Podcast: Diagnosing Foreign Body Obstructions via Radiography & Ultrasonography with Dr. Seitz

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In this episode, host Alyssa Watson, DVM, talks to Marc Seitz, DVM, DACVR, DABVP, about his recent Clinician’s Brief articles, “Diagnosing Foreign Body Obstructions via Radiography” and “Diagnosing Foreign Body Obstructions via Ultrasonography.” Dr. Seitz shares excellent advice on how to use radiography to the fullest—even if it means getting a wooden spoon or carbonated beverage—and how to apply point-of-care ultrasound at the general practice level.

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Episode Transcript

This podcast recording represents the opinions of Dr. Watson and Dr. Seitz. Content, including the transcript, is presented for discussion purposes and should not be taken as medical advice. No guarantee is given regarding the accuracy of any statements or opinions made on the podcast. The transcript—which was prepared with the assistance of artificial intelligence—is provided as a service to our audience.

Dr. Watson [00:00:07] Welcome back, everyone, to Clinician's Brief: The Podcast, where we bring you in-depth conversations with the experts behind all of your favorite Clinician's Brief content. I'm the host of this program, Dr. Alyssa Watson. And today I am delighted to welcome Dr. Marc Seitz, an accomplished author and the recipient of the Zoetis Distinguished Veterinary Teaching Award. He's making his first appearance on today's podcast, but he has been on some other podcasts before, so I'm excited for this conversation today. Our focus is going to revolve around a really critical aspect in general practice and that is the utilization of radiography as well as ultrasonography when we're trying to identify gastrointestinal foreign bodies. Dr. Seitz is an associate clinical professor of diagnostic imaging at Mississippi State University. So I don't think there's really anyone better to guide us through this conversation. How are you doing today, Dr. Seitz? Thank you so much for coming on the program.

Dr. Seitz [00:01:04] Oh Alyssa, I am delightful today. I am down in Mississippi, so we're already into shorts weather at least this week, and we're just enjoying it.

Dr. Watson [00:01:13] I am in Vegas, and so also, we're definitely moving into our spring season. And it's nice to be outside in shorts and a t-shirt again.

Dr. Seitz [00:01:24] It is. Thank you, Groundhog.

Dr. Watson [00:01:29] So we have a ton to talk about today. But before we do that if you could just give us just a quick bio, introduce yourself to the audience.

Dr. Seitz [00:01:40] I would love to, so I am proud to be a Bulldog. I graduated from Mississippi State in 2007, and afterwards, I honestly had aspirations of practice ownership and going into private practice. So I worked with some phenomenal colleagues in Atlanta, Georgia for three years in GP, but I was also dabbling my toe in the emergency waters, and the emergency bug bit me bad. When we moved up to Philadelphia, or the Greater Philly area, for my wife to go to grad school, I decided to give full time ER a try, and oh my goodness, it was such a great fit for me. I am a bit of a sensation seeker, as my wife has pointed out, I love adrenaline, and so it is just wonderful, the caseload, the people, loved it. And all that time I was doing tons of ultrasound. Obviously, you know, obstructions are something we see a lot in both GP and ER But because of that ultrasound theme, as my ER career continued, it took me about ten full years, but I finally embrace the dark side and realize, you know what? Diagnostic imaging has all the things I love about ER just compressed and actually got to embrace other loves like physics. And, after taking a little bit of a career risk and doing a mid-career residency, I'm now a boarded-radiologist. But when I write and teach, I try to write and teach from the perspective of the caseload that I experienced, and I try to deliver things that, you know, I wanted and would have helped me out when I was on the clinic floor.

Dr. Watson [00:03:10] I absolutely love that. And, you know, it's one of the things that we try to do at Clinician's Brief as well, bring this really practical approach to these things that you're seeing in GP all the time. And I'm in general practice. And so, when I was getting ready for this episode, I was really kind of reflecting on my career. I was a little bit ahead of you. Not not too far, but I graduated in 2003 from Iowa State. And I, back then, I mean, we didn't really have digital radiography, you know, so I wasn't dipping films, we had a machine that processed them, at least. But, there has been just this huge shift in my practice career. Well, I, I've been practicing about the speed with which you can take X-rays and being able to, you know, digitally send them someplace else to have someone else look at them. And that has been a real game changer. But I love the fact that you are so passionate about having people look and interpret at their, their own films, because I think that that is a huge skill that I do not want to see lost. And so why do you think everybody should be able to do this? Everybody should be able to look at in an abdominal radiograph and evaluate it for signs of obstruction?

Dr. Seitz [00:04:36] Yeah. So I'll start with the heart I think at the heart I don't want to see the role the general practitioner change in veterinary medicine. It's one of the things I'm proud of. And I guess what I'm hinting at when we look at the human model, things have gotten very fractured. And I think that art of taking care of the patient as a whole patient gets lost. And so my my main motivation is actually I love in, in medicine that general practitioners, and this is a guideline that give students are empowered to treat, diagnose and treat 80%, 90% of what walks in their door. And so as my imaging part of that, I tell my students flat out, my goal is that you can leave here and not leave me 80%, 90% of the time and only come get me when it's really challenging. And then we both get to have some fun. What I don't want is to create students and veterinarians who are dependent on me because honestly, there are not enough radiologists to go around, and telemedicine is on a huge backlog. So the the more important though part is we've got a patient in front of us. And that patient, especially for some of these more emergent things, needs intervention. And we know the sooner we intervene and fix them, the better the outcome. So if I can train vets who are already out, as well as students to be self-sufficient, everybody benefits. They feel good, the pet gets better faster, less money is spent. Hospitalizing rather than just send it out. Yeah, there might be a stat read in a few hours, but you're waiting. Or maybe it's a few days and you're waiting. So I think it benefits us, the patient, and just keeps a case moving forward.

