76970 vs 76645

2010 Medlearn "Ultrasound Coder" book: "76645: This code is reported for the evaluation of cystic or solid lesions within the breast(s). Breast ultrasonography may be performed as a stand-alone procedure as well as an adjunct to mammography to determine if the suspected lesion is cystic or solid." Also, "76970: this code is reported when there is no other specific code to describe a follow-up examination."

We are also in discussion about cysts vs seroma vs abscess? How does one define a seroma; as a cyst or abscess? Would it be more/less descriptive to use 76645 as a stand-alone procedure, with appropriate dx describing 998.13 Seroma complicating a procedure or 998.51 Infected postoperative seroma? Would it be more/less descriptive to use 76970 due to after a procedure with post-complication, regardless of anatomy location?

Google leads me to believe cysts are fluid filled sacs, a seroma is post-op fluid sac in wound, and abscess is inflamed puss filled pockets. I am curious as to another's responce/research on this topic.

Thank you,
Nicole S., CPC