Laparoscopic and robotic extravascular stenting of the left renal vein for anterior nutcracker syndrome in a single-center series

Abstract

Background

Nutcracker syndrome (NCS) arises from extrinsic compression of the left renal vein (LRV) between the superior mesenteric artery and the abdominal aorta. Extravascular stenting (EVS) has emerged as a minimally invasive alternative to historical operations and endovascular stents. We report a single-center series spanning 2010 to 2025 and propose a standardized, reproducible framework that couples intraoperative process quality with objective postoperative hemodynamic targets.

Methods

We retrospectively analyzed 22 consecutive NCS patients treated with laparoscopic or robot-assisted EVS. We standardized five intraoperative steps (five-in-a-row: fibrotic-ring resection, proper length tailoring/placement, sufficient superior mesenteric artery mobilization, complete division of LRV tributaries, stable anterior fixation). Postoperative duplex ultrasound metrics included aortomesenteric (AM) LRV peak systolic velocity and the AM/hilum peak systolic velocity (PSV) ratio. Thresholds were determined by receiver operating characteristic-Youden index; performance was summarized at fixed cutoffs, with bootstrap for the ratio and exploratory OR/AND combinations.

Results

Complete success was achieved in 18 of 22 patients (81.8%). Data-driven analysis identified a postoperative AM PSV of ≤72 cm/s as the primary attainment threshold, yielding a sensitivity of 1.00, specificity of 0.75, accuracy of 0.95, and area under the receiver operating characteristic curve (AUC) of ≈0.917. The AM/hilum ratio showed a Youden-optimal cutoff of ≈1.90 (clinically ≈2.0) with an AUC of ≈0.56, supporting its role as a sensitivity/replicability metric rather than a standalone gatekeeper. OR and AND combinations demonstrated expected trade-offs; a simple 0/1/2 composite score achieved an AUC of ≈0.78. The five-in-a-row checklist was concordant with attaining the AM-PSV target on Doppler ultrasound examination.

Conclusions

Laparoscopic or robot-assisted EVS is a safe, feasible, and effective option for NCS. We a propose postoperative AM PSV of ≤72 cm/s as a unified, reproducible primary quantitative end point, with an AM/hilum ratio of ≈2.0 as a secondary, replicability-oriented metric. Integrating these targets with a standardized five-in-a-row checklist establishes a process-outcome loop that enhances procedural reproducibility and supports sustained symptom relief over the available follow-up.