Post-thyroidectomy cervical haematoma (PTCH) requiring reoperation occurs in fewer than 5% of patients but can be fatal or leave severe neurological sequelae if compressive. Risk factors besides anticoagulant treatments are discussed. Preoperative prevention complies with the recommendations of the French Society of Anaesthesia and Resuscitation (SFAR) for the management of antiaggregants and anticoagulants before and after the operation. Intraoperative prevention is centred on careful haemostasis, sometimes aided by coagulation tools and haemostatic agents, although there is no firm evidence of their effectiveness against the occurrence of PTCH. Systematic drainage of the thyroid cavity is no longer standard practice for the prevention of PTCH. Postoperatively, maintenance of normal blood pressure is essential to prevent PTCH, together with control of pain, coughing, nausea and vomiting. To reduce the risk of serious complications, medical and paramedical teams must be trained to recognise a haematoma and manage it so that it can be evacuated as a matter of extreme urgency, if necessary bedside, and then treated for its cause in the operating theatre.