Hilum

The hilum is the anatomical region where blood vessels, lymphatics, nerves, and ducts enter or exit an organ. In sonography, the hilum is an important landmark in several organs. The renal hilum is where the renal artery and vein enter and exit the kidney and the ureter originates. The splenic hilum is where the splenic artery and vein connect to the spleen. The hepatic hilum, or porta hepatis, is where the portal vein, hepatic artery, and bile duct enter the liver. On ultrasound, the hilum typically appears as an echogenic region at the center of an organ, and identifying it helps sonographers orient themselves and locate important vascular and ductal structures.