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Lower GI Bleed Embolization Procedure Walkthrough

Author Thomas "T.J." Turner covers Lower GI Bleed Embolization Procedure Walkthrough on BackTable VI

Thomas "T.J." Turner • May 5, 2024 • 136 hits

A lower gastrointestinal (GI) bleed case can prove challenging even for a seasoned interventional radiologist. From aberrant anatomy to the decision to intervene at all, confidence in handling these tricky cases can translate into other skill sets in the angio suite. In this article, Dr. Aaron Fritts and Dr. Kevin Henseler break down what to look for in pre-procedural imaging, choice of embolic, and how to handle the dreaded ghost bleed.

This article features transcripts for the BackTable Podcast. We’ve provided the highlight reel here, and you can listen to the full podcast below.

The BackTable Brief

• Computed Tomography Angiography (CTA) is crucial in the workup of lower GI bleeds to identify the vascular territory involved, especially given that initial angiography may not always reveal the bleed.

• Coils are the preferred embolic agent for lower GI bleeds due to their safety profile, minimizing the risk of ischemia and other complications. The use of glue (cyanoacrylate) is recognized but requires specific expertise due to risks such as catheter adhesion.

• Sometimes the suspected bleed may be hard to visualize once the patient is on the table. The decision to use nitroglycerin to induce vasodilation should be made with careful consideration of support services and available resources.

• The choice of techniques and embolics is influenced by the operator’s comfort and experience with the modalities, as well as the resources and support available at the institution.

Lower GI Bleed Embolization Procedure Walkthrough

Table of Contents

(1) Working Up a Lower GI Bleed: Pre-Procedure Imaging & Planning

(2) Access & Catheter Selection for Lower GI Bleed Embolization

(3) Artery Selection & Angiography in Lower GI Bleed Embolization

(4) Ghost Bleed: Tips for Finding the Bleed Intraprocedurally

(5) Intro to Embolization Devices for GI Bleeding

Working Up a Lower GI Bleed: Pre-Procedure Imaging & Planning

In the management of lower GI bleeds, computed tomography angiography (CTA) plays a pivotal role, particularly in hemodynamically stable patients. CTA allows for good characterization of the vascular bed, thereby guiding catheter placement for potential embolization and improving procedural efficiency by reducing the time required for selective catheterization. This approach is supported even in emergent situations, underscoring the negligible time cost relative to the significant benefits in procedural accuracy and speed. Furthermore, CTA is a reliable tool in helping to rule out active bleeding. In patients with suspected GI bleeds, accurate and timely information transfer between healthcare providers is important, and decisions to intervene should be based on the most recent and direct observations of patient status.

[Dr. Aaron Fritts]
My next question is, in your workup, walk us through your lower GI embo workup pre-procedure imaging, are you pushing for a CTA? Does it depend on the time of day?

[Dr. Kevin Henseler]
When I think about lower GI bleeds, again, this tend to be patients that are generally more hemodynamically stable. They're often patients who have had a scope or who come into the ER, and have had some bloody stools and maybe have some soft vital signs. In those cases, I really do want to get a CTA because I think it's really important that I know the vascular territory because often your first couple of angio runs, you're not going to see the bleed. If you know where to go, you can get your catheter out much further.

For me what I like to do is a much more aggressive hand injection, and I will often blow whatever clot there was that kept me from seeing the bleeding away if I know where it is. In our practice, almost everyone in the lower GI bleed is going to get a CTA. I can't think of many reasons even if they're crashing. Our IR suite is next to the CT scanner and the extra five minutes it takes to get that information really probably saves me three times that in trying to sub-select.

[Dr. Aaron Fritts]
That's true.

[Dr. Kevin Henseler]
For my standpoint, the CTA is important. I think one of the things that is important, again, a pearl that I would give is the custody of information is really important in these cases because you'll often get a call from the GI PA who will say, "Yes, this person is bleeding." The nurse called and said, "They're bleeding." We've scoped them and we couldn't find a bleeding. When you actually talk to the closest person to the patient which is often the nurse, they'll say, "Yes, they had some bloody stools three hours ago, like 4:00 AM." It's hand-off in nursing rounds and it's 8:00 AM and they get that, and so then they call the GI service and say, "He's bleeding overnight."

