Microwave Scissors-Based Sutureless Laparoscopic Partial Nephrectomy Versus Conventional Open Partial Nephrectomy in a Porcine Model: Usefulness and Complications.

BACKGROUND: This study aimed to compare the benefits and safety of microwave scissors-based sutureless laparoscopic partial nephrectomy (MSLPN) with those of conventional open partial nephrectomy (cOPN). METHODS: Each kidney in nine pigs underwent MSLPN using microwave scissors (MWS) via transperitoneal laparoscopy or cOPN via retroperitoneal open laparotomy. The kidney's lower and upper poles were resected under temporary hilar-clamping. The renal calyces exposed during renal resections were sealed and transected using MWS in MSLPN and were sutured in cOPN. For MWS, the generator's power output was 60 W. Data on procedure time (PT), ischemic time (IT), blood loss (BL), normal nephron loss (NNL), and extravasation during retrograde pyelogram were compared between the two techniques. RESULTS: The authors successfully performed 22 MSLPNs and 10 cOPNs. Compared with cOPN, MSLPN was associated with significantly lower PT (median, 9.2 vs 13.0 min; p = 0.026), IT (median, 5.9 vs 9.0 min; p < 0.001), BL (median, 14.4 vs 38.3 mL; p = 0.043), and NNL (median, 7.6 vs 9.4 mm; p = 0.004). However, the extravasation rate was higher in the MSLPN group than in the cOPN group (54.5 % [n = 12] vs 30.0 % [n = 3]), albeit without a significant difference (p = 0.265). Pelvic stenosis occurred in one MSLPN procedure that involved deep lower pole resection near the kidney hilum. CONCLUSIONS: The study data show that MSLPN can improve intraoperative outcomes while reducing technical demands for selected patients with non-hilar-localized renal tumors. However, renal calyces, if violated, should be additionally sutured to prevent urine leakage.

Feasibility of Microwave Scissors-Based Off-Clamp Laparoscopic Partial Nephrectomy in a Porcine Model.

OBJECTIVES: To assess the feasibility of off-clamp laparoscopic partial nephrectomy using microwave scissors. METHODS: We performed transperitoneal laparoscopic partial nephrectomy, without hilar clamping or renorrhaphy, using only microwave scissors for renal resection in a porcine model. For each kidney, 2 types of procedures were performed: a middle pole resection excising an area of 2-cm diameter and approximately 1-cm depth and a lower pole resection at the level of the lower polar line. The renal calyces exposed during renal resection were sealed and transected using microwave scissors. After 3 days of follow-up, the pigs were reoperated to inspect for postoperative complications. Euthanasia was performed to collect the remaining kidneys for histopathological examination. RESULTS: Ten procedures were successfully performed, without hilar clamping or suturing of the renal calyces and parenchyma, in 5 kidneys from 3 pigs. The median resecting time, blood loss, and lateral thermal injury were 23.2 min, 47.1 mL, and 6.8 mm in the middle pole resection, and were 15.1 min, 26.5 mL, and 6.9 mm in the lower pole resection, respectively. No complications were noted during reoperation, such as postoperative hemorrhage and major urine leakage. Extravasation occurred in 2 middle pole resections and 3 lower pole resections during retrograde pyelogram. Hematoxylin and eosin staining revealed thermal injury characterized by tissue microwave fixation in the near zone and acute coagulative necrosis in the intermediate zone. CONCLUSIONS: Microwave scissors-based off-clamp laparoscopic partial nephrectomy is feasible in pigs and can be used for clinical applications.

Vessel-Sealing Capability of Novel Microwave Sealer: Experimental Study in Animal Models.

Background. Ultrasonically activated dissectors (UADs) and radiofrequency-based devices have been considered excellent surgical devices because of their reliability and flexibility. Meanwhile, microwave-based devices have demonstrated potential with their unique heating mechanism. This study aims to compare the sealing function of a newly invented forceps-like microwave sealer (MS) with that of currently available UADs. Materials and Methods. MS and 2 examples of UADs (Harmonic Focus+ [HF+] and Sonicision [SNC]) were employed to perform mesenterectomies (in vivo) and sealing sizable vessels (ex vivo). Vessel diameter, seal time, burst pressure (BP), sealing completion, and instrument sticking were recorded. The samples underwent histological investigation for thermal damage evaluation. Results. During mesenterectomies, MS required 3 seconds and 30 W to secure a complete seal. The BP achieved by the MS seal was higher than that of HF+ and SNC on arteries (851 ± 203.7 vs 682.4 ± 287.3, P < .05; vs 833.1 ± 251.2 mmHg, P = .4523, respectively) but was not statistically different on veins (324.9 ± 203.5 vs 460.1 ± 320.3 vs 508.3 ± 350.7 mmHg, P = .215). In all trials, MS caused less sticking but exhibited similar heat-induced alterations to UADs. MS's thermal spread was not statistically more extended than that of UADs on either arteries or veins. Conclusions. MS was capable of not only sealing tiny vessels but also achieving high-pressure endurance on sizable vessels. Its forceful grasping and synchronous heating process helped create solid stumps with an acceptable thermal spread.

