Intussusception in children: Current concepts in diagnosis and enema reduction

Intussusception cannot be reliably ruled out with clinical examination and plain radiography, However, a contrast material enema study and ultrasonogr aphy (US) allow definitive diagnosis of intussusception. The components of an intussusception produce characteristic appearances on US scans. These ap pearances include the multiple concentric ring sign and crescent-in-doughnu t sign on axial scans and the sandwich sign and hayfork sign on longitudina l scans. Indicators of ischemia and irreducibility are trapped fluid at US and absence of blood flow at Doppler imaging. The aim of enema therapy is t o reduce the greatest number of intussusceptions without producing perforat ion. Barium, water-soluble contrast media, water, electrolyte solutions, or air may be used with radiographic or US guidance. The differences in reduc tion and perforation rates between the various types of enemas are probably due more to perforations that occurred before enema therapy and the pressu re exerted within the colon than to the contrast material used. The pressur e within the colon is more constant with hydrostatic reduction than with ai r reduction; this fact may explain the lower risk of perforation with hydro static reduction. Radiation exposure is lower with air enema therapy than w ith barium enema therapy and is absent in US-guided enema therapy.