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Intussusception is telescoping of one portion of the intestine (intussusceptum) into an adjacent segment (intussuscipiens), causing intestinal obstruction and sometimes intestinal ischemia.
Intussusception generally occurs between ages 3 mo and 3 yr, with 65% of cases occurring before age 1. It is the most common cause of intestinal obstruction in this age group. Most cases are idiopathic. However, there is a slight male predominance as well as a seasonal variation; peak incidence coincides with the viral enteritis season. In older children, there may be a lead point (ie, a mass or other intestinal abnormality that triggers the telescoping). Examples include polyps, lymphoma, Meckel's diverticulum, and Henoch-Schönlein purpura. Cystic fibrosis is also a risk factor.
The telescoping segment obstructs the intestine and ultimately impairs blood flow (see Fig. 1: Gastrointestinal Disorders in Neonates and Infants: Intussusception. ), causing ischemia, gangrene, and perforation.
Symptoms and Signs
The initial symptoms are recurrent colicky abdominal pain that occurs every 15 to 20 min, often with vomiting. The child appears relatively well between episodes. Later, as intestinal ischemia develops, pain becomes steady, the child becomes lethargic, and mucosal hemorrhage causes heme-positive stool on rectal examination and sometimes spontaneous passage of a currant-jelly stool. The latter, however, is a late occurrence, and physicians should not wait for this symptom to occur to suspect intussusception. A palpable abdominal mass, described as sausage-shaped, is sometimes present. Perforation results in signs of peritonitis, with significant tenderness, guarding, and rigidity. Pallor, tachycardia, and diaphoresis indicate shock.
Diagnosis
Studies and intervention must be done urgently, because survival and likelihood of nonoperative reduction decrease significantly with time. Approach depends on clinical findings. Ill children with signs of peritonitis require fluid resuscitation (see Dehydration and Fluid Therapy in Children: Resuscitation), broad-spectrum antibiotics (eg, ampicillin, gentamicin, clindamycin), nasogastric suction, and surgery. Others require imaging studies to confirm diagnosis and treat the disorder.
Barium enema was once the preferred initial study because it revealed the classic “coiled spring” appearance around the intussusceptum. In addition to being diagnostic, barium enema was also usually therapeutic; the pressure of the barium often reduced the telescoped segments. However, barium occasionally enters the peritoneum through a clinically unsuspected perforation and causes significant peritonitis. Currently, ultrasonography is the preferred means of diagnosis; it is easily done, relatively inexpensive, and safe.
Treatment
If intussusception is confirmed, an air enema is used for reduction, which lessens the likelihood and consequences of perforation. The intussusceptum can be successfully reduced in 75 to 90% of children. Children are observed overnight after reduction to rule out occult perforation. If reduction is unsuccessful, immediate surgery is required. Without surgery, the recurrence rate is 5 to 10%.
Last full review/revision November 2007 by William J. Cochran, MD
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