Explainable artificial intelligence prediction-based model in laparoscopic liver surgery for segments 7 and 8: an international multicenter study.

BACKGROUND: Artificial intelligence (AI) is becoming more useful as a decision-making and outcomes predictor tool. We have developed AI models to predict surgical complexity and the postoperative course in laparoscopic liver surgery for segments 7 and 8. METHODS: We included patients with lesions located in segments 7 and 8 operated by minimally invasive liver surgery from an international multi-institutional database. We have employed AI models to predict surgical complexity and postoperative outcomes. Furthermore, we have applied SHapley Additive exPlanations (SHAP) to make the AI models interpretable. Finally, we analyzed the surgeries not converted to open versus those converted to open. RESULTS: Overall, 585 patients and 22 variables were included. Multi-layer Perceptron (MLP) showed the highest performance for predicting surgery complexity and Random Forest (RF) for predicting postoperative outcomes. SHAP detected that MLP and RF gave the highest relevance to the variables "resection type" and "largest tumor size" for predicting surgery complexity and postoperative outcomes. In addition, we explored between surgeries converted to open and non-converted, finding statistically significant differences in the variables "tumor location," "blood loss," "complications," and "operation time." CONCLUSION: We have observed how the application of SHAP allows us to understand the predictions of AI models in surgical complexity and the postoperative outcomes of laparoscopic liver surgery in segments 7 and 8.

Refractory Choledocholithiasis Causing Endogenous Endophthalmitis: A Case Report.

BACKGROUND Endogenous bacterial endophthalmitis is caused by a breach of the blood-ocular barrier by pathogens originating from distant infective foci. Here, we report a case of endogenous endophthalmitis due to cholangitis complicated by common bile duct stones, which is a rare source of infection. CASE REPORT A 73-year-old man with type II diabetes mellitus underwent endoscopic choledocholithotripsy 20 years ago and laparoscopic cholecystectomy 18 years ago. He had choledocholith-related cholangitis 6, 5, and 1 years previously and 4 times in the last year and underwent endoscopic choledocholithotripsy each time. Three days after the last surgery, the patient developed right endogenous endophthalmitis and vitrectomy was performed. Four months later, the patient relapsed with cholangitis and required surgery for recurrent endophthalmitis. Roux-en-Y choledochojejunostomy was performed with curative intent, and the patient was followed up for 5 years without recurrence of choledocholith, cholangitis, or endophthalmitis. CONCLUSIONS The recommended treatment strategy for patients diagnosed with common bile duct stones or choledocholithiasis is stone extraction. Endoscopic retrograde cholangiopancreatography (ERCP) with endoscopic intervention is a widely accepted procedure. However, in cases of recurrent choledocholithiasis, the rate of recurrence increases and the interval between ERCP becomes shorter in proportion to the number of recurrences. In such intractable cases requiring numerous sessions of endoscopic stone removal, bypass Roux-en-Y choledochojejunostomy should be performed to prevent possible rare complications such as endogenous bacterial endophthalmitis.

Increasing incidence and severity of post-hepatectomy adhesion around the liver may be influenced by the hepatectomy-related operative procedures.

