THE SWEDISH UROLOGY EXPERIENCE
Our experience with RP-RALPN began in June 2006, and 68 procedures have been performed since. The mean age for the group is 58.9 years (range, 34–82 years). There were 44 (65%) men and 24 (35%) women, with 37 (55%) and 31 (45%) renal masses on the right and left, respectively. Mean BMI for the group was 27.5 kg/m2. The mean preoperative tumour size was 2.5 cm (range 1–5 cm), and 95% were found incidentally during radiographic evaluation for other reasons. Thirty-six were located posteriorly, 17 laterally, three medially and one anteriorly. Four masses were complex cysts, whereas the remainder were solid renal masses. One procedure was performed in a solitary kidney whereas another was performed in a polycystic kidney.
Mean operative time was 125 min and mean blood loss was 97 ml. Mean warm ischaemia time was 20.7 min for the group and decreased to 15.2 min for the last 10 patients. The collecting system was entered and repaired in 25 (37%) patients. The mean hospital stay was 2.34 days.
Pathologic analysis revealed renal cell carcinoma in 51 (75%) patients with clear cell in 30, papillary in 16 and chromophobe in five. There were 16 benign tumours, with oncocytoma in six, angiomyolipoma in six and benign cysts in two patients. Mean postoperative tumour size was 2.69 cm. There were three (4.4%) positive margins. One patient had a 4.7-cm type I papillary tumour and has been followed for 48 months with no evidence of recurrence. The other positive margin was in a patient with a 4.5-cm clear cell carcinoma. Laparoscopic radical nephrectomy (LRN) was performed after RP-RALPN, and there was evidence of residual carcinoma in the radical nephrectomy specimen. This patient went on to have a recurrence of renal cell carcinoma in the spine. The final positive margin was a patient with renal vein involvement of the large intrarenal veins with Fuhrman grade 3 clear cell carcinoma. Completion nephrectomy was performed 4 weeks later with no evidence of residual disease in the nephrectomy specimen. The patient went on to have a recurrence in the pelvic bone 1 year after surgery.
Complications occurred in five (7.3%) patients. The most common complication was delayed bleeding due to arterial pseudoaneurysm formation in the partial nephrectomy resection bed. This was identified in three (4.4%) patients at postoperative days 3, 4, and 16. All three patients were successfully treated with angioembolization. One of the patients had von Willebrand's disease and required a transfusion during the episode of bleeding. The other transfusion occurred in a patient with incomplete ischaemia who had significant intraoperative bleeding and estimated blood loss of 1600 ml. One patient suffered a myocardial infarction on the basis of cardiac enzymes and recovered without sequelae. One patient developed hypercapnea, which was refractory to anaesthesia's efforts to increase minute ventilation. The pneumoretroperitoneum had to be taken down temporarily to allow a correction of hypercapnea. The procedure was then completed at a lower pneumoretroperitoneal pressure. Postoperative chest radiograph revealed a small pneumothorax in the ipsilateral pleural space, which resolved without tube thoracostomy. There were no episodes of urine leakage in the series.
The retroperitoneal approach for robotically assisted laparoscopic renal surgery has been applied to multiple procedures, including laparoscopic pyeloplasty, LRN and LPN. Patel et al. reported a series of 10 patients who underwent robotic retroperitoneal renal surgery (three partial nephrectomies, three radical nephrectomies, two simple nephrectomies, one pyeloplasty and one cryoablation). Their patient population had a mean age of 56 years (range 36–72 years). They reported a mean console time of 166 min (range 120–300 min). Mean blood loss was 82 ml (range 50–100 ml) and the average hospital stay was 2.6 days (range 1–5 days). There were no perioperative complications reported; however, one patient was converted to an open nephrectomy due to severe adhesions from xanthogranulomatous pyelonephritis .
