A hematoma (US spelling) or haematoma (UK spelling) is a localized collection of blood outside the blood vessels , due to either disease or trauma including injury or surgery  and may involve blood continuing to seep from broken capillaries . A hematoma is initially in liquid form spread among the tissues including in sacs between tissues where it may coagulate and solidify before blood is reabsorbed into blood vessels. An ecchymosis is a hematoma of the skin larger than 10mm. 
Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.