BACKGROUND: The incidence of postoperative adhesions is directly correlated with the difficulty level of repeat hepatectomies. However, the incidence, location, and severity of postoperative adhesions in relation to hepatectomy-related operative procedures are yet unclear. METHODS: First hepatectomy-induced hard dense adhesions were evaluated from the surgical records and/or videos of 168 patients who underwent second hepatectomies. RESULTS: The incidence of postoperative hard dense adhesions around the liver was significantly associated with locations, such as the hepatic cut surface, dissected areas around the liver, and peri-incision peritoneum, and hepatectomy-related operative procedures, such as Pringle maneuver and cholecystectomy. The incidence of hard dense adhesions after dissection was higher around the right liver than in the left infraphrenic space. Further, the incidence of hard dense adhesions around the hepatoduodenal ligament or Morison pouch was greater than 30% even in patients who did not undergo Pringle maneuver, cholecystectomy, or hepatorenal ligament dissection. Although the incidence of hard dense adhesions of the peritoneum around the incision was higher after open hepatectomy than after laparoscopic hepatectomy, adhesion barrier use reduced the incidence of such adhesions in patients after open hepatectomy. CONCLUSION: Hepatectomy-related operative procedures such as peri-hepatic dissection, Pringle maneuver and cholecystectomy are directly associated with postoperative hard dense adhesions. However, the incidence of postoperative hard dense adhesions around the hepatoduodenal ligament and Morison pouch was high even when the above-mentioned operative procedures were not performed. These findings may help inform clinical decisions regarding the indications and sites for adhesion barrier use during hepatectomies.

Comparison of clinicopathological characteristics between resected ampullary carcinoma and carcinoma of the second portion of the duodenum.

BACKGROUND: Few studies compared the oncological and biological characteristics between ampullary carcinoma (AC) and cancer of the second portion of the duodenum (DC-II), although both tumors arise from anatomically close locations. AIM: To elucidate differences in clinicopathological characteristics, especially the patterns of lymph node metastasis (LNM), between AC and DC-II. METHODS: This was a retrospective cohort study of 80 patients with AC and 27 patients with DC-II who underwent pancreaticoduodenectomy between January 1998 and December 2018 in two institutions. Clinicopathological factors, LNM patterns, and prognosis were compared between the two groups. RESULTS: The patients with AC and DC-II did not exhibit significant differences in 5-year overall survival (66.0% and 67.1%, respectively) and 5-year relapse-free survival (63.5% and 62.2%, respectively). Compared to the patients with DC-II, the rate of preoperative biliary drainage was higher (P = 0.042) and the rates of digestive symptoms (P = 0.0158), ulcerative-type cancer (P < 0.0001), large tumor diameter (P < 0.0001), and advanced tumor stage (P = 0.0019) were lower in the patients with AC. The LNM rates were 27.5% and 40.7% in patients with AC and DC-II, respectively, without significant difference (P = 0.23). The rates of LNM to hepatic nodes (N-He) and pyloric nodes (N-Py) were significantly higher in patients with DC-II than in those with AC (metastasis to N-HE: 18.5% and 5% in patients with DC-II and AC, respectively; P = 0.0432; metastasis to N-Py: 11.1% and 0% in patients with DC-II and AC, respectively; P = 0.0186). CONCLUSION: Although there were no significant differences in the prognosis and recurrence rates between the two groups, metastases to N-He and N-Py were more frequent in patients with DC-II than in those with AC.

Jejunal Mesentery Preservation Reduces Leakage at Esophagojejunostomy After Minimally Invasive Total Gastrectomy for Gastric Cancer: a Propensity Score-Matched Cohort Study.

PURPOSE: The mesentery of the jejunum (MJ) of the Roux limb is conventionally divided when Roux-en-Y reconstruction is performed after total gastrectomy for gastric cancer (GC). However, the impact of dividing or preserving the MJ on anastomotic leakage (AL) at the esophagojejunostomy (EJS) site after minimally invasive total gastrectomy for GC is unclear. METHODS: This retrospective cohort study enrolled 226 patients with GC who underwent EJS after laparoscopic or robotic total gastrectomy, including preservation of the MJ (n = 87) and division of the MJ (n = 137). The prevalence of anastomotic complications at the EJS and short-term outcomes were compared between groups using propensity score (PS) matching. RESULTS: After PS matching, 69 patients were selected for the preserving and dividing MJ groups. There were no significant intergroup differences in patient backgrounds, including oncological stage, body mass index, and gender ratio. After PS matching, overall and severe complications after surgery were compared between the preserving and dividing MJ groups (21.7% vs. 27.5%, p = 0.554 and 8.7% vs. 13.8%, p = 0.137, respectively). However, the rate of AL at the EJS was significantly lower in the preserving than that in the dividing MJ group (1.4% vs. 13.0%, p = 0.017). In addition, the median postoperative hospital stay was significantly shorter in the preserving than that in the dividing MJ group (13.0 days vs. 16.0 days, p = 0.005). CONCLUSIONS: Preserving the MJ significantly reduced AL at the EJS after minimally invasive total gastrectomy for GC.

