Since we were familiar with the anatomical frame, landmarks, and operative technique of radical nephrectomy for cT1-3aN0 M0 renal tumors via the translumbar approach, we also employed this approach for single MIES nephrectomy . Our results demonstrate that radical nephrectomy can be safely performed as a single MIES procedure. As can be seen in Table 3, the background factors, operating time, blood loss, and postoperative recovery time of our series were compatible with previous results reported by Kihara et al. . Therefore, as Kihara et al. also concluded, radical nephrectomy by single MIES is safe, reliable, and minimally invasive.
The extraperitoneal subcostal translumbar approach avoids the risk of peritoneal contamination and also results in earlier resumption of normal bowel function following surgery. We used images created by 3D-CT to display the location of the kidney in relation to the lower rib cage, iliac crest, and spine, thereby helping the surgeon to accurately plan the initial incision. The position of the kidney and the location and size of the tumor(s) determined the length of the incision.
Preoperative 3D imaging of the renal arteries and veins provides useful information for laparoscopic nephrectomy . Single MIES is performed via a single small incision, detailed anatomical information is required in order to approach the renal artery and vein safely as the operation progresses step-by-step with manipulation of the endoscope and instruments through the narrow single incision. Retrospective analysis of the initial 20 MIES nephrectomies suggested several issues. First, it is very important to define the location and the number of renal arteries and veins, as well as their relations to gain structures, before performing MIES nephrectomy. Second, it is necessary to gain sufficient knowledge in order to accurately approach and locate the renal vessels during MIES nephrectomy, because the renal artery must be ligated and divided before the renal vein. Therefore, it is important to approach the renal artery in a safe and appropriate manner. Third, there are reported to be some anatomical differences of these vessels between the right and left sides (Figure. 3).
In order to overcome these problems, we performed preoperative 3D-CT. We used the volume rendering method for reconstruction of 3D images because it retains all data by summing the contributions from each voxel along a line set at any viewing angle through a stack of axial images. After 3D images have been created, two-dimensional images can also be obtained. That is, the 3D-CT images can be employed to view the kidney in different positions and 2-dimensional images can be created in any desired plane, allowing clear demonstration of the relation between the tumor and the renal vessels or adjacent structures. If perirenal collateral veins are detected in a patient by 3D-CT, we must pay careful attention when dissecting the kidney from the surrounding fibrous connective tissue. Marukawa et al. reported that 3D imaging achieved almost perfect detection of renal arteries and veins, and that 3D simulation of retroperitoneal laparoscopic nephrectomy could help surgeons to avoid various operative risks and possible complications . In our study, the number of renal arteries and veins corresponded completely with the preoperative 3D-CT data (100% sensitivity and 100% specificity). With preoperative virtual surgery, we cannot actually perform dissection between the psoas fascia and Gerota's posterior fascia to approach the renal hilar vessels, but performing the virtual procedure is likely to provide more information than that gained from careful study of standard axial CT scans.
Comparison between our first 20 nephrectomy procedures and the next 20 revealed a shorter operating time and smaller blood loss in the latter group, while the third and fourth nephrectomy groups also had a shorter operating time and smaller blood loss than the first group (Figure. 4). Irrespective of the lack of a difference in tumor size or side among patients from the first to fourth groups undergoing right nephrectomy, blood loss was markedly decreased and the operating time was shorter in patients from the second to fourth nephrectomy groups with preoperative virtual surgery than in those from the first group without it (Figure. 5). Also, the operating time was dramatically shorter and blood loss tended to be smaller in second to fourth groups than the first group of patients undergoing left nephrectomy (Figure. 5). These findings suggest that both the approach and the time required to manage the renal hilar vessels differ between the right and left sides. On the right side, the renal artery is easily located on the posterior surface of the IVC at the level of the middle part of the kidney and handling the renal vein is relatively simple, while it takes more time to find the left renal artery and to manage the left renal vein and its branches. Based on data from preoperative 3D simulation, MIES nephrectomy itself, and re-evaluation of our surgical technique by reviewing operative videos for the subsequent 60 nephrectomies, we have developed a successful method of approaching the kidney and handling the hilar vessels. As described in Methods, our surgical approach to the hilar vessels was improved by reviewing the 3D-CT information.
