Prediction of post-hepatectomy liver failure by preoperative gadoxetate disodium-enhanced magnetic resonance imaging.

BACKGROUND: Approximately 15% of patients experience post-hepatectomy liver failure after major hepatectomy. Poor hepatocyte uptake of gadoxetate disodium, a magnetic resonance imaging contrast agent, may be a predictor of post-hepatectomy liver failure. METHODS: A retrospective cohort study of patients undergoing major hepatectomy (≥3 segments) with a preoperative gadoxetate disodium-enhanced magnetic resonance imaging was conducted. The liver signal intensity (standardized to the spleen) and the functional liver remnant was calculated to determine if this can predict post-hepatectomy liver failure after major hepatectomy. RESULTS: In 134 patients, low signal intensity of the remnant liver standardized by signal intensity of the spleen in post-contrast images was associated with post-hepatectomy liver failure in multiple logistic regression analysis (Odds Ratio 0.112; 95% CI 0.023-0.551). In a subgroup of 33 patients with lower quartile of functional liver remnant, area under the curve analysis demonstrated a diagnostic accuracy of functional liver remnant to predict post-hepatectomy liver failure of 0.857 with a cut-off value for functional liver remnant of 1.4985 with 80.0% sensitivity and 89.3% specificity. CONCLUSION: Functional liver remnant determined by gadoxetate disodium-enhanced magnetic resonance imaging is a predictor of post-hepatectomy liver failure which may help identify patients for resection, reducing morbidity and mortality.

Systematic Reviews and Meta-analyses of the Procedure-specific Risks of Thrombosis and Bleeding in General Abdominal, Colorectal, Upper Gastrointestinal, and Hepatopancreatobiliary Surgery.

OBJECTIVE: To provide procedure-specific estimates of symptomatic venous thromboembolism (VTE) and major bleeding after abdominal surgery. BACKGROUND: The use of pharmacological thromboprophylaxis represents a trade-off that depends on VTE and bleeding risks that vary between procedures; their magnitude remains uncertain. METHODS: We identified observational studies reporting procedure-specific risks of symptomatic VTE or major bleeding after abdominal surgery, adjusted the reported estimates for thromboprophylaxis and length of follow-up, and estimated cumulative incidence at 4 weeks postsurgery, stratified by VTE risk groups, and rated evidence certainty. RESULTS: After eligibility screening, 285 studies (8,048,635 patients) reporting on 40 general abdominal, 36 colorectal, 15 upper gastrointestinal, and 24 hepatopancreatobiliary surgery procedures proved eligible. Evidence certainty proved generally moderate or low for VTE and low or very low for bleeding requiring reintervention. The risk of VTE varied substantially among procedures: in general abdominal surgery from a median of <0.1% in laparoscopic cholecystectomy to a median of 3.7% in open small bowel resection, in colorectal from 0.3% in minimally invasive sigmoid colectomy to 10.0% in emergency open total proctocolectomy, and in upper gastrointestinal/hepatopancreatobiliary from 0.2% in laparoscopic sleeve gastrectomy to 6.8% in open distal pancreatectomy for cancer. CONCLUSIONS: VTE thromboprophylaxis provides net benefit through VTE reduction with a small increase in bleeding in some procedures (eg, open colectomy and open pancreaticoduodenectomy), whereas the opposite is true in others (eg, laparoscopic cholecystectomy and elective groin hernia repairs). In many procedures, thromboembolism and bleeding risks are similar, and decisions depend on individual risk prediction and values and preferences regarding VTE and bleeding.

Hospital learning curves for robot-assisted surgeries: a population-based analysis.