Mucinous cystic neoplasm of the liver with polypoid nodule prolapsing into the bile duct: a case report and review of literature.

BACKGROUND: Mucinous cystic neoplasm of the liver (MCN-L) is a rare cystic tumor as defined by the 2010 World Health Organization classification. MCN-L usually does not communicate with or grow into the bile duct. Herein, we present a rare case of MCN-L with a polypoid nodule protruding into the bile duct. CASE PRESENTATION: A 69-year-old woman was referred to our hospital for elevated serum liver enzyme levels and obstructive jaundice. The patient also complained of abdominal pain in the right hypochondriac region. Abdominal ultrasonography showed a cystic lesion in segment 4 (S4) of the liver. Computed tomography revealed a 4-cm multilocular cystic lesion with a thick wall and multiple septal formations, showing a cyst-in-cyst appearance in S4. Endoscopic retrograde cholangiography showed a contrast defect between the left hepatic duct and the common bile duct, which was suspected to be a nodular lesion in the bile duct. Bile cytology and biopsy of the nodular lesion showed no malignant findings. Based on these findings, the differential diagnosis in this patient included intraductal papillary neoplasm of the bile duct and MCN-L, which had malignant potential. The patient underwent left hemihepatectomy, including caudate lobe excision with bile duct resection and right hepatocholangiojejunostomy. Macroscopic findings showed a 40 × 29 mm multilocular cystic lesion with a polypoid nodule that protruded into the left intrahepatic bile duct. As an ovarian-like stroma was observed in both cystic and polypoid lesions microscopically, the histopathological diagnosis was MCN-L. The postoperative course was uneventful, and the patient was discharged 24 days after surgery. The patient is currently alive without recurrence 22 months after the surgery. CONCLUSION: Although MCN-L rarely communicates with the bile duct, it is necessary to consider that MCN-L could grow into the bile duct, occasionally causing obstructive jaundice.

An International Retrospective Observational Study of Liver Functional Deterioration after Repeat Liver Resection for Patients with Hepatocellular Carcinoma.

Whether albumin and bilirubin levels, platelet counts, ALBI, and ALPlat scores could be useful for the assessment of permanent liver functional deterioration after repeat liver resection was examined, and the deterioration after laparoscopic procedure was evaluated. For 657 patients with liver resection of segment or less in whom results of plasma albumin and bilirubin levels and platelet counts before and 3 months after surgery could be retrieved, liver functional indicators were compared before and after surgery. There were 268 patients who underwent open repeat after previous open liver resection, and 224 patients who underwent laparoscopic repeat after laparoscopic liver resection. The background factors, liver functional indicators before and after surgery and their changes were compared between both groups. Plasma levels of albumin (p = 0.006) and total bilirubin (p = 0.01) were decreased, and ALBI score (p = 0.001) indicated worse liver function after surgery. Laparoscopic group had poorer preoperative performance status and liver function. Changes of liver functional values before and after surgery and overall survivals were similar between laparoscopic and open groups. Plasma levels of albumin and bilirubin and ALBI score could be the indicators for permanent liver functional deterioration after liver resection. Laparoscopic group with poorer conditions showed the similar deterioration of liver function and overall survivals to open group.

[Synchronous Double Primary Non-B, and Non-C Intrahepatic Cholangiocarcinoma and Hepatocellular Carcinoma-A Case Report].