Dr. Watson [00:06:16] Yeah. I think and we're going to talk a little bit about, you know, radiographic signs as well as some tricks and hacks we can do with positioning, you know, as well as some of these radiographic techniques. But also I think just knowing when you need to do those, being able to look at the film and say, oh, it would really benefit me to take a different view here. You know, because I've seen that happen in general practice where, like you said, you take the x rays, you send them out, and then several hours later or the next day, you get something back from a radiologist that says, oh, I really would have liked to have this view. Or wouldn't it have been great if you had done a contrast study? So.

Dr. Seitz [00:06:55] Right, right, I agree.

Dr. Watson [00:06:58] So now that we have established why this is such a really important diagnostic skill, let's talk a little bit about abdominal radiographs when you suspect a GI foreign body. So there are definitely other causes of, of mechanical obstruction. So what, what other conditions, you know, besides GI, foreign bodies can, can cause obstruction, either mechanical or functional, of the GI tract.

Dr. Seitz [00:07:28] Yeah that's a great question. So by and large foreign body is the most common. And for me my brain is such that I like to compartmentalize because it helps me remember detail. So when I think about this, it's probably like a lot of us were taught or a lot of us think about it. But if we think of the GI tract like plumbing, you can clog the pipe up, you can make the pipe thicker or you can compress the pipe. And so when we look at causes the main intraluminal causes, you know, plug in the pipe are going to be foreign bodies, potentially a mass growing into the lumen. And then intussusceptions, trichobezoar, I kind of think of like a foreign body, but some people consider that separate. Those would be intraluminal causes. When we think a mural, we get into, unfortunately, infiltrative of diseases, we think of, infectious diseases down in the South, we see a lot of fungal disease and Pythium. And then, unfortunately, cancer as patients get older, and we can have cancers that grow completely mural and compress or grow a mass off of and destroys wall layering and clogs stuff up. And then finally, least common are going to be that extraluminal compression. But again in the South we see a lot of trauma. So one thing I see probably most often is bowel getting entrapped, through a hernia of some sort, or even entrapped inside, like through mesenteric rent or around a GTV site or something of that nature. So granted, there are zebras out there in the sense that much less common. But those are the common things that we see on the clinic floor. And I'd say of those foreign bodies, intussusceptions, infiltrative disease, cancer and infections are going to be most common.

Dr. Watson [00:09:06] Okay. You do recommend three view abdominal survey films. You know, and this is something that's also changed a little bit over my career. We we always did two view. And then I remember when we were starting to talk about, oh from, you know, met check in the thorax, you really need that third view. But now I think it's really standard to do these three view abdominal rads as well. But you had mentioned something, in the article that I hadn't heard before, and that it's actually the order that you take them in is important. Could you expand on that a little bit?

Dr. Seitz [00:09:41] Yeah. So what I'd like to stress is that at the end of the day, let's get some rads. And, you know, a paramount importance is that left lateral projection, that's going to be, by and large, our most important projection when evaluating for a foreign body. In fact, I'm so passionate about that. When you look at all the things we could be looking for in rads, there's only a single condition that's common that would necessitate a right lateral and that's a GDV. So, yeah, I recommend three view, but if you're in a clinic that still unfortunately charges for two view, swap your left in for your right. Now, getting directly into your question, the order I am in the camp that I want to see gas go into as many places as I can that a foreign body could live. And the reason for that gas is this free, negative contrast agent that can outline foreign bodies that might otherwise be invisible, and blending in with the fluid and food that's in our intestines. So, for example, in that left lateral gas goes into the pylorus. So you can see a pyloric outflow obstruction. But if you start with that left lateral and then you move him into V/D, you've trapped gas in the pylorus. It then moves into the duodenum. And then in right lateral it goes even more toward the duodenum. What you do in about 70% of these dogs is you force gas into the duodenum, and it won't be a lot, but you'll see this little gas stripe on your V/D going down the body wall. And even on your lateral, you can now see where the duodenum is located. And I find this as a huge advantage because once you know where it is. And two, if there's a foreign body, it will kind of outline it and form a meniscus sign of sort or at least sign some margin, outline some margin of it. And if there's no foreign body, you have the comfort of saying, all right, I definitively see an empty pylorus. I definitively see gas in the duodenum. I know there's no foreign body there. And you to check that off your list.

Dr. Watson [00:11:36] Excellent. I love using things that are free.

Dr. Seitz [00:11:40] Yes, I do too.

Dr. Watson [00:11:44] So there are kind of three really common patterns, that we will see with obstructive foreign bodies. Can you can you walk us through those?

Dr. Seitz [00:11:53] Absolutely. So when when we're looking at what to look for in radiographs, I very much take a checklist approach. I come from a background where checklists were very emphasized. Aviation. I was the, the idiot jumping out of the planes. I didn't fly them. But, checklists keep us safe, and I find I bring that into my imaging and that you, of course, want to look at rads and get this global perspective and not miss anything and read the whole film. But studies have actually shown you're more accurate if you look at your rads with a clinical question. So very much, if you palpate something abnormal and there's painful bowel and it's a two year old lab, it's okay to say, is there an obstruction here, and do I see a foreign body? So now when we look at our rads there are three obstructions. And they create these three distinct patterns and granted more than one can occur at a time. But the first pattern is a pyloric obstruction. Something gets lodged in the pylorus. With that we will see gastric dilation that varies in size. All right. And ideally we're looking for the foreign body itself inside the pylorus. The second is going to be a small bowel obstruction characterized by that segmental dilation that we talk about two populations of bowel where something stuck in the small bowel. So what's behind it. Or orad gets dilated with gas and fluid or and then beyond that toward the colon is normal. And then the third is going to be that dreaded linear foreign body which I will give you is tough to diagnose sometimes, but we're looking for that bowel to plicate like we know it does. So pyloric obstruction, small bowel obstruction, plication, and then occasionally you're unlucky enough anchors in the pylorus causing an obstruction with linear foreign body. Right. So you can start to combine them a little bit.