BACKGROUND: Robot-assisted surgery has been rapidly adopted. It is important to define the learning curve to inform credentialling requirements, training programs, identify fast and slow learners, and protect patients. This study aimed to characterize the hospital learning curve for common robot-assisted procedures. STUDY DESIGN: This cohort study, using administrative health data for Ontario, Canada, included adult patients who underwent a robot-assisted radical prostatectomy (RARP), total robotic hysterectomy (TRH), robot-assisted partial nephrectomy (RAPN), or robotic portal lobectomy using four arms (RPL-4) between 2010 and 2021. The association between cumulative hospital volume of a robot-assisted procedure and major complications was evaluated using multivariable logistic models adjusted for patient characteristics and clustering at the hospital level. RESULTS: A total of 6814 patients were included, with 5230, 543, 465, and 576 patients in the RARP, TRH, RAPN, and RPL-4 cohorts, respectively. There was no association between cumulative hospital volume and major complications. Visual inspection of learning curves demonstrated a transient worsening of outcomes followed by subsequent improvements with experience. Operative time decreased for all procedures with increasing volume and reached plateaus after approximately 300 RARPs, 75 TRHs, and 150 RPL-4s. The odds of a prolonged length of stay decreased with increasing volume for patients undergoing a RARP (OR 0.87; 95% CI 0.82-0.92) or RPL-4 (OR 0.77; 95% CI 0.68-0.87). CONCLUSION: Hospitals may adopt robot-assisted surgery without significantly increasing the risk of major complications for patients early in the learning curve and with an expectation of increasing efficiency.

Current Practices in Hepatic Artery Infusion (HAI) Chemotherapy: An International Survey of the HAI Consortium Research Network.

BACKGROUND: An increasing number of hepatic artery infusion (HAI) programs have been established worldwide. Practice patterns for this complex therapy across these programs have not been reported. This survey aimed to identify current practice patterns in HAI therapy with the long-term goal of defining best practices and performing prospective studies. METHODS: Using SurveyMonkeyTM, a 28-question survey assessing current practices in HAI was developed by 12 HAI Consortium Research Network (HCRN) surgical oncologists. Content analysis was used to code textual responses, and the frequency of categories was calculated. Scores for rank-order questions were generated by calculating average ranking for each answer choice. RESULTS: Thirty-six (72%) HCRN members responded to the survey. The most common intended initial indications for HAI at new programs were unresectable colorectal liver metastases (uCRLM; 100%) and unresectable intrahepatic cholangiocarcinoma (uIHC; 56%). Practice patterns evolved such that uCRLM (94%) and adjuvant therapy for CRLM (adjCRLM; 72%) have become the most common current indications for HAI at established centers. Referral patterns for pump placement differed between uCRLM and uIHC, with most patients referred while receiving second- and first-line therapy, respectively, with physicians preferring to evaluate patients for HAI while receiving first-line therapy for CRLM. Concern for extrahepatic disease was ranked as the most important factor when considering a patient for HAI. CONCLUSIONS: Indication and patient selection factors for HAI therapy are relatively uniform across most HCRN centers. The increasing use of adjuvant HAI therapy and overall consistency of practice patterns among HCRN centers provides a robust environment for prospective data collection and randomized clinical trials.

Rectus sheath catheters reduce opiate use in pancreaticoduodenectomy: a pre- and postintervention cohort study.

