# Intraoperative complexity markers are associated with morbidity but not mortality in emergency abdominal surgery: a two-year cohort study

## TL;DR

This study shows that intraoperative complexity during emergency abdominal surgery is linked to more complications and longer hospital stays, but not higher death rates.

## Contribution

The study introduces objective intraoperative complexity markers and their association with postoperative outcomes in emergency abdominal surgery.

## Key findings

- 32% of patients had at least one intraoperative complexity marker.
- Bleeding ≥750 mL and prolonged operative time were strongly linked to extended hospitalization.
- Iatrogenic injuries correlated with longer hospital stays and increased reoperations.

## Abstract

Patients undergoing major emergency abdominal surgery are often elderly with multiple comorbidities and previous abdominal operations, contributing to procedural complexity. Factors such as adhesions increase technical challenges, potentially influencing postoperative recovery. This study examined how objectively defined intraoperative complexity markers are associated with postoperative morbidity and mortality in this high-risk cohort.

In a prospective cohort of 754 consecutive patients undergoing major emergency abdominal procedures, we investigated three indicators of intraoperative complexity: iatrogenic injury, blood loss ≥ 750 mL, and operative duration ≥ 2.5 h. A composite variable incorporating all three was also created to reflect overall complexity. We analyzed associations with postoperative outcomes, including complication severity, length of stay (LOS), reoperations, and mortality.

At least one complexity marker was observed in 32% of patients. Bleeding ≥ 750 mL and prolonged operative time each independently increased the likelihood of extended hospitalization by 23.0 and 22.1% points, respectively. Iatrogenic injuries were identified in 14% and correlated with longer LOS and increased reoperations. Although complexity markers were consistently linked to higher morbidity, including elevated Comprehensive Complication Index scores, reoperations, and prolonged LOS. No significant association with mortality was observed.

Intraoperative complexity is frequent in major emergency abdominal surgery and is closely associated with postoperative morbidity and healthcare utilization. Bleeding exceeding 750 mL and operative time over 2.5 were the strongest associations with postoperative morbidity. These findings provide a pragmatic framework for quantifying surgical complexity and may inform future work on preoperative risk stratification and resource planning. The observed dissociation between morbidity and mortality may reflect improved perioperative care and patient selection, but should be interpreted cautiously given the limited number of deaths.

The online version contains supplementary material available at 10.1007/s00423-025-03941-z.