Renal Hilum - Anatomy, Location, Diagram, Function

The renal hilum is the vertical slit-like opening located on the medial border of each kidney. It serves as the entry and exit point for vital structures, including the renal artery, renal vein, ureter, lymphatic vessels, and autonomic nerves. The hilum marks the transition between the kidney and its connection to the renal sinus and the rest of the urinary tract.

Structure

The renal hilum is bordered by the renal parenchyma and leads internally to the renal sinus, a fat-filled cavity housing the renal pelvis, calyces, vessels, and nerves. The hilum is not a solid structure but a passageway organized in a specific anteroposterior arrangement:

Structure	Relative Position (Anterior to Posterior)
Renal vein	Most anterior
Renal artery	Middle
Renal pelvis (ureter)	Most posterior

Surrounding connective tissue and fat help stabilize these structures and protect them from compression or kinking during respiration or body movement.

Location

The renal hilum is located:

On the medial border of each kidney
Roughly at the level of the L1–L2 vertebrae in adults
Directed slightly anteriorly and inferiorly in orientation

Function

Though not involved in filtration or secretion, the renal hilum plays a vital role as a passage and organizational landmark:

Entry point: Renal artery brings oxygenated blood to the kidney
Exit point: Renal vein drains filtered blood; ureter transports urine to the bladder
Neurovascular conduit: Carries lymphatics and autonomic nerves that regulate kidney and ureter function

Clinical Significance

Renal vascular conditions: Stenosis or thrombosis of renal vessels often occurs at or near the hilum
Ureteropelvic junction obstruction (UPJO): Commonly occurs at the hilum where the renal pelvis narrows into the ureter
Imaging: The anteroposterior arrangement is key in CT and ultrasound interpretation of renal hilum anatomy
Transplant surgery: Precise identification and handling of the hilum are essential during kidney transplantation for vascular and ureteral anastomosis

The renal hilum is a critical anatomical gateway that organizes and protects the kidney’s vascular, excretory, and nervous connections. Its arrangement is a key reference point in both clinical and surgical contexts.