Abstract Objective To evaluate the clinical effects of laparoscopic radiofrequency ablation-assisted partial nephrectomy with preserved renal units in the treatment of renal tumors. Methods From March 2008 to December 2009, 10 patients were treated with radiofrequency-assisted laparoscopic partial nephrectomy for renal tumors. Among them, there were 6 cases of renal cell carcinoma (tumor diameter 2.0-4.5 cm, mean 2.3 cm). Four cases of renal malformation tumor (tumor diameter 3.5-6.0 cm, average 4.2 cm) were treated. The tumor was firstly exposed through the posterior laparoscopic route and then radiofrequency was performed. one cycle of radiofrequency (12 min) was performed for tumors less than 3 cm, and radiofrequency was performed for tumors larger than 3 cm for 24-36 min. after radiofrequency ablation, the tumor was sharply excised along the edge of the tumor, and electrocoagulation was used to stop the bleeding at the base of the tumor, and radiofrequency was used to stop the bleeding (2-4 min). RESULTS: All 10 surgeries were successful, with no intermediate openings. The operative time was 63-95 min (average 71 min), intraoperative bleeding was 50-150 ml (average 100 ml), and there was no postoperative bleeding, no urinary fistula, no pelvic ureteral stenosis and other complications. Postoperative hospitalization ranged from 3 to 5 d (mean 3.5 d), and no local recurrence of tumor or distant metastasis was detected during the follow-up period of 3 to 18 months (mean 10 months). Conclusion Radiofrequency ablation-assisted posterior laparoscopic partial nephrectomy with preserved renal units for renal tumors has less bleeding, eliminates the need for laparoscopic suture hemostasis, significantly shortens the operative time, and shortens the learning curve of posterior laparoscopic partial nephrectomy. Keywords laparoscopic partial nephrectomy; radiofrequency ablation; renal tumor The number of renal tumors detected by physical examination is gradually increasing, and laparoscopic partial nephrectomy with preservation of the renal unit for small renal cancer has been accepted by everyone. Radiofrequency ablation is a new method of local minimally invasive treatment for tumors developed in recent years. From March 2008 to December 2009, the authors treated 10 cases of renal tumors with radiofrequency-assisted posterior laparoscopic nephrectomy with preserved renal unit, and the clinical results were satisfactory, which are reported as follows. 1, Data and Methods 1.1 General Data 10 patients, 7 males and 3 females; age 45-72 years old, average 55.8 years old. The tumors were located in the dorsolateral side of the kidney in 7 cases (4 cases were located in the middle and lower pole of the kidney and 3 cases were located in the upper pole) and in the ventral lower pole of the kidney in 3 cases. 7 cases were exophytic tumors and 3 cases were intermediate type. 10 cases had no obvious clinical symptoms and were admitted to the hospital for the detection of renal tumors by ultrasound during physical examination. 7 cases underwent CT plain scan + enhanced tumor and renal vascular three-dimensional reconstruction. 10 patients with renal tumors included renal Six patients had clear cell carcinoma (tumor diameter 2.0-4.5 cm, average 2.3 cm); four patients had renal malformation tumor (tumor diameter 3.5-6.0 cm, average 4.2 cm). The tumors were first ablated by radiofrequency under the posterior laparoscope, and then sharply excised along the edge of the tumor after radiofrequency ablation, and the base of the tumor was hemostatic by electrocoagulation. 1.2 Surgical method After establishing the retroperitoneal space through the posterior laparoscopic route, the renal artery was firstly freed for blocking, the renal fat capsule was opened, the renal tumor was freed and revealed, attention was paid to preserving the fat on the surface of the tumor, the kidney was fully freed, so that the tumor was placed in an easy position for puncture and resection, the radiofrequency needle was penetrated into the tumor under the guidance of the laparoscopic ultrasound probe under direct vision, and then the cold circulation pump and radiofrequency generator were turned on in turn. The cold circulation pump continuously pumps ice water into the built-in tube of the electrode to keep the needle tip temperature at 16℃～20℃. One cycle (12 min) of radiofrequency ablation is performed, and the local tissue temperature rises above 60 ℃ at the end of