Simplified approach to umbilical remnant abnormalities.

To facilitate an understanding of abnormalities related to the umbilical remnants, the authors present a simplified classification scheme on the basis of embryologic anatomic relationships. In a type 1 remnant, the entire duct (vitelline or urachus) is patent; in type 2, only one end is patent; and in type 3, only the midportion is patent. The authors illustrate and describe various entities in terms of this classification, including patent vitelline duct, umbilical sinus, Meckel diverticulum, vitelline cyst, patent urachus, urachal sinus, urachal diverticulum, and urachal cyst. With this scheme, imaging characteristics of the types of remnant abnormalities can be predicted. The result is a cogent approach to the radiologic evaluation of the patient with a suspected umbilical remnant anomaly.