Major abdominal surgeries, such as gastrointestinal resections, hepatectomies, and colorectal operations, are associated with significant morbidity and mortality despite advances in surgical and anesthetic care. Identifying reliable, inexpensive, and easily measurable predictors of adverse outcomes is essential to improve perioperative risk assessment and patient management.

The neutrophil-to-lymphocyte ratio (NLR), derived from a routine complete blood count (CBC), reflects the balance between inflammation and immune response. Elevated NLR has been linked to poor outcomes in various medical and surgical conditions, including sepsis, cancer, and cardiovascular diseases. However, its prognostic role in major abdominal surgeries remains underexplored.

This study aims to evaluate whether preoperative and postoperative NLR can serve as a cost-effective and reliable predictor of in-hospital and 30-day mortality following major abdominal surgery. If proven effective, NLR could be integrated into preoperative assessments, aiding early identification of high-risk patients and optimizing postoperative care strategies.

This is a prospective observational study. Eligible patients will be recruited preoperatively after obtaining written informed consent. Routine preoperative and postoperative (day 1) blood samples will be analyzed for neutrophil and lymphocyte counts to calculate NLR. No additional invasive procedures will be performed. Clinical, surgical, and outcome data—including type and duration of surgery, intraoperative events, postoperative complications, ICU stay, and mortality—will be collected using a structured data collection form.The primary outcome is in-hospital mortality. Secondary outcomes include 30-day mortality, postoperative complications, ICU admission, and length of hospital stay.