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Bowel Obstruction and Ileus: Ileus & Small Bowel Obstruction – Radiology | Lecturio

Bowel Obstruction and Ileus: Ileus & Small Bowel Obstruction – Radiology | Lecturio


[Music] so one of the most common reasons for performing an abdominal imaging study is to evaluate for bowel obstruction or Ilias so let’s take a look at these findings that we would see this is 25 year old patient that came in with right lower abdominal pain it’s a female patient let’s take a look at this case and see what you can see here and keep this in mind until we get through the lecture and then we’ll go back to this at the very end so what do you look for when you’re looking for a bowel obstruction you want to look for dilated loops of large or small bowel you want to see if it’s focal or diffuse you want to take a look at air fluid levels you want to see if there’s air within the rectum and you want to see if there’s a transition point when you’re performing a CT so what’s the difference between a functional ileus and a mechanical obstruction a functional ileus is loss of normal peristaltic function due to irritation a mechanical obstruction is a physical obstruction in the small or large bowel and this may be partial or it may be complete a functional ileus may be localized or generalized and a mechanical obstruction as we said could be either complete or partial a functional ileus usually affects the small bowel and it doesn’t tend to have a transition point while with a mechanical obstruction you do have a transition point and this is the point at which the bowel changes Calibur from being dilated to being collapsed the small bowel caliber is typically less than three centimeters in a functional ileus so it’s not significantly dilated in a mechanical obstruction the small bowel can become significantly dilated and the caliber is usually more than about three centimeters in a functional Ilyas you would see air within the rectum because the air continues to pass past the site of a peristalsis while in a mechanical obstruction if you have a complete obstruction you would have no air within the rectum because nothing is getting past that point of obstruction so a partial or early small bowel obstruction within the first day or two can appear identical to an ileus so it’s actually very hard to differentiate and usually what we do is follow-up imaging to see how it evolves so in a localized functional Ilyas you would have dilatation of a loop or a few loops of small bowel and these are called the sentinel loops this is caused by adjacent irritation it can result from really any kind of abdominal pathology that causes focal inflammation types of pathologies include acute cholecystitis pancreatitis appendicitis diverticulitis or even ureteral stones so anything that causes pain in the patient can cause a localized functional ileus a generalized functional ileus is most often post operative and it can involve the entire bowel both small and large so if you take a look at this patient here you have multiple dilated loops of both large and small bowel they’re actually so dilated that we really aren’t able to tell the difference between large and small bowel and you can see that this patient is post operative they have surgical staples along the midline of the abdomen a small bowel obstruction is usually caused by a lesion that obstructs the lumen of the bowel it results in dilatation of the bowel proximal to the obstructing lesion and then compression of the bowel after the obstructing lesion this is an example of a normal large bowel and a normal small bowel on the right we have an image of a small bowel obstruction so the large bowel is slightly decreased in caliber because there’s less air getting through the point of obstruction which is right here at the terminal ileum the small bowel that’s proximal to this part point of obstruction is dilated there are many different causes of small bowel obstruction the most common include adhesions from prior surgery tumors a hernia and we’ll take a look at an example of this inflammatory bowel disease can cause multiple small bowel obstructions intussusception which is bowel tunneling within other bowel it’s kind of like a telescoping effect where a piece of bowel tunnels within another piece of bowel and can cause an obstruction at that level intraluminal lesions other than tumors can also cause small bowel obstruction and they can be from a variety of different reasons including an ingested foreign body you can have a gallstone ileus which is when a gallstone penetrates through the gob a wall and enters the small bowel and causes an obstruction within the small bowel or you can have bees wires which are abnormal collections that the patient may be ingests certain psychiatric patients may ingest different types of foreign bodies that can collect together and cause an obstruction so this is an example of a patient that’s presenting with abdominal pain let’s take a look at this film so how does this Bal gas pattern look this patient has a prominent loop of small bowel in the left upper abdomen the differential of this includes a focal Ilyas or an early or partial small bowel obstruction as we said it’s really hard to differentiate in a patient that’s presenting with symptoms that lasted less than one to two days because early on both can have similar imaging findings the following day however the patient had a repeat film because they had increased increasing abdominal pain so what do you see on these films here here we have a supine film and then this one is an upright film so as you can see there’s increasing dilatation of multiple loops of small bowel now a majority of the small bowel loops appear dilated you can see that on this supine film you also have increasing air fluid levels which we can see best on this upright film this is very concerning for a small bowel obstruction so what else can you perform to help you figure out why this is occurring so in this patient a CT scan was performed here we have two axial images from an adduct aminal CT scan and we have a coronal image so let’s take a look at each of these images here on this axial CT image we have what looks like a little outpouching of the anterior abdominal wall that contains a loop of bowel on this next image we again have a loop of bowel that looks a little bit dilated in the same region as the outpouching and it has a mottled appearance and here we have a decompressed loop of bowel on this coronal image you can see a large loop of small bowel that appears dilated so this is a thickened loop of bowel within a ventral hernia that’s causing a bowel obstruction and here we have a transition point at the level of obstruction this modeled loop of small bowel here is what we call the small bowel feces sign so you normally should not have any stool within the small bowel when you do have stool within the small bowel you should suspect a small bowel obstruction and that’s called a small bowel feces sign so what are some CT findings of small bowel obstruction you should see dilated loops of small bowel greater than about three centimeters you may or may not see a transition point you should see collapsed bowel distal to the transition point and you may see the small bowel feces sign so what is a closed loop obstruction this is an obstruction of a loop of bowel in two separate places you normally don’t see any significant dilatation proximal to the closed loop and often this is caused by adhesions from prior surgery this could actually result in strangulation so this is a surgical emergency it can cause blocked blood flow to the bowel which can result in necrosis on imaging we see a thickened wall and you may see decreased enhancement of the bowel wall so close loop obstruction needs immediate surgical treatment because there’s a very high risk of perforation from this strangulation [Music] you

3 comments on “Bowel Obstruction and Ileus: Ileus & Small Bowel Obstruction – Radiology | Lecturio

  1. In patients with acute small bowel obstruction, routine laboratory studies help assess the presence and severity of hypovolemia and electrolyte abnormalities and may indicate the possibility of complications (eg, leukocytosis, metabolic acidosis).

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