All right, so Dr. Vicari and I will be going over radiology studies case number four on colonic pseudoobstruction, and we have no disclosures. So, our patient is a 68-year-old man who was hospitalized following a right hip replacement four days ago. He's been immobile. He's been receiving IV morphine. His labs show hypokalemic. He's had abdominal distension with no bowel movement for the past three days, and his abdominal films and CT demonstrate findings consistent with colonic ileus. So, polling question, which is the most likely cause of the acute colonic pseudoobstruction for this patient? Okay, great. So, most of you said correctly, all of the above. So, patients who have undergone recent surgery, who are receiving opioids, or who have electrolyte imbalances are all at increased risk for developing an acute colonic pseudoobstruction. So, an acute colonic ileus typically involves the cecum and right colon, but occasionally that colonic distension will extend down to the rectum. There's certain medications that can alter the gut motility, such as anticholinergics, calcium channel blockers, and opioids. Those are all risk factors for colonic ileus, and patients with electrolyte imbalances, such as hypokalemia, hypomagnesium, hypercalcemia, also are at increased risk for developing a colonic pseudoobstruction. Acute colonic pseudoobstructions typically occur in hospitalized patients with severe illness. Oftentimes, these patients have had recent surgery, particularly abdominal, cardiac, or orthopedic surgeries, and the precise mechanism is unknown. So, clinical signs and symptoms in patients with a colonic ileus, mild distension, or I'm sorry, abdominal distension that usually occurs gradually over the course of three to seven days, mild abdominal pain, nausea, vomiting, constipation, and paradoxically diarrhea. On physical exam, these patients are distended with tympani to percussion. They have present bowel sounds, and approximately 65% will have mild abdominal tenderness. Patients with more severe abdominal tenderness with peritoneal signs or fever, that would be more concerning for possible colonic ischemia or perforation. So we typically perform a complete blood count, check electrolytes, serum lactate, as well as check a TSH to assess for hypothyroidism. For imaging, abdominal films, a flattened upright x-ray can assess for bowel distension, air fluid levels, pneumatosis, or free air. Abdominal CT in patients with an acute colonic ileus, often, again, they have that proximal colonic dilatation that can extend down to the rectum. CT can also evaluate for evidence of mechanical obstruction or assess for any other intra-abdominal pathology that may have precipitated the colonic ileus, such as a retroperitoneal hematoma. And I'm going to pass the baton off to Dr. Beccari. Well, thank you, Janelle. So management is pretty straightforward. If the sacral diameter is less than 12 centimeters and the patient does not show any signs of toxicity as outlined by Janelle, the initial management is conservative. So identify and treat the underlying cause. So if there are electrolyte abnormalities, address that. If the patient's been immobile and can move around, start getting them to move around and remove any offending agents, such as anticholinergics, calcium channel blockers, and if possible, the opioids in post-op patients. NGD compression can be helpful and cautious tap water enemas. Each day when you see the patient, physical exam, trying to detail the physical exam, the abdomen nicely so that when you go back to your notes or someone else is picking up the patient the next day, they get an idea of what the abdomen was like the day before. Daily abdominal films and daily labs. For those patients that present with a sacral diameter greater than 12 centimeters or they have failed conservative management, then we should proceed to neostigmine. Neostigmine resolves the ileus in up to 85 to 95 percent of the patients. There are some complications that can occur with neostigmine, such as bradycardia, bronchoconstriction, hypotension. So these patients need to be monitored in a cardiac type of setting or in an ICU setting. If after 24 hours the patients haven't improved, you can give a second dose of neostigmine as long as they're stable and not worsening. And if you decide to give a second dose or if you decide to give one and they're not any better, the next step is colonic decompression. So failed therapy for neostigmine is an indication to proceed with decompression with colonoscopy. Please know that it is a technically difficult exam because the colon is unprepped. It's dilated and it can be easy to make a wrong turn or get yourself into trouble because of the lack of prep in the colon and the dilated nature of the colon. As you do the colonoscopy, you're suctioning out air and debris as much as possible to desufflate the colon and many experts recommend leaving a decompression tube in place when the procedure is over. And keep in mind, since this is technically a difficult procedure, perforation is not small. In most studies, it's about 2 percent when you proceed with colonic decompression in an