A 78-year-old man without hepatitis virus B or C underwent right hemi-hepatectomy and lymph node dissection for a tumor 5 cm in diameter located in the hepatic hilum of the posterior segment of the liver with portal vein thrombi extending into the main portal trunk and a tumor 1.5 cm in diameter in the peripheral side of segment 5 of the liver. Histopathologically, the former was diagnosed as intrahepatic cholangiocarcinoma and the latter as hepatocellular carcinoma(HCC). Five months after the surgery, intrahepatic and lymph node metastases were diagnosed based on computed tomography(CT); therefore, chemotherapy with S-1 for 3 months and gemcitabine and cisplatin(GC)for 5 months was administered, after which the metastatic lesions were not detected. Nineteen months after the surgery, partial resection of segment 2 of the liver was performed for a tumor 3 cm in diameter, which was diagnosed as HCC histopathologically. Two years after the second surgery, 2 recurrent nodules in the liver in segments 3 and 4 were detected on CT. Platinum-based hepatic arterial infusion chemotherapy(HAIC)and transcatheter arterial chemoembolization(TACE)were performed, and chemotherapy with GC was then administered for 7 months. For a new tumor detected in segment 1 in the liver, TACE was performed 17 months after initial HAIC. Seventy-four months after the initial surgery, 5 new nodules less than 1 cm in diameter were detected, and chemotherapy with sorafenib was administered for 5 months, after which the patient died of coronavirus disease 2019.

[Locally Advanced Pancreatic Cancer Treated with Two-Staged Pancreaticoduodenectomy after Laparoscopic Median Arcuate Ligament Section-A Case Report].

A 76-year-old male was diagnosed as locally advanced pancreatic cancer because abdominal CT scan revealed a pancreatic head tumor with involvement of the proper hepatic artery. Gemcitabine plus nab-paclitaxel was initiated, but was discontinued because interstitial pneumonia was occurred. The treatment was switched to S-1 therapy and achieved stable disease for 22 months. Therefore, conversion surgery was scheduled. Because stenosis of the celiac artery origin due to median arcuate ligament(MAL)compression and dilatation of pancreatoduodenal artery arcade were observed, laparoscopic MAL section was performed. The patient was discharged on postoperative day 5 without complications. Postoperative CT scan revealed no stenosis of the celiac artery origin and disappearance of dilatation of pancreatoduodenal artery arcade. On postoperative day 14, subtotal stomach-preserving pancreaticoduodenectomy(PD)with portal vein resection was performed. The patient was discharged on postoperative day 19 without complications. Two-staged PD after MAL section make possible to evaluate blood flow accurately and select an appropriate operative method. Laparoscopic MAL section is minimally invasive and may be useful for two-staged PD in patients with celiac axis stenosis.

Indications of Laparoscopic Repeat Liver Resection for Recurrent Hepatocellular Carcinoma.

AIM: This study aimed to evaluate the indications of laparoscopic repeat liver resection (LRLR) for recurrent hepatocellular carcinoma from the viewpoint of its difficulty. METHODS: One hundred and one patients who underwent LRLR and 59 patients who underwent open repeat liver resection (ORLR) were included. The difficulty was classified according to the preoperative predictive factors for difficult LRLR, including an open approach during previous liver resection, history of two or more previous liver resections, history of previous major liver resection, tumor near the resected site of the previous liver resection, and intermediate or high difficulty with the difficulty scoring system. We compared the surgical outcomes between the LRLR and ORLR groups based on the difficulty class (low- or intermediate difficiulty class, 0 to 3 predictive factors; high difficiulty class, 4 or 5 factors). RESULTS: In the low- or intermediate difficiulty class, intraoperative blood loss and the proportion of patients with postoperative complications were significantly lower in LRLR than in ORLR, and the duration of the postoperative hospital stay was significantly shorter in LRLR than in ORLR. In the high difficiulty class, total operative time and operative time before starting hepatic parenchymal resection were significantly longer in LRLR than in ORLR, and there were no significant differences in other surgical outcomes between the two groups. CONCLUSION: LRLR is recommended for patients in the low or intermediate difficulty class. However, LRLR does not have an advantage with longer operative time for patients in the high difficulty class compared with ORLR.