BACKGROUND: Pancreaticoduodenectomy is the only curative option for patients with pancreatic cancer; however, pain remains a considerable problem postoperatively. With many centres moving away from using epidural analgesia, there is the need to evaluate alternative opiate sparing techniques for postoperative analgesia. We sought to determine if rectus sheath catheters (RSCs) had an opiate sparing and analgesic effect compared with standard care alone (opiate analgesia). METHODS: We conducted a retrospective pre- and postintervention cohort study of patients undergoing pancreaticoduodenectomy at a single tertiary academic hospital in Toronto, Canada, between April 2018 and December 2019. All patients undergoing a pancreaticoduodenectomy were eligible for inclusion. Among the 101 patients identified, 84 (61 control, 23 RSCs) were analyzed after exclusion criteria were applied (epidural analgesia, admission to intensive care intubated or reintubated within the first 96 hours). The pre-intervention group received a semi-standardized course of analgesics, including intravenous hydromorphone, acetaminophen, ketamine, with or without nonsteroidal anti-inflammatory, and with or without intravenous lidocaine; the latter 2 drugs were at the individual anesthesiologist and surgeon's preference. For the postintervention group, the same course of analgesics were used, with the addition of RSCs. These were inserted at the end of the operation, with a loading dose of ropivacaine administered and followed by a programmed intermittent bolus regime for 72-96 hours. The primary outcome measure was total postoperative opiate consumption (oral morphine equivalents). Secondary outcomes included pain scores (numeric rating scale) and treatment-related adverse effects. RESULTS: Opiate consumption (oral morphine equivalents) at 96 hours was significantly lower (median 188 mg, interquartile range [IQR] 112-228 v. 242.4 mg, IQR 166.8-352) with and without RSC, respectively (p = 0.01). The RSC group used significantly less opiates at each time point from 24 hours postoperatively, with no significant difference in pain scores between the groups and no significant catheter-related complications. CONCLUSION: The use of RSCs was associated with significant reductions in postoperative opiate consumption. Given the ease of placement and management, with minimal complications, RSCs should be incorporated into a course of postoperative multimodal analgesia. A large scale randomized controlled trial should be conducted to further investigate these findings.

Association Between Biliary Pathogens, Surgical Site Infection, and Pancreatic Fistula: Results of a Randomized Trial of Perioperative Antibiotic Prophylaxis in Patients Undergoing Pancreatoduodenectomy.

OBJECTIVE: To establish the association between bactibilia and postoperative complications when stratified by perioperative antibiotic prophylaxis. BACKGROUND: Patients undergoing pancreatoduodenectomy experience high rates of surgical site infection (SSI) and clinically relevant postoperative pancreatic fistula (CR-POPF). Contaminated bile is known to be associated with SSI, but the role of antibiotic prophylaxis in mitigation of infectious risks is ill-defined. METHODS: Intraoperative bile cultures (IOBCs) were collected as an adjunct to a randomized phase 3 clinical trial comparing piperacillin-tazobactam with cefoxitin as perioperative prophylaxis in patients undergoing pancreatoduodenectomy. After compilation of IOBC data, associations between culture results, SSI, and CR-POPF were assessed using logistic regression stratified by the presence of a preoperative biliary stent. RESULTS: Of 778 participants in the clinical trial, IOBC were available for 247 participants. Overall, 68 (27.5%) grew no organisms, 37 (15.0%) grew 1 organism, and 142 (57.5%) were polymicrobial. Organisms resistant to cefoxitin but not piperacillin-tazobactam were present in 95 patients (45.2%). The presence of cefoxitin-resistant organisms, 92.6% of which contained either Enterobacter spp. or Enterococcus spp., was associated with the development of SSI in participants treated with cefoxitin [53.5% vs 25.0%; odds ratio (OR)=3.44, 95% CI: 1.50-7.91; P =0.004] but not those treated with piperacillin-tazobactam (13.5% vs 27.0%; OR=0.42, 95% CI: 0.14-1.29; P =0.128). Similarly, cefoxitin-resistant organisms were associated with CR-POPF in participants treated with cefoxitin (24.1% vs 5.8%; OR=3.45, 95% CI: 1.22-9.74; P =0.017) but not those treated with piperacillin-tazobactam (5.4% vs 4.8%; OR=0.92, 95% CI: 0.30-2.80; P =0.888). CONCLUSIONS: Previously observed reductions in SSI and CR-POPF in patients that received piperacillin-tazobactam antibiotic prophylaxis are potentially mediated by biliary pathogens that are cefoxitin resistant, specifically Enterobacter spp. and Enterococcus spp.

Piperacillin-Tazobactam Compared With Cefoxitin as Antimicrobial Prophylaxis for Pancreatoduodenectomy: A Randomized Clinical Trial.

