Role of Heavy Water in Modified University of Wisconsin Solution for Extended Cold Storage of Rat Liver.

To resolve the critical donor shortage worldwide, enlarging the potential donor pool to include expanded criteria donors is necessary. Despite numerous attempts to establish new preservation solutions, no dramatic innovation has occurred since University of Wisconsin (UW) solution displaced Euro Collins' solution; UW solution remains the global gold standard. We previously developed a heavy water (D2O)-containing organ storage solution, Dsol, which is effective for livers subjected to extended cold storage (CS), and reported its effectiveness. Dsol is a modified UW solution; however, the substances or conditions that exhibit a synergistic or additive effect with D2O are unclear. Here we made UWD solution by removing hydroxyethyl starch (HES) from and adding 30%-D2O to UW solution, and compared the effects of these solutions. After 48 hours of CS, the livers were reperfused at 37 °C on an isolated perfused rat liver apparatus, and their perfusion kinetics, functions, and injuries were compared. In the UW group, portal vein resistance significantly increased and the oxygen consumption rate and bile production decreased; in contrast, these changes were suppressed in the UWD group. Organ expansion and liver damage progressed in both groups. These results confirmed that the removal of HES from and addition of D2O to the UW solution reduced CS-induced cellular function impairments and microcirculatory disorders. However, to reduce injury during reperfusion after CS, it is necessary to provide conditions that inhibit injury progression after reperfusion.

Robot-assisted distal gastrectomy and local resection for gastric cancer and gastrointestinal stromal tumor.

Gastrointestinal stromal tumors surrounding the esophagogastric junction are often challenging to resect, with no consensus regarding the optimal surgical technique. Here in, we present a case of concurrent gastric cancer in the antrum and gastrointestinal stromal tumors adjacent to the esophagogastric junction. The patient underwent simultaneous distal gastrectomy and local resection assisted by a surgical robot, avoiding the need for total gastrectomy. The utilization of robot-assisted surgery has become an increasingly popular technique, holding promise for simplifying complex surgical procedures across diverse medical settings.

Important Constituents of Heavy Water-containing Solution for Cold Storage and Subsequent Reperfusion on an Isolated Perfused Rat Liver.

The University of Wisconsin (UW) solution is the most effective preservation solution currently used; however, to safely use expanded-criteria donor grafts, a new cold storage solution that alleviates graft injury more effectively is required. We prepared a heavy water (D2O)-containing buffer, Dsol, and observed strong protective effects during extended cold storage of rat hearts and livers. In the current study, we modified Dsol (mDsol) and tested its efficacy. The aim of the present study was to determine whether mDsol could protect the rat liver more effectively than the UW solution and to clarify the roles of D2O and deferoxamine (DFX). Rat livers were subjected to cold storage for 48 hours in test solutions: UW, mDsol, mDsol without D2O or DFX (mDsol-D2O[-], mDsol-DFX[-]), and subsequently reperfused on an isolated perfused rat liver for 90 minutes at 37°C. In the UW group, the liver was dehydrated during cold storage and rapidly expanded during reperfusion. Accordingly, the cumulative weight change was the highest in the UW group, together with augmented portal veinous resistance and ALT leakage and decreased oxygen consumption rate and bile production. These changes were significantly suppressed in the mDsol-treated group. In the mDsol-D2O(-) and mDsol-DFX(-) groups offered partial protection. In conclusion, mDsol appeared to be superior to the UW solution for simple cold storage of the rat liver, presumably due to improved microcirculation in the early phase of reperfusion. Both heavy water and deferoxamine are essential for alleviating seamless organ swelling that occurs during cold storage and subsequent reperfusion.

Hyaline-vascular type unicentric Castleman disease with dysplastic follicular dendritic cell proliferative lesions: a case report.

Castleman disease (CD) is a rare lymphoproliferative disease. Hyaline-vascular type unicentric CD has a good prognosis if completely resected during surgery. However, follicular dendritic cell proliferative lesions have the potential for recurrence and metastasis. A 22-year-old man was referred to our hospital with the chief complaint of nausea and vomiting. These symptoms were caused by a right mesocolonic tumor pushing the duodenum. The patient underwent laparoscopic tumorectomy and complete surgical excision. The postoperative course was uneventful, with no complications. Pathological examination confirmed that the tumor was an enlarged lymph node, typical of hyaline vascular-type CD; however, follicular dendritic cell proliferative lesions were noted. We report a rare case of hyaline-vascular-type CD with follicular dendritic cell proliferative lesions associated with malignancy, as limited case reports exist on this particular disease.