The invention of microwave surgical scissors for seamless coagulation and cutting.

PURPOSE: We developed a microwave energy-based scissors device (MWCX) that is capable of performing cutting and coagulation using 2.45 GHz microwave energy. This paper aims to present the concept of the device and assess the basic functions including the hemostasis, cutting, and sealing abilities. METHODS: Seven beagle dogs were used in our experiments. In six dogs, we measured the coagulation time (CT), lateral thermal injury (LTI), bursting pressure (BP). The dogs were then subjected to re-laparotomy 1 week later to allow us to investigate the results. In one dog, the same factors and the quantities of smoke and mist emitted were compared to those observed when using a Harmonic Focus (HF) device. RESULTS: At 60 W, the MWCX could cut and seal small (5 s, diameter 1-2 mm) and medium-sized (10 s, 3-4 mm) vessels with complete hemostasis. The liver (length 2 cm) was cut for 30 s. Harvested vessels were sealed for 10 s (artery, 17 times; vein, six times). The mean BP was 887. 8 ± 41.5 mmHg in the medium arteries and 457.2 ± 118.0 mmHg in veins, with a mean diameter of 4.5 ± 1.3 mm. In a comparative study, the MWCX showed similar results to the HF with regard to the CT, BP and LTI, and emitted less smoke and mist. CONCLUSION: The MWCX showed similar levels of functionality and safety to HF, as well as the advantages offered by the use of microwave energy. Microwave devices might be used in the majority of applications for which traditional energy devices are used.

[A Case of Gastric Cancer Underwent Two-Stage Gastrectomy after Chemotherapy-Induced Perforation].

A 70's man presenting with a chief complaint of stomachache was found to have advanced gastric cancer with a deep ulcer and some lymph-node metastases. We decided performing a curative operation after 2 courses of S-1 plus cisplatin. On the first course day 13 of chemotherapy, he complained of severe epigastralgia, and we diagnosed as generalized peritonitis due to perforation of gastric cancer. We performed an urgent laparoscopic operation, which made perforation simple closure and omentopexy. Curative distal gastrectomy with D2 lymph node dissection was successfully performed on postoperative day 16.

Feasibility and safety of hyperthermic intraperitoneal chemotherapy using 5-fluorouracil combined with cisplatin and mitomycin C in patients undergoing gastrectomy for advanced gastric cancer.

BACKGROUND AND OBJECTIVES: We conducted a dose-finding study for 5-fluorouracil (5-FU) administered with cisplatin (CDDP) and mitomycin C (MMC) to find an improved regimen for hyperthermic intraperitoneal chemotherapy (HIPEC) for advanced gastric cancer (GC). METHODS: The appropriate HIPEC regimen previously determined in vitro was 5-FU (200 µg/mL), MMC (2 µg/mL), and CDDP (10 µg/mL) at hyperthermic conditions (42°C) for 30 min. This was a clinical study to determine the recommended dose of 5-FU in combination with MMC and CDDP at 42°C for 30 min and to evaluate HIPEC safety in patients at high risk of developing peritoneal metastases following GC surgery. RESULTS: Twelve patients were treated with surgery plus HIPEC using 5-FU at 0, 500, 750, and 1000 mg combined with MMC (10 mg) and CDDP (50 mg) in the perfusate (5 L). Dose-limiting toxicities did not develop until 1000 mg 5-FU was reached. Four patients experienced grade 1 or 2 adverse events. The recommended dose was 1000 mg 5-FU/5 L perfusate. Eight (66.7%) patients demonstrated no recurrence of peritoneal metastases; 5-year overall survival rate was 83.3%. CONCLUSION: Gastrectomy and HIPEC with MMC, CDDP, and 5-FU is feasible, safe, and may protect against peritoneal metastasis following surgery for advanced GC.