I think one of the things to do is to always be sure what the value of the information you're getting because sometimes it's very old information. The other thing I like about the CTA is that, for me, if the CTA is negative, I'm not doing an angio because I think the overall likelihood of a positive angiogram is going to be very, very small. The difficulty with that is when they have GI bleeding, you get the CTA. If it's negative, and then the next day they're bleeding again, then what do you do? You keep on getting the CTAs. Do you just say, "I'm just going to do the angio and try to figure out what's going on." I think that's on a per-patient basis that you-- Depends upon the time of the day where things are.
I think the CTA is incredibly valuable, and I think there would be very rare instances that I didn't use all the information I could possibly get, and that's a really valuable piece of information.

[Dr. Aaron Fritts]
The tricky thing for me with the CTA is that you get the CTA, and it will be negative, and then the GI doc still stops by, the department's like, "Hey, they're still bleeding." It might even be right after the CTA. You're like, "I don't see anything." So you don't know. Was that just a little blood that was in their bowel that they just pooped out for the CTA.

That's where it gets tricky and that's where we tend to say, "Okay, let's do another H and H. Let's trend it. As long as their vital signs are stable, let's just wait and watch."

That was the case with that case I was talking about last week is the GI doc was really pushing us to do something and we're like, "It's a surgical anastomosis. We don't want to embolize unless we absolutely have to."

Listen to the Full Podcast

New Innovations in Lower GI Bleed Embolization with Dr. Kevin Henseler on the BackTable VI Podcast)
Ep 321 New Innovations in Lower GI Bleed Embolization with Dr. Kevin Henseler
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Access & Catheter Selection for Lower GI Bleed Embolization

In the case of lower GI bleed embolization, the choice and manipulation of catheters are critical to achieving optimal outcomes. Typically, a Glide Sim catheter is employed for its ability to navigate distally into the ileocolic artery, facilitating precise and aggressive injections necessary to identify the bleeding site. This is often supplemented by a larger microcatheter to ensure adequate vessel distention. A Bentson wire is used to engage the vessel initially, followed by the deployment of a Glidewire to reach the target area adequately. Access for these procedures predominantly utilizes the femoral approach, given the relative ease and familiarity among operators. While radial access may be considered by clinicians trained extensively in its use, the femoral route remains preferred for its practicality and effectiveness, especially in emergent, non-cooperative patient scenarios.

[Dr. Kevin Henseler]
The other thing that I think is helpful from a pearl's standpoint is, at least for me, for most of these, I'm going to use a Glide Sim catheter. I can get that Glide Sim catheter all into the ileocolic artery if I want to. I can get it really, really far out, and getting a 5 French catheter really far out gets you a really, really good injection. If you can't do that, then a larger microcatheter because I think it's really critical that you distend that vessel that is the target vessel because you're going to miss the bleed if you're not giving that a relatively aggressive injection.

[Dr. Aaron Fritts]
That was my next question is approach. It sounds like if you're using a Sim, then it's probably femoral.

[Dr. Kevin Henseler]

[Dr. Aaron Fritts]
Are you ever doing radial approach for GI bleeds?

[Dr. Kevin Henseler]
Not really. The way that I look at it, first of all, I don't do a lot of PVD in my practice. I think you got to do enough radial access that you're good at it, and I have in an awful lot of experience in the groin and not as much in the wrist, and so I'm just as comfortable in the groin than the wrist. Now, you appear something like that, wrist access may be something to consider. In these patients, they're flailing around. I don't see that as a great case for a wrist unless you are incredibly-- If you're really, really fast eye with radial access, you go at it. Again, if you're new, these patients tend not to be cooperating very well. I think that groin access is just fine.

[Dr. Aaron Fritts]
Yes. That tends to be the case. The people I know who approach this with radial are people who-- That was just part of their training. They did a lot of radial – like, Sinai or some place like that, and so they're just as comfortable with radial as they are with femoral. I'm not because I didn't do a lot of radial in training. Like you said, femoral is how I'm use to done pretty much every GI bleed femoral. It wouldn't make any sense for me to go radial unless there was just such a crazy angle. I couldn't get anything, and the patient's really dire straits. Then I might try it from above.

You mentioned your catheter of choice. You said Glidewire as well? Is that what you're typically using to get access?