Exploration of Optimal pH in Hypothermic Machine Perfusion for Rat Liver Grafts Retrieved after Circulatory Death.

Ex vivo hypothermic machine perfusion (HMP) is a strategy for controlling ischemia-reperfusion injury in donation after circulatory death (DCD) liver transplantation. The pH of blood increases with a decrease in temperature and water dissociation, leading to a decrease in [H+]. This study aimed to verify the optimal pH of HMP for DCD livers. Rat livers were retrieved 30 min post-cardiac arrest and subjected to 3-h cold storage (CS) in UW solution (CS group) or HMP with UW-gluconate solution (machine perfusion [MP] group) of pH 7.4 (original), 7.6, 7.8, and 8.0 (MP-pH 7.6, 7.8, 8.0 groups, respectively) at 7-10 °C. The livers were subjected to normothermic perfusion to simulate reperfusion after HMP. All HMP groups showed greater graft protection compared to the CS group due to the lower levels of liver enzymes in the former. The MP-pH 7.8 group showed significant protection, evidenced by bile production, diminished tissue injury, and reduced flavin mononucleotide leakage, and further analysis by scanning electron microscopy revealed a well-preserved structure of the mitochondrial cristae. Therefore, the optimum pH of 7.8 enhanced the protective effect of HMP by preserving the structure and function of the mitochondria, leading to reduced reperfusion injury in the DCD liver.

Combination of Cold Storage in a Heavy Water-Containing Solution and Post-Reperfusion Hydrogen Gas Treatment Reduces Ischemia-Reperfusion Injury in Rat Livers.

We previously reported the efficacy of cold storage (CS) using a heavy water-containing solution (Dsol) and post-reperfusion hydrogen gas treatment separately. This study aimed to clarify the combined effects of these treatments. Rat livers were subjected to 48-hour CS and a subsequent 90-minute reperfusion in an isolated perfused rat liver system. The experimental groups were the immediately reperfused control group (CT), the CS with University of Wisconsin solution (UW) group, the CS with Dsol group, the CS with UW and post-reperfusion H2 treatment group (UW-H2), and the CS with Dsol and post-reperfusion H2 group (Dsol-H2). We first compared the Dsol-H2, UW, and CT groups to evaluate this alternative method to conventional CS. The protective potential of the Dsol-H2 group was superior to that of the UW group, as evidenced by lower portal venous resistance and lactate dehydrogenase leakage, a higher oxygen consumption rate, and increased bile production. Multiple comparison tests among the UW, Dsol, UW-H2, and Dsol-H2 groups revealed that both treatments, during CS and after reperfusion, conferred a similar extent of protection and showed additive effects in combination therapy. Furthermore, the variance in all treatment groups appeared smaller than that in the no-treatment or no-stress groups, with excellent reproducibility. In conclusion, combination therapy with Dsol during CS and hydrogen gas after reperfusion additively protects against graft injury.

Rapid and Reliable Steatosis Rat Model Shrsp5-Dmcr for Cold Storage Experiment.

Interventions for liver grafts with moderate macrovesicular steatosis have been important in enlarging donor pools. Here, we tested a high-fat and cholesterol (HFC) diet to create a steatosis model for cold hepatic preservation and reperfusion experiments. The aim of the present study was to assess the steatosis model's reliability and to show the resulting graft's quality for cold preservation and reperfusion experiment. Male SHRSP5-Dmcr rats were raised with an HFC diet for up to 2 weeks. The fat content was evaluated using magnetic resonance imaging (MRI) proton density fat fraction (PDFF). The nonalcoholic fatty liver disease activity score (NAS) was evaluated after excision. Steatosis created by 2 weeks of HFC diet was subjected to 24-hour cold storage in the University of Wisconsin and the original test solution (new sol.). Grafts were applied to isolated perfused rat livers for simulating reperfusion. The NAS were 2.2 (HFC 5 days), 3.3 (HFC 1 week), and 5.0 (HFC 2 weeks). Ballooning and fibrosis were not observed in any group. An MRI-PDFF showed 0.2 (HFC 0 days), 12.0 (HFC 1 week), and 18.9 (HFC 2 weeks). The NAS and MRI-PDFF values correlated. Many indices in the isolated perfused rat liver experiment tended to improve in the new sol. group but were insufficient. Although the new sol. failed to be effective, it acted at multiple sites under difficult conditions. In conclusion, the HFC diet for 2 weeks in SHRSP5-Dmcr rats, together with MRI-PDFF evaluation, is a reliable method for creating simple steatosis and provides good-quality cold preservation and reperfusion experiments.

