Postoperative abdominal wall hematomas have a distinctive appearance on ultrasonography.

In six patients a large abdominal wall hematoma developed 1 1/2 to 6 months after operation. In each case differentiation of incisional hernia from hematoma was difficult, but the distinctive appearance on ultrasonography of an ovoid mass with thick straight internal septae, characteristic of hematoma, was noted in all. Ultrasonography also showed the multilocular nature of the lesion which made percutaneous aspiration difficult.