unprepped colon for a colonic ileus. For those who fail all therapies, so refractory symptoms or show signs of ischemia, perforation or toxicolitis, then they should be referred to surgery. You've heard throughout the importance of understanding the clinical context of a disease to correctly interpret imaging studies and that's the reason why I think we all gave some clinical background. And as you'll see when we get into the images, if you understand the clinical aspects of colonic pseudo-obstruction or colonic ileus, it becomes very easy to interpret and use the film to confirm your diagnosis. Some general comments I think that could apply to all imaging. So how do I become proficient at interpreting imaging studies in colonic pseudo-obstruction and frankly in any imaging studies, first develop an interest. Anytime we develop an interest in something, we're more likely to succeed. If you want to learn more about imaging, then seek support from your mentor or your physician APP leader within your practice. Those practices that are most successful and of high quality, they want you to achieve your intellectual and academic goals within the practice. So ask for support in how you can learn about imaging and become more proficient. Like anything else, it's practice, practice, and more practice. So we have access to the reports, we have access to the images. It's very easy now with technology. So read your reports and start reviewing images. So approach your practice leaders and if you're really interested, ask if you can have some dedicated time with radiologists. That becomes more important for those who spend time predominantly or solely in the clinic that will allow you to spend time with the expert. For those of you who are a hospitalist or in a hybrid type of model where you do clinic and hospital, it's much easier to go down to radiology, spend time with the radiologist when you have some downtime and review the images and learn. So practice, practice, and more practice, and patience, patience, and more patience. You're not going to become an expert overnight, but over time as I've seen with Janelle and other APPs in our practice, you can become very skilled at reading images. So before we look at some films, some basic characteristics of the normal colon, as you think of plain films and CTs, the colon is a tubular, has a tubular, saccular shape. So it's got these almost little sacs as you look throughout the colon and I'll show you that on a normal film. Typically the diameter is 5 centimeters or less and it typically has a wall thickness of 3 millimeters. It's course through the abdomen is simple. The cecum starts in the right lower quadrant. It goes, it ascends the right abdomen as the ascending colon till it reaches the right upper quadrant or at the liver it turns and that's the hepatic flexure and then traverses from right to left across the upper abdomen. It then turns again at the spleen or the splenic flexure and then descends down the left side of the abdomen and at the very end of the colon there's an S shape to it or the sigmoid colon and then it enters the rectum. Okay, so let's start looking at some films. This is a normal abdominal plain film. When I first saw this, I thought it was actually a post air contrast barometer, but it was just a really good image of a normal colon that had some air. As a reference, the R means the right side of the body, so when we look at plain films, the right side of the body is actually on our left. So when I describe things, I'll describe it in the anatomical terms of right and left. Other things to look at, you have vertebral bodies in the center. You have some ribs at the top and if you look in the lower half of the film, you see on both sides the iliac wings of the pelvis and in the very lower part of the film on both sides, you see the femoral head. So those are just some landmarks. If you look in the right lower quadrant, you'll see a bit of a wider part of the colon and that's the cecum and then ascends and you can see some haziness in the right upper quadrant. That's the liver and as it turns, that's the hepatic flexure. It goes across the abdomen to the left upper quadrant where it turns at the splenic flexure and then descends down the left side into the descending colon and sigmoid colon. If you take a close look, you'll see that saccular appearance I'm talking about. If you look in the right upper quadrant, you'll see some semicircles that point to the saccular appearance of the colon and you can see that again throughout the colon. So keep this normal image in mind. Here is an abnormal image of the colon we see in the right femoral and the right femoral head is now a prosthesis. You see a prosthesis after a hip surgery and then we see a dilated left colon and dilated right colon and you also start to see, if you look at the walls, loss of that saccular shape. So this patient has a dilated left colon and a dilated right colon consistent with the clinical information we have of colonic ileus and we start to see flattening of the wall of the colon or loss of the saccular shape. So very easy, very simple in the right clinical setting