Hypothermic Machine Perfusion with Hydrogen Gas Reduces Focal Injury in Rat Livers but Fails to Restore Organ Function.

BACKGROUND: We have previously reported the efficacy of post-reperfusion H2 gas treatment in cold storage (CS) and subsequent reperfusion of the rat liver. The present study aimed to evaluate the effect of H2 gas treatment during hypothermic machine perfusion (HMP) in rat livers retrieved from donation after circulatory death (DCD) and elucidate the mechanism of action of H2 gas. METHODS: Liver grafts were procured from rats after 30 min of cardiopulmonary arrest. The graft was subjected to HMP for 3 hours at 7°C using Belzer MPS with or without dissolved H2 gas. The graft was reperfused using an isolated perfused rat liver apparatus at 37°C for 90 minutes. Perfusion kinetics, liver damage, function, apoptosis, and ultrastructure were evaluated. RESULTS: Portal venous resistance, bile production, and oxygen consumption rates were identical in the CS, MP, and MP-H2 groups. Liver enzyme leakage was suppressed by MP (vs control), whereas H2 treatment did not show a combination effect. Histopathology revealed poorly stained areas with a structural deformity just below the liver surface in the CS and MP groups, whereas these findings disappeared in the MP-H2 group. The apoptotic index in the CS and MP groups was high but decreased in the MP-H2 group. Mitochondrial cristae were damaged in the CS group but preserved in the MP and MP-H2 groups. CONCLUSIONS: In conclusion, HMP and H2 gas treatment are partly effective in DCD rat livers but insufficient. Hypothermic machine perfusion can improve focal microcirculation and preserve mitochondrial ultrastructure.

The survival impact of preoperative FOLFOX for resectable locally advanced rectal cancer: the R-NAC-01 study.

PURPOSE: In this follow-up of the R-NAC-01 study, we assessed the long-term oncological benefit of four courses of modified leucovorin, 5-fluorouracil (FU), and oxaliplatin (mFOLFOX6) chemotherapy before rectal surgery. METHODS: In this prospective, multicenter study (UMIN 000012559) involving 11 hospitals in Japan, patients with lower rectal cancer underwent four cycles of mFOLFOX6 chemotherapy and subsequent surgery within four to six weeks. The 3-year recurrence-free survival and local recurrence rates were then reported. RESULTS: Of 41 patients (36 males, 5 females; mean age: 60.8 years old) who received 4 courses of chemotherapy, 40 underwent total mesorectal excision, and 1 underwent total pelvic exenteration. R0 resection was achieved in 40 patients, but none showed a pathological complete response. Twenty-nine patients received adjuvant chemotherapy for an average of 4 months. The 3 year recurrence-free survival and local recurrence rates in patients undergoing curable resection were 72.8% and 8.5%, respectively. cStage III patients with adjuvant chemotherapy had a significantly higher 3 year recurrence-free survival than those without adjuvant chemotherapy (76.6 vs. 40.0%, log-rank p = 0.03). CONCLUSION: Four courses of mFOLFOX6 chemotherapy before surgery may be a promising treatment strategy for locally advanced rectal cancer. Adjuvant chemotherapy might be needed for cStage III patients, even after four courses of neoadjuvant mFOLFOX6.

Laparoscopic repair of inguinal hernia in a patient with a ventriculoperitoneal shunt: A case report.

Laparoscopic surgery in patients with a ventriculoperitoneal (VP) shunt is reportedly associated with increased intracranial pressure secondary to high intraperitoneal pressure and retrograde infection due to intraperitoneal infection. We herein report the first case of transabdominal preperitoneal (TAPP) inguinal hernia repair without catheter manipulation for a patient with a VP shunt. A 69-year-old man with a VP shunt was suspected to have an inguinal hernia based on symptoms and examination findings. With a pneumoperitoneum pressure of 10 mm Hg, the VP shunt was not clamped and mesh was placed while confirming cerebrospinal fluid outflow from the tip of the catheter. The patient developed no shunt-associated complications and was discharged 3 days postoperatively. TAPP inguinal hernia repair without catheter manipulation is a potential surgical option for patients with a VP shunt.