Importance: Despite improvements in perioperative mortality, the incidence of postoperative surgical site infection (SSI) remains high after pancreatoduodenectomy. The effect of broad-spectrum antimicrobial surgical prophylaxis in reducing SSI is poorly understood. Objective: To define the effect of broad-spectrum perioperative antimicrobial prophylaxis on postoperative SSI incidence compared with standard care antibiotics. Design, Setting, and Participants: Pragmatic, open-label, multicenter, randomized phase 3 clinical trial at 26 hospitals across the US and Canada. Participants were enrolled between November 2017 and August 2021, with follow-up through December 2021. Adults undergoing open pancreatoduodenectomy for any indication were eligible. Individuals were excluded if they had allergies to study medications, active infections, chronic steroid use, significant kidney dysfunction, or were pregnant or breastfeeding. Participants were block randomized in a 1:1 ratio and stratified by the presence of a preoperative biliary stent. Participants, investigators, and statisticians analyzing trial data were unblinded to treatment assignment. Intervention: The intervention group received piperacillin-tazobactam (3.375 or 4 g intravenously) as perioperative antimicrobial prophylaxis, while the control group received cefoxitin (2 g intravenously; standard care). Main Outcomes and Measures: The primary outcome was development of postoperative SSI within 30 days. Secondary end points included 30-day mortality, development of clinically relevant postoperative pancreatic fistula, and sepsis. All data were collected as part of the American College of Surgeons National Surgical Quality Improvement Program. Results: The trial was terminated at an interim analysis on the basis of a predefined stopping rule. Of 778 participants (378 in the piperacillin-tazobactam group [median age, 66.8 y; 233 {61.6%} men] and 400 in the cefoxitin group [median age, 68.0 y; 223 {55.8%} men]), the percentage with SSI at 30 days was lower in the perioperative piperacillin-tazobactam vs cefoxitin group (19.8% vs 32.8%; absolute difference, -13.0% [95% CI, -19.1% to -6.9%]; P < .001). Participants treated with piperacillin-tazobactam, vs cefoxitin, had lower rates of postoperative sepsis (4.2% vs 7.5%; difference, -3.3% [95% CI, -6.6% to 0.0%]; P = .02) and clinically relevant postoperative pancreatic fistula (12.7% vs 19.0%; difference, -6.3% [95% CI, -11.4% to -1.2%]; P = .03). Mortality rates at 30 days were 1.3% (5/378) among participants treated with piperacillin-tazobactam and 2.5% (10/400) among those receiving cefoxitin (difference, -1.2% [95% CI, -3.1% to 0.7%]; P = .32). Conclusions and Relevance: In participants undergoing open pancreatoduodenectomy, use of piperacillin-tazobactam as perioperative prophylaxis reduced postoperative SSI, pancreatic fistula, and multiple downstream sequelae of SSI. The findings support the use of piperacillin-tazobactam as standard care for open pancreatoduodenectomy. Trial Registration: ClinicalTrials.gov Identifier: NCT03269994.

A radiomic biomarker for prognosis of resected colorectal cancer liver metastases generalizes across MRI contrast agents.

Introduction: Contrast-enhanced MRI is routinely performed as part of preoperative work-up for patients with Colorectal Cancer Liver Metastases (CRLM). Radiomic biomarkers depicting the characteristics of CRLMs in MRI have been associated with overall survival (OS) of patients, but the reproducibility and clinical applicability of these biomarkers are limited due to the variations in MRI protocols between hospitals. Methods: In this work, we propose a generalizable radiomic model for predicting OS of CRLM patients who received preoperative chemotherapy and delayed-phase contrast enhanced (DPCE) MRIs prior to hepatic resection. This retrospective two-center study included three DPCE MRI cohorts (n=221) collected between January 2006 and December 2012. A 10-minute delayed Gd-DO3A-butrol enhanced MRI discovery cohort was used to select features based on robustness across contrast agents, correlation with OS and pairwise Pearson correlation, and to train a logistic regression model that predicts 3-year OS. Results: The model was evaluated on a 10-minute delayed Gd-DO3A-butrol enhanced MRI validation cohort (n=121), a 20-minute delayed Gd-EOB-DTPA (n=72) cohort from the same institute, and a 5-minute delayed Gd-DTPA cohort (n=28) from an independent institute. Two features were selected: minor axis length and dependence variance. The radiomic signature model stratified high-risk and low-risk CRLM groups in the Gd-DO3Abutrol (HR = 6.29, p = .007), Gd-EOB-DTPA (HR = 3.54, p = .003) and Gd-DTPA (HR = 3.16, p = .04) validation cohorts. Discussion: While most existing MRI findings focus on a specific contrast agent, our study shows the potential of MRI features to be generalizable across main-stream contrast agents at delayed phase.