[A Case of Recurrent Gastric Cancer of Multiple Organ Metastasis with Long-Term Survival Due to Multimodal Treatment].

A 67-year-old man was introduced to examine for abnormal findings in physical examination. Upper gastrointestinal endoscopy detected the 3 lesions and diagnosed multiple gastric cancers with biopsy. Laparoscopic total gastrectomy was performed and final pathological diagnosis was pT2N1M0, pStage ⅡA with HER2 positive(3+). Adjuvant chemotherapy was not administrated. CT findings 6 months after procedure showed 2 liver metastases(S6, S7)and laparoscopic partial liver resection was performed. Pathological findings proved the metastasis of previous gastric cancer. Although adjuvant chemotherapy of S-1 was started 2 months after hepatectomy, CT findings showed second recurrences in liver and right adrenal gland. Chemotherapy was changed to S-1 plus cisplatin(SP)plus trastuzumab. AS these recurrence sites and ascites could not be detected by CT after 6 courses, therapeutic effect was judged as clinical CR(cCR)and SP plus trastuzumab was stopped due to side effect. Since then, regular follow-up CT showed preservation of status of cCR without chemotherapy and he has been alive without recurrence for 8 years and 9 months after gastrectomy. We report a case of recurrent gastric cancer of multiple organ metastasis with long-term survival due to multimodal treatment.

[A Case of pStage IB Gastric Cancer Relapsed on Both Pleura and Peritoneum Eight Year after Radical Gastrectomy].

An 86-year-old man presented with upper abdominal pain and was diagnosed with type 0-Ⅲ gastric cancer located at the posterior wall of the upper stomach by upper gastrointestinal endoscopy. Laparoscopic total gastrectomy(D1+)was performed for gastric cancer of cStage Ⅰ. As final pathological diagnosis was pT2N0(0/27)M0H0P0CY0, pStage ⅠB, adjuvant chemotherapy was not administrated. The patient has been alive with no recurrence for 5 years after surgery. 8 years and 1 month after procedure, he visited our hospital with chief complaint of abdominal distention and anorexia. Chest and abdominal CT showed pleural fluid and ascites, but PET-CT could not detect any sites of recurrence. Cytopathology and cell blocks by immunohistochemical staining of ascites proved recurrence of previous gastric cancer. Any treatment was rejected, and the patient died 3 months after recurrence and 8 years and 4 months after gastrectomy. Late recurrence on both pleura and peritoneum of gastric cancer is very rare. We report a case of pStage ⅠB gastric cancer relapsed on both pleura and peritoneum 8 year after radical gastrectomy.

Prognostic Factors and Lymph Node Metastasis Patterns of Primary Duodenal Cancer.

BACKGROUND: The effectiveness and extent of regional lymph node dissection in primary duodenal cancer (DC) remains unclear. This study aimed to analyze the prognostic factors and lymph node metastasis (LNM) patterns in DC. METHODS: Fifty-three patients who underwent surgical resection for DC between January 1998 and December 2018 at two institutions were retrospectively analyzed. Univariate and multivariate analyses were performed on the prognostic factors of resected DC. Moreover, the relationships between depth of tumor invasion and incidence of LNM and between tumor location and LNM stations were analyzed. RESULTS: The five-year survival rate of the study population was 68.9%. Multivariate survival analysis demonstrated that histologic grade G2-G4, presence of LNM, pT3-4, and elevated preoperative CA19-9 were the independent poor prognostic factors. No patient with pTis-T2 had LNM. On the other hand, LNM was found in 70% of patients with pT3-4. Among 36 patients who underwent pancreaticoduodenectomy (PD), LNM around the pancreatic head was observed, regardless of the duodenal cancer site, including the duodenal bulb and the third to the fourth portion. CONCLUSIONS: Histologic grade G2-G4, presence of LNM, pT3-T4, and elevated preoperative CA19-9 were the independent poor prognostic factors in patients with resected DC. Our results suggested that lymph node dissection could be omitted for DC Tis-T1a. Moreover, based on the high frequency of LNM in T3-4 cases, PD with lymph node dissection in the pancreatic head region was considered necessary for T3-4 DC at any site.