[Dr. Kevin Henseler]
I would start with the Bentson just to get into the vessel and get it engaged, and then I would get my Glidewire quite a ways out into the vascular arcade so that I can get my as distal as I think I need it to be.

Artery Selection & Angiography in Lower GI Bleed Embolization

In the management of lower GI bleeds localized to the superior mesenteric artery (SMA) territory via CTA, efforts should be made to minimize vessel manipulation to reduce risk of vascular dissection. A direct approach is employed when SMA involvement is confirmed, typically bypassing further exploration of the inferior mesenteric artery (IMA) unless specific clinical indications or accidental engagement suggest otherwise. Given the frequent anatomical constraints and the low probability of active bleeding in the IMA, additional diagnostic efforts in this vessel are generally unwarranted. This selective approach highlights the significance of effective pre-procedural imaging and situational awareness, including familiarity with patient-specific vascular anatomy to optimize intervention strategies. Hand injections are recommended for diagnostic imaging to maintain control over contrast media delivery and to accommodate patient variability in respiratory movement, enhancing procedural efficacy and safety.

[Dr. Aaron Fritts]
Yes, so assuming that you know where the source is, it's a SMA territory. Let's say you accidentally pop an IMA, are you going to do an IMA run if you know it's SMA territory on the CTA?

[Dr. Kevin Henseler]
That's a good question. It depends upon which way the coin flips whether it's a head or a tail. If I see the bleed on CT and it's an SMA bleed, and I find the bleed and I embolize it. The textbook would tell you, "Well, you still need to do your celiac and your IMA run." Sometimes I forget to read the textbook and I might just say that's fine. If it slips into the IMA, absolutely. I'm going to do that without a question, or if I'm concerned or there's been something else going on with a patient that makes me think that we should check for something else. Generally, my rule of thumb is get out of the vessel as soon as you can. I don't like screwing around inside the vessels.

The next thing you're going to do is you're going to dissect the IMA trying to get into it, and you haven't done anybody any good.

[Dr. Aaron Fritts]
Even worse.

[Dr. Kevin Henseler]
Right, so I tend to try to minimize the time that I spend in the vessels, and generally wouldn't as a matter of course look at every single vessel unless there's an indication.

[Dr. Aaron Fritts]
I totally agree. As you know, most of these patients with the lower GI bleeds are elderly and their IMA is minuscule or just completely occluded already. It just doesn't make it sense even to try because on the CTA, it doesn't look like you are going to get in with any catheter especially if you see it on the SMA and like you said, it's coiled is done like should just get out of there, I think.

[Dr. Kevin Henseler]
One of the things I think that you bring up is also don't underestimate the value of that CTA. Sometimes, especially when it's two in the morning, you're at home, you turn on your computer, you see the bleed, you call your team, you go in and you can forget to look what the iliacs look like. What does the femoral look like? Which side are you going to be going on? Is there a replaced right hepatic? If you're doing, if you're going to do a middle colic embolization so that you know where your anatomy is.

Certainly, take time to look at those other things. Don't just say, "Okay, there's a positive GI bleed, I'm going to go in," because you can end up wishing you had spent 30 seconds reviewing everything before you go in.

[Dr. Aaron Fritts]
Like you said, the CTA is a diagnostic exam that you just got 30 minutes before. If there's no bleed in the IMA distribution, then why are you mucking around with it? Just because we are trained that way or hardware that way. From training, it doesn't make any sense practically and it can hurt the patient.

[Dr. Kevin Henseler]
I would even say that part of that is that when I trained, you had to look at all those vessels because we didn't have. We had to find the bleeding and so you weren't ever sure where the bleeding was, so you had to find anything. Now it's a different world.

[Dr. Aaron Fritts]
Real quick question, what is your typical injection rate for the SMA?

[Dr. Kevin Henseler]
I do hand injections for all of these. Again, it's a time in the vessel. I feel very comfortable doing that. I can control it so I'm not stepping out and doing power injections.

[Dr. Aaron Fritts]
Got it. Are you trying to get them to hold their breath to reduce that respiratory motion?

