Gray scale features of hematomas: an ultrasonic spectrum.

Forty-eight B-scan ultrasound examinations were performed on 25 patients with hematomas. Hematomas are usually spherical or ovoid within the abdomen, and lentiform within the pleural space or abdominal wall. They generally decrease in size with time, and usually have irregular walls. Hematomas contain a variable amount of internal echoes during the first month, and then gradually become anechoic. The sonographic appearance is not specific; an abscess may have a similar appearance. An old, anechoic hematoma may contain a gelatinous material which cannot be aspirated.