Thromboprophylaxis with low molecular weight heparin is efficient, effective and generates savings in health costs in hospitals. However, outside hospitals, there are situations of apparent risk of thrombosis, where there seems to be no such consensus. This occurs in traumatic lower limb injuries which are not undergoing surgery and need a period of immobilization. These are processes with multidisciplinary interventions (Emergency, Family Physicians and Traumatology), although during outpatient follow up it is not easy to find criteria for using thromboprophylaxis. We report a case of a pulmonary embolism, with unusual symptoms, in an ambulatory patient with a fractured fibula and metatarsal, who was being treated with Bemiparin. As we shall see, this is a rare complication, but it shows the importance of proper risk assessment of thromboembolic disease in these patients. We emphasize the accompanying tomographic images for their clarity and eloquence.