This is a prospective two-center observational cohort study in adult patients undergoing major abdominal and/or pelvic oncologic surgery with pre-existing malnutrition. The study describes the course of postoperative gastrointestinal dysfunction and evaluates whether real-world exposure to parenteral serotonin as part of routine postoperative care is associated with a higher proportion of patients whose gastrointestinal dysfunction regresses to LIFE score less than or equal to 1 by postoperative day 5 (plus or minus 1 day), compared with patients not exposed to serotonin.
All treatment decisions, including the use of parenteral serotonin, metoclopramide, neostigmine, nutritional support, and other postoperative management, are made solely by the treating physicians in accordance with routine clinical practice. The protocol does not assign, randomize, require, or restrict any drug treatment; it records real-world care, daily LIFE assessments during postoperative days 1 through 7, nutritional status measures, body composition where available, delirium screening, complications, length of stay, and mortality.
Age ≥ 18 years.
Histologically confirmed malignant tumor of the abdomen or pelvis with planned radical or cytoreductive surgery.
Baseline malnutrition defined as NRS2002 ≥ 3 and at least one phenotypic and one etiologic GLIM criterion.
Expected postoperative hospitalization ≥ 7 days.
Severe decompensated hepatic or renal failure rendering surgery infeasible.
Documented preexisting severe cognitive impairment or dementia precluding valid postoperative cognitive/delirium assessment (e.g., MoCA < 18 or documented dementia).
Pregnancy or breastfeeding.
Participation in another interventional randomized clinical trial within the prior 30 days that could confound outcomes.