treatment, which can ensure the killing of tumor cells. The coagulation foci of single needle electrode can reach 3 cm, and the cluster electrode can produce spherical coagulation foci of about 6 cm. Multi-point and multiple ablations can be performed if necessary. Before the end of radiofrequency, the output power is adjusted to keep the needle tip temperature at 90℃～100 ℃ for 10 seconds, thus carbonizing the needle tract to stop bleeding and also preventing the needle tract from metastasis. For tumors smaller than 3 cm, one cycle of radiofrequency (12 min) is required, and for tumors larger than 3 cm, radiofrequency is performed for 24-36 min. After radiofrequency is completed, the tumor is sharply excised with scissors along the border of the tumor, and the bleeding is stopped by electrocoagulation. It is not necessary to block the renal artery and no suture is needed. The wound can be sprayed with coagulation bioprotein gel to prevent bleeding. The wound can be sprayed with coagulation bioprotein gel to prevent bleeding. If the collecting system is incised, absorbable thread should be used to close it exactly. All 10 cases were successful, with an operative time of 62-95 min, intraoperative bleeding of 50-150 mL, no need for blood transfusion, postoperative hospitalization of 3-5 d, no postoperative bleeding, no urinary fistula, pelvic ureteral stenosis and other complications, no need for bed rest after surgery, and appropriate bed activity on the second day. Six cases of renal clear cell carcinoma (one of them showed tumor adjacent to the cut edge) and four cases of renal vascular smooth muscle lipoma were found in the postoperative pathology. No local recurrence or distant metastasis was detected during the follow-up period of 3 to 18 months (mean 10 months). In the postoperative CT follow-up, the CT scan showed that the original tumor of the kidney showed a semilunar defect, and the density of the renal parenchyma at the base of the tumor was uneven, with lamellar mixed density shadow. CT enhancement). 3, Discussion Radiofrequency ablation, cryoablation, microwave ablation, and high-energy focused ultrasound are several modalities of local minimally invasive tumor treatment developed in recent years, which have been gradually carried out in some foreign medical centers [1], and our department has adopted radiofrequency, and cryoablation to treat many cases of urological tumors. Radiofrequency ablation is mostly used for patients who are not suitable for surgery or isolated renal tumors, and our department is the first in China to carry out laparoscopic radiofrequency ablation for small renal cancer, and the clinical results are satisfactory after a short clinical follow-up [2]. The authors have also achieved satisfactory results in the treatment of renal tumors by using this approach as an adjunct to partial nephrectomy with preservation of renal units. Radiofrequency ablation is recommended as an alternative minimally invasive local tumor treatment in foreign guidelines for the treatment of renal tumors [1]. This technique refers to the use of single-beam or cluster electrodes, under the guidance of ultrasound, CT, MRI or laparoscopy, the radiofrequency electrodes are inserted into the tumor tissues, and the current intensity flowing through the tissues is changed by the radiofrequency output, which causes the ionic shock and friction of the target tissue cells to generate heat, generating friction at the molecular level, raising the intracellular temperature and heating the local tissues to a temperature of 80-90°C. When the temperature exceeds When the temperature exceeds 60℃, the tumor cells rapidly undergo protein denaturation and coagulation, producing a spherical or sphere-like ablation zone in the target area, dehydrating and drying the tumor tissues around the electrode, followed by coagulative necrosis, and finally forming liquefied foci or fibrous tissues to inactivate the tumor tissues. Laparoscopic suturing is a complicated and time-consuming operation, and the learning curve of skilled suturing is relatively long. We applied this technique to partial nephrectomy for kidney tumors, which eliminates the complicated operation of laparoscopic suturing to stop bleeding. Without affecting the therapeutic effect, the learning curve of laparoscopic partial nephrectomy with preserved renal units is greatly shortened, and only the tumor needs to be exposed intraoperatively, which reduces the blocking time of