Preoperative Evaluation and Indications
Conventional absolute indications for PN include bilateral tumors, renal insufficiency, or a solitary functional kidney.11 Indications for NSS have evolved to encompass the majority of tumors <4 cm in patients with a normal contralateral kidney, and in select patients with cT1b and T2 lesions.5
However, the presence of regional lymphadenopathy or systemic disease is a contraindication to PN. There are currently no absolute anatomic contraindications to a robotic-assisted approach. Although port placement and perinephric dissection can be more challenging in obese patients or following prior abdominal surgery, successful outcomes have been reported for patients with a body mass index (BMI) >30 kg/m2,12 previous intra-abdominal procedures,13 hilar lesions,14-16 tumors >4cm,17, 18 complex (endophytic) lesions,15, 19 and multifocal disease.20 Patients who have had primary ablative procedures to treat renal lesions and have recurrence may be better suited for OPN as dissection may extremely challenging owing to scarring, necrosis, and obliteration of surgical dissecting planes.
Patients being considered for PN should be evaluated with a radiographic staging workup consisting of bi- or tri-phasic abdominal computed tomography (CT) scanning or contrast-enhanced magnetic resonance imaging (MRI), chest non-contrast CT or radiograph, and serum chemistries including electrolytes, renal and liver function tests, and coagulation studies. Anticoagulants and anti-platelet therapies should be stopped 5 to 7 days prior to surgery and a gentle bowel preparation can be utilized in select patients the day prior to surgery.21
Robotic-Assisted LPN Technique
Although RPN techniques vary, most series utilize a 4-5 port configuration with the patient in a full or modified lateral position (Figure 1). The vast majority of the reported experience is transperitoneal. In our practice, the camera (12mm) port is placed off the patient’s midline at the level of the renal hilum, with two 8mm instrument ports placed in the upper and lower quadrants at a minimum of 8mm from the camera port site to avoid arm collision. Techniques using a fourth robotic instrument to minimize the need for a bedside assistant have been described. A 12mm assistant port is placed in the plane between the inferior robotic arm and the ipsilateral lower quadrant, to facilitate access to the hilum and the tumor.
Occasionally, an additional 5mm assistant port is placed in the upper midline, most commonly used for right-sided tumors requiring liver retraction. For complex lesions abutting or invading the collecting system, an ipsilateral open-ended ureteral catheter under cystoscopic guidance can be used at the beginning of the procedure to facilitate identification of collecting system injuries and facilitate closure.
However, it is often not required. Some initial series described laparoscopic kidney mobilization followed by robotic-assisted tumor excision and reconstruction,22 but the majority of surgeons now perform the entire procedure, including renal mobilization and hilar dissection, robotically. It is our preference to perform intra-operative ultrasound with TilePro™ (Intuitive Surgical, Inc., Sunnyvale, Calif.) projection onto the console screen to confirm tumor margins and guide scoring of the renal capsule for tumor excision in all cases. This is especially helpful for complex intrphytic tumors and lesions close or abutting the renal hilum.
In the majority of cases requiring warm ischemia, bulldog clamps are used for arterial clamping while venous occlusion is performed at the surgeon’s discretion. Tumor excision is performed using round-tipped scissors to achieve a 2-3mm margin of normal renal parenchyma (Figure 2a). Collecting system defects and open arterioles/venules are closed intracorporeally using absorbable suture, and the base of the tumor bed is biopsied then coagulated using argon beam or monopolar cautery. An experienced bedside assistant is essential and performs vital tasks including application of the vascular pedicle clamp(s), retraction and suction during tumor excision, and introduction of suture and bolster material.
Various techniques have been described for renal reconstruction,23 including the “sliding-clip renorrhaphy” which utilizes interrupted 2-0 polyglactin suture over rolled oxidized cellulose bolsters secured with WECK® Hem-o-lok (Teleflex Medical, Inc., Durham, N.C.) and Lapra-Ty® (Ethicon EndoSurgery, Cinncinati, Ohio) clips,24 and two-layered closures incorporating V-Loc™ barbed suture (Covidien, Mansfield, Mass.).25 At our institution, we have recently transitioned to a single- layer renorrhaphy using interrupted or running V-Loc™ sutures pledgeted with surgical bolsters (Figure 2b). In all cases, sutures are cut and removed following reperfusion to minimize WIT. Closed-suction drainage is routine at our institution, but also is subject to surgeon discretion.