 Welcome to the lectures, and I'm delighted to be able to do this. It is the pediatric section. We're going to do some imaging of acute problems starting with right lower quadrant pain, looking at appendicitis, but going beyond that. So I'm going to discuss the role of ultrasound in evaluation of acute right lower quadrant pain in children. Describe the ultrasound features of acute appendicitis, but also look at other causes of right lower quadrant pain. Cute right lower quadrant pain, it's really one of the common problems. And if you look at the causes, we always think about appendicitis, but if you were to line up, let's say 100 patients, up to 25% would have appendicitis. 30, 35% other diagnosis related to the bowel or gynecologic diseases. And in 40, 45%, you're not going to make a diagnosis, probably because it's some type of a viral illness. There's a key point in children that's different than adults. We're not going to see these diseases, cholecystitis, pancreatitis, diverticulitis, ischemic bowel disease or perforation. So it makes our job maybe a little easier because there are fewer diagnoses, but still they've got to be done correctly. So the imaging studies, ultrasound remains the screening study of choice. And a definite ultrasound result, either positive or negative, is reliable enough to guide treatment without further imaging. In the pediatric population, we use CT in obese patients. And if there's a high suspicion of an acute abdomen and a negative ultrasound, but we start with ultrasound. And we're going to focus on ultrasound for this lecture. The technique was first described by Pooley-Arts in 1986, and it's great at compression. This is from the article. You take a high-frequency linear ray transducer. You start around the iliac crest. You take transverse long-axis images from the iliac crest to the bladder. And you gradually compress the abdomen. Normal bowel is compressible. It's going to move out of the field. Inflamed bowel will not. Before you start the exam, ask the patient where they hurt. Point with one finger. It's going to make the study faster, but also it's going to help you find the appendix that may be an unusual location. Maybe in the retrocecal area or deep in the pelvis. So you start the ultrasound, identify the cecum, which is here, and identify the iliac vessels and the psoas. There are landmarks for locating the appendix. If you can find these, the appendix in most patients will be someplace right up in here arising from the cecum. Enter a needle through the structures and put on color images to increase your security that you're looking at the vessels. This is just one example before we get into a lot of detail about appendicitis. Cecum, psoas, artery and vein. And this is the appendix. It lies anterior to these structures. So what does it look like? I'm going to offer some. Non-perforated appendicitis appears as a blind ending tube greater than 6 mm diameter. It is fluid filled. It may have air. We should see if it's non-perforated multiple layers of the wall. We may see an appendicle lip and we may see fluid around the appendix. Surgical specimen, that's what we're going to be seeing. We'll translate that to an image. Blind ending tube. Identify the blind end to make sure it's not small bowel. You see the wall is hypocholic, the echogenic mucosa, and some mucosa and a little bit of fluid in the lumen. That's appendicitis. You want to trace the echogenic mucosa and some mucosa around the appendix. If it's absent, it's more likely that this appendix is ischemic or it's going to perforate. Transverse views, it's a target sign. And here's the specimen for correlation. One more. Here's the cecum. Here is the appendix. It's dilated. It's got a blind end. Here's the echogenic mucosa, some mucosa, fluid in the lumen. We've got the target sign on cross-section image. This is really the image you want to make the diagnosis. You make measurements where the appendix is largest. I like doing it on the long view, but you can do it on the short view or both views. The numbers are pretty similar. This was 7 millimeters. That's appendicitis. And here are the vessels. You may see an appendiculate that occurs in about 65% of cases. Specificity for acute appendicitis is 87% because sometimes you can get an appendiculate and the patient doesn't have acute appendicitis. This is an incidental finding. You've got to look for the other findings. It's an ecogenic focus, not surprisingly, with acoustic shadowing. Here's another one. And the interesting thing about the appendiculate, it is associated with a higher risk of perforation. You can see fluid around the appendix. Here's one. Here's a little free fluid. It does not mean perforation. It's just reactive. It's not a good sign for perforation. Color Doppler can increase your confidence in the diagnosis. Normal soft tissues are avascular. If the appendix is inflamed but not perforated, you'll see flow in the wall. You can see the appendix. Minimal flow in the soft tissues. If it's perforated, you