Predictive detection areas for identifying additional MRI-detected breast lesions on second-look ultrasonography.

PURPOSE: Identifying an additional MRI-detected breast lesion on second-look ultrasonography (US) is technically challenging because of lesion displacement with the patient's position change. The aim of this study is to help identify MRI-detected lesions on second-look US by developing a probing area, called "the predictive detection area" (PDA), and by assessing the PDA. METHODS: We measured the nipple-to-lesion distances (NLDs) for 16 breast lesions on prone- and supine-position MRI sets and calculated the difference and angle between the two NLD vectors, representing the lesion displacement. The minimum and maximum differences and angles were chosen to form the PDA. Another 22 breast lesions, detected in the prone MRI, were identified on US by probing the PDA to evaluate the probability of existence. RESULTS: The width between the minimum and maximum differences in two NLDs and the angle to form the PDA for the upper-inner, upper-outer, and lower-outer quadrants were 23.0 mm and 95.0°, 29.0 mm and 41.0°, and 18.0 mm and 17.0°, respectively. The respective probabilities of existence were 100, 80, and 100%. CONCLUSIONS: The PDA had a high probability of existence and was acceptably accurate; therefore, the PDA in a second-look US has the potential to help operators to quickly identify additional MRI-detected lesions.

[Clinical Evaluation of Hyperthermic Intraperitoneal Chemotherapy(HIPEC)in Colorectal Cancer Patients at High Risk of Peritoneal Recurrence].

PURPOSE: We herein report the clinical outcomes of hyperthermic intraperitoneal chemotherapy(HIPEC)in patients at high risk of colorectal peritoneal metastasis. PATIENTS AND METHODS: We enrolled 21 patients with advanced colorectal cancer who were received HIPEC between 2009 and 2014. Retrospectively, we evaluated the short-term and long-term outcomes of these cases. RESULTS: We performed HIPEC for 12 patients with primary cancer and 9 with recurrent cancer. Perioperative complications characteristic of HIPEC did not occur. Seventeen patients(81%)had postoperative recurrence, 5 of whom had a peritoneal recurrence, and all of them already had synchronous peritoneal metastasis at the time of HIPEC. Patients with a higher peritoneal cancer index(PCI)had a tendency towards a higher rate of peritoneal recurrence than those with a lower PCI(11[median]vs 4; p=0.08).

[Surgery for Multiple Gastrointestinal Stromal Tumors of the Small Intestine in Patients with Neurofibromatosis Type 1 - A Report of Three Cases].

We report 3 cases of multiple GIST of the small intestine in 3 patients with NF1 who have been followed for over 5 years. All patients presented with melena, and tumors of the small intestine suspected to be GIST were found on endoscopy. We performed partial resections of the small intestine for all 3 patients. After surgery, 1 patient had residual tumors that gradually enlarged during 8 year 2 months and another had residual tumors that have been stable for 8 years. In the third patient, we resected all the tumors, and there has been no sign of recurrence in 6 year 1 month.

[Stage IV Gastric Cancer with Positive Peritoneal Washing Cytology or Peritoneal Dissemination Was Successfully Treated with Gastrectomy and Hyperthermic Intraperitoneal Chemotherapy(HIPEC)Followed by Systemic Chemotherapy - A Report of Two Cases].

Survival of Stage IV gastric cancer is poor. We report 2 cases of Stage IV gastric cancer with positive peritoneal washing cytology or peritoneal dissemination that were successfully treated with gastrectomy and hyperthermic intraperitoneal chemotherapy( HIPEC)followed by systemic chemotherapy. Case 1: A 59-year-old woman. She was diagnosed with advanced gastric cancer and underwent gastrectomy with HIPEC. Her peritoneal washing cytology was positive during the gastrectomy. After the surgery, she underwent chemotherapy consisting of 8 courses of combination S-1 plus CPT-11 and 19 courses of PTX. It has been 5 years and 7 months since she had the surgery and she survives without recurrence of the cancer. Case 2: A 60-year-old woman. She was diagnosed with advanced gastric cancer and peritoneal dissemination(peritoneal cancer index: 3 points). She underwent gastrectomy, hemi-colectomy, and HIPEC. After the surgery, she underwent chemotherapy, 35 courses of combination S-1 plus PSK/DOC, and 13 courses of S-1 plus PSK. It has been 5 years since her surgery and she survives without exacerbation of the cancer. These cases suggest a gastrectomy and HIPEC followed by systemic chemotherapy may represent an effective treatment for advanced gastric cancer with a small amount of peritoneal metastasis.