Resection of dorsal, lower pole and/or large tumors took longer and was associated with more blood loss (Figure. 6). In addition to a shorter operating time and smaller blood loss, our results indicated that the incision was smaller in the second to fourth nephrectomy groups than in the first group despite a similar tumor size, and there were no serious complications (Figure. 4C). In particular, for patients with T1a renal tumors 2-3 cm in diameter that were not protruding outside the kidney, we could safely perform MIES nephrectomy via a 4.5-5 cm incision. Furthermore, in comparison to the initial 20 nephrectomies without preoperative simulated surgery, the time to reach renal artery was shorter for the subsequent 60 nephrectomies with simulated surgery (15.8 ± 12.7 vs. 24.1 ± 18.6 min, P = 0.0711, data not shown), indicating that we found the vessels at the expected location. Therefore, the use of 3D-CT data not only improves the surgical incision and the approach to the renal hilar vessels, but may also decrease operative complications. The body habitus of the patient is well known to significantly influence the operating times. In the present study, patients with a BMI > 25 had a longer operating time and more bleeding than those with a BMI < 25. Also, the operating time was shorter for patients with a BMI > 25 and bleeding was significantly less for those with a BMI < 25 when the subsequent 60 nephrectomies were compared to the initial 20 nephrectomies (Figure. 7). These results may reflect both the feedback effect and the learning curve related to accumulation of experience with virtual operations and actual MIES nephrectomy, indicating that virtual surgery based on 3D-CT data may be useful for identifying the renal hilar vessels and their relations to adjacent structures, allowing MIES nephrectomy to be performed more safely. However, a randomized trial comparing the outcome for patients with or without preoperative virtual surgery should be performed in order to confirm that simulation employing 3D-CT images is useful.
Single MIES is based on standard open surgery, but we use a flexible high-definition laparoscope for easy identification of tissue planes and more precise dissection with minimal trauma. Many of the longer instruments used in open surgery can be inserted into the narrow incision and employed for single MIES, so it has a lower cost than conventional laparoscopic surgery (30-40% lower). Moreover, the assistants are now performing single MIES as chief operators at our hospital. Because of their experience with the surgical technique, including direct vision and viewing video images as assistants during single MIES procedures, they had a relatively short learning period. Another advantage of single MIES is that the incision can be extended quickly if required.
In patients with a single, small (<4 cm), and localized renal cell carcinoma, nephron-sparing surgery has become more common due to advances in renal imaging, improved surgical techniques, an increase of incidentally discovered low-stage renal cell carcinomas, and good tumor control and potentially better overall survival have been reported in patients undergoing this procedure . Therefore, radical nephrectomy is no longer the standard type of surgery for such tumors and may even be detrimental . It has been reported that 3D-CT provides superior images of the renal vessels and collecting system, and thus is useful for nephron-sparing surgery [10, 11, 21]. The technique of performing MIES nephrectomy after virtual surgery based on 3D-CT with reconstruction of images by the volume rendering method can also be used for MIES nephron-sparing surgery and MIES adrenalectomy. At present, we perform all of these types MIES after preoperative virtual surgery. MIES nephron-sparing surgery has been increasing every year. We performed this nephron-sparing procedure via a 3-4 cm incision for the above-mentioned renal tumors and have had no complications or local recurrence (data not shown).
Since we have no experience of LESS or NOTES, we could not determine whether those procedures or single MIES were superior or not. However, any of these new single-site laparo-endoscopic procedures may be a potential alternative to conventional open or laparoscopic surgery.