Modified Clavien-Dindo classification for postoperative complications
| Grades | Definition |
| Grade 1 | Any deviation from the normal postoperative course without the need for pharmacological treatment or surgical, endoscopic and radiological interventions |
| Allowed therapeutic regimens: drugs as antiemetics, antipyretics, analgetics, diuretics and electrolytes and physiotherapy. This grade also includes wound infections opened at the bedside. | |
| Grade 2 | Requiring pharmacological treatment with drugs other than such allowed for grade 1 complications |
| Blood transfusions and total parenteral nutrition were also included. | |
| Grade 3 | Requiring surgical, endoscopic or radiological intervention not under general anaesthesia |
| Grade 4 | Intervention under general anaesthesia |
| Grade 5 | Life-threatening complication (including CNS complications)* requiring IC/ICU management, single-organ dysfunction (including dialysis) |
| Grade 6 | Life-threatening complication (including CNS complications)* requiring IC/ICU management, multiorgan dysfunction |
| Grade 7 | Death of a patient |
| Grade 8 | Complication at discharge, category cannot be defined (ie, recurrent nerve paralysis after thyroid surgery) |
| Grade 9 | Other (ie, wrong medication, postponement/cancellation of surgery) |
CNS, central nervous system; IC, intensive care; ICU, intensive care unit.