One of the earliest evaluations of the retroperitoneal approach was performed by McDougall and Clayman  for laparoscopic nephrectomy for benign conditions. They compared 23 patients undergoing transperitoneal-laparoscopic nephrectomy with 10 patients undergoing the retroperitoneal technique. The two groups were similar with regard to age, American Society of Anesthesiologist (ASA) score and specimen weight. They found no significant difference between the two groups with regard to operative time, hospital stay and analgesic requirements as measured by morphine equivalents. They did note earlier return of bowel function in the retroperitoneal group, and when the weight of the nephrectomy specimen was 100 ml or less. The retroperitoneal patients required less narcotic medication (11 mg morphine equivalent vs. 28 mg for transperitoneal approach). They concluded that the retroperitoneal approach was their method of choice for removal of kidneys for benign indications.
Desai et al.  preformed the only randomized comparison of the TP and retroperitoneal approaches for patients undergoing LRN. They randomized 102 patients with a renal mass to receive either transperitoneal or retroperitoneal LRN with intact specimen extraction. The two groups were comparable with regard to age, BMI, ASA score, laterality of tumour and tumour size (mean mass size 5.3 cm transperitoneally and 5.0 retroperitoneally). They found a significantly shorter time to vessel exposure and shorter operative time with the retroperitoneal approach than with the transperitoneal technique. However, there was no significant difference with regard to estimated blood loss, hospital stay, complications or postoperative analgesic requirements. Although the retroperitoneal approach did not result in an anticipated faster discharge from the hospital, the authors noted several advantages of the retroperitoneal technique and this was the preferred method for LRN at this institution.
Ng et al.[7▪] reported their experience with LPN via the retroperitoneal approach in 63 patients and compared it with the transperitoneal technique in 100 patients. They used tumour location as the determining factor to choose the approach, with posterior tumours excised with the retroperitoneal technique and anterior and lateral tumours removed with the transperitoneal technique. The two groups were very comparable except for tumour size, with the transperitoneal approach associated with larger tumours (3.2 vs. 2.5 cm; P < 0.001). When comparing the two approaches, they found the retroperitoneal technique to result in statistically significantly shorter operative time (208 vs. 173 min; P < 0.001), warm ischaemia time (31 vs. 28 min; P < 0.04) and hospital stay (2.9 vs. 2.2 days; P < 0.01). Blood loss, analgesic requirements, complications and postoperative renal function were without significant difference between the two techniques. Despite the advantages seen with the retroperitoneal approach, the authors stated that they prefer the transperitoneal approach for LPN due to the larger working area and superior suturing angles necessary for renal reconstruction.
Kieran et al.  retrospectively compared their experience with 27 RP-LPN with 45 TP-LPN. The two groups were similar except that the tumour size was smaller (2.1 retroperitoneally vs. 2.7 cm transperitoneally; P = 0.03), and the retroperitoneal technique was used more commonly on right kidneys. They found shorter operative time (160 vs. 192 min; P = 0.008), decreased blood loss (100 vs. 225 ml; P = 0.06) and earlier hospital discharge (1.0 vs. 2.0 days; P = 0.001) in the retroperitoneal group as compared with the patients undergoing TP-LPN. They concluded that depending on the patient and anatomic considerations, the retroperitoneal technique may have advantages over the transperitoneal approach and that these differences may become more apparent with surgeon experience and increasing patient number.
Similar to Kiernan's experience, we found the retroperitoneal approach to offer several advantages over the transperitoneal technique for LPN . Using tumour location to determine the approach, we compared 19 transperitoneal with 32 retroperitoneal patients. Patients with posterior or lateral tumours underwent RP-LPN, whereas anterior and medial tumours were treated with the transperitoneal approach. The retroperitoneal approach resulted in shorter operative time (3.2 vs. 5.4 h, P = 0.0001), less blood loss (192 vs. 403 ml, P = 0.002), shorter time to regular diet (1.2 vs. 1.7 days, P = 0.02) and shorter time to discharge from the hospital (2.3 vs. 3.6 days, P = 0.0008). There was no difference in warm ischaemia time for the two groups.
