Background and Aims:Infected necrotizing pancreatitis(INP),particularly with diffuse distribution,is a life-threatening condition.The optimal initial intervention-minimally invasive step-up therapy vs.direct open necrosectomy-remains controversial.Moreover,the impact of necrosis morphology("wet"or"dry")and the presence of severe acute pancreatitis(SAP)on treatment selection has not been fully clarified.This study aimed to compare the efficacy and safety of these two approaches in diffuse INP and to evaluate the guiding value of CT-based necrosis type and SAP status in clinical decision-making.Methods:A retrospective analysis was conducted on 458 patients with diffuse INP admitted to the Third Xiangya Hospital of Central South University from January 2012 to March 2023.Patients were divided into a minimally invasive step-up group(n=256)and a direct open surgery group(n=202).SAP was defined according to the determinant-based classification,and necrosis was categorized as"wet"or"dry"based on CT features.The primary endpoint was a composite of death or major complications,while secondary endpoints included mortality,length of hospital stay,and incision-related complications,were compared between the two groups,with subgroup analyses performed accordingly.Results:Overall,the open surgery group had higher rates of the primary endpoint(62.4%vs.48.1%,P=0.003)and mortality(27.2%vs.16.8%,P=0.008)compared with the step-up group.Among SAP patients,the step-up approach resulted in a significantly lower primary endpoint rate(66.7%vs.97.7%,P=0.003).In non-SAP patients,the primary endpoint rates were similar,but open surgery was associated with a shorter hospital stay[(36.5±10.4)d vs.(45.6±18.6)d,P<0.001]and higher incidences of wound infection and incisional hernia(both P<0.001).Multivariate analysis identified infection onset time,effusion characteristics,gas bubbles,and necrosis location as independent predictors of prolonged hospitalization in the step-up group(all P<0.05).Patients with"wet"necrosis benefited more from the step-up approach,whereas those with"dry"necrosis experienced shorter hospitalization following open surgery.Conclusion:For diffusely distributed INP,treatment strategies should be individualized based on SAP status and necrosis liquefaction/imaging characteristics.The step-up minimally invasive approach is preferred for SAP patients and those with"wet"necrosis on CT,while direct open necrosectomy may be advantageous for"dry"necrosis(particularly with limited liquefaction)by shortening hospital stay and reducing certain major outcomes,though at the cost of increased incision infection and incision herina.CT imaging features and SAP classification can serve as valuable tools for risk stratification and guiding individualized timing and modality of intervention.

Background and Aims:Infected necrotizing pancreatitis(INP),particularly with diffuse distribution,is a life-threatening condition.The optimal initial intervention-minimally invasive step-up therapy vs.direct open necrosectomy-remains controversial.Moreover,the impact of necrosis morphology("wet"or"dry")and the presence of severe acute pancreatitis(SAP)on treatment selection has not been fully clarified.This study aimed to compare the efficacy and safety of these two approaches in diffuse INP and to evaluate the guiding value of CT-based necrosis type and SAP status in clinical decision-making.Methods:A retrospective analysis was conducted on 458 patients with diffuse INP admitted to the Third Xiangya Hospital of Central South University from January 2012 to March 2023.Patients were divided into a minimally invasive step-up group(n=256)and a direct open surgery group(n=202).SAP was defined according to the determinant-based classification,and necrosis was categorized as"wet"or"dry"based on CT features.The primary endpoint was a composite of death or major complications,while secondary endpoints included mortality,length of hospital stay,and incision-related complications,were compared between the two groups,with subgroup analyses performed accordingly.Results:Overall,the open surgery group had higher rates of the primary endpoint(62.4%vs.48.1%,P=0.003)and mortality(27.2%vs.16.8%,P=0.008)compared with the step-up group.Among SAP patients,the step-up approach resulted in a significantly lower primary endpoint rate(66.7%vs.97.7%,P=0.003).In non-SAP patients,the primary endpoint rates were similar,but open surgery was associated with a shorter hospital stay[(36.5±10.4)d vs.(45.6±18.6)d,P<0.001]and higher incidences of wound infection and incisional hernia(both P<0.001).Multivariate analysis identified infection onset time,effusion characteristics,gas bubbles,and necrosis location as independent predictors of prolonged hospitalization in the step-up group(all P<0.05).Patients with"wet"necrosis benefited more from the step-up approach,whereas those with"dry"necrosis experienced shorter hospitalization following open surgery.Conclusion:For diffusely distributed INP,treatment strategies should be individualized based on SAP status and necrosis liquefaction/imaging characteristics.The step-up minimally invasive approach is preferred for SAP patients and those with"wet"necrosis on CT,while direct open necrosectomy may be advantageous for"dry"necrosis(particularly with limited liquefaction)by shortening hospital stay and reducing certain major outcomes,though at the cost of increased incision infection and incision herina.CT imaging features and SAP classification can serve as valuable tools for risk stratification and guiding individualized timing and modality of intervention.