Intususseption

Intussusception

Background: Intussusception is the telescoping or prolapse of one portion of the bowel into an immediately adjacent segment. Contrast enema can reduce the intussusception in approximately 75% of cases.


Pathophysiology: Intussusception most commonly occurs at the terminal ileum (ie, ileocolic). The telescoping proximal portion of bowel (ie, intussusceptum) invaginates into the adjacent distal bowel (ie, intussuscipiens).

The mesentery of the intussusceptum is compressed, and the ensuing swelling of the bowel wall quickly leads to obstruction. Venous engorgement and ischemia of the intestinal mucosa cause bleeding and an outpouring of mucous, which results in the classic description of red "currant jelly" stool.

Most cases (90%) are idiopathic, with no identifiable lesion acting as the lead point or pathological apex of the intussusceptum.


Frequency:


In the US: Intussusception is the predominate cause of intestinal obstruction in persons aged 3 months to 6 years. The estimated incidence is 1-4 per 1000 live births.
Mortality/Morbidity: Most patients recover if treated within 24 hours.

Mortality with treatment is 1-3%. If left untreated, this condition is uniformly fatal in 2-5 days.
Recurrence is observed in 3-11% of cases. Most recurrences involve intussusceptions that were reduced with contrast enema.
Sex:

Overall, the male-to-female ratio is approximately 3:1.
With advancing age, gender difference becomes marked; in patients older than 4 years, the male-to-female ratio is 8:1.
Age: Intussusception is most common in infants aged 3-12 months, with an average age of 7-8 months.

Two thirds of the cases occur before the patient's first birthday.
Intussusception occurrence is rare in persons younger than 3 months, and it becomes less common in persons older than 36 months.




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History:

The typical presentation is a previously healthy infant boy aged 6-12 months with sudden onset of colicky abdominal pain with vomiting.
Paroxysms of pain occur 10-20 minutes apart.
Initially, loose or watery stools are present concurrent with vomiting and, within 12-24 hours, blood or mucous is passed rectally.
Early in the course, the patient appears completely well between the episodes of abdominal pain.
Lethargy may dominate the initial presentation. However, lethargy usually occurs later in the process.
The classic triad of colicky abdominal pain, vomiting, and red currant jelly stools occurs in only 21% of cases.
Physical:

Usually, the abdomen is soft and nontender early, but it eventually becomes distended and tender.
A vertically oriented mass may be palpable in the right upper quadrant.
Currant jelly stools are observed in only 50% of cases.
Most patients (75%) without obviously bloody stools have stools that test positive for occult blood.
Fever is a late finding and is suggestive of enteric sepsis.
Causes: Most cases are idiopathic. In neonates and in patients older than 3 years, a mechanical lead point usually can be found.

Predisposing factors
Recent upper respiratory illness
Recent diarrheal illness
Henoch-Schönlein purpura
Cystic fibrosis
Chronic indwelling GI tubes
Processes that result in a mechanical lead point
Meckel diverticulum
Intestinal polyp (eg, Peutz-Jeghers syndrome, familial polyposis coli, juvenile polyposis)
Intestinal lymphosarcoma
Blunt abdominal trauma with intestinal or mesenteric hematomas
Hemangioma
Foreign body
Henoch-Schönlein purpura (small bowel hematomas cause small bowel intussusception)

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