The evolving use of robotic surgery: a population-based analysis.

INTRODUCTION: Robotic surgery has integrated into the healthcare system despite limited evidence demonstrating its clinical benefit. Our objectives were (i) to describe secular trends and (ii) patient- and system-level determinants of the receipt of robotic as compared to open or laparoscopic surgery. METHODS: This population-based retrospective cohort study included adult patients who, between 2009 and 2018 in Ontario, Canada, underwent one of four commonly performed robotic procedures: radical prostatectomy, total hysterectomy, thoracic lobectomy, partial nephrectomy. Patients were categorized based on the surgical approach as robotic, open, or laparoscopic for each procedure. Multivariable regression models were used to estimate the temporal trend in robotic surgery use and associations of patient and system characteristics with the surgical approach. RESULTS: The cohort included 24,741 radical prostatectomy, 75,473 total hysterectomy, 18,252 thoracic lobectomy, and 4608 partial nephrectomy patients, of which 6.21% were robotic. After adjusting for patient and system characteristics, the rate of robotic surgery increased by 24% annually (RR 1.24, 95%CI 1.13-1.35): 13% (RR 1.13, 95%CI 1.11-1.16) for robotic radical prostatectomy, 9% (RR 1.09, 95%CI 1.05-1.13) for robotic total hysterectomy, 26% (RR 1.26, 95%CI 1.06-1.50) for thoracic lobectomy and 26% (RR 1.26, 95%CI 1.13-1.40) for partial nephrectomy. Lower comorbidity burden, earlier disease stage (among cancer cases), and early career surgeons with high case volume at a teaching hospital were consistently associated with the receipt of robotic surgery. CONCLUSION: The use of robotic surgery has increased. The study of the real-world clinical outcomes and associated costs is needed before further expanding use among additional providers and hospitals.

Regional Therapy for Colorectal Cancer Liver Metastases: Which Modality and When?

For patients with unresectable colorectal liver metastases (uCRLM), regional therapies leverage the unique, dual blood supply to the liver; the hepatic artery is the main blood supply for liver tumors, whereas the portal vein supplies most normal hepatic parenchyma. Infusion of cancer therapies via the hepatic artery allows selective delivery to the tumors with relative sparing of normal liver tissue and little extrahepatic exposure, thus limiting systemic side effects. There is a paucity of randomized controlled trial evidence to inform the optimal integration of regional therapies into the management of CRLM. Hepatic arterial infusion pump (HAIP) chemotherapy has a potential survival benefit when used in the adjuvant setting after resection of CRLM. HAIP chemotherapy can be safely given with contemporary systemic therapies and is associated with a high objective response and rate of conversion to resectability in patients with uCRLM. Drug-eluting beads coated with irinotecan transarterial chemoembolization is associated with high objective response rates within the liver and has a well-established safety profile in patients with uCRLM. Transarterial radioembolization achieves high rates of response within the liver but is not associated with improvements in overall survival or quality of life in the first- or second-line setting for uCRLM. The best treatment approach is the one that most aligns with a given patients' values, preferences, and philosophy of care. In the first-line setting, HAIP could be offered to motivated patients who hope to achieve conversion to resectability. After progression on chemotherapy, HAIP, transarterial chemoembolization, and transarterial radioembolization are valuable treatment options to consider for patients with liver-limited or liver-predominant CRLM who seek to optimize response rates and regional control.

Adverse events following robotic surgery: population-based analysis.