Laparoscopic liver resection with open partial resection of the thoracoabdominal wall for cancer along the transhepatic biliary drainage tract: A case report.

INTRODUCTION AND IMPORTANCE: Recently, laparoscopic liver resection has been established as a standard procedure for a certain group of hepatic resections; its indications and procedures have been expanding. CASE PRESENTATION: A 67-year-old woman was referred with a chief complaint of left subcostal pain. Eight years and nine months before, she underwent pancreatoduodenectomy for cancer of the ampulla of Vater after endoscopic retrograde biliary drainage for obstructive jaundice. A trans-anastomotic internal-external retrograde transhepatic biliary drainage (RTBD) catheter was placed intraoperatively. Based on radiological findings, intrahepatic cholangiocarcinoma, or local recurrence of cancer of the ampulla of Vater, invading the anterior thoracoabdominal wall, diaphragm, and pericardium, without distant metastasis, were considered. Laparoscopic lateral segmentectomy of the liver combined with open en bloc resection of the invaded portion of the anterior thoracoabdominal wall with costal cartilage, diaphragm, and pericardium was performed. The postoperative course was uneventful, and the patient was discharged 17 days post-surgery. The patient died of cancer recurrence 46 months later. CLINICAL DISCUSSION: The cancer invaded along the RTBD tract. Although the mechanisms of carcinogenesis remain unclear, transhepatic biliary drainage is a risk factor for cancer invasion along the tract. Laparoscopic liver resection before open thoracoabdominal wall resection ensured clear delineation of the cancer margins invading the thoracoabdominal wall and minimized the defect of the thoracoabdominal wall. CONCLUSION: Laparoscopic liver resection for hepatic cancer invading adjacent structures or organs would be feasible and useful in selected patients, even if resection of the invaded area is performed by open surgery.

Multicenter Propensity Score-Based Study of Laparoscopic Repeat Liver Resection for Hepatocellular Carcinoma: A Subgroup Analysis of Cases with Tumors Far from Major Vessels.

Less morbidity is considered among the advantages of laparoscopic liver resection (LLR) for HCC patients. However, our previous international, multi-institutional, propensity score-based study of emerging laparoscopic repeat liver resection (LRLR) failed to prove this advantage. We hypothesize that these results may be since the study included complex LRLR cases performed during the procedure's developing stage. To examine it, subgroup analysis based on propensity score were performed, defining the proximity of the tumors to major vessels as the indicator of complex cases. Among 1582 LRLR cases from 42 international high-volume liver surgery centers, 620 cases without the proximity to major vessels (more than 1 cm far from both first-second branches of Glissonian pedicles and major hepatic veins) were selected for this subgroup analysis. A propensity score matching (PSM) analysis was performed based on their patient characteristics, preoperative liver function, tumor characteristics and surgical procedures. One hundred and fifteen of each patient groups of LRLR and open repeat liver resection (ORLR) were earned, and the outcomes were compared. Backgrounds were well-balanced between LRLR and ORLR groups after matching. With comparable operation time and long-term outcome, less blood loss (283.3±823.0 vs. 603.5±664.9 mL, p = 0.001) and less morbidity (8.7 vs. 18.3 %, p = 0.034) were shown in LRLR group than ORLR. Even in its worldwide developing stage, LRLR for HCC patients could be beneficial in blood loss and morbidity for the patients with less complexity in surgery.

