Developmental abnormalities of the pediatric yolk duct, often manifested as protuberant inflammation, can be divided into six causes according to the type of pathology: the first type of umbilical velvet, also called umbilical polyp, for the umbilical mucous membrane remains; the second type of umbilical sinus, refers to the umbilical end of the yolk duct remains a relatively short, unclosed blind tube; the third type of yolk duct fistula, also known as umbilical enterocutaneous fistula, for the whole of the oval duct is not closed; the fourth type of yolk duct cysts, refers to the yolk duct ends of the closure, only the middle part still maintains the original inner lumen, and cysts are formed by the collection of its mucosal secretions; the fifth type of Michael’s diverticulum, which is the unclosed intestinal end of the vitelline duct, leaving a diverticulum in the wall of the terminal ileum; and the sixth type of umbilical intestinal cords, which is the remnant of the vitelline duct and its vascularized fibrotic cords.