[Dr. Kevin Henseler]
Actually, generally not. I think that holding their breath, they tend to move around more when they're holding their breath, and then halfway through your run, they take a big huge breath out, and then you've screwed. I just let them be who they are, especially when they're under some sedation. They're generally not taking really big deep breaths. I think another thing that trainees can always remember is glucagon is your friend, if especially big GI bleeds, there often is hypermobility of the bowel. If you need to give a little bit of glucagon, I think that's just as helpful as trying to do breath holds and then you've got that bowel at least reasonably hexed in place for a few minutes as you're doing some runs.

Again, I'm a minimalist from that standpoint and try to just let the patient breathe shallow breaths like they're doing normally.

[Dr. Aaron Fritts]
That's a good tip. That's a great tip.

[Dr. Kevin Henseler]
To end that is also always remember looking at these runs. Look at them subtracted and unsubtracted. Every single one of these runs you should be looking at both of them just to make sure you're not getting faked out and also that you're not missing anything.

[Dr. Aaron Fritts]
On that, we've talked about this before in the show. I was always trained to take your gloves off, go out and sit down in the control room and look at the proper images instead of trying to stand there and look through your fogged-up glasses. I know you mentioned that you like to make it speedy. Let's keep the case going, get it in and out as fast as possible. What's your take on that?

[Dr. Kevin Henseler]
My take is, my advice would be that before you are done, you should take your gloves off and look at everything. Especially if you've had a negative angiogram. I think that's important. I'm doing everything in the suite. I'm not taking my gloves off and I'm not going back and looking. I think the other thing that again is a pearl for trainees is you often have people standing next to you who have been doing this for 20 years. I always say, does anyone see anything? 75% of the time people will say, "Hey, yes, yes, I see something." You're like, "Okay, no, that's not that, that's something different."

Then you're looking at it and you're walking through it and you're making sure that that's in fact not it, but 25% or 10% of the time someone's going to say, "I see that." You look at it and you're like, "Oh yes, maybe that is something and you might do another obliquity or do something else." It's a good time to be humble when you're in these cases and ask for help. Your techs have lots of experience and they're not perfect and they don't have the knowledge base that you have, but they have eyeballs and experience and so use that.

Ghost Bleed: Tips for Finding the Bleed Intraprocedurally

When conventional imaging fails to localize a lower GI bleed source, interventional radiologists may consider the use of nitroglycerin to induce vasodilation and potentially reveal occult bleeding sites. This approach is favored due to its reversibility and low risk, especially appropriate in hemodynamically stable patients where vasospasm may obscure the bleed. The decision to use such an intervention, however, is contingent on careful evaluation of the clinical scenario and available support systems. For instance, practitioners in less equipped facilities or those without immediate surgical backup may opt for more conservative measures to avoid complications like uncontrollable bleeding or the need for emergent surgical interventions.

[Dr. Aaron Fritts]
Yes, you're right. They have seen many of GI bleeds, sometimes they've seen a lot more than you have and it is good to have, like you said, an extra pair of eyeballs looking through those images. What happens if you don't see a bleed? Do you ever do anything provocative? We've done episodes talking about that before. I know it's a new thing, but–

[Dr. Kevin Henseler]
I would be on the wimpy end of that spectrum. I'm certainly not going to put TPA in heparin. I would consider in situations and I've done it a couple of times, I like it because you can reverse it if you need to or if all of a sudden you've got five bleeding sources and you're getting overwhelmed. One thing that I think is helpful is nitroglycerin. These vessels often are again, have vasospasm when they're bleeding. If you have a negative and you really know where it is, so nitroglycerin could go a long way to opening the vessel and seeing that bleed. That's a fairly low-risk medication to be giving a patient and that's as long as their pressures are okay.

[Dr. Aaron Fritts]
Yes, with a short half-life. Yes, that I'm on the whimpy side too. I can't go do what Sabeen does with the TPA and everything. It just nitros as far as I've gone and I think I agree with you, it should help open up those vessels. Only in the case where the CTA shows, there's something in that area that I'd be like, "Okay, let's put some nitro in here," and especially if they're hypertensive, those vessels are going to clamp down.

[Dr. Kevin Henseler]
One of the things also I think when you having that calculus is where are you? Because a lot of these, oh, I'd like to say you bloom where you grow. I'm in a outer-rim hospital that's a pretty good size. It's almost 500-bed hospital. Our general surgeons are good, but they don't want this patient crashing because you gave them TPA and you can't control the bleeding or there's multiple sources and you're going to burn bridges doing that.