[Short- and Long-Term Surgical Outcomes for Patients with Colorectal Cancer Aged 80 Years or Older].

This study aimed to assess short-term and long-term outcomes and to identify the factors that affect outcomes for patients with colorectal cancer aged 80 years or older. Two hundred patients with colorectal cancer who were underwent resection of the primary tumor between January 2013 and December 2018 were enrolled. Short-term outcomes of elderly patients with poor PS and of those who take antithrombotic agents and of those who were underwent open surgery were poor. Long-term outcomes of elderly patients with high GNRI and of those who were underwent D3 lymph nodes dissection were better. Laparoscopic surgery with D3 lymph nodes dissection for elderly patients who were more than 80 years old should be useful to improve short- and long-term outcomes. GNRI might be a prognostic predictive factor for patients with colorectal cancer aged 80 years or older.

[Prognostic Analysis of Colorectal Cancer Patients by the Controlling Nutritional Status(CONUT)Score].

We examined the controlling nutritional status(CONUT)score and the long-term prognosis of colorectal cancer surgery cases. We retrospectively examined the prognosis of colorectal cancer patients who underwent surgery between January 2013 and December 2015. We targeted 449 patients who were able to calculate the CONUT score. A total of 266 patients (59.2%)had normal nutritional status(1 or less)and 183 patients(40.8%)had mildly poor or worse nutritional status (2 or more). The CONUT score was calculated through preoperative blood tests. The relationship between the CONUT score and overall survival was examined in the low and high groups. Overall survival was significantly shorter in the high group but relapse-free survival did not differ significantly between the 2 groups. There was no difference in cancer-specific survival between the 2 groups, but the survival time due to death from other diseases was significantly shorter in the high group. The CONUT score obtained from preoperative blood sampling suggested that the overall survival time was short in the malnourished group, and that it could be used as an index of prognosis due to death from other diseases.

[Short-Term Clinical Outcome of Robotic Surgery for Advanced Rectal Cancer after Neoadjuvant Therapy].

We examined 14 cases who underwent robotic rectal resection with neoadjuvant chemotherapy(NAC)or neoadjuvant chemoradiation therapy(NACRT)for local advanced rectal cancer in our hospital from 2018 June to 2020 December. Two patients underwent NACRT, 12 patients underwent NAC. Sex was 10 males and 4 females. The median age was 66. The surgical procedure was ISR 2 cases, LAR 8 cases, APR 4 cases. The median operation time was 397 minutes and the median blood loss was 73 mL. The histological response grade were Grade 3: 1 case, 2: 7 cases, 1b: 3 cases, and 1a: 3 cases. Surgical margin was negative in all cases. Postoperative complications(≥Clavien-Dindo Grade Ⅲ)required reoperation due to intestinal obstruction in 1 case. Urinary dysfunction was nothing in all cases. Although long-term results such as prognosis and function preservation need to be examined, short-term results of robot-assisted rectal resection after NAC or NACRT were generally good.

[A Case of Robot Assisted Low Anterior Resection for a Patient with Persistent Descending Mesocolon].

Persistent descending mesocolon(PDM)is caused by absence of fusion of the descending colon to the retroperitoneum. A 67-year-old man with bloody stools was diagnosed with rectal cancer on colonoscopy. A computed tomography showed a medial displacement of his descending colon. The preoperative clinical diagnosis was rectal cancer with PDM, and robot assisted low anterior resection was performed. We found that the left-sided colon was shifted to the midline and adhered the cecum and the mesentery of small intestine. Robot assisted surgery enables surgery with the precise adhesiotomy in a stable field. PDM is a relatively rare anatomic abnormality. Character of PDM is adhesion between the left-sided colon and other organs and radially branch from the inferior mesenteric artery. It is important to understand the anatomical characteristics of PDM and to improve on existing surgical procedures to ensure safe robot assisted surgery these patients.