Dr. Watson [00:13:39] Sure. How does the degree like partial versus a full obstruction or the chronicity, how long it's been going on affect those radiographic signs that we're going to see?

Dr. Seitz [00:13:51] That is a great question, a lot actually. So let's let's compare and contrast acute versus chronic and look at it in the various places with an acute obstruction. Sometimes stuff hasn't had enough time to dilate. So if it's per acute like a couple hours the pattern can be deceptively normal, especially pyloric obstructions. A lot of times I've seen a foreign body watch in the pylorus and the stomach is completely normal, so we actually coach our students. You can't use a normal stomach size to rule out a pyloric obstruction. You have to look in that pylorus. Same thing. If you do have gastric dilation and that animal vomits, they evacuate that gas and fluid. And so it may reduce the stomach back to its normal size, specific to the stomach. With acute obstruction they tend to be gas dilated with chronic they tend to be fluid dilated. The small bowel. That doesn't really apply unfortunately. And then of course with acute or linear foreign body friends, it just may not have had enough time to plicate yet. So now we go to chronic. We kind of hinted the big thing with chronic. When you have a chronic obstruction of the stomach, you'll get fluid dilation. You'll also sometimes get this fun little sign called a gravel sign, where food isn't getting out and it starts to solidify and mineralized. And you get this mineral opaque, granular or gravel looking material at the pyloric outflow track. We can see this with small bowel obstruction, too, especially with neoplasms that grow really, slow because you start getting food stuck there. But some stuff is getting by and it just starts to pack in and solidify, and it's really gross. Curiously, with small bowel obstructions other than the size of them, there really isn't a good fluid versus gas difference between them. So chronic small bowel obstructions can be a little bit challenging sometimes.

Dr. Watson [00:15:45] Okay. And then how useful do you really feel like those when we're talking about those small bowel obstructions? When how useful do you feel those ratio calculations are? You know, I've seen them been taught that intestinal diameter. Compare it to the vertebra. And it seems like I've seen a couple of different formulas over the years.

Dr. Seitz [00:16:06] Yeah. So this is what's really fun. We're in this really fun realm in radiology. If I can give a global perspective, if you can think of something in the body, we figured out a way as radiologists to measure it. And we've done a study on it. All right. So to be fair, because there's been some good studies when you look at the multiple and I mean over half a dozen studies measuring bowel in various ways, they they are decently accurate depending on where you put your cutoff in sensitivity and specificity for diagnosing obstruction or ruling it out. What's really interesting, though, a phenomenal author did a meta analysis of every measurement, and I won't quote the exact numbers. But in short, the majority of measurements we measure in radiology did not increase the accuracy of the person reading and making the diagnosis. So the way I kind of teach it to students is, all right, we're going to teach you this. It's a tool. But at the end of the day, your your ability as a doctor to look at the history, the exam, your radiographs and make a call is most of the time as accurate, if not more accurate than a single number that you measure on the screen. It just so me personally as a radiologist rarely use them, occasionally use them to teach a student or prove a point. But most of the time I look at it, make my call and move on. And there there's been some significant evidence to demonstrate we are actually as accurate, if not more. Or said another way, the numbers don't make us more accurate.

Dr. Watson [00:17:42] Sure, absolutely. That's some very good advice. Thank you. Yeah. Let's move on and discuss a couple of those techniques we kind of hinted at earlier because there's, you know, looking back, I've even had some cases recently where I was like, gosh, I wish I would have thought to do that, especially when we're talking about free air. So can you talk a little bit, about, you know, a technique like, pneumocolonography? How is that performed? What clinical scenarios would you be using that for?

Dr. Seitz [00:18:16] Oh, I love it. It's actually one of my favorite little MacGyver hacks. This goes in the MacGyver medicine you can charge is as little or as much as you want for the technique. So when we look at kind of the the old fashioned radiology way, we would, you know, distend it a whole lot, do barium enema, yada, yada, yada. Let's put that aside for a minute. So when would you do a pneumocolonogram? The primary indication to do it is when you have either seen a foreign body and you can't tell if it's in the small bowel or colon, or if you've seen a dilated loop and you're trying to decide, is that loop colon/cecum, or am I dealing with segmental small bowel dilation that would support going in? Because we got to remember, we don't always have to see the foreign body to get a green light to cut. If I have segmental dilation that is indicative of an obstruction, I'm telling a surgeon to go in. Or when I was in private practice, it was me going in. I didn't have to see the foreign body. So, I've had a lot of fun cases where there's a rock on the left side of the abdomen on your V/D, and you play the game. Is this in descending colon, or is the rock and small bowel one will pass, the other needs cut or same thing? Is that real gas dilute a little loop cecum or is it small bowel? So what we would do is take a red rubber catheter, and base it based on the size of the dog. Bigger is always better. Lubricate it. We're going to insert it and we're going to give about 1 to 3. I usually start at three, three mil per kg of air. I've seen people report doses up to 20 mil per kg. Do not use this dose. It will overfill the bowel and create segmental dilation, which is what we're looking for now. By starting at three. You may need to repeat it a couple times, but I'd much rather you serial serially. Fill the bowel, fill the colon, then accidentally fill half the jejunum. And then you can't take it out of the animal. So you're going to insert your red rubber. Usually they don't need sedation, but you can always give a little bit of tor, valuim, etc.. You're going to inject free air. All right. It doesn't have to be sterile. It's going into the colon. And then remove hands out of the beam and immediately take your film. Take your lateral, take your V/D. Then you're then going to look if you can see gas going up the colon all the way around to the cecum, then you're done. The studies done. If the gas goes halfway up and you haven't filled it all, then repeat it until you get the effect. The goal is to fill gas to the cecum. By doing that, you'll now know definitively where colon is, and you'll be able to see of a foreign bodies in it. Or is that bowel loop small bowel or is it colon? If that the weird loop went away then it was probably colon cecum.

