(A) Intusussception # Ultrasound Axial images of intussusception showed a doughnut pattern.> Hypoechoic external ring was formed by the everted returning limb of intussusceptum and, to a lesser degree, by the intussuscipiens.> Doughnut's center varied according to the scan level.> Scans obtained at the middle or at the base of the intussusception showed a characteristic hyperechoic crescent in all cases.> This crescent was formed by the mesentery enclosing the entering limb of the intussusceptum, which the authors have termed the Crescent-in-doughnut sign'.> On scans obtained at the apex of the intussusception, the center was hypoechoic owing to the entering limb of the intussusceptum and the absence of the mesentery.> Crescent-in-doughnut sign appears to be a characteristic feature of intussusception.> Contrast enema remains the gold standard, demonstrating the intussusception as an occluding mass prolapsing into the lurren, giving the "coiled spring" appearance (barium in the lumen of the intussusceptum and in the intraluminal space).> Main contraindication for an enema is a perforation.