Abstract: Background: The fasting time after gastrointestinal bleeding has always been a controversial area. It is rarely to be reported for children with gastrointestinal bleeding about fasting time and diet management at home and abroad. Objective: To explore whether children with massive gastrointestinal bleeding need early strict fasting and preliminarily explore the reasonable choice of food when starting feeding. Design: Retrospective cohort study. Methods: The clinical data of children with massive gastrointestinal bleeding hospitalized in West China Second Hospital of Sichuan University from October 2011 to October 2021 were collected. Patients were divided into four groups according to fasting time: less than 24 hours group, 24 to 48 hours group, 48 to 72 hours group and greater than 72 hours group. Meanwhile, patients were divided into three groups according to different diet when starting feeding: carbohydrate diet group, protein diet group and mixed diet group. The research analysed the different variables in demographic characteristics, clinical features, laboratory examinations and clinical outcomes in fasting time group and different diet group, respectively. The variables with statistically significant differences among groups were analyzed by multivariate regression analysis. Main outcome measures: Rebleeding and hospital stay. Results: A total of 266 patients with massive gastrointestinal hemorrhage were selected into this study, including 175 males（65.8%）and 91 females（34.2%）with the median age of 6.0(2.4, 10.9) years. As less than 24 hours group as the reference, the multivariate logistic regression analysis showed that fasting time was disassociated with rebleeding and nosocomial infection and there was no statistically significant difference(P>0.05). Multiple linear regression analysis showed that patients with fasting time greater than 72 hours had prolonged length of hospital stay(lnLOS) (0.192, 95%CI: 0.047 to 0.337, P=0.010). As carbohydrate diet group as the reference, multivariate logistic regression analysis showed that the type of diet was disassociated with rebleeding and adverse reactions after feeding and there was no statistically significant difference(P>0.05). Multiple linear regression analysis revealed that there were no statistically significant differences in lnLOS between carbohydrate diet group and protein diet group(P>0.05), while hospital stays of mixed diet group was shorter than other two groups (-0.176, 95%CI: -0.318 to -0.034, P=0.015). Conclusion: Fasting time for less than 24 hours in children with massive gastrointestinal bleeding will not increase the risk of adverse outcomes such as rebleeding and nosocomial infection, and early feeding within 24 hours tend to have shorter hospital stays. When patients began to take food after massive gastrointestinal bleeding, carbohydrate + protein mixed food which can be used as the initial diet choice, was more conducive to shorten the hospital stay and may not increase the rebleeding rate and the incidence of the adverse reaction after feeding.

Key words: Gastrointestinal hemorrhage, Children, Fasting time, Diet, Rebleeding, Nosocomial infection