Dr. Watson [00:21:00] Okay. Yeah. And you actually preemptively answered one of my questions because I have also seen, references where they're using. Yeah, four times as much air as that. And so this is in order to get, you know, a better indication of where the colon is, not so much because more air is going to be dangerous to the patient, right?

Dr. Seitz [00:21:21] No, no, that's just it. The big the big thing is inconvenience. I've seen people get away with that amount, but I've also seen them overfill and give segmental dilation. And then they're sitting there going oh my gosh I've gas dilated a small bowel. If you want to split the difference you could start with five. You know, I don't see a lot of patients get overfilled with five. That would be reasonable to do as well. Five mil per kg of just gas. And then one, one tip I actually. Yeah, of just air. I love to leave the red rubber catheter in because sometimes they, pass gas pass the gas back out. And, at least if the red rubber's in there, you know how far it's in, you can see at least that portion of the colon. So it's just a little pro tip as well.

Dr. Watson [00:22:05] Excellent. We love those little pearls. So let's talk about a pneumogastrogram. This is something where. Yeah, this was really, really neat. So the describe this for our audience. I've never done this. I'm waiting for a case to use it on now, and I've got my carbonated beverage. I'm gonna. Do you have Liquid Death in Mississippi?

Dr. Seitz [00:22:32] Wait, what is liquid death? I'm not familiar with this term.

Dr. Watson [00:22:35] It. It's just carbonated water. They sell it. So I'm in Vegas. They sell it all over Vegas, and it looks like it should be some horrible alcoholic beverage, but it's just carbonated water.

Dr. Seitz [00:22:47] Oh, that's really funny. I'm sure we have it. I'm a pretty vanilla guy sometimes, so I've got my official 40 ounce of just tap water. So. But no, we probably do. So you could use that. But, where this technique comes in handy is if you go to take your left lateral projection and there's insufficient gas in the stomach to outline the pylorus, you, you may have suspicion of pyloric outflow obstruction. You want to fill it up to see if you can see a foreign body. And so I actually want to give a shout out to, I first learned about this technique, not as a radiologist. I learned it my first year in private practice from my first boss. And she came to me and said, hey, we're going to do this on this patient. And I looked at her like she had three heads. And I'm like, what? What? And I didn't know it. Looking back, she had she was up to date with the literature because the articles from JAAHA and she always read the literature and, she was just practicing an up to date medicine. So historically we've done pneumogastrograms by sedating the patient, placing a tube, and instilling 10 to 20 mil per kg of air. But to a general practitioner, that's a lot to note or that's a lot. You may even have to intubate them to do that, you know, to protect from reflux. So what somebody's geniusly figure it out. What do you do when you drink a soda often? You burp. So we're going to use the power of carbonation and we're going to feed carbonated beverage. And it's funny the doses that's reported isn't per body weight. It's just I think 60 mils. Not all animals take that. So I kind of say 30 to 60, maybe 30 for smaller, 60 for bigger. And you're going to get it in the dog much the way you would give charcoal. And what I mean by that, if you put charcoal in front of a golden retriever, they're going to lap it up. Chihuahua, they're not going to eat the most delicious steak sandwich in the world. You have to, like, feed it to them, right. So, however you would give charcoal, that's how you want to get it in. People ask me, oh, do you ever like tube it? I mean, you can, but I just I try to avoid that if I can, but either syringe it in or let them lap it up. But as soon as they drink that carbonated beverage, make certain it's non caffeinated, right. So we're looking sprite,, 7UP or the water you listed.

Dr. Watson [00:24:59] Liquid death.

Dr. Seitz [00:25:00] As soon as, liquid death, get it in them. And then immediately put them in left lateral and take a radiograph. You can then turn them V/D and take it. If there wasn't enough repeat it. it I won't you know, pass it off as magic there times it doesn't work. But there are times it's actually made the difference of me sending the animal to scope to surgery versus saying, nope, we're fine and never having to go to ultrasound, which I love ultrasound. But if I can save that money toward treatment, I feel like I've done the owner a better service.

Dr. Watson [00:25:33] Excellent. Yeah, it's really neat trick. I can't wait to use it. I have used when where I've used carbonated beverages is. I have used them a couple times to unclog, like a gastroesophageal tube, that has got clogged. And that that bubbles for some reason helps, helps clear that tube. So. But I'm excited to try it.

