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Bowel Abnormalities in Pediatric Radiology

by Hetal Verma, MD
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    00:01 So let's talk about some common bowel abnormalities that are specific to the pediatric population.

    00:06 The most commonly seen are necrotizing enterocolitis, malrotation and midgut volvulus, meconium plug syndrome, Hirschsprung disease, hypertrophic pyloric stenosis and intussusception.

    00:20 Each of these can occur at different ages in the pediatric population, so let's go into these in a little bit more detail.

    00:26 So necrotizing enterocolitis is one of the most common neonatal GI emergencies.

    00:31 It's idiopathic but we think that it's likely related to an infection or abnormality of perfusion.

    00:36 It's most commonly seen in premature infants and it usually occurs within the first and second week of life.

    00:42 Clinically, it presents with feeding intolerance, abdominal distention and decreased bowel sounds.

    00:48 Usually, we've seen that it affects the terminal ileum or the ascending colon and on imaging, it presents with a few distended loops of bowel or possibly just a single persistently dilated loop of bowel.

    01:01 You can also have bowel thickening that's associated with it.

    01:04 If you see pneumatosis intestinalis or air within the bowel wall, this is actually pathognomonic.

    01:11 It can also result in portal venous air and it can result in free intraperitoneal air.

    01:16 So these are important findings to look for.

    01:19 Long term bowel strictures can often be seen as a complication in survivors.

    01:24 This is a radiograph of a one week old.

    01:28 You can see that there are dilated loops of bowel and there are areas of bowel thickening which you can see best because there is abnormal separation of the bowel loops.

    01:35 So normally, you should see gas flowing through the entire bowel but here you can see distinct separation of the bowel loops that's abnormal in an infant.

    01:45 You can also see pneumatosis intestinalis and portal venous gas in this patient.

    01:50 This can be difficult to see so let's take a closer look here.

    01:53 The arrow points to an example of pneumatosis intestinalis.

    01:57 You can see that outside of this lumen that's filled with air, there's a very thin strip of air within the bowel wall.

    02:04 Within the liver, you can also see these lucencies that are scattered around.

    02:10 They appear linear and these are areas of portal venous air.

    02:14 Malrotation and midgut volvulus is a surgical emergency because a delay in diagnosis can result in bowel necrosis and death.

    02:22 You have abnormal positioning of the duodenojujenal junction and the ileocecal junction, so this predisposes the small bowel to twisting and developing volvulus or twisting of the bowel.

    02:34 This can occur at any age but most commonly it occurs within the first month of life and it often presents with bilious vomiting.

    02:41 So in a patient that's presenting with bilious vomiting, you always wanna suspect malrotation with or without volvulus and whether or not there is a volvulus, this is a surgical emergency.

    02:53 So malrotation is usually diagnosed in an upper GI series.

    02:58 You wanna determine the position of the duodenal jejunal junction, so as the contrast flows through the stomach and the bowel, you wanna see where this junction is. It's real time evaluation.

    03:08 Normally, the junction is to the left of the spine and it's at the same level or superior to the duodenal bulb but if there's a volvulus, there's duodenal obstruction and you may have a corkscrew appearance to the duodenum and jejunum.

    03:21 So this is an example of an upper GI series in a normal patient.

    03:25 You can see that there is a normal, duodenojejunal junction which is to the left of the spine and superior to the position of the duodenal bulb.

    03:35 This is a patient that presented with malrotation.

    03:40 The patient had clinical signs of bilious vomiting, the patient had an NG tube that was placed and through the NG tube we administered contrast.

    03:48 Here you can see that there's an abnormally positioned duodenal junction which is to the right of the spine.

    03:54 You can see the spine right here, so it's to the right of the spine and it's actually inferior to the duodenal bulb which is up here.

    04:01 So meconium plug syndrome is the most common cause of failure to pass meconium in neonates.

    04:07 It's due to a lack of normal motility in the distal colon which can result in a functional obstruction.

    04:13 We think it's usually caused by functional immaturity of the ganglion cells.

    04:17 This usually diagnosed with a contrast enema and the enema demonstrates multiple filling defects within the colon which are consistent with meconium plugs.

    04:25 The enema is actually often therapeutic and results in release of the plugs.

    04:30 This is an example of a contrast enema that was performed in a patient with meconium plug syndrome and you can see that there are multiple filling defects within the colon. The largest is right here pointed out by the arrow.

    04:43 Hirschsprung disease is caused by an absence of ganglion cells within the colon.

    04:51 So this also results in a functional obstruction.

    04:54 The affected portions of the colon are small in caliber and the more proximal unaffected portions are dilated because of this distal obstruction.

    05:02 This is actually very similar to meconium plug syndrome and the patients present with failure to pass the meconium in the neonatal period but they can also present a little bit later in life and their usual presenting symptom is constipation.

    05:15 This is diagnosed with a contrast enema as well.

    05:18 You see an abnormally small rectum and distal colon with a transition point to a more dilated proximal colon.

    05:25 You have an abnormal rectosigmoid ratio so the sigmoid colon diameter is larger than the diameter of the rectum and this occurs when only the rectum is involved.

    05:35 So let's take a look at this image from a contrast enema.

    05:38 You can see here that there are multiple filling defects that are consistent with meconium plugs.

    05:43 This is a newborn that failed to pass meconium.

    05:47 Let's point out some of these areas.

    05:49 So you can see here some of these areas that represent meconium plugs.

    05:52 Here where the arrow is, you can see a transition in diameter from a small distal colon to a more dilated unaffected proximal colon.

    06:01 So this is the normal portion of the colon and this entire colon is abnormal.

