Assessing the risk of venous thromboembolism (VTE) and preventing it in patients admitted to hospital is an important way to improve safety, prevent morbidity and mortality, and save money.1 The linked prospective cohort study by Sweetland and colleagues (doi:10.1136/bmj.b4583) is a wake-up call to all surgeons.2 It investigated a group of middle aged women at relatively low risk of VTE, without a history of VTE or cancer who had a single operation as an inpatient or day case.2 3 The types of surgery included minor operations and biopsies, and more than 60% of patients had day surgery. All types of surgery were associated with significantly increased risks of VTE—event rates increased from 0.06 per 1000 person months in those not undergoing surgery to 2.6 per 1000 person months during the first 12 weeks after inpatient surgery, and in most cases the risk remained for 12 months.

The risk was greatest in the first six weeks after surgery, peaking in the third week. Risk continued to be strong between seven and 12 weeks and …