Intussusception With a Pathological Lead Point

A 4-month-old girl was admitted to a rural hospital with nonbilious vomiting and bloody stools that began the prior evening. The parents reported that the infant had periods of excessive irritability mixed with periods of calm. She had no fever, exposure to illness, or surgical history.

Results of a complete blood cell count and chemistry panel were normal. Plain abdominal radiographs revealed dilated loops of bowel with air-fluid levels, indicative of bowel obstruction (Figure 1).

Figure 1 - The plain abdominal film and left lateral decubitus film of a 4-month old girl show dilated loops of bowel (A) and air-fluid levels (B), indicative of bowel obstruction. The cause was an intussusception with a pathological lead point.

The patient was referred to a regional medical center for pediatric consultation. Her temperature was 36.6C (98F); heart rate, 162 beats per minute; respiration rate, 38 breaths per minute; and blood pressure, 122/89 mm Hg. The abdomen was markedly distended with hyperactive bowel sounds. Fullness, without a palpable mass, was noted over the central abdomen. There were no external anal fissures or rectal prolapse. On digital rectal examination, no masses were palpated; the stool was dark red and had the consistency of mucus.

Neither a pneumatic enema nor a hydrostatic enema with water-soluble contrast showed the level of obstruction or abnormality. Because there was a clear obstruction that was not corrected by radiological means, a laparotomy was performed. It revealed an ileoileal intussusception with a pathological lead point (PLP) (Figure 2). The cause of the obstruction was a mass, consistent with an adenomyoma that protruded into the bowel lumen. At discharge 5 days later, the infant was consuming a regular diet (of formula) appropriate for her age.

Figure 2 - The ileoileal intussusception before reduction is shown (A). An external view shows the pathological lead point-a hamartoma of the small bowel (B).

INTUSSUSCEPTION: AN OVERVIEW

In children with intussusception, the proximal bowel telescopes or becomes entrapped within the distal bowel.¹ Most cases of intussusception (roughly 80%) occur before the second year of life-typically, between 3 months and 2 years of age.¹ The disorder is usually idiopathic² and related to lymphatic tissue hypertrophy.³

Children with a PLP are often older than 5 years and have one of the following comorbidities^2,4:

• Meckel diverticulum.

• Cystic fibrosis.

• Henoch-Schnlein purpura.

• Polyps (as in Peutz-Jeghers syndrome).

• Intestinal duplication.

• Lymphoma.

These children are also less likely to have ileocolic intussusception than younger persons without cormordid conditions.⁵ In the patient discussed here, the PLP was a hamartoma of the small bowel- a rare cause of intussusception in children.⁶

CLINICAL MANIFESTATIONS

Intussusception. The classic clinical features are irritability and colicky pain. The parents may describe alternating intervals of well-being and extreme irritability. During an irritable period, the child may flex the lower extremities toward the abdomen. Some patients present with profound lethargy.

Bloody diarrhea, or "currant jelly" stool, is the result of ischemic insult sustained when the venous blood supply to the mesentery and bowel becomes obstructed within the intussusception. Subsequent edema further obstructs arterial blood flow and results in the passage of a dark red, mucus-like stool.^1,7 At this point, a rectal examination often reveals currant jelly stool on the examiner's gloved finger.

Vomiting is usually nonbilious when the intussusception is ileocolic. 2 When the intussusception is higher in the GI tract, bilious vomiting may be present. In this setting, consider other diagnoses associated with bilious vomiting, such as mid-gut volvulus.

In children with intussusception, a mass may be palpated in the upper abdomen. Because of the lack of bowel created by the intussusception, emptiness in the right lower quadrant- the Dance sign-may be observed.^1,7,8

Intussusception with PLP. When a child presents with acute abdominal pain and any of the signs and symptoms suggestive of the comorbidities listed above, include intussusception with a PLP in the differential. For instance, this diagnosis should be considered in a child with a history of lower extremity vasculitis who presents with cramping abdominal pain. Children with Henoch- Schnlein purpura are at increased risk for intussusception caused by bowel wall hematomas.⁷

DIAGNOSIS AND INTERVENTION

Dilated loops of bowel with air-fluid levels, suggestive of bowel obstruction, is a possible radiographic finding in any patient who has intussusception, regardless of the location. Plain abdominal films help identify bowel perforation and may therefore obviate the need for more extensive diagnostic studies, including abdominal ultrasonography, pneumatic or hydrostatic enema with attempts at reduction, and CT.⁹

Abdominal ultrasonography can identify the intussusception via the pseudokidney appearance longitudinally and the doughnut or target sign transversely.^1,8 In one retrospective study, ultrasonography correctly predicted the presence of a PLP in 23 of 35 patients known to have a PLP.⁵ Thus, ultrasonography may be helpful when a PLP is suspected. In the absence of a PLP, ultrasonography is often recommended as a primary study because it can elucidate the difference between an unsuccessful enema reduction and residual edema or a postreduction doughnut sign.⁹

Radiological reduction of an intussusception is accomplished by ultrasonographic or fluoroscopic guidance. The decision about whether to perform a pneumatic or hydrostatic enema is often debated; pneumatic is usually preferred over hydrostatic enema, and water contrast instead of barium is preferred for convenience and safety.⁹ CT may be used when the PLP is thought to represent lymphoma and staging of the cancer is necessary.⁵

SURGERY

If radiological procedures fail to reduce the intussusception, as in this patient's case, exploratory laparotomy is needed to restore or excise the affected bowel. In patients with bowel perforation, which can occur secondary to radiological reduction, surgery is urgently necessary. ³A single recurrence can be reduced radiologically, whereas a second recurrence often requires surgery. The recurrence rate after radiological or surgical reduction is fairly low and about the same for both procedures.

A PLP and its cause require surgical intervention.⁵ Recurrent intussusception can be caused by a PLP: operative correction is necessary.

References:

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• Wyllie R. Ileus, adhesions, intussusception, and closed-loop obstructions. In: Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics. 17th ed. Philadelphia: Saunders; 2004:1241-1243.

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• Leung AK, Wong AL, Kao CP. Photo essay: GI obstructions in children, part 2. Consultant. 2002;42: 491-495.

• Ko HS, Schenk JP, Troger J, Rohrschneider WK. Current radiological management of intussusception in children. Eur Radiol. 2007 Feb 17; [Epub ahead of print].