Ruptured appendicitis mimicking an intussusception

Imaging description A six-year-old child presented to the ER with abdominal pain. A ultrasound (US) study (Fig. 44.1a, b) demonstrated a lesion in the right lower quadrant with a pattern of alternating sonolucent and hyperechoic layers, giving an appearance of a bowel loop-within-loop, suggesting intussusception. A plain radiograph of the abdomen (Fig. 44.1c) revealed blurring of the right flank fat plane, medial displacement of ascending colon gas, and subtle scoliosis of the spine, indicating a right-sided inflammatory process or mass. A contrast enema was obtained to reduce the intussusception diagnosed on US (Fig. 44.1d). The study revealed a possible filling defect at the hepatic flexure which rapidly disappeared (? reduced intussusception) and normal reflux of contrast was noted into the ileum (Fig. 44.1d). The child continued to have abdominal pain, fever, and high white blood cell count. Repeat US the following morning demonstrated a similar, slightly more complex layered pattern and marked surrounding echogenic inflammation was noted (Fig. 44.1e). Taking into account the clinical and laboratory findings as well as the child’s age (old for typical idiopathic intussusception), perforated appendicitis with phlegmon/abscess was suggested as a more likely diagnosis. CT examination confirmed ruptured acute appendicitis with an appendicolith and periappendiceal fluid collection/abscess (Fig. 44.1f, g).