Invagination intestinale aiguë du nourrisson et de l'enfant

Intussusception is the most common abdominal emergency in infancy and early childhood, but it can occur at any age. The penetration of an intestinal segment into the distal contiguous segment causes obstruction of the digestive lumen and vascular compression at the neck level. The radiologist's role is essential for diagnosis as well as for treatment. Sonography (US) has become the gold standard to diagnose or exclude intussusception. US detects an intestinal mass of 20 to 45 mm in anteroposterior diameter, with a doughnut or target shape centered by the invaginated segment and its meso. It enables identification of the anatomic form, suspicion of vascular compromise, and depiction of a focal pathological leadpoint, providing guidance for therapeutic management. An enema is performed solely for therapeutic reasons. US may also be indicated to guide hydrostatic enema, to check for a successful reduction and to detect recurrence during follow-up. Idiopathic ileocolic intussusception, by far the most common form, is due to lymphoid hyperplasia of the ileocecal area. It is usually reduced by enema therapy. Surgery should be undertaken only when there is an ischemic bowel and/or a pathological leadpoint. In contrast, pathological small bowel intussusception is very rare and produces bowel obstruction. It is associated with a predisposing condition (recent surgery, Henoch-Schonlein purpura, cystic fibrosis, Peutz-Jeghers syndrome) and/or with a pathologic leadpoint (Meckel's diverticulum, localized Burkitt lymphoma, cystic duplication, polyp). It usually requires surgery except in proven disseminated lymphoma where chemotherapy can produce spontaneous reduction. Colocolic invagination, exceptional, is secondary. It is easily reduced by therapeutic enema, but will recur if the leadpoint (polyp) is not removed. Transient small bowel intussusception is very frequent, small (10 to 19 mm in anteroposterior diameter), peristaltic, with no bowel obstruction and reduces spontaneously. It must be differentiated from pathological intussusceptions.