Christopher Kim

Intussusception is defined as the invagination of one bowel segment into another (telescoping into a distal segment).This leads to obstruction of venous and lymphatic flow. If the obstruction isn't reduced, there will be mesenteric artery obstruction leading to ischemia of the bowel.

Epidemiology

1. In the U.S. 2.4/1000 live births
2. Most commonly between 5-9 months
3. Twice as frequent in males.than females

1. The telescoping can produce obstruction, ischemia, and eventual strangulation of the bowel
2. 90% are idiopathic. 10% involve a discrete lead point.
3. Common lead points include Meckel's diverticulum, intestinal polyps, appendicitis, neoplastic lesions, and foreign bodies. 
4. Lymphoid hyperplasia is frequently found in idiopathic cases, and a viral illness, commonly a URI or gastroenteritis, can precede the event.  This may account for seasonal incidence differences.
5. 80% are ileocolic. Ileoileal, colocolic, jejunojejunal, and cecocolic can also occur.
6. There is an association with HSP in older children, usually ileoileal. Because of location, often unreducible with barium enema. 

1. Triad of abdominal pain, vomiting, and bloody stools.(currant jelly)  Bloody stools are a late finding.
2. Other findings include RUQ mass, fever, and diarrhea. A rectal exam may demonstrate the mass and will also have the presence of blood and mucus on the glove. 
3. There may be irritability, child pulls legs up and screams intermittently, and this is followed by paleness and being limp. Frequently the child is lethargic and not uncommonly the patient is admitted with the diagnosis of meningitis.

1. A plain film of the abdomen is often performed and may show a mass and an obstructive pattern
2. Ultrasound of the abdomen is often the first test of choice. Sensitivity of almost 100%. A positive test will demonstrate a doughnut or onion skin pattern.
3. Barium enema is also diagnostic but is contraindicated with perforation of the intestines, peritonitis, and prolonged obstruction.

1. NOTE: Often there is spontaneous resolution
2. Barium enema performed by an experienced radiologist will be effective in 80% of the cases. There is a 10% recurrence rate. Parents are advised of symptoms to watch for and if there are recurrences, barium enema may be tried again. After multilple recurrence, surgery may be done to find a specific lead point or resect some bowel. The rate of reduction decreases the longer the obstruction is present. 
3. Operative reduction is needed for patients who fail barium reduction or have contraindications of barium enema. 
4. Fluid resuscitation, nasogastric tube, pain medication, and antibiotics are usually started. 

1. Winslow BT, Westfall JM and Nicholas RA. Intussusception. American Family Physician. 1996. 54(1): 213-217
2. Index of Suspicion  Case 2 Pediatrics in Review April 2001
3. Bines J. et al. Risk Factors for Intussusception in Infants in Vietnam and Australia: Adenovirus Implicated, but not Rotavirus.  Journal of Pediatrics October 2006