Dr. Seitz [00:25:55] Exactly. Oh, no. What I was going to say hopefully what I hope people are here and and we'll talk about the last one. But I am a huge fan of maximizing diagnostic yield. And so for all these like at state, we include these as part of the original study. But if you need to you charge 50-100 whatever. But you're still far cheaper than an ultrasound. And I really do feel people are forgetting how helpful radiographs can be. And you know, I've made the point. I would say the majority of our obstructions at state are made on rads, and I really don't think it's just because we're radiologists. It's because we've got all these tips and tricks we pull out. And if we need ultrasound, sure. But most of the time we can look at the rads and move on with our life. It's it's wonderful. That's what I like to empower vets to do, because not everybody has ultrasound. We can talk about ultrasound and I love it. But man, maximize your rads. They're wonderful, especially with digital radiography.

Dr. Watson [00:26:49] Right. Yeah. And and we will talk about ultrasound today after the break. But last thing before we go to break. Compression radiography. So this is one. This is. Yeah, I do have a range of wooden spoons and spatulas sitting, you know, in, in my radiology department. So.

Dr. Seitz [00:27:10] Yeah, I love it. I love it. So yeah, this is going to be a technique. Wood compression is going to be a technique when you're looking at your bowel and you see bowel collected together bunching possibly plicated. And what we're trying to differentiate in really obese animals or sometimes just normal cats, they they love to do this. They will just naturally their bowel will lay in the right lateral abdomen. And you look at them and you think, why is that happening? And so you're trying to differentiate is there a linear foreign body or is this normal bunching. When that is the case you pull out your wood spoon. And like you we have several. We break them every once in a while. But you're going to take a wooden spoon. And the key is it has to be wooden. I've unfortunately I don't know if you've done this. I've seen people grab metal and then you can't see anything. So wood spoon and with a leaded, you want to wear your lead. Because you're now touching the patient, getting scattered radiation, you're going to push down at the spot where the bowel is collecting. That's usually mid abdomen. And you're just going to have somebody push down with hand out of the primary beam, but with a lead glove holding. And then make your exposure. The x rays are able to pass through the wood. You'll see a little outline of it. But what it's going to do is push the bowel away. So if the bowel is free to move and it's normal, it pushes out of the way. But if there's a plicated linear foreign body, especially at the duodenum, the plications will stay there and they'll be right under the wooden spoon. And you're going to do this in both a lateral and V/D, even though it's not the topic. It's also very useful for pyometras, for pushing lightly and I mean lightly in the caudal abdomen. So you don't rupture the pyo to displace the small bowel cranially so that you can see the dilated tubes go in the you, you know uterine body and the uterine horns going to that space between colon and urinary bladder.

Dr. Watson [00:29:02] That's another great tip. Thank you.

Dr. Seitz [00:29:05] You're welcome.

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Dr. Watson [00:30:01] Okay, we're back from our break. Let's switch gears a little bit and let's go ahead and talk about ultrasonography. Because there was a, in your article, there was a sentence that I found a little bit surprising. You said that ultrasonography can diagnose small intestinal mechanical obstruction with greater accuracy than radiography, but we just finished saying that you generally, diagnose most of your foreign bodies with radiography. So can you clarify that statement a little bit? Are you talking about only, a boarded radiologists such as yourself or, you know, talk us, talk us through that statement a little bit more.

Dr. Seitz [00:30:43] Absolutely. So this is where I think it's important to know what we're studying when we study and report these results. All right. So the this the the couple studies that have been done and there have been several they have absolutely established that ultrasound is more accurate for diagnosing small bowel obstructions and linear foreign bodies than, than radiography. And I think already we need to recognize the terminology we used. I did not say pyloric obstruction. I said small bowel and linear foreign body. Okay. And the other is we have to recognize, depending on the study done, some of them are going to have a selection bias. Oftentimes the ones going on to ultrasound are harder ones that were equivocal on rads. Now there have been some studies that have said, nope, we're going to do both on everything. And those are a little bit better to look at. But also a lot of them are done in academia. Those are usually going to be more challenging cases that a GP may be did not address. So there's all sorts there. So the perspective I think we have to take when that animal comes in, we don't know if they're obstructed or not. And if they have a very obvious metal or mineral foreign body boom, it's off the table. You're going to see it immediately. So I love rads first for several reasons. One, if there's a foreign body there that's metal or mineral or gas. So even ping pong balls show up. Great. You're going to see it. You're done. You know there's a foreign body there. Now you're just matching the pattern with it. The the second thing is that gas is the enemy of ultrasound. And so in those dogs that are really obstructed, I mean severe pyloric obstruction, that's really gas dilated. You're actually often going to see that easier on rads than you ever will in ultrasound. Because when you look at a stomach with ultrasound, you see that near field border, that wall and then it shadows and you see nothing underneath. And so I've seen instances where foreign bodies and gastric masses were missed on ultrasound that were very, very obvious to see on radiographs. So on one hand, yes, ultrasound is more accurate for small bowel stuff because it's easier to get to and see. But on the other hand, a dog doesn't come in with a post-it note that says I have a small bowel obstruction. It just comes in vomiting and you don't know. Is it not obstructed? Is it a big tumor? Is it a GDV? Is it septic peritonitis? Is it a gastric pyloric outflow obstruction? Is it linear? So because of that just vast array of what it could be. Start with your rads and move on. But you move on with confidence that if radiographs don't answer that question, which they do 70% of the time, they don't answer the question, you're in that 30% of patients. Ultrasound is a better next step. That's probably going to yield you an answer. For small bowel it's like 97% accurate. But notice I didn't say 100, 1 out of 30 patients. You will make the wrong call. And that's a boarded radiologist. It's a little scary to think about it that way, but if you see if I'm up obstructions, you're still going to have a negative explore.