Imaging Mass Spectrometry Reveals the Changes in the Taurine Conjugates of Dihydroxycholanoic Acid During Hepatic Warm Ischemia and Reperfusion in a Rat Model.

Warm ischemia and reperfusion injury (IRI) is a prognostic factor in donation after cardiac death donor transplantation. However, a reliable method to predict IRI before transplantation has not been established. The aim of this study was to identify predictive markers of hepatic IRI by simultaneous measurement of endogenous molecules using matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS). Rats were subjected to hepatic warm ischemia (70%) for 30 or 90 minutes and subsequent reperfusion. The livers were collected at the end of ischemia and 1 hour, 6 hours, and 24 hours after reperfusion. The liver tissue sections were applied to IMS (m/z 200-2000). Candidate molecules were identified by tandem mass spectrometry. Imaging mass spectrometry (IMS) revealed a significant increase in the taurine conjugates of dihydroxycholanoic acid (TDHCA) during ischemia and a tendency to return to the basal level after reperfusion. Notably, high-resolution measurements revealed focal accumulation of TDHCA in the intrahepatic bile duct with ischemic time. In conclusion, IMS is a useful method to detect minute changes provoked by ischemia, which are barely detectable in assays involving homogenization. Accordingly, focal accumulation of TDHCA during ischemia may be a candidate marker for predicting later IRI.

Heavy Water (D2O) Containing Preservation Solution Reduces Hepatic Cold Preservation and Reperfusion Injury in an Isolated Perfused Rat Liver (IPRL) Model.

BACKGROUND: Heavy water (D2O) has many biological effects due to the isotope effect of deuterium. We previously reported the efficacy of D2O containing solution (Dsol) in the cold preservation of rat hearts. Here, we evaluated whether Dsol reduced hepatic cold preservation and reperfusion injury. METHODS: Rat livers were subjected to 48-hour cold storage in University of Wisconsin (UW) solution or Dsol, and subsequently reperfused on an isolated perfused rat liver. Graft function, injury, perfusion kinetics, oxidative stress, and cytoskeletal integrity were assessed. RESULTS: In the UW group, severe ischemia and reperfusion injury (IRI) was shown by histopathology, higher liver enzymes leakage, portal resistance, and apoptotic index, oxygen consumption, less bile production, energy charge, and reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio (versus control). The Dsol group showed that these injuries were significantly ameliorated (versus the UW group). Furthermore, cytoskeletal derangement was progressed in the UW group, as shown by less degradation of α-Fodrin and by the inactivation of the actin depolymerization pathway, whereas these changes were significantly suppressed in the Dsol group. CONCLUSION: Dsol reduced hepatic IRI after extended cold preservation and subsequent reperfusion. The protection was primarily due to the maintenance of mitochondrial function, cytoskeletal integrity, leading to limiting oxidative stress, apoptosis, and necrosis pathways.

Preoperative FOLFOX in resectable locally advanced rectal cancer can be a safe and promising strategy: the R-NAC-01 study.

PURPOSE: The aim of this study was to assess the safety of rectal surgery after 5-fluorouracil-leucovorin-oxaliplatin chemotherapy (FOLFOX6). METHODS: This was a prospective, multicenter study in 11 Japanese hospitals. We included patients with rectal cancer who received 4 courses of modified FOLFOX6 (mFOLFOX6) before rectal surgery and examined the postoperative complication rate, the clinicopathological response, and the rate of chemotherapy-related adverse events (UMIN 000012559). RESULTS: The study population included 36 men and 5 women. The average age of the patients was 60.8 years and the average body mass index was 23.1 kg/m2. After 4 courses of chemotherapy, grade 2 peripheral nerve disorder and other grade 3 adverse events were seen in 3 patients each (7.3%). Twenty-eight (73.7%) and 8 (21.1%) patients underwent low anterior resection and abdominoperineal resection, respectively. The pelvic nerves were preserved in 35 patients. Surgical morbidity (grade ≥ 3) occurred in 4 patients (10.5%). Anastomotic leakage occurred after surgery in 2 patients (7.1%). No patients achieved pathologically complete remission. However, downstaging of the clinical stage and N stage was seen in 17 (41.5%) and 22 (53.7%) patients, respectively. CONCLUSIONS: Surgery after four courses of mFOLFOX6 chemotherapy can be a safe and promising strategy for patients with locally advanced rectal cancer.

