the luxury of getting an 18Ga catheter or even a 20Ga. Unless the patient needs large volumes of blood transfused at a fast rate or have a surgery, please refrain from using large bore catheters unless they're clinically indicated. We must always keep the vessel integrity in mind, always. 

"Using an 18G catheter ensures the patient can get any radiologic studies they need as well as blood transfusions or fluid resuscitations.”

  • This is no longer true. Most radiological studies can use a 20Ga catheter. The same applies for trauma, routine/rapid blood transfusions and routine/rapid fluid resuscitation. Again, if you're using US guidance make sure the vessel is greater than 0.7cm in diameter for anything greater than an 18Ga, if it is clinically indicated. Also, make sure your facility carries large bore catheters that are 2 inches or more. Only a small few manufacturers produce 14Ga and 16Ga catheters over 2 inches in length.

"Longer catheters are your friend. The longer the catheter, the less chance the catheter will dislodge.”

  • This is not always true. I've inserted catheters that are 2.5in length in vessels as deep as 1.5cm in the UA and have dislodged. With vessels this deep and deeper, the only angle to use is 45 degrees. In every case, more than 50% of the catheter dwells within the vessel at that angle of insertion with a length of 2.5in. For a very long time, inserting 18Ga x 2.5in catheters in almost all my patients, I noticed a lot of their USGPIVs became dislodged within 24 hours of placement. Before I even leave the room, I switch to the longitudinal plane view to ensure that at least 50% of the catheter is within the vein. In every single case it is. However, in my many cases they become dislodged. I figured it out eventually. I now know that if the patient's UA has a lot of loose skin the chances of dislodgment increase significantly. If I observe that the patient has a lot of loose skin above the AC, I do not attempt to cannulate. It's futile. This will only discredit your skills and reputation. Do your best to assess the entire arm before you attempt to insert an IV anywhere above the AC. If it is deeper than 1.2cm deep, have a midline or PICC line placed instead.

"Patients with large arms with loose skin need to be reminded to keep their arms still.”

  • This is wrong and inappropriate on so many levels. This is an utter inconvenience for the patient. The point I mention right before this remedies this problem. Do not insert an IV into a large arm with loose skin. Obviously, not the entire arm has loose skin. In almost all cases, the forearm and AC have decent skin integrity, even if the UA has very loose skin, especially in a patient who has had massive weight loss. Avoid those areas. The likelihood that the PIV will not dislodge is highly unlikely. The patient shouldn't have to not move their arm or keep it still. Spend more time assessing all vessels in both arms. If you fail to find anything call the PICC team. 

The most important thing to know, and the most obvious, is to familiarize yourself with the superficial and deeper anatomy of the UEs. Not only should you tell the difference from an artery to a vein, you should also discern what a nerve looks like on US. The median nerve of the upper arm is very distinct if you have an US machine with great resolution. It appears as a small "honeycomb" on the screen. It can sometimes blend in with the surrounding tissue if you don't have a good quality US machine. However, not only should you assess the veins and their pathways, you should also assess nerves in the upper arms and forearms. The last thing you want to do is pierce through a nerve while trying to cannulate a vein. It's extremely painful and there is no going back once you make that mistake. Patients do not forget. Please be careful.

Thank you and good luck!

Specializes in Emergency Room and ICU.

Mr. Ortiz,

I enjoyed reading your response. You are obviously patient about patient care. I will have to disagree with your comments. After you have worked for almost two decades as a trauma nurse, let's talk.

Best regards,