Imaging of the umbilicus and periumbilical region.

Umbilical disorders can be classified according to embryonic remnants contained in the umbilicus, including the urachus, omphalomesenteric duct, and round ligament of the liver; the extraperitoneal paravesical spaces; the umbilical ring; and the umbilicus itself. Only one of the five types of congenital urachal abnormalities (urachal cyst) is common. All anomalies associated with the omphalomesenteric duct are rare except the Meckel diverticulum, which is the most common congenital abnormality of the gastrointestinal tract. The round ligament contains the remnant of the umbilical vein, which in the presence of portal hypertension, may open, recanalize, and form a portosystemic collateral vessel. Extraperitoneal paravesical spaces that run from the umbilicus to the bladder may contain fluid collections. The umbilical ring and the umbilicus may give rise to many masses, including omphalocele, gastroschisis, various hernias, inflammatory and suppurative processes, and neoplasms. Clinical manifestations of umbilical disorders are usually nonspecific; use of cross-sectional imaging can help identify most of these entities because of their typical locations and distributions in continuity with the urinary bladder and the umbilicus and guide therapy. Understanding the anatomy and the differential diagnosis of umbilical disorders is key to arriving at a correct diagnosis and proper patient treatment.