Misdiagnosis with breast ultrasound? is it possible to have differing results from an ultrasound and a mammogram? in my case, the mammogram didn't show anything but an ultrasound did. which method is usually more reliable and how does this happen?

Yes, : Yes, results from an ultrasound can differ from the findings on a mammogram. Each imaging modality has its own strengths and weaknesses. The resolution of mammography is far superior to that of ultrasound. Mammography can detect tiny microcalcifications that could never be detected on ultrasound. Ultrasound is excellent at detecting cysts and can be used to evaluate blood flow in the area of interest. Many lesions often appear very subtle on a particular imaging study, but can be much more obvious on a different imaging modality. For this reason, it is extremely important for the radiologist to compare the images obtained in both studies. Ultrasound and mammography are complementary studies that should be used together to arive at the most likely diagnosis. The most reliable result is the one obtained after completing all imaging studies and analyzing the findings together in order to achieve the most likely diagnosis.

The mammogram: A mammogram gives a lot more detail than an ultrasound. If a lump is detected, further studies are needed. If the mammogram is negative, waiting a few months or doing an MRI are some ways to go.

They are: complementary tests, imaging different tissue characteristics. It is not unusual for an abnormality to be seen on one and not the other. If you have dense breasts, it is especially true that an ultrasound abnormality may be invisible on mammo due to the density. Not seeing it on both does not negate a finding on one.