Background We applied a new concept of ''image overlay surgery'' consisting of the integration of virtual reality (VR) and augmented reality (AR) technology, in which dynamic 3D images were superimposed on the patient's actual body surface and evaluated as a reference for surgical navigation in gastrointestinal, hepatobiliary and pancreatic surgery. Methods We carried out seven surgeries, including three cholecystectomies, two gastrectomies and two colectomies. A Macintosh and a DICOM workstation OsiriX were used in the operating room for image analysis. Raw data of the preoperative patient information obtained via MDCT were reconstructed to volume rendering and projected onto the patient's body surface during the surgeries. For accurate registration, OsiriX was first set to reproduce the patient body surface, and the positional coordinates of the umbilicus, left and right nipples, and the inguinal region were fixed as physiological markers on the body surface to reduce the positional error. Results The registration process was non-invasive and markerlesss, and was completed within 5 min. Image overlay navigation was helpful for 3D anatomical understanding of the surgical target in the gastrointestinal, hepatobiliary and pancreatic anatomies. The surgeon was able to minimize movement of the gaze and could utilize the image assistance without interfering with the forceps operation, reducing the gap from the VR. Unexpected organ injury could be avoided in all procedures. In biliary surgery, the projected virtual cholangiogram on the abdominal wall could advance safely with identification of the bile duct. For early gastric and colorectal cancer, the small tumors and blood vessels, which usually could not be found on the gastric serosa by laparoscopic view, were simultaneously detected on the body surface by carbon dioxide-enhanced MDCT. This provided accurate reconstructions of the tumor and involved lymph node, directly linked with optimization of the surgical procedures. Conclusions Our non-invasive markerless registration using physiological markers on the body surface reduced logistical efforts. The image overlay technique is a useful tool when highlighting hidden structures, giving more information.

Purpose To investigate the risk factors for post-pancreatectomy hemorrhage (PPH). Methods The incidence, outcome, and risk factors for PPH were evaluated in 1169 patients who underwent pancreatectomy. Results The incidence and mortality rates of PPH were 3% and 11% in all pancreatectomies, 4% and 11% in pancreatoduodenectomy, 1% and 20% in distal pancreatectomy, and 3% and 0% in total pancreatectomy, respectively. Male sex [odds ratio (OR) 2.32], body mass index (BMI) ≥ 25 kg/m 2 (OR 3.70), absence of diabetes mellitus (DM; HbA1c ≤ 6.2%; OR 3.62), and pancreatoduodenectomy (OR 3.06) were risk factors for PPH after all pancreatectomies. The PPH incidence was 0%, 1%, 2%, 6%, and 20% in patients with risk scores of 0 (n = 65), 1 (n = 325), 2 (n = 455), 3 (n = 299), and 4 (n = 25), respectively. The differences between risk-score groups 0-2 (2%) and 3-4 (7%) were significant (P < 0.05, OR 4.7). In patients who had undergone pancreatoduodenectomy, postoperative pancreatic fistula (POPF; OR 31.7) and absence of DM (OR 3.45) were risk factors for PPH. There was no significant association between POPF and PPH after distal pancreatectomy (P = 0.28). The incidence of POPF post-pancreatoduodenectomy was 20%. BMI ≥ 25 kg/m 2 (OR 3.17), serum albumin < 3.5 g/dl (OR 1.77), absence of DM (OR 1.75), distal extrahepatic bile duct carcinoma (OR 4.05), and carcinoma of the papilla of Vater (OR 5.19) were risk factors for POPF post-pancreatoduodenectomy. Conclusion Our study clarified the preoperative risk factors for PPH and recommends using a risk scoring system that includes Babsence of DM^for predicting PPH.

R1-HD/CIS should be avoided in patients undergoing surgery for node-negative and distant metastasis-negative PHC.

For patients with PHC, the associated risk of postoperative tumor dissemination in the ENBD group was lower than in the PTBD group and equivalent to that in the WD group. Thus, ENBD is the ideal procedure for preoperative biliary drainage.

Short-term outcomes for patients with perihilar cholangiocarcinoma and undergoing vascular resection were poor compared to those without vascular resection. Long-term survival in R0M0 disease was more favorable; aggressive surgery is recommended.

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Transvaginal and transgastric NOTES cholecystectomy is technically feasible and safe in both humans and animals. New instrumentation needs to be developed to perform a pure NOTES cholecystectomy without transabdominal assistance.

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