to understand this is a post-op hip that has a colonic ileus. Here's another film. This is showing a different image. We have a transverse colon and a right colon that is dilated. We clearly see loss of the house struts really flattened out if you look at the walls of the colon and I will go back to the original normal image for comparison. So there's our normal image, abnormal, and then again abnormal. So very easy if you keep that normal image in mind, we have loss of house strut, dilation of the colon. Here again we see a dilated left colon, a dilated right colon, we see loss of house strut and we see findings consistent in the right clinical setting with colonic ileus. Not very difficult. I'm not trying to oversimplify it. It's not very difficult to understand colonic ileus on imaging once you understand the basics and you understand the clinical setting. And this is my final film to review before I turn it over to Janelle. On the left we have a plain film and on the right we have a coronal CT image. So you can see the arrows pointing to the dilated left and right colon. Again loss of house strut. If you look at the coronal CT image on the right side of the body, so you see the liver in the right upper quadrant, below that a dilated right colon with loss of house strut. And in the left colon you can kind of see some house strut remaining in the left upper quadrant, the middle part of the left upper quadrant, but again a dilated colon with flattening and loss of house strut. I'll now turn it over to Janelle to review some other CT images. All right, thanks Joe. So this is a CT of the abdomen and pelvis with a coronal view of a patient with a colonic pseudo obstruction. So when you're getting used to looking at CTs, I find that the coronal views are easier to start with because you're visualizing the organs, it's easy to see the colon, and you're looking at the abdomen the same way you would with an x-ray. It's just kind of an overview of the abdomen but in slices just like Sarah had mentioned in the previous study. So evaluating the colon on axial views can be a little bit more difficult just because the imaging is different from our typical front views like on x-ray or coronal images like we just saw. On the axial views, you're viewing the abdomen through up and down slices. So on axial views, when I'm looking at the colon, I will typically start at the anal rectum and just kind of run the colon upwards. The darker areas are lower density. The lighter gray or white is higher density. So you can see on these images, the colon is distended with the air, which is black. And again, when you're looking at the CT images, you're looking at the areas of the colon that appear dilated and to what degree. This is another axial view of CT demonstrating a significantly dilated transverse colon. You can see the loss of houstra that Dr. Bakeri just referred to. So in general, I just wanted to kind of give a couple of things. When you're learning to view CT imaging, I think just becoming familiar with how to use a basic PAX viewer, finding a mentor who's willing to review imaging with you, and then just as Dr. Bakeri said, practice, practice, practice. Because the more images you look at, the easier it becomes to identify abnormal findings. And I'm going to put this back to Dr. Bakeri to finish out this discussion. All right. So some pearls. First, I encourage all of you to develop an interest in imaging, obviously not just colonic imaging. I think it makes us a more well-rounded clinician. Find that mentor to help support you in your endeavor to become skilled at reading images. Spend time reviewing imaging studies. Understand the normal anatomy of the imaging studies that you're going to review. And as with everything we've talked about, the understanding of the clinical context is so important. Once you understand the clinical disease state, reading these films at the level that we need to become proficient at becomes much easier, and it's not as hard as you think. In addition to learning more about the disease states and the images, you'll learn a new language of radiology, and you'll gain more knowledge and understanding of disease states by understanding the images, which is going to allow you to deliver a higher quality of care to your patients. Once again, you can come off as a confident, knowledgeable provider when you can sit down and review an imaging study in very clear terms that is very easy for the patient to understand, and you just show that you are really a high-quality provider. So those are our pearls. And unless Janelle has anything to add, I think we will then wrap it up and move on to our QA. Janelle, anything else to add? Nope. I think I'm good. Thanks, Joe. All right. Thank you very much, Janelle, for collaborating with me on this case study. I think we've pointed out how much the physicians enjoy collaborating with our APP colleagues and teammates. It's really fun to work with all of you, and I think it makes our professional lives much more rewarding. So thanks again for collaborating.

colonic pseudoobstruction

hip surgery

imaging studies

clinical context

patient management