Simultaneous Laparoscopic Cholecystectomy and Combined Endoscopic and Laparoscopic Surgery for an Endoluminal Tumor of the Sigmoid Colon: A Case Report.

BACKGROUND One treatment for colon endoluminal tumors is endoscopic resection, i.e., endoscopic mucosal resection (EMR). In this report we describe a case of an endoluminal tumor resected safely and completely by combined endoscopic and laparoscopic surgery (CELS). CASE REPORT A 70-year-old female was admitted to our hospital for cholelithiasis, and we planned a cholecystectomy. She had a surgical history for endometrial cancer, and she was taking amlodipine 2.5 mg/day for hypertension. A preoperative colonoscopy for screening revealed an 18-mm endoluminal tumor in the sigmoid colon. We tried to resect it by EMR, but flexion of the colon, which was considered to be due to adhesion from the former surgical treatment, was severe, so it was difficult to resect the endoluminal tumor by endoscopy. We conducted laparoscopic cholecystectomy and sigmoid colon mobilization. Sigmoid colon flexion was released, enabling us to conduct EMR to the endoluminal tumor. No intraoperative or postoperative complications were observed. CONCLUSIONS CELS can make an endoluminal tumor resectable by EMR without colon resection, and performing simultaneous CELS and laparoscopic cholecystectomy is less invasive.

Laparoscopic abdominoperineal resection with lateral lymph node dissection for advanced rectal and prostate cancer with synchronous lateral lymph node metastases.

Here we report a case of advanced rectal and prostate cancer with synchronous lateral lymph node (LLN) metastases that was treated with laparoscopic surgery. A 71-year-old man presented with fecal occult blood and was diagnosed with rectal cancer. A metastatic right LLN was suspected after CT examination of a 19-mm lymph node (proximal internal iliac artery region) and a 13-mm lymph node (distal internal iliac artery region) in the right lateral region. We planned neoadjuvant chemotherapy to suppress local and distant recurrence. This treatment decreased the size of the primary rectal tumor. We performed laparoscopic abdominoperineal resection and right LLN dissection. The histopathological diagnosis was LLN metastases from the rectal and prostate cancers. It is rare for synchronous metastases from rectal and prostate cancers to be observed in the LLN. It may be difficult to determine an appropriate treatment strategy in cases like this.

Case of chronic pain after laparoscopic percutaneous extraperitoneal closure in an adolescent girl with inguinal hernia in which open repair was effective.

Chronic pain after laparoscopic percutaneous extraperitoneal closure is very rare. Here, we report a case of chronic pain after laparoscopic percutaneous extraperitoneal closure in an adolescent patient with inguinal hernia who underwent open repair. A 15-year-old girl was diagnosed with a left indirect inguinal hernia, and laparoscopic percutaneous extraperitoneal closure was performed. However, 6 months later, after strenuous exercise, she developed localized pain around the hernia site. Her pain was well controlled by internal treatment but failed to completely resolve. The pain type was somatic, Tinel's sign was negative, and there was no recurrence of the inguinal hernia. Because she strongly wished to undergo surgery, the Potts procedure with removal of the ligature and excision of the round ligament was performed. Her pain improved after surgery, and further medical treatment was not required. The Potts procedure may be an effective treatment for chronic pain such as in this case.

Endoscopic Retrograde Cholangiopancreatography (ERCP) with Laparotomic Small-Intestinal Incision Approach for Extraction of a Common Bile Duct (CBD) Stone Following Total Gastrectomy and Roux-en-Y (R-Y) Anastomosis: A Case Report.