BACKGROUND: Robotic surgery was integrated into some healthcare systems despite there being few well designed, real-world studies on safety or benefit. This study compared the safety of robotic with laparoscopic, thoracoscopic, and open approaches in common robotic procedures. METHODS: This was a population-based, retrospective study of all adults who underwent prostatectomy, hysterectomy, pulmonary lobectomy, or partial nephrectomy in Ontario, Canada, between 2008 and 2018. The primary outcome was 90-day total adverse events using propensity score overlap weights, and secondary outcomes were minor or major morbidity/adverse events. RESULTS: Data on 24 741 prostatectomy, 75 473 hysterectomy, 18 252 pulmonary lobectomy, and 6608 partial nephrectomy operations were included. Relative risks for total adverse events in robotic compared with open surgery were 0.80 (95 per cent c.i. 0.74 to 0.87) for radical prostatectomy, 0.44 (0.37 to 0.52) for hysterectomy, 0.53 (0.44 to 0.65) for pulmonary lobectomy, and 0.72 (0.54 to 0.97) for partial nephrectomy. Relative risks for total adverse events in robotic surgery compared with a laparoscopic/thoracoscopic approach were 0.94 (0.77 to 1.15), 1.00 (0.82 to 1.23), 1.01 (0.84 to 1.21), and 1.23 (0.82 to 1.84) respectively. CONCLUSION: The robotic approach is associated with fewer adverse events than an open approach but similar to a laparoscopic/thoracoscopic approach. The benefit of the robotic approach is related to the minimally-invasive approach rather than the platform itself.

Fear of innovation: public's perception of robotic surgery.

BACKGROUND: Robotic surgery is used in several surgical procedures with limited evidence of clinical benefit. In some jurisdictions, the demand for robotic surgery may have been fueled by public perception of this novel technology. Therefore, we sought to investigate the public's perception of robotic surgery. STUDY DESIGN: We conducted a cross-sectional survey using a series of vignette-associated questions designed to examine the public's perception of robotic surgery. Eligible participants were recruited through Amazon Mechanical Turk's system and randomized to one of two pairs of vignettes: laparoscopic surgery compared to (1) robotic surgery, or (2) "novel surgical technology" (without using the term "robotic"). Outcomes of interest were anticipated postoperative outcomes using the surgical fear questionnaire, procedure preference, perception of error, trust, and competency of the surgeon. RESULTS: The survey included 362 respondents; 64.1% were male with median age of 53 years. There were no differences in the distribution of responses of the questionnaire based on use of the term "robotic" or "novel surgical technology"; therefore, the two cohorts were combined to examine perception of robotic compared to laparoscopic surgery. More respondents feared outcomes of robotic surgery than laparoscopic surgery (78.2% vs 14.9%, p < 0.001). Participants preferred laparoscopic to robotic surgery (64.4% vs 35.6%, p < 0.001). CONCLUSION: The public fears recovery after robotic surgery and prefers laparoscopic surgery. The propagation of robotic surgery is unlikely based on public demand and may be more related to institutional or surgeon perceptions. Surgeons who provide robotic surgery should ensure their patients are comfortable with and understand this technology.

PATCH-DP: a single-arm phase II trial of intra-operative application of HEMOPATCH™ to the pancreatic stump to prevent post-operative pancreatic fistula following distal pancreatectomy.

BACKGROUND: Post-operative pancreatic fistula (POPF) is the most significant cause of morbidity following distal pancreatectomy. Hemopatch™ is a thin, bovine collagen-based hemostatic sealant. We hypothesized that application of Hemopatch™ to the pancreatic stump following distal pancreatectomy would decrease the incidence of clinically-significant POPF. METHODS: We conducted a prospective, single-arm, multicentre phase II study of application of Hemopatch™ to the pancreatic stump following distal pancreatectomy. The primary outcome was clinically-significant POPF within 90 days of surgery. A sample size of 52 patients was required to demonstrate a 50% relative reduction in Grade B/C POPF from a baseline incidence of 20%, with a type I error of 0.2 and power of 0.75. Secondary outcomes included incidence of POPF (all grades), 90-day mortality, 90-day morbidity, re-interventions, and length of stay. RESULTS: Adequate fixation Hemopatch™ to the pancreatic stump was successful in all cases. The rate of grade B/C POPF was 25% (95%CI: 14.0-39.0%). There was no significant difference in the incidence of grade B/C POPF compared to the historical baseline (p = 0.46). The 90-day incidence of Clavien-Dindo grade ≥3 complications was 26.9% (95%CI: 15.6-41.0%). CONCLUSION: The use of Hemopatch™ was not associated with a decreased incidence of clinically-significant POPF compared to historical rates. (NCT03410914).

