Discussion Author: Jason Broomhall
Intussusception occurs when one portion of the bowel telescopes into the lumen of a more distal portion of the bowel. The proximal portion of bowel which invaginates into the distal portion is known as the âintussusceptum,. The distal portion of bowel is known as the âintussuscipiens.â Intussusception can result in complete obstruction of the lumen of the GI tract, but the major cause of morbidity and mortality is actually due to vascular compromise with infarction and necrosis of bowel.
Intussusception is commonly thought of as a disease of childhood, with most cases appearing before the age of 4-5 years old, with two-thirds of cases reported between 3-12 months of age. The etiology of intussusception in very young is frequently idiopathic, but is hypothesized to involve lymphoid hyperplasia within the intestinal wall. When an intussusception occurs in an older child (>5 years)or adult, âlead pointsâ must be excluded. Possible lead points may include Meckelâs diverticulum, duplication cyst, lymphoid hyperplasia, lymphoma, polyps, appendicitis, Henoch-Schonlein purpura secondary to intramural areas of hemorrhage, and cystic fibrosis secondary to thick secretions altering the compliance/elasticity of the bowel wall. The site of intussusception is characteristically at the ileocecal valve, resulting ileocolic intussusception (ileum telescoping into ascending colon), accounting for approximately 80% of cases. Lead points are found with increasing incidence as age increases, with fewer than 4% found in age less than 2 years whereas 40% are found in patients greater than 4 years old. The most common lead point found is a Meckelâs diverticulum, found in 40% of cases. Lymphomas (Burkittâs) are a relatively uncommon lead point for intussusception, found in only 9.5% of cases.
Intussusception usually presents with obstruction. Patients may complain of crampy, colicky, and intermittent abdominal pain (necessitating the patient to draw knees up into chest during painful episodes), a palpable abdominal mass (described as âsausage-shapedâ), and currant jelly stools (stools with blood and mucus mixed); however, this classic triad is only present in 20-50% of cases, with currant jelly stools observed late in the course of the disease process. The patient may act normally between episodes of abdominal pain. When an older child presents with abdominal pain, the differential diagnosis should include intussusception as nearly one-third of cases will present after 1 year of age and appropriate diagnostic evaluation should be pursued.
In most cases of intussusception a plain radiograph is likely to be completed prior to ultrasound or air enema. This is necessary to exclude free air in the abdomen (suggesting perforation), in which case non-surgical management is contraindicated. Plain radiographs may also show a soft tissue mass, âmeniscus sign,â paucity of gas in the GI tract proximal to the obstruction, and absence of gas and stool in the cecum, all of which may clue the clinician to a diagnosis of intussusception but are not very reliable for the diagnosis. Ultrasound may show the classic âpseudokidney,â described as hyperechoic mesenteric fat in a crescent-shape and associated lymph nodes and vessels within the intussusception. When ultrasound is not available or the suspicion for intussusception is high, an air-contrast enema is recommended as both diagnostic and therapeutic.
Prompt treatment is essential to avoid bowel necrosis, perforation, and shock. Prior to reduction, the patient should be stabilized with fluids and pain medications if needed. In most cases, non-surgical means of reduction (air-contrast enema) can be performed under either fluoroscopy or ultrasound guidance with much success in reducing the intussusception and should be the first procedure undertaken as long as no contraindications exist (i.e.- evidence of perforation prior to reduction). Air (pneumatic) enema is the preferred method as it usually is associated with less radiation exposure as well as lower complication rates if reduction results in perforation. Recurrence is described in 8-15% of patients (regardless of technique used), and two-thirds will occur in the first few days following reduction. Therefore, it is recommended that patients be followed closely. If recurrence does happen, patients may undergo repeat non-surgical reduction.
If a lead point is demonstrated or if necrotic bowel is suspected, surgical repair should be undertaken to remove the lead point and resect the necrotic bowel in order to prevent recurrences and decrease complications.
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