Intramuscular Hematoma on the Psoas Muscle.

Intramuscular hematomas on the psoas muscle are rare and usually occur as a result of trauma, iatrogenic etiology during lumbar surgery, rupture of the aortic aneurysm, and hematologic diseases. The incidence of spontaneous psoas muscle hematomas has slowly increased as a result of using anticoagulation and antiplatelet agents. Magnetic resonance (MR) imaging is a more sensitive option compared to computed tomography (CT) when diagnosing a hematoma. Coronal T2-weighted images are more useful. CT imaging is also useful to establish the rapid diagnosis of hematoma. When a prolonged prothrombin time and international normalized ratio and decrease platelet count are noted, psoas muscle hematomas should be considered, if there was no lesion in the spinal canal. Most hematomas resolve spontaneously without clinical complications if the hematoma is not large or it is not compressing the surrounding important structures, irrespective of cause.