Preoperative Fish Oil PN and Prognosis After Constipation Surgery

This is a prospective, multicenter, real-world observational study to evaluate the impact of perioperative parenteral nutrition (PN) with fish oil-containing lipid emulsion on outcomes in adult patients with constipation undergoing elective colon surgery. The study will compare two clinical nutrition strategies: (1) PN with fish oil-containing lipid emulsion started before surgery and continued after surgery, and (2) PN with fish oil-containing lipid emulsion started only after surgery. Eligible participants are adults (18-75 years) with slow-transit constipation (STC) or megacolon who are scheduled for elective colon surgery and have nutritional risk (NRS2002 score \>=3). The primary objective is to compare the incidence of postoperative complications between these two PN timing strategies. Secondary objectives include comparison of perioperative nutritional status, postoperative inflammatory status, prognosis, and safety outcomes. This study will collect and analyze clinical data, laboratory indicators, perioperative recovery outcomes, follow-up assessments, and safety information in routine clinical practice. Outcomes include postoperative complication rates, changes in nutritional and inflammatory markers, bowel function recovery, length of hospital stay, constipation-related symptoms, quality of life, and adverse events. No experimental intervention will be assigned as part of this observational study. The planned sample size is 306 participants. The findings may help optimize perioperative nutritional support strategies for patients with constipation undergoing surgery.