The largest retroperitoneal experience for LPN was reported by Pyo et al.  in 2008, who reported on 110 patients. They applied the retroperitoneal approach irrespective of tumour location. Mean tumour size was 2.4 cm. Mean operative time was 199 min, mean blood loss was 260 ml and mean length of stay was 2.6 days. There were no positive margins in the series. With a mean follow up of 23 months, there was one local recurrence noted 1 year after LPN in a patient with a negative margin of resection. Residual cancer was confirmed at subsequent radical nephrectomy. There were two persistent urine leaks despite placement of double-J stents in almost all patients. They concluded that the retroperitoneal approach offers perioperative outcomes comparable with open and transperitoneal LPN, with excellent cancer control and preserved renal function. They also point out the advantage of containing blood and urine outside the peritoneal cavity, which decreases patient morbidity.
Although the retroperitoneal technique has been employed for LPN, this approach has not been routinely used for RALPN. Gettman et al. reported the first experience with RALPN in 13 patients and described both the transperitoneal and retroperitoneal techniques in this series. However, there was no indication as to how many patients underwent the retroperitoneal approach and there were no results reported for the retroperitoneal patients. We perform TP-RALPN for anterior and medial tumours and tailor the surgical approach to the tumour location. The two approaches complement each other, and we have found medial tumours to be very difficult to remove with the retroperitoneal technique.
More recently, Weizer et al.  reported their series on robotic retroperitoneal partial nephrectomy detailing intraoperative and perioperative outcomes. They had 16 patients who underwent robotic retroperitoneal partial nephrectomy, with nephrometry scores indicative of moderately complex tumours, two of which were abutting the renal hilum. Average operative time was 185 min, with a mean warm ischaemia time of 27.5 min. Mean blood loss was 100 ml. Mean hospital stay was 2 days. The average increase in serum creatinine was 0.1. None of the surgical specimens had a positive margin, and one patient developed a postoperative urine leak, which was managed with a ureteral stent. Importantly, they did demonstrate a progressive decrease in operative and warm ischaemia time as surgeon experience increased.
In addition to radical and partial nephrectomy, there have been two published series on robotic retroperitoneal dismembered pyeloplasty. Kaouk et al. have a series of 10 patients who underwent pyeloplasty via a robotic retroperitoneal approach. Median surgical time was 175 min [95% confidence interval (CI) 128–185), median estimated blood loss was 50 ml (95% CI, 26–62) and the median hospital stay was 48 h (95% CI, 27–65). No complications occurred. At a mean follow-up of 30 months (range 24–36 months), there was no evidence of recurrence in any of the patients. Cestari et al. have a series of 36 patients who were compared with 19 patients undergoing pyeloplasty via a transperitoneal approach. Operative time, blood loss and hospital stay were identical in the two groups. There were two recurrences of ureteropelvic junction obstruction, which both occurred in the retroperitoneal group. No significant perioperative complications were noted in either group.
Although the body of literature dedicated specifically to the topic of robotic retroperitoneal kidney surgery is small, all of the studies seem to indicate that the retroperitoneal approach offers a feasible, reproducible option for dealing with surgical renal disease. There does not appear to be any significant increase in perioperative metrics or complications. In addition, surgical outcomes appear to be comparable to transperitoneal series. This technique is ideal for patients who have had previous abdominal surgery and avoids any adhesions that may be present. Retroperitoneal surgery sequesters any urine leakage or blood that may result from partial nephrectomy. With experience, the limitations associated with the retroperitoneal approach can be minimized and adequate working space can be created for the daVinci robot.
Conflicts of interest
Mayank Patel, MD, has no conflict of interest.
James Porter, MD, is a speaker for Intuitive Surgical.
REFERENCES AND RECOMMENDED READING
Papers of particular interest, published within the annual period of review, have been highlighted as:
- ▪ of special interest
- ▪▪ of outstanding interest
Additional references related to this topic can also be found in the Current World Literature section in this issue (p. 100).
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This is one of the largest series published comparing the laparoscopic transperitoneal approach with the retroperitoneal approach on the basis of tumour location. The study highlights some of the advantages of the retroperitoneal technique, which include shorter operative time, shorter ischaemia time and shorter hospital stay. The authors also discuss the disadvantages of the retroperitoneal technique, which include smaller working space for large renal tumours.
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Keywords:© 2013 Lippincott Williams & Wilkins, Inc.
partial nephrectomy; retroperitoneal surgery; robotic surgery; technique