What are the step‑by‑step steps to expose the left renal vein for creation of a left‑sided portosystemic shunt in an adult patient?

Surgical Exposure of the Left Renal Vein for Portosystemic Shunt Creation

The left renal vein is exposed through a trans-peritoneal approach by mobilizing the descending colon medially after incising the white line of Toldt, which provides direct access to the retroperitoneum and the left renal vein running horizontally at the L1-L2 vertebral level. 1

Pre-operative Imaging and Planning

• Obtain a pre-operative CT angiogram with venous-phase acquisition to map the left renal venous anatomy and identify any anatomical variants before surgery 1
• Cross-sectional imaging with portal venous contrast phase should be obtained to determine vascular anatomy, including the presence or absence of portosystemic shunts and gastrorenal shunts 2
• The left renal vein typically runs horizontally from the renal hilum to its junction with the inferior vena cava at the L1-L2 vertebral level 1

Patient Positioning

• Position the patient supine with the left side modestly elevated approximately 15-30 degrees to enhance access to the left upper quadrant during the trans-peritoneal approach 1
• General anesthesia or deep sedation using propofol is required for the procedure 1

Surgical Exposure Steps

Step 1: Colon Mobilization

• Incise the white line of Toldt along the lateral peritoneal reflection of the descending colon 1
• This incision runs along the lateral border where the peritoneum reflects from the posterior abdominal wall onto the colon 1

Step 2: Medial Reflection

• Reflect the left colon and mesocolon medially after completing the incision along the white line of Toldt 1
• This maneuver exposes the retroperitoneum and grants direct access to the anterior surface of Gerota's fascia 1

Step 3: Retroperitoneal Exposure

• The medial reflection of the colon exposes the retroperitoneum, providing direct visualization of Gerota's fascia and the underlying renal vessels 1
• The left renal vein lies anterior to the left renal artery and can be identified running horizontally across the retroperitoneum 1

Intra-operative Considerations

• Portal pressure must be measured before and after shunt creation, with the goal being a reduction of at least 20% or to a value below 12 mm Hg 1
• Meticulous hemostasis is essential because of the high-pressure venous system involved in portosystemic shunt surgery 1
• Coagulation evaluation should be performed with thromboelastography rather than INR, as INR is unreliable in liver disease 1
• Platelet transfusion is recommended when the platelet count is below 50 × 10⁵/L 1
• Prophylactic antibiotics should be administered for this complex abdominal operation 1

Post-operative Surveillance

• A Doppler ultrasound performed at one week post-procedure should confirm shunt patency, especially in patients with pro-thrombotic conditions 1
• Subsequent Doppler ultrasound examinations are recommended at 6-12 month intervals to monitor long-term shunt integrity 1

Common Pitfalls and Caveats

• Failure to identify anatomical variants pre-operatively can complicate the surgical approach; this is why pre-operative CT angiography with venous phase is essential 1
• In cases where extensive portal thrombosis involves the splenic and superior mesenteric veins, traditional splenorenal shunting may be unfeasible, and a makeshift portosystemic shunt between a suitable portal varix and the caval system may be required 3
• The presence of large spontaneous splenorenal shunts may result in portal flow steal; in such cases, left renal vein ligation can be performed to prevent this phenomenon, though it carries the risk of moderate and temporary renal function impairment 4, 5