hematoma /hē′mətō″mə, hem′-/ pl. hematomas, hematomata [Gk, haima + oma, tumor] , a collection of extravasated blood trapped in the tissues of the skin or in an organ, resulting from trauma or incomplete hemostasis after surgery. Initially there is frank bleeding into the space; if the space is limited, pressure slows and eventually stops the flow of blood. The blood clots, serum collects, the clot hardens, and the mass becomes palpable to the examiner and is often painful to the patient. A hematoma may be drained early in the process and bleeding arrested with pressure or, if necessary, with surgical ligation of the bleeding vessel. Considerable blood may be lost, and infection is a serious complication. Also spelled haematoma.
