Are kidneys supplied by the infrarenal (lower renal) artery?

Renal Arterial Supply: Anatomical Facts and Clinical Implications

No, kidneys are not supplied by the infrarenal artery. The kidneys are supplied by the renal arteries, which originate from the lateral aspect of the abdominal aorta at the level of the L1-L2 vertebrae, in the suprarenal (above the renal) position of the aorta 1.

Normal Renal Arterial Anatomy

• The main renal arteries typically arise from the abdominal aorta at the level of L1-L2 vertebrae
• Each kidney is classically supplied by a single renal artery, though variations exist
• The renal arteries branch directly from the aorta in the suprarenal position, not the infrarenal position
• After entering the hilum, the renal artery typically divides into:
  • Anterior division (supplies anterior portions of the kidney)
  • Posterior division (supplies posterior portions of the kidney)

Segmental Arterial Supply

The renal artery further divides into segmental arteries that supply different regions of the kidney 2:

• Apical segmental artery (found in 16.9% of cases)
• Upper segmental artery (present in 98% of kidneys)
• Middle segmental artery
• Lower segmental artery
• Posterior segmental artery

These segmental arteries are end arteries, meaning they do not anastomose with each other, creating independent renal segments 2.

Common Anatomical Variations

1. Multiple renal arteries occur in approximately 9.85% of kidneys 3
2. Accessory renal arteries may enter at the upper or lower poles (4% of kidneys) 4
3. Supernumerary renal arteries may arise from:
   • The aorta directly
   • The inferior mesenteric artery (rare variation) 5
   • Other nearby vessels

Clinical Implications

The anatomical position of renal arteries has significant implications for:

1. Abdominal Aortic Aneurysm (AAA) Repair:

   • Infrarenal AAAs include a proximal aortic neck below the renal arteries
   • Juxtarenal AAAs are adjacent to or include the lower margin of the renal arteries
   • Suprarenal AAAs extend above the orifice of renal arteries 1

2. Renal Artery Stenosis Management:

   • High-grade renal artery stenosis (>70%) with viable kidney tissue may benefit from revascularization
   • Severely atrophic kidneys (<7 cm length) with minimal function (<10% of total) generally don't benefit from revascularization 6

3. Surgical Approaches:

   • Aortorenal bypass is the most common open surgical approach for renovascular disease
   • Reversed saphenous vein is the preferred conduit when bypassing small renal arteries 1
   • Knowledge of segmental arterial anatomy is crucial for partial nephrectomy 3

Pitfalls to Avoid

• Don't confuse infrarenal aortic position (below renal arteries) with the origin of renal arteries themselves
• Be aware that accessory or polar renal arteries may arise from different locations and can be missed during imaging
• Recognize that renal artery variations are common and clinically significant during surgical planning
• Understanding that segmental arteries are end arteries is crucial to avoid inadvertent ischemia during partial nephrectomy

The anatomical relationship between renal arteries and the collecting system is also important, as the posterior segmental artery crosses posteriorly to the upper caliceal infundibulum and renal pelvis in 93% of cases 3, 7.