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Intussusception 407

areas of lucency due to mesenteric fat of the intussusceptum; and (2)
the meniscus sign (a crescent of gas in the colonic lumen outlining the
intussusceptum).
Plain radiographs most often display multiple air-fluid levels
indicating intestinal obstruction (Figure 68.7(b)). These are usually
late signs. Sometimes, a plain abdominal radiograph in the presence of
intussusception may be unremarkable, however. 26
If the caecum is found to be filled with gas or faeces in its normal
position on a plain abdominal radiograph, then intussusception can
often be excluded. Plain abdominal radiographs are done to exclude
pneumoperitoneum, especially in children who present late with
intussusception. Once one or two of the cardinal signs of intussusception
are present, however, the radiograph can be used, if available, to help
confirm the diagnosis.
Computed Tomography
Figure 68.5: Ultrasound scan showing the doughnut appearance (target lesion) Computed tomography (CT) scan and magnetic resonance imaging
of an intussusception. (MRI) very rarely are used for the diagnosis of intussusception, espe-
cially in poorly resourced countries. They are of use when the diag-
nosis of intussusception is in doubt, or the presentation is atypical of
intussusception, or when the child has vague abdominal complaints of
unknown cause. Also, in a few cases where the US scan is inconclusive
or atypical, then either a CT scan or an MRI can be used to make the
diagnosis. The presence of a bowel-within-bowel configuration with
inclusion of mesenteric fat and/or mesenteric vessels is pathognomonic
for intussusception on MRI or CT scan.
Other Investigations
Other supportive investigations include a full blood count (FBC), and
blood urea, creatinine, and electrolytes to assess the extent of dehydration.
By using the various investigations (e.g., plain radiography,
abdominal ultrasonography, barium enema, CT scan, and MRI), and
finally after laparotomy, intussusception can be classified as: 1,25
• Enterocolic: ileocolic (the most predominant type of intussusception
Figure 68.6: Intussusception with lead point. seen in infants and toddlers); ileo-ileocolic; ileocaecal;
• Enteroenteric: jejunojejunal, jejunoileal, ileo-ileal; or
• Colocolic: caecocolic, colocolic.
• Special forms of intussusception include the following:
• Retrograde intussusception: 14,16 Invagination of the distal bowel
(intussusceptum) into the proximal bowel (intussuscipiens).
• Postoperative intussusception: Complicates the postoperative period
in about 0.5–16% of laparotomies. 11,12 A majority of cases occur after
retroperitoneal dissection or extensive bowel manipulation.
• Spontaneous reduction of intussusception: More than half of intus-
susceptions are asymptomatic and are frequently diagnosed during
ultrasonography, barium enema examinations, or CT scan for one
reason or another.
• Other: Intussusceptions can occur around different catheters (e.g.,
(A) (B)
various feeding tubes such as gastrojejunostomy tubes, nasojejunal
Figure 68.7: (A) Intussusception on plain abdominal x-ray showing the target sign. 14
(B) Plain erect abdominal radiograph of a 6-month-old child with intussusception, tubes, etc.).
showing multiple air-fluid levels consistent with intestinal obstruction.
Treatment
The treatment of intussusception in children is an emergency, by either
Plain Abdominal Radiographs nonoperative or operative methods. Delay in treatment will lead to
Plain abdominal radiographs can also be used to diagnose intussuscep- ischaemia and necrosis of the intestine, bowel perforation, peritonitis,
tion because there are a number of radiographic signs of intussusception, shock, and possibly death. Nonoperative reduction (NOR) is the first
but they have a poor sensitivity of about 45%. These signs include a soft line of approach where facilities are available; if that fails, the next
tissue mass seen at the right upper quadrant, reduced air in the small logical step is operative management.
6
intestine or a gasless abdomen, and air in a displaced appendix. The Contraindications to the use of NOR in the treatment of a child
two more specific radiographic findings of intussusception are (1) the with intussusception are obvious peritonitis, 16,26 pneumoperitoneum
16
16
target sign, seen in Figure 68.7(a) at the right upper quadrant over the secondary to bowel perforation, shock, a grossly distended abdomen
kidney, which consists of a soft tissue mass with concentric circular (relative contraindication), small-bowel intussusception such as ileo-