Systematic reviews of observational studies of Risk of Thrombosis and Bleeding in General and Gynecologic Surgery (ROTBIGGS): introduction and methodology.

BACKGROUND: Venous thromboembolism (VTE) and bleeding are serious and potentially fatal complications of surgical procedures. Pharmacological thromboprophylaxis decreases the risk of VTE but increases the risk of major post-operative bleeding. The decision to use pharmacologic prophylaxis therefore represents a trade-off that critically depends on the incidence of VTE and bleeding in the absence of prophylaxis. These baseline risks vary widely between procedures, but their magnitude is uncertain. Systematic reviews addressing baseline risks are scarce, needed, and require innovations in methodology. Indeed, systematic summaries of these baseline risk estimates exist neither in general nor gynecologic surgery. We will fill this knowledge gap by performing a series of systematic reviews and meta-analyses of the procedure-specific and patient risk factor stratified risk estimates in general and gynecologic surgeries. METHODS: We will perform comprehensive literature searches for observational studies in general and gynecologic surgery reporting symptomatic VTE or bleeding estimates. Pairs of methodologically trained reviewers will independently assess the studies for eligibility, evaluate the risk of bias by using an instrument developed for this review, and extract data. We will perform meta-analyses and modeling studies to adjust the reported risk estimates for the use of thromboprophylaxis and length of follow up. We will derive the estimates of risk from the median estimates of studies rated at the lowest risk of bias. The primary outcomes are the risk estimates of symptomatic VTE and major bleeding at 4 weeks post-operatively for each procedure stratified by patient risk factors. We will apply the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to rate evidence certainty. DISCUSSION: This series of systematic reviews, modeling studies, and meta-analyses will inform clinicians and patients regarding the trade-off between VTE prevention and bleeding in general and gynecologic surgeries. Our work advances the standards in systematic reviews of surgical complications, including assessment of risk of bias, criteria for arriving at the best estimates of risk (including modeling of the timing of events and dealing with suboptimal data reporting), dealing with subgroups at higher and lower risk of bias, and use of the GRADE approach. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42021234119.

Non-operative Management of Small Bowel Obstruction in Patients with No Previous Abdominal Surgery: A Systematic Review and Meta-analysis.

While the contemporary management of adhesive small bowel obstruction (SBO) often includes a trial of non-operative management (NOM), surgical dogma dictates urgent operative exploration in patients without previous abdominal surgery. This dogma has been challenged by recent evidence suggesting most obstructions in this population are adhesive in nature. The objectives of this review were to evaluate the feasibility of NOM in patients with SBO and no history of previous abdominal surgery, to examine the etiologies of SBO in this population, and to explore the rate of adverse events seen following NOM. Embase, Medline, Cochrane, and Google Scholar were searched from inception to September 24, 2019. Articles reporting on NOM for SBO in patients without previous abdominal surgery and without clinical or radiographic features necessitating an emergent operation were included. Data were combined to obtain a pooled proportion of patients discharged without operation following a trial of NOM. 6 studies reporting on a total of 272 patients were included. The pooled proportion of patients discharged following NOM was 49.5% (95% CI 23.7-75.3%). Adhesions were found to be the predominant cause of obstruction. NOM did not appear to increase short-term complications. Most SBOs in patients without previous abdominal surgery are adhesive in nature and many patients can be discharged from hospital without surgery. While the short-term outcomes of NOM are acceptable, future studies are needed to address the long-term outcomes and safety of NOM as a treatment strategy for SBO in patients without previous abdominal surgery.

