As stated earlier, preoperative CT and MRI imaging has poor sensitivity for detecting LN mets <11 mm. New technologies are emerging that may improve the accuracy of MRI including restriction spectrum imaging (RSI ), in addition to diffusion weighted imaging (DWI ) [7]. Novel methods are emerging to preoperatively detect LN metastases and subsequently detect these LNs intraoperatively. In one study, fluorescent-labeled tilmanocept was injected into male dogs, a pelvic PET/CT scan was performed for sentinel lymph node mapping, and robotic-assisted sentinel lymph node dissection using a fluorescence-capable camera system was completed [5].

The same preoperative preparation instruction and orders used for robotic-assisted laparoscopic prostatectomy are given for pelvic lymph node dissection. One important consideration is the administration of pharmacologic venous thromboembolism (VTE) prophylaxis prior to surgery. VTE rates following robotic-assisted radical prostatectomy range from 0.2 to 8%. In a large series of 2572 robotic-assisted prostatectomies, a 0.7% prevalence of VTE was observed; however, the addition of a pelvic lymph node dissection increased the risk of deep venous thrombosis (DVT ) and pulmonary embolism (PE) by eight- and six-fold, respectively [8]. Pelvic lymphocele is thought to be a contributing factor to VTE because compression of large pelvic veins can worsen lower extremity stasis and associated pain may result in immobility. While lymphocele formation may be related to surgical technique and extent of PLND, there is some evidence to suggest that pharmacological VTE prophylaxis may increase the risk of lymphocele formation—anticoagulation may increase the drainage of lymph by preventing lymphatic coagulation. For the surgeon, the decision to administer preoperative VTE prophylaxis should be based on patient risk factors for VTE and need for PLND, as well as its extent. At our institution, we do not routinely administer preoperative VTE prophylaxis beyond sequential compression devices and early ambulation unless the patient is high risk (i.e., previous history of VTE) and we routinely use hemo-lock or titanium clips extensively to occlude lymphatic vessels and minimize the risk of lymphocele formation.

At the time of PLND , the patient will already be positioned appropriately in steep Trendelenburg and the same trocar configuration for transperitoneal robotic-assisted laparoscopic prostatectomy is utilized.