When there is post-operative swelling after breast surgery or core needle biopsy, a breast ultrasound examination may be indicated in order to differentiate between a hematoma and other possible post-surgical complications such as abscess or seroma,[4] A recent hematoma is usually visible in a mammogram.[1] and it also shows typical signal intensities on MR imaging.[5] If a differentiation from breast cancer is necessary, a hematoma biopsy may be indicated.