Dr. Watson [00:33:49] Yeah. I think, when I was in school, they said, if you don't have a negative explore once in a while, you're not doing enough of them. So. But that was before we had all these other wonderful imaging modalities.

Dr. Seitz [00:34:02] Yeah. Yeah. But Alyssa to to jump on that. I still agree with that. I do hear sometimes young surgeons, residents, doctors say, oh, with all this technology you should never have a negative explore. And I want to remind people some seminal studies that when when you look at how much ultrasound and surgery agree or let me look the another way disagree, they will disagree about 25% of the time. And the the tissues most likely to be wrong are GI tract and liver. Like we have to recognize the limitations of ultrasound. So from that perspective, I truly believe surgery is the most accurate diagnostic test we have. And oh by the way, it's treatment. So if we're looking at our ultrasound and it's not giving us the answer, we think but the patient is screaming cut me. Sometimes you just need to cut them and get in there.

Dr. Watson [00:34:56] Yeah, absolutely. I thank you for that. And I think it's great advice, you know, to a lot of especially, you know, newer grads or maybe somebody that's never had a negative explore. I've definitely had a few negative explorers in my career and and sometimes they're just necessary. So, let's talk a little bit. So I sometimes get confused about all the different terms there are out there, like point of care ultrasound and, and fast scans and focused scans. And can you just describe your technique when you're performing a point of care ultrasound on the GI tract.

Dr. Seitz [00:35:34] Yeah. So let's make it simple. We're undergoing a lot of terminology change because mainly driven by human medicine, we're realizing that the nature and how we do these scans has changed the terminology that most of us are familiar with is FAST, which stands for Focus Assessment with sonography for trauma. And people have expanded this for triage and tracking, which is great. But at the end of the day, I love what they've embraced in human medicine. It's point of care or bedside or cage side. So point of care, you're next to the patient. And I think honestly that that captures that a little bit better. So I prefer point of care ultrasound or focus exams. But for the audience they're all the same thing. So the standardized technique that's been validated in veterinary medicine based on humans is a four point technique. And again, terminology is vastly reported. There are different words reported for the four sites. I'm going to use what I kind of love which are easier to remember, but I'll give both. First location is going to be the subxiphoid, also called the diaphragmatico hepatic. The second is going to be the paralumbar or the flank, also called the splenorenal. Third is going to be the bladder, also called the cystocolic. And then the fourth is going to be on midline or just off it if they're on their side. I call it the umbilicus, but it's also called the hepatarenal. But it's kind of misnamed now because we don't look for liver and we don't look for right kidney when you're down there.

Dr. Watson [00:37:00] And then what is the classic ultrasound appearance of the majority of GI foreign bodies?

Dr. Seitz [00:37:06] Yeah. So since we're seguing out of point of care, one of the things I want to, I guess, drive home is that point of care has a strong role for suspected obstructions to look for abnormal fluid, that could be associated with gastric perforation and septic peritonitis. It's also pretty accurate at diagnosing free gas to date, unfortunately. Point of care has not been validated to accurately diagnose obstructions. And I know I'll hear people go, oh, well, I'm an emergency clinician and I diagnose with point care all the time. You're not doing point of care anymore. You're doing a limited single organ diagnostic ultrasound. So we may get there. We may develop a three, 4 or 5 point system to look for an obstruction. But at this time I do like to think of them separate. So when we look at diagnostic ultrasounds, ability to find an obstruction, here's the good news. You're looking for the same thing that we just talked about on rads. You're just seeing it in a different way. You're seeing the cross-sectional anatomy. So for the pyloric outflow track you're able to see the actual pyloric outflow track. And you're looking for structure in it. You're looking for is the stomach big. If it's gas filled it's just it's going to be big and push stuff around. You'll only see one wall layer of it. Then you get to pylorus and you're looking for a structure in it for, small bowel obstruction. You're looking for bowel loops that are big and filled with fluid and gas and ones that are not. And then most of the time you can find the foreign body and where it transitions from dilation to normal. For linear, you're looking for plication with the hyperchoic cloth ribbon, something going through it. And often they anchor in the pylorus. The big difference is on radiographs we can see the opacity of the structure. If it's bone, it's it's mineral, opaque, etc. on foreign body the really confuse or ultrasound. The thing that confuses a lot of people is that most foreign bodies are going to be less visible, meaning because there's a change in in tissue density, in the speed of sound, you will see a hyperchoic surface and then shadowing, you won't see the complete foreign body, you only see the surface of it. So if you're in the pyloric outflow track and you see a curvilinear hyperchoic line with the shadow, that's probably a bowl or toy. Occasionally we get lucky. Some foreign bodies, like potatoes, transmit sound, so you'll see the whole thing. Or a squeaker toy filled with gastric fluid. It will transmit and you'll see the whole thing. Big wads of meat. I've seen animals like, swallow like a whole steak, and it obstructs, you'll see through that. But most of the time you're looking for surface and shadowing below it. Clean shadowing usually, unless it has gas and it'll be a dirty shadow.

Dr. Watson [00:39:50] Okay when you have something in the pylorus. Are there any positioning tricks that you can use in order to help better visualize that area with your ultrasound?

