KUB refers to a diagnostic medical imaging technique of the abdomen, and stands for Kidneys and Urinary Bladder, although in fact the ureters only show if they are abnormally distended. A KUB ultrasound is examination, which is requested by your doctor to evaluate the urinary tract that includes the kidneys, ureters, and urinary bladder. In the male patient, the prostate gland is also scanned.