[Invagination].

Intussusception is the most common abdominal emergency in infancy and childhood. Most cases are idiopathic ileocolic intussusceptions; rarely is a lead point present. Abdominal ultrasound is the imaging modality of choice for the demonstration as well as the exclusion of an intussusception. The target (transverse section) and pseudokidney (longitudinal section) signs are pathognomonic sonographic findings. Simultaneous depiction of lead points or lymph nodes or the presence of an entero-enteral intussusception may lead to different appearances. When an intussusception has been diagnosed with ultrasound, further complications such as small bowel obstruction or free intraperitoneal fluid have to be excluded at the same time. In addition, the perfusion of the intussusceptum can be evaluated with color Doppler ultrasound. There is general consensus that the only contraindications for conservative reduction are bowel perforation, peritonitis and hypovolemic shock. The oldest and most widespread method is hydrostatic reduction with barium under fluoroscopic control. Pneumatic reduction under fluoroscopic monitoring has gained more and more acceptance. An alternative technique is sonographically guided hydrostatic reduction with normal saline solution. Both latter methods are reported to have success rates of 80-90% and are clearly superior to the barium technique. In our opinion ultrasound monitoring offers the most precise control of the whole reduction process, with distinct demonstration of the intraluminal structures, especially of the ileocecal valve and of a possible lead point. A complication can be recognized immediately. The primary advantage is the lack of radiation exposure. Therefore, with appropriate equipment and experience this method may be regarded as most promising in the management of intussusception in infancy and childhood.