V12-09 the anatomic scalene triangle: a useful landmark for pelvic lymphadenectomy during retzius-sparing robotic-assisted radical prostatectomy

Objective: Pelvic lymphadenectomy (PLN) during Retzius-Sparing Robotic-Assisted Radical Prostatectomy (RS-RARP) may be challenging because the medial umbilical ligaments are not released, and the anterior structures are preserved. The incidence of symptomatic lymphoceles following PLN during RS-RARP has been reported to be higher than standard approaches (anterior technique) for RARP. We describe the anatomic scalene triangle as a useful landmark to facilitate PLN during RS-RARP and compare outcomes of PLN using this technique versus PLN for standard RARP. Patients and Surgical Procedure: This is a single center, institutional review board approved, retrospective case-control study of 200 consecutive patients undergoing RS-RARP or standard RARP. We compared perioperative factors such as age, BMI, PSA, grade group, tumor stage, lymph node yield, and incidence of symptomatic lymphoceles using t-test for continuous variables and Fisher's exact test for categorical variables. A P-value of < 0.05 was considered statistically significant. In the RS-RARP, group the anatomic scalene triangle was used as a landmark for PLN. The scalene triangle is formed superiorly by the vas deferens, medially by the medial umbilical ligament, and laterally by the external iliac vein. The peritoneum overlying the triangle is incised and an avascular plane in this space is developed. Retraction of the vas deferens and medial umbilical ligament facilitates exposure of the lymph node packet and obturator nerve. Once the lymph node packet is isolated, surgical clips are applied and mobilization of the lymph nodes is performed cranially. Once the proximal extent of the dissection has been reached, the lymph node packet is divided and removed. Results: There were no statistically significant differences between RS-RARP and standard RARP with respect to age, BMI, PSA, grade group, tumor stage, lymph node yield, or incidence of symptomatic lymphoceles. There were 4 symptomatic lymphoceles in the RS-RARP group and 1 symptomatic lymphocele in the standard RARP group. These were all treated with percutaneous drainage by interventional radiology. Conclusions: The anatomic scalene triangle is a useful landmark to facilitate a safe, reproducible, and efficient PLN during RS-RARP. We observed a 4% incidence of symptomatic lymphoceles compared to prior, smaller series which have demonstrated 8–16% incidence of symptomatic lymphoceles with PLN during RS-RARP. Although there was a higher incidence of symptomatic lymphoceles in the RS-RARP group compared to standard RARP, this was not statistically significant.