[Salvage Surgery after CRT for Advanced Esophageal Cancer Resulting in a Pathological Complete Response and More Than Five Years' Survival].

A 62-year-old woman visited our hospital because of dysphagia. She was diagnosed with upper-middle esophageal type 4 cancer, which was 9 cm in length, according to the results of endoscopy. Squamous cell carcinoma was demonstrated using endoscopic biopsy. A CT scan revealed that the tumor had directly invaded into the trachea(cT4). Chemoradiotherapy(CRT) (5-FU and CDDP with 50 Gy of radiation)was administered. Although CT after CRT resulted in shrinkage of the tumor and no further tracheal invasion, esophageal stenosis remained. Therefore, salvage surgery(subtotal esophagectomy with 3-field lymph node dissection)was performed. Pathologically, no carcinoma cells were found in the resected specimen and a com- plete response(grade 3)was diagnosed. The patient received adjuvant chemotherapy(tegafur/uracil at 300mg/day per os) for 1 year. The patient is alive with no relapse of carcinoma more than 5 years after the first treatment.

[A Case of Breast Metastasis of Eccrine Porocarcinoma].

An 80's woman was diagnosed with eccrine porocarcinoma of the head in 2010.T he tumor was removed surgically but relapsed in the cervical and axillary lymph nodes 2 years later.The patient underwent surgery, and received systemic chemotherapy and radiation.Chest CT after treatment revealed an irregular mass and thickened skin in the left breast.Core needle biopsy specimens were used to diagnose metastasis of eccrine porocarcinoma.A wide excision with a 1 cm margin was performed under local anesthesia.After surgery, supraclavicular lymph node recurrence was detected.The patient received palliative care because there was no effective treatment available.Eccrine porocarcinoma is a rare malignant tumor of the intraepidermal sweat duct.Breast metastasis from malignant disease is also rare.To our knowledge, breast metastasis of eccrine porocarcinoma has not been reported.

Minimally invasive surgery using the open magnetic resonance imaging system combined with video-assisted thoracoscopic surgery for synchronous hepatic and pulmonary metastases from colorectal cancer: report of four cases.

Simultaneous resection of hepatic and pulmonary metastases (HPM) from colorectal cancer (CRC) has been reported to be effective, but it is also considered invasive. We report the preliminary results of performing minimally invasive surgery using the open magnetic resonance (MR) imaging system to resect synchronous HPM from CRC in four patients. All four patients were referred for thoracoscopy-assisted interventional MR-guided microwave coagulation therapy (T-IVMR-MCT) combined with video-assisted thoracoscopic surgery (VATS). The median diameters of the HPM were 18.2 and 23.2 mm, respectively. The median duration of VATS and T-IVMR-MCT was 82.5 and 139 min, respectively. All patients were discharged without any major postoperative complications. One patient was still free of disease at 24 months and the others died of disease progression 13, 36, and 47 months without evidence of recurrence in the treated area. Thus, simultaneous VATS + T-IVMR-MCT appears to be an effective option as a minimally invasive treatment for synchronous HPM from CRC.

Initial experiences with MR Image-guided laparoscopic microwave coagulation therapy for hepatic tumors.

PURPOSE: Percutaneous thermal ablation is used for treating hepatic tumors. Recent advances in laparoscopy and imaging modalities have led to the development of a novel image-guided minimally invasive loco-regional treatment. The aim of this trial was to apply laparoscopic assistance to magnetic resonance (MR) image-guided thermoablation instead of ultrasonography, because of its various advantages. METHODS: Patients with hepatic tumors and liver cirrhosis underwent magnetic resonance (MR) image-guided laparoscopic microwave coagulation therapy using a borescope and endoscopic forceps. Six cases of laparoscopic microwave coagulation treatment using MR image guidance were successfully performed between January 2000 and December 2008. Tumors were detected, punctured, and ablated in an open-configured MR scanner. A total of nine hepatocellular carcinoma nodules were preoperatively identified in S3, S5 and S6 (mean diameter = 20.8 ± 5.4 mm). RESULTS: MR-guided microwave coagulation was laparoscopically achieved in all patients without any significant complications that required invasive treatment. The mean length of the operation was 275.3 ± 60.5 min, and the mean postsurgical hospital stay was 10.0 ± 2.3 days. Postoperative confirmation scanning was performed without moving the patients. CONCLUSION: MR-guided laparoscopic microwave coagulation therapy is an effective treatment for hepatic tumors adjacent to other organs, as it allows for more accurate detection of lesions and for tumors to be treated safely while avoiding adjacent organs. It is less invasive than conventional procedures, because the MR real-time guidance enabled continuous monitoring throughout the procedure.

