On a CT scan of the abdomen, a cross-sectional image at the level of L1 shows the aorta, IVC, and a structure passing anterior to the aorta from right to left. This structure, when enlarged, can cause 'nutcracker syndrome'. Identify this structure:

• A Left renal artery
• B Cisterna chyli
• C Left renal vein ✓
• D Superior mesenteric artery

Explanation

The left renal vein crosses anterior to the aorta (and posterior to the superior mesenteric artery) to drain into the IVC. In nutcracker syndrome, the left renal vein is compressed between the aorta posteriorly and the superior mesenteric artery anteriorly, causing venous hypertension in the left kidney with haematuria and left flank pain. On axial CT, it is the horizontal vessel anterior to the aorta at the L1–L2 level. The left renal artery arises from the aorta directly and runs posteriorly to the vein. Cisterna chyli is a lymphatic structure that is not visible in normal CT unless distended.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.