What is the difference between a screening mammogram, a diagnostic mammogram, and an ultrasound?

Different views.: A screening mammogram, typically, takes an x-ray of the breast from two views (a-p: anterior-posterior/front to back and cc (cranio-caudal: from top to bottom). Diagnostic mammograms use multiple views. Ultrasound, of course, uses a whole different technology (sound waves) focusing on the detection of solid and/or well defined structures (e.g. Cysts, etc..).

Radiologist presence: A routine mammogram is done and reviewed later by a radiologist. A diagnostic mammogram is indicated when there is a problem and is read immediately by a radiologist to determine if further work up is indicated. Ultrasound is another modality which does not replace mammogram but helps us determine if there is a mass in the breasts and if it is cystic or solid suspicious or benign ( not cancer).

A screening: mammogram is a study of both breasts that is performed on asymptomatic women to try and detect signs of breast cancer. A diagnostic mammogram consists of special views, and is usually targeted to a specific area of the breast, to further evaluate a potential abnormality seen on screening mammo or felt on clinical exam.