Surgery-induced peritoneal cancer cells in patients who have undergone curative gastrectomy for gastric cancer.

BACKGROUND: Some patients who undergo curative gastrectomy with lymph node dissection (LND) for gastric cancer (GC) show subsequent peritoneal metastasis. The source of these metastatic cells remains unclear. METHODS: Curative gastrectomy with LND was performed in 102 patients with GC. Peritoneal washing was collected before and after gastrectomy. Cytology, reverse transcription-polymerase chain reaction, and cell culture were used to determine the presence of cancer cells. The proliferative potential of tumor cells was evaluated using Ki-67 staining. Tumorigenic capacity was assessed by cell injection into the peritoneal cavity of NOD/ShiJic-scid mice. Peritoneal recurrence-free survival (RFS) and peritoneal recurrence rate (RR) were examined to determine the clinical relevance of detected cancer cells. RESULTS: Of 102 peritoneal washing samples obtained before gastrectomy, 57 showed no CEA or CK20 mRNA amplification. After gastrectomy, CEA or CK20 mRNA was detected in 35 of these 57 samples, and viable cancer cells were identified in 24. The viable cancer cells in all 24 cases showed Ki-67 positivity, indicating proliferative activity. Cultured viable cancer cells generated peritoneal nodules after spilling over the peritoneal cavity in NOD/ShiJic-scid mice in 4 cases. The peritoneal RFS of patients with CEA or CK20 mRNA amplification after gastrectomy was significantly poorer than that of patients with negative amplification (p < .05). The 24 patients with viable cancer cells in the peritoneal cavity after gastrectomy showed higher peritoneal RR than those without them (p = .033). CONCLUSIONS: Viable tumorigenic cancer cells spilled into the peritoneal cavity during surgery, indicating that surgery induces peritoneal metastasis.

Cell transplantation therapy for a rat model of secondary lymphedema.

BACKGROUND: Although lymphedema is a progressive and lifelong condition, substantial advances in therapeutic intervention are limited. The development of a novel therapy for lymphedema is urgent for those patients suffering from it. The aim of this study was to investigate the usefulness of a new cell transplantation therapy in the rat tail model of secondary lymphedema. MATERIALS AND METHODS: We prepared two cell sources, human dermal microvascular endothelial cells (HDMECs) and lymphatic endothelial cells (LECs), which were collected from the resected normal dermis of patients with breast cancer. After the animal model of secondary lymphedema of the nude rats' tails was established, phosphate-buffered saline, purified LECs, or unpurified HDMECs were injected in the rats' tails five times for more than 14 d. The evaluations were performed by measuring the circumference, fluorescence lymphography, and histologic analysis of the rats' tails between each group. RESULTS: The isolated cells by the simple immunomagnetic sorting from HDMECs were positive for a pan-endothelial marker (CD31) and lymphatic-specific markers (podoplanin, lymphatic vessel endothelial hyaluronan receptor-1 [LYVE-1], and prospero homebox 1 [Prox-1]), and were considered to be LECs. In the cell transplantation group, which was injected with human LECs, the circumference, lymphatic flow, and thickness of the skin of the rat tail became thinner than the groups injected with unpurified HDMECs or phosphate-buffered saline. Immunohistochemistry of the rat tails showed that the number of own lymphatic vessels was increased in the purified LEC transplantation group compared with the other groups. Furthermore, in the LEC transplantation group, some vessels were immunopositive for human-podoplanin or -LYVE-1 and the areas adjacent to the vessels were rat-podoplanin or -LYVE-1 immunopositive. CONCLUSIONS: Our findings indicate that cell transplantation therapy using human LECs improved the secondary lymphedema in the nude rat tail. This therapeutic strategy may merit clinical investigation in patients with lymphedema.

Resectable carcinoma developing in the remnant pancreas 7 years and 10 months after distal pancreatectomy for invasive ductal carcinoma of the pancreas: report of a case.