the renal artery and thus the damage to the kidney due to thermal ischemia. The local tissues show solid necrotic changes after radiofrequency, and thermal injury leads to acute necrosis of organelles, but the morphology of cells does not change, and they do not fall off. In tumor organelle necrosis after radiofrequency, although cell staining can find organelles with necrotic manifestations, the structure and morphology of cells do not change in a short time [3]. Therefore, the pathological section of the tumor resected after radiofrequency still shows renal clear cell carcinoma, which indicates that although the cells are necrotic after radiofrequency, the morphology of the cells has not been changed. The tumor tissue shrinks after radiofrequency, and the pathology sent for examination can still diagnose kidney cancer and can clarify the margins of tumor tissue, and the cut margin returns were negative in this group of cases. The postoperative follow-up CT showed a defect in the area of the original lesion and no suspicious enhancement after contrast injection (see Figures 3 and 4). Suturing requires blocking the renal blood flow, and laparoscopic suturing is not an easy task for a very skilled laparoscopist; if the suturing time is long, the renal thermal ischemia time is also prolonged, which may cause impairment of renal function. Radiofrequency-assisted surgery of small renal tumors does not require blocking renal blood flow, thus minimizing the damage to renal function. The depth of RF needle entry is adjusted under the guidance of the laparoscopic ultrasound probe so that the destruction after RF ablation extends beyond the 0.5-1.0 cm area of the tumor peripheral tissue, which is the same as the 0.2-1 cm distance from the tumor margin recommended for partial nephrectomy [4], and resection can be performed along the RF fixation between the tumor margin and normal kidney tissue, and for suspected inadequate destruction the RF can be performed again. The therapeutic effect of radiofrequency ablation for exophytic renal tumors smaller than 3 cm is currently considered to be more desirable. After tumor resection, there is still a relatively thick renal parenchyma left at the base, and the chance of radiofrequency damage to the collecting system for urinary leakage is small; if the process of resection damages the collecting system it should be sutured to prevent postoperative leakage. This method is not suitable for tumors located at the renal hilum, endogenous type or close to the collecting system. If the renal tumor is not blocked, there will be a lot of bleeding in the process of resection. We first perform radiofrequency ablation and reduction of the tumor, and then the bleeding in the process of resection is obviously reduced, basically there is no need to block the renal tissues, which reduces the damage to the kidney. Most foreign centers mostly use percutaneous radiofrequency, which can be performed under CT,MR and ultrasound guidance, or laparoscopic or open approach [1.5.6.7]. There are not many reports in China, but the authors adopted the method of radiofrequency before resection, which makes laparoscopic partial nephrectomy relatively simple and easy, especially for small exophytic renal tumors, which basically does not need to block renal blood supply, avoiding renal thermal ischemic injury and significantly reducing intraoperative bleeding. It also shortens the learning curve of laparoscopic partial nephrectomy, and the application of radiofrequency ablation-assisted partial nephrectomy has been reported in foreign literature[6,7] . This method can significantly shorten the operation time and reduce the renal blood supply blocking time without blocking the renal vessels, which reduces renal thermal ischemia. Intraoperative bleeding is low, and there is no secondary bleeding after surgery, and the postoperative bed rest time is short and recovery is fast, and both can get out of bed and move appropriately on the second day after surgery, and its bed rest time is significantly less than that of partial nephrectomy, and postoperative complications are significantly reduced, and the postoperative recovery time in hospital is short [7]. No laparoscopic suture operation is required, which significantly shortens the learning curve of laparoscopic partial nephrectomy, and radiofrequency-assisted laparoscopic partial nephrectomy is an alternative effective and relatively simple and easy method when performed.