Will an ultra sound miss breast cander?

US can miss CA: Ultrasound (us) is good at looking at breast masses and determining if they're cysts or solid. Generally, cysts are nothing to worry about, while solid masses may be of concern. Us can frequently tell whether a solid mass is suspicious for cancer. Since many breast cancers show only calcifications without a mass, and us doesn't see calcifications well, us cannot detect all breast cancer.

As a: screening test, ultrasound is probably about 70% sensitive for detecting cancer, so the answer is yes it can miss cancers. No test is 100% accurate.