Dr. Seitz [00:40:01] Yeah. So let's start with how most people probably scan, which is an animal laying on their back right there in dorsal recumbent. See. And you're approaching the pylorus from subxiphoid in, in a lot of bigger dogs you will not see the pylorus from subxiphoid. So the next trick is to come around to the right lateral body wall and do, an intercostal approach in transverse. I'll play around in this area, I would say 95% of the time if I didn't see it from subxiphoid I will see it intercostally. It's wonderful. You can also see pancreatic body vessels, gallbladder and all sorts of other stuff from this intercostal approach as well. In the rare dog where you still can't see it and it will happen, then you let gravity be your friend and the rule is put them in any position you can try. I will then take them out of dorsal and I'll put them in left lateral so their right side is up and sometimes body and fundus will fall away and pylorus is there. Then if that doesn't work I stand them up and I try an intercostal approach and try my subxiphoid. So sometimes I oblique them and I do 45. So the big thing is just keep moving. Know that that's the benefit of ultrasound. You're you can change things real time and watch how it changes on your screen. So start on their back. Move to left lateral. Stand them up. You're really not going to put them in right lateral because in the pylorus is down. But try all three of those positions and then you finally give up and hopefully you haven't. But if you're truly worried about the pylorus and you haven't gotten rads, go get your left lateral projection. Hopefully you did that, but if not, go get your left lateral.

Dr. Watson [00:41:41] And then we spoke a little bit before the break about you. You talked about the usefulness and really the limitations of those calculations of intestinal diameter when we're talking about radiography. Are there more predictive measurements that can be obtained when we're using our ultrasound?

Dr. Seitz [00:42:01] Yes, yes. So this is again, this number that I'm going to give you is based on a single study to my knowledge. I don't know if anybody's replicated, but in the study that sort of established that ultrasound was really accurate, like 97% and more accurate than rads. What they found is that when small bowel diameter exceeded 1.5cm, regardless of body weight, it was highly predictive of small bowel obstruction. Now there are a couple of keys to this, right? One, it has to be segmental dilation. I have seen dogs that are diffusely dilated and it's just really bad functional ileus. And it goes just above that cutoff. All right. Two. It's just a number, right? If I have a Great Dane in there, 1.6 and nothing else is really checking a box, I may ignore it. If it's a cat and it's 1.4 and it's horribly segmental dilated, I may count it. So where that where that number can be helpful is that if you don't see a foreign body because it's hiding somewhere, you can still make the call of presumptive obstruction. If you see segmental dilation where the segmental dilated loops are greater than 1.5. And for those in our audience who may not ultrasound a lot, just make certain you're measuring true diameter, which is measured serosa to serosa. A lot of us are used to measuring thickness, which is lumen to serosa. That's only half of it. This number is referring to serosa to serosa, a full diameter measurement.

Dr. Watson [00:43:34] That's a really important distinction. Thank you. And then you kind of alluded to this a little bit earlier. But when you were talking about how plication, you know, looks, how those linear form bodies look, but do you is there a very reliable way to really distinguish plication just from normal peristalsis when we're looking with our ultrasound?

Dr. Seitz [00:43:56] Great question. So let's talk about peristalsis versus corrugation versus plication. And let's reverse that order. All right for a minute plication which is what we're all concerned about is where you have that abnormal bunching together. And the big thing that is going to look different is the serosal margin is going to tightly undulate. You're going to get these really, really tight hairpin turns and it's going to go back forth, back and forth, back forth. Sometimes they plicates so bad it actually gets hard to distinguish where the bowels ending and beginning. It can look like a mess. But the big key is the serosa is involved with the undulation. You see undulation to the serosal margin itself. When we compare that to corrugation, corrugation is irritation of the bowel that forms an undulate surface, but it's undulate along the mucosal margin and the lumen. You know the serosa we find this intact. So you have this nice straight hyperechoic serosa and undulating mucus and submucosa. So it's going to be corrugation just normal peristalsis are going to be these nice relaxed curves. And that's the key. They're relaxed. They're not really really tight together. And the other key they're going to move. So if you hold your transducer on it the the peristalsis will change to another location. And then you'll be left with this straight segment again.

Dr. Watson [00:45:20] Wonderful. So that kind of brings me towards the end of the questions that I had. You know, regarding radiography as well as ultrasonography when looking at foreign bodies, this has been, highly, highly educational. And I'm excited to try some of these techniques. You did talk a little bit about how ultrasound is, you know, takes longer and definitely is more expensive, you know, compared to standard abdominal radiography. So do you. As just before we wrap up, is there really any scenario where it's more practical to jump straight to an ultrasound and skip those radiographs, or do you really always want those radiographs done first?

Dr. Seitz [00:46:09] No, that's actually an excellent point. The one reliable, situation where you can get a free pass to skip is if you've done point of care or physical exam and you know, there's a tremendous amount of free fluid in that bowely. Even just with our puppies, I still like rads because often you see some serosal detail, especially with digital radiography, and you can still see that gas pattern and you get to appreciate stomach, etc.. The other is, if your word, your obstruction with your peritoneal fusion is chronic and may be of a neoplastic etiology or an infectious etiology. In those cases, we'll we'll go ahead and skip, because at the heart of it, we don't think it's going to be a valued study. It's not going to provide us information that helps move the case along. The other situation, I think it's important to comment on if you diagnosed obstruction on your rads. Is there a reason to do an ultrasound? And I see confusion over this. I'll have patients where, you know, well-meaning vet, they'll make the diagnosis, they'll say obstructed needs ultrasound. And I would say in most situations, if you confidently make the call on radiographs and you are fairly confident a foreign body go in, you do not need an ultrasound. This situation where you may need an ultrasound is the older patient. And you are concerned that there might be something worse causing it other than a foreign body, for example, cancer. And the owner's like, you know what? If you find a big tumor, I don't want it cut out. In those situations, I think it's a very fair to ultrasound, even if we know the answer, to give the owner of the best information, to make the best decision for their pet.

