Renal artery

The renal arteries originate from the abdominal aorta and enter the renal hila to supply the kidneys.  Any variant in arterial supply is important to clinicians undertaking surgery or other interventional renal procedures.

Gross anatomy

Origin

They arise from the abdominal aorta at the L1-2 vertebral body level, inferior to the origin of the superior mesenteric artery. 

Course

The right renal artery courses inferiorly and passes posterior to the IVC and the right renal vein to reach the renal hilum. The left renal artery is much shorter and arises slightly more superior to the right main renal artery. The left renal artery courses more horizontally, posterior to the left renal vein to enter the renal hilum. Renal arteries are between 4-6 cm in length and usually 5-6 mm in diameter.

Branches

Each renal artery gives off small branches in its proximal course, prior to dividing into dorsal and ventral rami. These branches are very small and often not visible on imaging studies:

• inferior adrenal artery
• ureteric artery
• capsular artery

The dorsal and ventral rami divide into segmental branches within the renal hilum before entering the parenchyma: apical, anterior superior, anterior inferior (middle), inferior and posterior segmental renal arteries. These then divide into lobar branches which successively branch into interlobar, arcuate, and interlobular arteries. The afferent arterioles, which supply the glomeruli, originate from the interlobular arteries.

Radiographic features

Doppler ultrasound

• can be technically difficult and only completed in 60% of patients
• normal peak systolic velocity is 150-180 cm/s and elevation beyond this may indicate renal artery stenosis of >60% ⁴
• normal renal arterial resistive index (RI) is ≈ 0.60

Variant anatomy

• accessory renal arteries
  • ​common; occur in ~30% of the population, bilateral in ~10%
  • enter the renal hilum
  • may arise from the aorta below (more commonly) or above the renal artery
  • termed aberrant renal arteries when they enter renal capsule in the upper or lower pole rather than the hilum
• early-branching (or prehilar branching): occurs in ~10% of the population
  • occurs within 1.5-2.0 cm of origin in the left renal artery or in the retrocaval segment of the right renal artery
  • important to recognize in renal transplant for successful anastomoses
• thoracic renal artery ⁵

Related pathology

• renal artery stenosis
• renal artery aneurysm
• renal artery dissection
• fibromuscular dysplasia
• renal transplant