Ella, a 9-month-old female, is brought to the emergency room by her parents due to episodes of crying and pulling her legs up to her chest that have been occurring every 15–20 minutes over the past day. During these episodes, Ella appears pale and irritable. The parents report that she has had non-bilious vomiting initially, but it became green and bilious as the day progressed. They also noticed a red, mucus-filled stool described as “currant jelly.” On examination, Ella appears lethargic between crying episodes, her abdomen is distended, and a palpable “sausage-shaped mass” is noted in the right upper quadrant. You suspect intussusception in this infant. What is the first-line diagnostic imaging modality for intussusception in children?