Dr. Watson [00:47:55] That is an excellent, excellent point. I have definitely seen some older animals, that have come in with foreign body because they've had pica, because they feel bad because of their cancer. And that happened to me more than once in my career. And, and so that's a good point to keep in mind when you're faced with those, patients that, you know, like you said, or maybe a little older, never, ever had a history of chewing up toys or anything like that when they were younger.

Dr. Seitz [00:48:24] Yeah. And, Alyssa, I do want to stress, I know there will be audience members who are phenomenal ultrasound and they will, you know, probably come in or write, hey, I go straight to ultrasound and I'm great at it. And for those situations, wonderful. I will have radiologists colleagues who say the same and I'll say wonderful. Again, the perspective, hopefully everybody's hearing. I'm working from the perspective of the average general practitioner who has none to moderate ultrasound experience, and also the average situation where ultrasound is 3 to 4 times as much as radiographs, or let's just say 2 to 3 times, where radiographs still have a very valuable role and can help a lot of patients without moving on. But are there going to be situations where maybe I wouldn't do an ultrasound and somebody would, and the pet still gets treated 100%, and that's the art and beauty of veterinary medicine. So if you're jumping straight to ultrasound, it's working great for you. We we still at state directs first because we've been going straight to ultrasound and I just I love being able to save clients money. I do.

Dr. Watson [00:49:30] Excellent. Well, before I let you go, then there's just one more thing that we do at the end of our episodes, we play a little game. It's kind of a series of would you rather questions. It's just for fun. Do you want to play it?

Dr. Seitz [00:49:45] Yes. I am more than happy. I bet you're going to quiz me. And I was going to get intimidated.

Dr. Watson [00:49:52] Now we're done with the highly intellectual things. This is just for fun.

Dr. Seitz [00:49:57] I love it. What's ironic? My daughter is eight, and she's playing this game a lot at the dinner table. So we play would you rather on a weekly basis. So this will be fun.

Dr. Watson [00:50:06] oh, my gosh, you're going to be a natural. Well, let's get started. If you were setting up a practice on a remote desert island and you could only bring one, would you bring your x ray machine or would you bring your ultrasound?

Dr. Seitz [00:50:19] 100% radiographs.

Dr. Watson [00:50:22] All right. Excellent. if you had a place, would you rather place an IV in a dehydrated kitten or in an obese basset hound?

Dr. Seitz [00:50:39] I'm actually going to go dehydrated kitten. Does it does it count if I like to go intraosseous?

Dr. Watson [00:50:48] Intraosseous? I knew you were going to say that. Yes. Because your an ER clinician I knew you, no you have to place a peripheral iv.

Dr. Seitz [00:50:57] Obese, obese basset, and we're just going to pull out our ultrasound guide it that way. Yeah. I've got a cheat. Either way, I'm cheating. I'm either going to.

Dr. Watson [00:51:07] You are a cheater.

Dr. Watson [00:51:13] Okay. If you had to swap places with one of your students for the day, would you rather be a freshman and sit in lectures all day? Or would you rather be an upperclassmen on the overnight ICU rotation?

Dr. Seitz [00:51:26] Oh, easy for me. Overnight ICU. Believe it or not, though, I'm a nerd. So close second, I do love my my lectures. But you said ICU, so I'm going for it. If you had said another specialty, and I'm not going to name it because I want to get in trouble, I would have picked lecture.

Dr. Watson [00:51:45] Okay. We won't get anybody in trouble today.

Dr. Seitz [00:51:49] Don't get me in trouble.

Dr. Watson [00:51:52] If they could both rate you on Yelp, would you rather you get a review from your last feline patient or from your last canine patient?

Dr. Seitz [00:52:01] Oh, like the actual patient. I'm going to go, my last feline patient. Because my last canine patient was a non-cooperative Chihuahua who did not like me. So I think the feline would have been a lot happier with me.

Dr. Watson [00:52:24] Here, Chihuahua is, like ten out of ten do not recommend.

Dr. Seitz [00:52:27] It did not want it's echocardiogram. And it very much objected and needed sedated after, some struggle time.

Dr. Watson [00:52:36] Poor baby. Okay. Well, actually that's great. That's perfect for our last question. So. Okay, last question. This is the most important. So I want you to give us some thought. If if a centaur came into you and was complaining of exercise intolerance, would you ultrasound the human heart? Or would you ultrasound the heart in the, horse's thorax?

Dr. Seitz [00:52:58] I am going to go with the human heart because, equine cardiac disease is very uncommon, and I would argue, much less common than human cardiac disease.

Dr. Watson [00:53:13] I think that's a fantastic answer. Well, that was it. See, it wasn't so bad.

Dr. Seitz [00:53:20] No, that was really fun. I like it. I'll have to tell my daughter. She will be thrilled that daddy got to play Would you rather at work.

Dr. Watson [00:53:29] I think that it's wonderful that your daughter likes to play this game at home, because my kids play it too, so.

Dr. Seitz [00:53:34] It's fun.

Dr. Watson [00:53:37] Well, thank you again so much for taking the time to sit down with us. This was wonderful. To all of our listeners at home, thank you for joining us, and we hope that you'll join us in future for some more conversations.

Dr. Seitz [00:53:48] Alyssa, it was a delight. Thank you for having me. And to all my colleagues on the front lines, thank you for what you do.

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The Team:

• Alyssa Watson, DVM - Host

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