Volume 7, Case 18
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
The radiographic signs of intussusception have been discussed in previous cases (Case 2 of Volume 1, Case 18 of Volume 3). The purpose of this current case is to display multiple cases of intussusception to see if you can identify the radiographic signs of intussusception on plain abdominal radiographs. The radiographic signs of intussusception are subtle, so this case series provides a lot of practice material to improve diagnistic skills in identifying these signs.
To summarize, the radiographic signs of intussusception are: 1) target sign, 2) crescent sign, 3) absent liver edge sign (also called absence of the subhepatic angle), and 4) a bowel obstruction.
Recall that the target sign is a mass in the right upper quadrant. It sometimes does not have a target appearnace and just resembles a solid mass. It is sometimes called a pseudokidney sign because it may have the shape of an oval mass in the RUQ.
The crescent sign is caused by the intusscepting lead point (intussusceptum) protruding into a gas filled pocket, which often results in a crescent shaped gas pocket. But if the pocket is large, it may not be crescent shaped. Thus, it should be more generically called the intussusceptum protruding into a gas filled pocket sign, but this is too long and it is not nearly as catchy as the "crescent" sign. Just realize that the crescent sign may not be crescent shaped.
Each new case can be viewed by clicking on one of the letters below.
This is a 2 year old month old female. There is a prominent target sign in the right upper quadrant. Although this is subtle, this is a very obvious target sign. Most target signs are even less subtle than this. There is a crescent sign in the left upper quadrant. This crescent sign is not really crescent shaped, but it represents the intussusceptum protruding into a large gas filled pocket. Note that the direction of the crescent always points in the direction of normal colon transit (superiorly if found in the ascending colon, right to left if found in the transverse colon, and inferiorly if found in the descending colon). In this case, the intussusceptum has traversed the ascending colon and most of the transverse colon as the lead point now points at the spleenic flexure.
This is a 3 year old female. There is a prominent crescent sign in the left upper quadrant. In this case, the crescent sign truly is crescent shaped. Note that it again points in the direction of normal colon transit. If the shape of the crescent is pointing the wrong way, consider the possibility of situs inversus or that this sign is somehow not due to intussusception. There is a target sign in the right upper quadrant. The target is smaller in this case and not as easy to identify. Once it is pointed out, you should be able to appreciate the target sign, which is subtle.
This is a 3 year old male. There is a crescent sign in the right upper quadrant, which is definitely not crescent shaped. The intussuscepting lead point is pointing cephalad at the hepatic flexure. The colonic air pocket is large in this case, so the classic crescent shape is not seen. This is why it should more accurately be called the intussusceptum protruding into a gas filled pocket sign, but this is too long to say. Note again that the intusscepting lead point always points in the direction of normal colon transit.
This is a 7 month old male. This radiograph demonstrates a bowel obstruction. Case 18 of Volume 3 describes the criteria for a bowel obstruction in children. There are four general criteria: 1) gas distribution, 2) bowel dilation, 3) air-fluid levels, and 4) orderliness.
The gas distribution is poor in that there is not much gas over most of the abdomen.
Bowel dilation may not seem prominent intially, but the criteria for bowel dilation is not a measured diameter of the bowel, but rather the loss of plications and haustrations of the bowel, such that a smooth hose-like or sausage-like appearance results. This particular radiograph is tricky because, there is not much gas anywhere. But look at the upright view on the right with the two bowel segments seen in the right upper quadrant. Note that these two bowel segments are smooth (hose-like) without plications or haustrations.
Air-fluid levels are not very prominent here since the entire abdomen is relatively gasless. However, examine the upright view on the right with two bowel segments in the right upper quadrant. These are not very striking, but they are air-fluid levels. Additionally, these air-fluid levels are not small, but they actually have the classic candy cane (or upside down J) appearance where the level in one half of the loop is different from the level in the other half of the loop. This is true for one of the bowel segments in the right upper quadrant. Such air-fluid levels are more suggestive of a bowel obstruction than small air-fluid levels which do not have the candy cane or upside down J appearance.
The last criterion, orderliness, is best appreciated on a supine view when lots of gas is evident. On this set of radiographs, there is not much gas present so that this orderliness criteria is less useful. However, one could simplify this to whether this view resembles a bag of sausages or a bag of popcorn. The two bowel segments in the right upper quadrant look more like two sausages and it would be hard to find a major component resembling popcorn here (see Case 18 of Volume 3).
Thus, all four bowel obstruction criteria indicate that this is a bowel obstruction. Bowel obstructions in infants and young children generally have this type of paucity of gas appearance or the appearance of lots of gas and dilated bowel. This paucity of gas type of bowel obstruction picture seen in infants and small children is typically seen in intussusception.
Additionally, there is a mass appearance in the right upper quadrant of the supine view on the left. This might be a target sign, but the overlying bowel gas is obliterating the center of the mass. This is also highly suggestive of intussception.
This is a 7 month old female. There is an overall paucity of gas. It would be difficult to definitively conclude that there is a bowel obstruction here. There is some evidence of bowel dilation, but it is hard to find a definite segment where the bowel walls are smooth. There are a few small air fluid levels in the right upper quadrant on the upright view (right image), but no definite candy cane type air fluid levels. The orderliness is indeterminate.
