| Grade I | Any deviation from the normal postoperative course without the need for pharmacological treatment or surgical, endoscopic and radiological intervention. Acceptable therapeutic regimens are drugs such as antiemetics, analgesia, diuretics and electrolytes and physiotherapy. This grade also includes wound infections opened at the bedside. |
| Grade II | Requiring pharmacological treatment with drugs other than those allowed for grade I complications. Blood transfusions and total parenteral nutrition are also included. |
| Grade III | Requiring surgical, endoscopic or radiological intervention. |
| Grade III-a | Intervention NOT under general anaesthesia |
| Grade III-b | Intervention under general anaesthesia |
| Grade IV | Life-threatening complication requiring HDU/ICU management |
| Grade IV-a | Single organ dysfunction (including dialysis) |
| Grade IV-b | Multi-organ dysfunction |
| Grade V | Death |
