Grade Definition Examples
Grade 0 No deviation from the ideal intraoperative course  
Grade I

Any deviation from the ideal intraoperative course:

Without the need for any additional treatment or intervention

Patient with no or mild symptoms

Bleeding: bleeding above average from small-caliber vessel: self-limiting or definitively manageable without additional treatment than routine coagulation
 
Injury: minimal serosal intestinal lesion, not requiring any additional treatment
 
Cautery: small burn of the skin, no treatment necessary
 
Arrhythmia: arrhythmia (eg, extrasystoles) without relevance
Grade II

Any deviation from the ideal intraoperative course:With the need for any additional minor treatment or intervention

Patient with moderate symptoms, not life-threatening and not leading to permanent disability

Bleeding: bleeding from medium-caliber artery or vein, ligation; use of tranexamic acid
 
Injury: nontransmural intestinal lesion requiring suture(s)
 
Cautery: moderate burn requiring noninvasive wound care
 
Arrhythmia: arrhythmia requiring administration of antiarrhythmic drug, no hemodynamic effect
Grade III

Any deviation from the ideal intraoperative course:

With the need for any additional moderate treatment or intervention

Patient with severe symptoms, potentially life-threatening or potentially leading to permanent disability

Bleeding: bleeding from large-caliber artery or vein with transient hemodynamic instability, ligation, or suture; blood transfusion
 
Injury: transmural intestinal lesion requiring segmental resection
 
Cautery: severe burn requiring surgical debridement
 
Arrhythmia: arrhythmia requiring administration of antiarrhythmic drug, transient hemodynamic effect
Grade IV

Any deviation from the ideal intraoperative course:

With the need for any additional major and urgent treatment or intervention

Patient with life-threatening symptoms or leading to permanent disability

Bleeding: life-threatening bleeding with splenectomy; massive blood transfusion; ICU stay
 
Injury: injury of central artery or vein requiring extended intestinal resection
 
Cautery: life-threatening burn injury by cautery leading to fire requiring ICU treatment
 
Arrhythmia: arrhythmia requiring electroconversion, defibrillation, or admission to the ICU
Grade V Any deviation from the ideal intraoperative course with intraoperative death of the patient  

The classification defines iAEs as any deviation from the ideal intraoperative course occurring between skin incision and skin closure. Any event related to surgery and anesthesia during the index surgery must be considered and should be rated directly after surgery.

Adopted fromDell-Kuster et al. Prospective validation of classification of intraoperative adverse events (ClassIntra): international, multicentre cohort study. BMJ. 2020 Aug 25; doi: 10.1136/bmj.m2917. PMID: 32843333