BACKGROUND Endoscopic retrograde cholangiopancreatography for common bile duct stone in patients who underwent gastrectomy and Roux-en-Y anastomosis is challenging. We report a case in which we performed endoscopic retrograde cholangiopancreatography through a small-intestinal incision approach for a common bile duct stone, which had developed after total gastrectomy and Roux-en-Y anastomosis. CASE REPORT An 86-year-old woman with a history of laparoscopic-assisted total gastrectomy and R-Y anastomosis and incision of the common bile duct and cholecystectomy for common bile duct stone by open surgery 3 years ago presented with abdominal pain. Examination revealed a 10-mm stone in the lower part of common bile duct. We planned a combined endoscopic and open surgical approach. An incision on the Y limb of the Roux-en-Y anastomosis 20 cm from the jejunojejunal anastomosis and insertion of an endoscope through this opening were performed to extract the common bile duct stone. The patient was discharged on postoperative day 22 without complications. CONCLUSIONS For a patient with a common bile duct stone, who underwent gastrectomy and Roux-en-Y anastomosis, with firm adhesions at the porta hepatis, combined endoscopy and open surgery using a small-intestinal incision approach can be effective when small-bowel endoscopes are unavailable or the cannulation to Vater's papilla by them is difficult.

Post-reperfusion hydrogen gas treatment ameliorates ischemia reperfusion injury in rat livers from donors after cardiac death: a preliminary study.

BACKGROUND AND PURPOSE: We reported previously that hydrogen gas (H2) reduced hepatic ischemia and reperfusion injury (IRI) after prolonged cold storage (CS) of livers retrieved from heart-beating donors. The present study was designed to assess whether H2 reduced hepatic IRI during donation of a cardiac death (DCD) graft with subsequent CS. METHODS: Rat livers were harvested after 30-min cardiac arrest and stored for 4 h in University of Wisconsin solution. The graft was reperfused with oxygenated buffer, with or without H2 (H2 or NT groups, respectively), at 37° for 90 min on isolated perfused rat liver apparatus. RESULTS: In the NT group, liver enzyme leakage, apoptosis, necrosis, energy depletion, redox status, impaired microcirculation, and bile production were indicative of severe IRI, whereas in the H2 group these impairments were significantly suppressed. The phosphorylation of cytoplasmic MKK4 and JNK were enhanced in the NT group and suppressed in the H2 group. NFkB-p65 and c-Fos in the nucleus were unexpectedly unchanged by IRI regardless of H2 treatment, indicating the absence of inflammation in this model. CONCLUSION: H2 was observed to ameliorate IRI in the DCD liver by maintaining microcirculation, mitochondrial functions, and redox status, as well as suppressing the cytoplasmic MKK4-JNK-mediated cellular death pathway.

Laparoscopic anterior resection for rectal cancer in a patient with a ventriculoperitoneal shunt.

Laparoscopic surgery has been relatively contraindicated in patients with ventriculoperitoneal shunts (VPS) because of concerns about the effect of the pneumoperitoneum on shunt function. However, there have been recent reports of laparoscopic surgery on the gallbladder and cecum. This is the first report of laparoscopic high anterior resection for rectal cancer without manipulation of the VPS catheter in a patient with VPS. We made a diagnosis of advanced rectal cancer in a 77-year-old man who had a VPS to treat hydrocephalus after a subarachnoid hemorrhage. We performed the procedure with the patient in a 15° head-down tilt and with 10-mmHg pneumoperitoneum pressure. There were no postoperative complications. We concluded that laparoscopic surgery for rectal cancer can be safely performed in patients with VPS.

Serosal Laceration During Firing of Powered Linear Stapler Is a Predictor of Staple Malformation.

BACKGROUND: Although several types of staplers have been developed, staple-line leaks have been a great problem in gastrointestinal surgery. Powered linear staplers were recently developed to further reduce the risk of tissue trauma during laparoscopic surgery. The aim of this study was to identify the factors that predict staple malformation and determine the effect of precompression and slow firing on the staple formation of this novel powered stapling method. METHODS: Porcine stomachs were divided using an endoscopic powered linear stapler with gold reloads. We divided the specimens into 9 groups according to the precompression time (0/60/180 seconds) and firing time (0/60/180 seconds). The occurrence and length of laceration and the shape of the staples were evaluated. We examined the factors influencing successful stapling and investigated the key factors for staple malformation. RESULTS: Precompression significantly decreased the occurrence and length of serosal laceration. Precompression and slow firing significantly improved the optimal stapling formation rate. Univariate analysis showed that the precompression time (0 seconds), firing time (0 seconds), and presence of serosal laceration were significantly associated with a low optimal formation rate. Multivariate analysis showed that these three factors were associated independently with low optimal formation rate and that the presence of serosal laceration was the only factor that could be detected during the stapling procedure. CONCLUSIONS: We have shown that serosal laceration is a predictor of staple malformation and demonstrated the importance of precompression and slow stapling when using the powered stapling method.