A Category 0 mammogram means that the assessment is not complete and additional imaging is required. By itself, a Category 0 result means that the radiologist may not have been able to see an abnormality completely, or that the abnormality was not completely defined. Additional imaging, including the use of spot compression, magnification, ultrasound, and special mammographic views may be used to help make a more complete evaluation.
A Category 0/Level 4 classification of a mammogram result tends to be more urgent, because it means the radiologist thinks there may be an abnormality, but was not able to see the abnormality completely. A second mammogram appointment needs to be scheduled as soon as possible.