When is a Ghost Really Gone? A Systematic Review and Meta-analysis of the Accuracy of Imaging Modalities to Predict Complete Pathological Response of Colorectal Cancer Liver Metastases After Chemotherapy.

BACKGROUND: Administration of chemotherapy to patients with colorectal liver metastases may result in disappearing liver metastases (DLM). This poses a therapeutic dilemma due to the uncertainty of true complete (pathological) response. OBJECTIVE: We aimed to examine the diagnostic performance of imaging modalities in detecting true complete response in patients with DLM after chemotherapy. METHODS: We performed a systematic search for articles assessing the diagnostic performance of imaging modalities in evaluating DLM following chemotherapy. True complete response was defined as 1-year recurrence-free survival in non-resected patients or complete pathological response on histologic examination in resected patients. We calculated the negative predictive value (NPV) for detecting true complete response of each imaging modality using a random effects model. RESULTS: Thirteen studies comprising 332 patients with at least one DLM were included. The number of DLMs after chemotherapy was 955 with computed tomography (CT), 104 with positron emission tomography (PET), 50 with intraoperative ultrasound (IOUS), 585 with magnetic resonance imaging (MRI), and 175 with contrast-enhanced IOUS (CEIOUS). Substantial variation in study design, patient characteristics, and imaging features was observed. Pooled NPV was 0.79 (95% confidence interval [CI] 0.53-0.96), 0.73 (95% CI 0.58-0.85), 0.54 (95% CI 0.37-0.7), 0.47 (95% CI 0.34-0.61), and 0.22 (95% CI 0.11-0.39) for CEIOUS, MRI, IOUS, CT, and PET, respectively. CONCLUSION: After chemotherapy, MRI or CEIOUS are the most accurate imaging modalities for assessment of DLM and should be used routinely in this context. Given the high NPV of these two modalities, surgical resection of visible CRLM is warranted if technically possible, even if DLM remain.

Clinical Trials of Systemic Chemotherapy for Resectable Pancreatic Cancer: A Review.

Importance: Adjuvant chemotherapy is the standard of care for resected pancreatic ductal adenocarcinoma (PDAC) based on level 1 evidence, but some studies suggest that a neoadjuvant approach (which is standard for borderline resectable PDAC) may be preferable for upfront resectable PDAC. An in-depth review was conducted of all randomized clinical trials that investigated neoadjuvant and adjuvant treatment of patients with resectable or resected PDAC, focusing on trial design, characteristics of enrolled population, and long-term outcomes. Observations: The existing resectable PDAC trials have good internal validity but variable applicability because of their restrictive eligibility criteria. In these trials, overall survival is the criterion standard end point, but disease-free survival is more feasible, proximate, and specific to the assigned intervention (at the cost of subjective outcome assessment) and thus an acceptable end point in certain contexts. The prolonged survival in the PRODIGE 24 trial highlights both the success of mFOLFIRINOX (modified fluorouracil, leucovorin, irinotecan, and oxaliplatin) and the importance of patient selection. Neoadjuvant and perioperative trials have shown promising preliminary results; however, the number of patients who are not subsequently eligible for surgery reflects the limitations of this approach. Head-to-head comparisons of neoadjuvant and adjuvant treatments are limited to date in Western countries. Precision oncology with genomic and somatic testing for actionable mutations has promising preliminary results and may refine the management of PDAC, although the implications for early-stage disease and neoadjuvant therapy are unknown. Conclusions and Relevance: This review found that adjuvant chemotherapy with mFOLFIRINOX is currently the standard of care in fit patients with resected PDAC; however, the role of neoadjuvant treatment is expanding. Precision oncology may help individualize the treatment regimen and sequence and improve outcomes. Enrollment of patients with resectable PDAC in clinical trials is strongly encouraged.