Preoperative nutritional status as a predictor of postoperative morbidity in pediatric gastrointestinal surgery: a systematic review and meta-analysis.

BACKGROUND: Malnutrition is common among children undergoing gastrointestinal surgery and is frequently compounded by underlying gastrointestinal pathology, chronic inflammation, and impaired nutrient intake. Although preoperative nutritional status has been suggested as an important determinant of postoperative outcomes in pediatric surgical patients, the magnitude and consistency of its association with postoperative morbidity in pediatric gastrointestinal surgery remain incompletely defined. OBJECTIVE: To systematically evaluate and quantitatively synthesize the association between preoperative nutritional status and postoperative morbidity in pediatric patients undergoing gastrointestinal surgery. METHODS: A systematic review and meta-analysis was conducted in accordance with PRISMA 2020 guidelines. PubMed MEDLINE, Embase, Scopus, and Web of Science were searched for English-language studies published between January 2017 and December 2026. Eligible studies included pediatric patients younger than 18 years undergoing gastrointestinal surgery with documented preoperative nutritional assessment and reported postoperative morbidity outcomes. Risk of bias was assessed using the ROBINS-I tool. Random-effects meta-analysis was performed to calculate pooled odds ratios with 95% confidence intervals. Statistical heterogeneity was evaluated using the I2 statistic. RESULTS: Twenty-four studies met inclusion criteria for qualitative synthesis, and four observational cohort studies comprising pediatric gastrointestinal surgical patients provided sufficient data for quantitative meta-analysis. Preoperative malnutrition was defined using standardized anthropometric indices and or serum albumin thresholds. Meta-analysis demonstrated a strong association between preoperative malnutrition and overall postoperative morbidity, with a pooled odds ratio of 4.73 (95% CI 2.98-7.52). Between-study heterogeneity was low (I2 = 0%), indicating consistent effects across studies. Malnourished children experienced higher rates of infectious complications, anastomotic complications, prolonged hospital stay, and postoperative mortality compared with well-nourished peers. CONCLUSIONS: Preoperative malnutrition is strongly and consistently associated with increased postoperative morbidity in pediatric patients undergoing gastrointestinal surgery. These findings highlight preoperative nutritional status as a key and potentially modifiable risk factor and support the integration of routine nutritional screening and optimization into perioperative care for pediatric gastrointestinal surgical patients.