see a lot more flow in the soft tissues. And here's a non-perforated one. Here's the appendix. It lights up. It's got hyperrenia. It just increases your confidence in the diagnosis. Okay, perforated appendix. If appendicitis is not treated, then it may become ischemic, necrotic, and perforated. That occurs 24 to 48 hours after onset of symptoms in 20 to 40 percent of cases. Once it perforates, in 50 percent of cases, you may not see the appendix. You have to look for secondary findings. So best predictors of perforation. Loss of that ectagenic semi-cosa that I showed you. Absent flow, suggesting ischemia. Secondary findings, abscess. Increased ectagenicity of the mesenteric fat. And hyperremic soft tissues on Doppler ultrasound. This is an appendicitis. There's a calculus. Follow the mucosa. You lose it at the tip. That's a sign of ischemia and likely perforation. Sensitivity and perforated appendicitis, about 75 percent of the cases, relatively high specificity. Here's another one. You can see bits and pieces of the ectagenic mucosa, semi-cosa. That's reflecting ischemic change. You're losing the semi-cosa and a high likelihood that this is perforated or will perforate. If you put color on and there's ischemia, you won't see much flow in the appendix. And again, look, you lost that mucosa, semi-cosa. That's an ischemic appendix. Abscess is a sign of perforation. And abscess is just an abscess. It's like an abscess in any place in the body. Round, complex mass with scattered internal echoes and lots of flow in the soft tissue. Lots of flow in the soft tissue. That's perforation. That's an abscess. Highly specific in perforation, we see an abscess, maybe 35, 36 percent of the time. This is normal again. Well-defined fat around the appendix is well-defined. Well, with perforation, the fat gets very echogenic. It's trying to wall off the perforation. So if you have acute perforated appendicitis, you'll see this finding 30 percent of the time, relatively specific though. Here's the appendix. We lost the mucosa. Lots of echogenic fat. Another one, lots of echogenic fat. That's perforation. Here's another one. This is an abscess in a lot of flow in the soft tissues. Lots of flow in the soft tissues indicates perforation. Okay. You're not going to see the appendix in perforation half the time. But if there's an abscess or even free air, it's not that common, peritonitis, and other findings I've showed you. Think of appendicitis. It is the most common cause of these findings, of the secondary findings. In adults, you have a range of diagnoses. Ptitulitis, esteemed bouts, not the case in children. If you see an abscess, complicated findings of appendicitis. False negative, 2 to 5 percent of appendix. That's because of focal tip appendicitis, which I'll show you, an abnormal location of the appendix. I told you about perforation. You may miss the diagnosis because you won't see the appendix, but look for your secondary signs. And then you can get false positive diseases, normal appendix, and other bowel diseases. The tip is dilated. Here are the vessels. If you don't look at the tip and only look at the proximal where it comes off the cecum, or the midbody, you're going to miss the diagnosis. And this is a miss that we've seen commonly because people see the appendix and think, oh, it measures normal. But appendicitis often starts in the tip, and that's where it's going to dilate first. Here's the transverse view, nearly eight millimeters. Here's another one. If you were just to look at the body, or the proximal or mid-segment, it's going to look normal. Look at the tip. You've got to see the tip. It's dilated, and it's got color. So that's focal tip appendicitis. Occasionally, the appendix is in the right pericollate gutter, and that's why we always ask, at the start of the exam, point with one finger where do you hurt. Pointing the flank, look in the flank. Here's the psoas. Here's the appendix. Normally, it's going to be over here, right? In front of the vessels, medial to the psoas. This is retrocecal. And here's the CT. Okay. How about this? Point you to mid-right flank. This is actually the appendix. This is some inflamed omentum. And here it is. Here's the appendix, and here's that inflamed omentum retrocecal. False positive normal appendix. Then see a large number of children with acute pain, okay? Because we do a lot of examinations for acute abdominal pain. As I said, maybe 20-some odd percent have appendicitis. And the others, you may see a normal appendix. Six millimeters, we say, is upper limits of normal. If we don't see any color flow, we say it's likely normal. If it's over six, we feel comfortable about appendicitis. But you're going to have some borderline cases. And all you can do is look at the size of the appendix and look at color flow. Overall, ultrasound in the best of hands is a sensitivity in 87 and 90 percent. Specificity up to 100 percent. CT, we know, is more sensitive and specific, yet it's not the first study of choice because of the radiation risk.