Whereas if you're in an academic center and you've got the chief surgical resident sitting outside the window and giving you the thumbs up to do that, that's just a completely different place to do it. You've got to be careful where you are and what support you have and you don't want to be a cowboy and then have a bunch of people look at you and say, "Look what you made me do. I know I had to open this guy's belly and I don't know where the bleeding is and I'm going to do a hemicolectomy and he's going to get an ostomy and you haven't really helped anybody."

Intro to Embolization Devices for GI Bleeding

In the treatment of lower GI bleeds, coils remain the go-to embolization device of choice due to their reliability and lower risk of complications such as ischemia or end-organ damage. This preference is contrasted with the use of particulate embolics, which can raise concerns about inducing ischemic damage to the colon. The use of cyanoacrylate glue as an embolic agent is acknowledged as effective but requires specific expertise and careful handling to avoid complications like catheter adhesion. Detachable coils and straightforward coil applications may be especially effective in cases where access to the target vessel is optimal, allowing for quick and efficient embolization.

[Dr. Aaron Fritts]
Let's get into the meat of it in terms of embolization devices, we've talked a fair amount previously on the show about detachable coils. We've talked about glue, actually Ziv Haskal was on the show talking about glue and you're going to help talk about new product that's soon to be on the market, but at first before we get into the new stuff, I want you to tell me what's been your traditional go-to embolization device for lower GI bleeds?

[Dr. Kevin Henseler]
Clearly coils. You hear or you see some research about particles which makes me cringe because I'm just so concerned about end-organ damage of the colon and causing ischemia. For me, it's always coils. Glue, I'm not a gluer, it's interesting when I went through fellowship, that was the time where people were gluing catheters in place and so glue was very, very high risk. We just didn't do very much glue. I think as Ziv said, I listened to that, if you have any desire to do glue, you should, by all means, listen to it. I must listen. I think he's right. It's not to be trifled with.

If you have glue in your training and you are very comfortable with glue, I would work hard to keep that skill set up because once you lose it or if you didn't get it, getting the experience with glue is a very, very tough road. If you've got it, try to keep it. If you don't have it, you got to be careful about trying to learn with glue because it's very operator dependent. There's a lot of variability. What dilution am I going to use? Am I going to have glue stuck on the end of the catheter that's going to embolize, God forbid am I going to glue my catheter in place? I tend not to use glue. For me, a lower GI bleed is a coil, a coil, and a coil. That's really all I'm going to use.

[Dr. Aaron Fritts]
Detachable, like you said before with the upper GI.

[Dr. Kevin Henseler]
Although there are times where when you are, if you can get very, very far out into the vasa recta, I'll put in just like a–

[Dr. Aaron Fritts]
Two millimeter Hilal or something.

[Dr. Kevin Henseler]
Two millimeters straight coil. Those are great cases and you're done and you're out.

[Dr. Aaron Fritts]
I love those, those are my favorite, those little and you can just shoot them in with a little syringe. Let's talk a little bit about this new embolization product that's coming on the market here shortly called Obsidio. Just give our audience a little bit of background about the product and how you became involved with it.

Podcast Contributors

Dr. Kevin Henseler discusses New Innovations in Lower GI Bleed Embolization on the BackTable 321 Podcast

Dr. Kevin Henseler

Dr. Kevin Henseler is an interventional radiologist with Midwest Radiology in St. Paul, Minnesota.

Dr. Aaron Fritts discusses New Innovations in Lower GI Bleed Embolization on the BackTable 321 Podcast

Dr. Aaron Fritts

Dr. Aaron Fritts is a Co-Founder of BackTable and a practicing interventional radiologist in Dallas, Texas.

Cite This Podcast

BackTable, LLC (Producer). (2023, May 12). Ep. 321 – New Innovations in Lower GI Bleed Embolization [Audio podcast]. Retrieved from

Disclaimer: The Materials available on are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.



New Innovations in Lower GI Bleed Embolization with Dr. Kevin Henseler on the BackTable VI Podcast)


Obsidio Embolic in Lower GI Bleeds: Applications & Advantages

Obsidio Embolic in Lower GI Bleeds: Applications & Advantages


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