BACKGROUND: Pancreatic ductal adenocarcinoma, which represents 90% of pancreatic cancers, is one of the most lethal and aggressive malignancies. Operative resection remains the only treatment providing prolonged survival, however, recurrence of pancreatic ductal adenocarcinoma occurs in up to 80% of patients with pancreatic cancer within 2 years of a potential curative resection. There are few reports of pancreatic carcinoma recurrence (primary second cancer) in the remnant pancreas after pancreatectomy. CASE PRESENTATION: A 52-year-old woman underwent a distal pancreatectomy for pancreatic cancer in September 2004. Adjuvant chemotherapy was started after surgery and continued for 4 years. In March 2012, marked elevation of DUPAN-II was observed, followed by an irregular stenotic finding in the main duct. We performed an en bloc resection of the remnant pancreas in July 2012. Histologically, the tumor contained a second primary pancreatic carcinoma with lymph node metastasis. At follow-up 20 months after the second operation, the patient was alive without recurrence. Fourteen cases of resectable cancer developing in the remnant pancreas after a pancreatectomy for cancer have been reported; a minority of these was identified as second primary tumors. Therefore, our patient's primary second cancer is a rare event. CONCLUSION: The patient is considered to have shown a rare, unique pancreatic cancer recurrence. Persistent elevation of a tumor marker and extensive imaging led to proper diagnosis and treatment.

Transmembrane mucin MUC1 overexpression and its association with CD10⁺ myeloid cells, transforming growth factor-ß1 expression, and tumor budding grade in colorectal cancer.

The prognostic value of mucin expression has been reported in several studies. We examined the association between mucin expression and other previously reported prognostic factors, including infiltration of CD10⁺ myeloid cells, transforming growth factor-ß1 (TGF-ß1) expression, and tumor budding at invasion fronts. Immunohistochemical analysis of 206 colorectal samples was carried out to determine whether MUC1, MUC2, MUC4, and MUC5AC expression could predict the survival of colorectal cancer patients. Serial sections were stained for CD10, TGF-ß1, and pan-cytokeratin in order to detect tumor budding. As per multivariate analyses, MUC1 expression appeared to be the most significant predictor of both recurrence-free survival and overall survival. MUC4 was only significant to predict recurrence-free survival, and MUC5AC could be a good marker in stage IV colorectal cancers that require additional chemotherapy. MUC1 (CD227) expression was associated with infiltration of CD10⁺ myeloid cells, TGF-ß1 expression, and tumor budding grade. These findings suggest that MUC1 is indicative of poor prognoses that may be associated with immunosuppression and epithelial-mesenchymal transition. Furthermore, MUC1 expression appears to be a chemoattractant for CD10⁺ stromal cells.

Comparison of off-clamp microwave scissors-based sutureless partial nephrectomy versus on-clamp conventional partial nephrectomy in a canine model.

Objectives: To compare the usefulness and safety of off-clamp microwave scissors-based sutureless partial nephrectomy (MSPN) with on-clamp conventional partial nephrectomy (cPN) in dogs. Methods: We performed off-clamp MSPN using microwave scissors (MWS) in six dogs, and on-clamp cPN in three dogs, in two-stage experiments. The bilateral kidney upper poles were resected via a midline incision under general anesthesia. After 14 days of follow-up, the lower pole resections were performed. The renal calyces exposed during renal resections were sealed and transected using MWS in off-clamp MSPN and were sutured in on-clamp cPN. In the off-clamp MSPN group, the generator's power output of MWS was set as either 50 W or 60 W for each kidney side. We compared the procedure time (PT), ischemic time (IT), blood loss (BL), and normal nephron loss (NNL) between the two techniques using the Mann-Whitney U-test. Results: We successfully performed 24 off-clamp MSPNs and 12 on-clamp cPNs. The off-clamp MSPN was significantly superior to on-clamp cPN in avoiding renal ischemia (median IT, 0 min vs. 8.6 min, p < 0.001) and reducing PT (median PT, 5.8 min vs. 11.5 min, p < 0.001) and NNL (median NNL, 5.3 mm vs. 6.0 mm, p = 0.006) with comparable BL (median BL, 20.9 ml vs. 23.2 ml, p = 0.804). No bleeding and major urine leakage were noted during the reoperations. Conclusions: Off-clamp MSPN outperforms on-clamp cPN in lowering the risks of postoperative renal function impairment in dogs.