    06:06 So hypertrophic pyloric stenosis is an idiopathic thickening of the muscle of the pylorus and this results in a gastric outlet obstruction.

    06:15 Usually, this presents between the first week and 3 months of life and is most commonly seen in males.

    06:21 Typical presentation is projectile vomiting and you can also feel the pylorus is an olive on a physical exam.

    06:29 So this can be highly suspected on physical exam even prior to imaging.

    06:33 On radiographs, you might see what's called the caterpillar sign which is gastric distention with peristaltic waves of the stomach and on ultrasound you can actually see the muscle itself which appears hypoechoic with the central hyperechoic mucosa.

    06:48 The muscle thickness is usually greater than 3 millimeters which is abnormally thickened and the length is usually greater than about 15 millimeters and this is when you would start suspecting pyloric stenosis.

    06:59 So this is an example of a longitudinal ultrasound image of a patient with pyloric stenosis.

    07:05 So this right here is the hypertrophied pyloric muscle and you can see here the hypoechoic portion is the actual muscle and the central hyperechoic region is the mucosa.

    07:18 Intussusception is an abnormality that's caused by forward peristalsis of the bowel which results in invagination of the proximal bowel into the distal bowel in a telescoping manner, so you have a larger distal bowel and the proximal bowel enters within the lumen of the distal bowel.

    07:35 Most commonly, this is seen in the ileocolic region and often this is idiopathic but occasionally this can also be pathologic and it results from a lead point such as a diverticulum or a mass.

    07:46 This commonly presents between about three months and one year of age and the classic symptoms include crampy abdominal pain and bloody stools that are described as currant jelly stools because of their dark red color.

    08:00 The patient also often presents with vomiting.

    08:02 Radiographically, you can see a soft tissue mass within the ascending colon or within the hepatic flexure, you can have signs of small bowel obstruction and you often have a lack of gas within the right side of the abdomen.

    08:15 On a left lateral decubitus film, you can actually see lack of air within the ascending colon if you're unsure of it on a standard upright view.

    08:24 On an ultrasound, you can see a mass that has alternating hyperechoic and hypoechoic rings because you have a bowel within bowel appearance.

    08:32 So this is an example of a radiograph in a patient that has intussusception.

    08:38 You can see lack of air within the ascending colon, so this entire area of the abdomen doesn't have any air within the bowel and here with the arrow, as you can see a soft tissue mass in the region of the transverse colon.

    08:49 So this is normal air within the transverse colon and here you can see the appearance of a soft tissue mass, thus projecting into the area of the transverse colon.

    08:58 On ultrasound, you have the alternating hypo and hyperechoic rings again bowel within bowel appearance.

    09:05 So you can see here the entire area of bowel and then again more bowel inside of this bowel.

    09:12 So increasing pressure within the colon can actually invert the intussusception into normal position and that's what we use to reduce the intussusception.

    09:22 We can use a contrast enema or we can use fluoroscopic air insufflation into the rectum and the surgery service should actually be present or at least aware that this is going on because there is a risk of bowel rupture associated with this.

    09:34 So we've gone over some of the common abnormalities that can be seen within the childhood period.

    09:39 Again, these are very different than adult abnormalities, so important to keep in mind when you see pediatric films.


    About the Lecture

    The lecture Bowel Abnormalities in Pediatric Radiology by Hetal Verma, MD is from the course Pediatric Radiology. It contains the following chapters:

    • Necrotizing Enterocolitis (NEC)
    • Malrotation and Midgut Volvulus
    • Meconium Plug Syndrome and Hirschsprung Disease
    • Hypertrophic Pyloric Stenosis
    • Intussusception

    Included Quiz Questions

    1. Upper GI series should be performed to evaluate for malrotation which is a surgical emergency
    2. Contrast enema should be carried out to evaluate for meconium plug syndrome
    3. Contrast enema should be performed to evaluate for intussusception
    4. Ultrasound should be conducted to evaluate for hypertrophic pyloric stenosis
    5. Upper GI series to evaluate for malrotation versus volvulus. Malrotation is not a surgical emergency, but volvulus is a surgical emergency.
    1. It occurs most commonly in the 2ⁿᵈ–3ʳᵈ month of life
    2. Congenital heart disease is a risk factor
    3. It presents with feeding intolerance, bloody BMs, abdominal distension and decreased bowel sounds
    4. It most commonly affects the terminal ileum and ascending colon
    5. Pneumatosis intestinalis is a pathognomonic finding
    1. Bowel strictures
    2. Pneumatosis intestinalis
    3. Bleeding
    4. Bowel malignancy
    5. Bowel perforation
    1. Lack of normal motility of the distal colon resulting in functional obstruction
    2. Presence of a stricture in the distal colon leading to accumulation of the meconium
    3. Premature functional maturity of the ganglion cells of the colon leading to obstruction
    4. Infection of the distal colon leading to functional obstruction
    5. Malrotation of the midgut leading to accumulation of the meconium
    1. Ganglion cells
    2. M cells
    3. Enterochromaffin cells
    4. Goblet cells
    5. Paneth cells
    1. The typical presentation is projectile vomiting
    2. It most commonly occurs between 1–2 months of life
    3. It is the thickening of the glandular tissue of the pylorus due to infection resulting in gastric outlet obstruction
    4. It is very easily missed on physical examination
    5. Radiographic appearance of a bird beak sign is very characteristic
    1. Duodenojejunal junction
    2. Currant jelly stools
    3. Vomiting
    4. Abdominal pain
    5. Bowel within bowel appearance

    Author of lecture Bowel Abnormalities in Pediatric Radiology

     Hetal Verma, MD

    Hetal Verma, MD


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