There is a suspicious mass appearance in the right upper quadrant and the liver margin is not seen. The right upper quadrant mass may be a kidney, or it may be a mass resembling a kidney (the pseudokidney sign) which is seen in intussusception.
This abdominal series is highly suspicious for intussusception.
This is an 8 month old female There is a poor distribution of bowel gas, but no definite bowel dilation or air fluid levels. There is a faint target sign in the right upper quadrant. The liver margin is indistinct. This is frequently seen in conjunction with a target sign, so whenever the liver margin cannot be easily identified, look hard for a target sign.
This is a 12 month old male. This is a supine view which demonstrates a bowel obstruction. Except for the two dilated bowel segments, there is a paucity of gas. Recall that this type of paucity of gas bowel obstruction in an infant or young child is most often due to intussusception. Examine the four criteria for determining that this is a bowel obstruction: 1) gas distribution, 2) bowel dilation, 3) air fluid levels, and 4) orderliness.
In this radiograph, the gas pattern demonstrates poor distribution. The bowel dilation is not obvious, but the only bowel segments which are visible, are the two bowel segments which look like a pair of sausages. The bowel walls are smooth (loss of plication and haustration) indicating that the bowel is distended. Air fluid levels cannot be assessed on this image since this is a supine view. The upright view from this patient did not show much gas except for a small amount of gas in the left upper quadrant. No air fluid levels were present. The orderliness criteria appears to favor a bowel obstruction in this case since this view more closely resembles a bag of sausages instead of a bag of popcorn. There are no target signs or crescent signs visible on this radiograph. However, the liver edge is not visible. The absence of the subhepatic angle is not as definitive for intussusception, but it adds to the suspicion for intussusception.
This is an 8 month old male. The inferior liver margin is not visible. Now look carefully for a target sign. There is a target sign in the right upper quadrant seen on the flat view (left image). There is also strong evidence for a bowel obstruction. There is an overall paucity of gas which is poorly distributed. There is evidence of bowel dilation, especially on the upright view (right image). Note that most of the bowel is smooth, resembling hoses. The smooth bowel wall appearance results when excessive bowel dilation results in the loss of haustration and plication. There aren't many air fluid levels, but the degree of orderliness resembles a bag of sausages more so than a bag of popcorn. This type of bowel obstruction with a paucity of bowel gas in an infant or young child is frequenty associated with intussusception.
This is a 3 year old old male. This series has three views. The two views on the left are flat views (one is supine and the other is prone). The view on the right is the upright view.
The image on the left demonstrates a well defined inferior liver margin, reducing the suspicion for intussusception. However, there might still be a target sign in this area. The middle image shows an absence of the subhepatic angle and a suspicious target sign in the right upper quadrant (though somewhat lower than its usual position).
The upright image on the right shows an outline of a mass in the shape of a kidney (the pseudokidney sign) which also raises the suspicion for intussusception.
This is a 2-1/2 year old month old female. This is a single upright view. The right side of the abdomen is almost gasless. The inferior liver margin is indistinct. Looking hard to a target sign in the right upper quadrant, and there might be one in the lower portion of the right upper quadrant. There is a general mass effect in the right upper quadrant which seems to be displacing any gas filled bowel to the left half of the abdomen.
The left upper quadrant demonstrates a possible crescent sign (which again is not crescent shaped). There is a protrusion into a gas filled pocket near the spleenic flexure. This is not likely to be a stomach air bubble. It may be the intussusceptum protruding into a gas filled spleenic flexure.
This is an 18 month old male. The supine view (left image) is not very suspicious except for some smoth bowel segments in the right upper quadrant. The inferior liver margin is easy to identify. However the upright view (right image) is almost gasless and there is a suspicious mass effect in the right upper quadrant. No definite target or crescent signs can be identified.
This is an 18 month old male. A series of three radiographs are shown here. The two on the left are flat views (one is supine and the other is prone). The view on the right is an upright view. These radiographs take up a lot of space on the screen, so even when enlarged, the radiographic signs of intusssuception may be difficult to identify. Here's a hint. The elusive crescent sign is present on one of these images. Can you find it.
These radiographs demonstrate a target sign in the right upper quadrant in the left left image. The middle image and the upright image on the right show a right upper quadrant mass effect, but it would be hard to say that there is a definite target sign here.
The middle image demonstrates a crescent sign on the left. In fact there might be two crescent signs here (but only one of them can be the real thing). The crescent sign is not very crescent shaped. This is not uncommon since the shape of this sign is highly dependent on the size of the air pocket into which the intussusceptum protrudes. One crescent sign that is pointed out in the "point" image, is in the transverse colon. Note that the intussceptum is pointing to the patient's left. Another possible crescent sign is in the left lower quadrant with a bulge into the air pocket, suggestive of a intussceptum pointing inferiorly, down the descending colon. This middle image also shows a suspicious mass effect in the right upper quadrant. The other views show a subtle target sign in this area.
This is a 3 year old male. There is a small target sign in the right upper quadrant of the upright view.
This is a 21 month old male. There is a right upper quadrant mass and obliteration of the liver margin. There possibly is a faint target sign in the right upper quadrant.
This is a 10 month old male. Bowel dilation is evident. Note the bowel wall is smooth (sausage or hose like). The liver edge is not visible. A right upper quadrant mass is present. The center of a target sign may be present.
This is a 3 year old male. A target sign is present in the right upper quadrant.
