The KUB X-ray stands for a detailed X-ray of the three vital organs of human body - Kidney, Ureter and Bladder. The X- ray enables the doctor to examine these three organs of your urinary and gastrointestinal systems. This test depicts the relative size, formation and position of these organs, and detects the abnormalities or complications in the system, if any. KUB X-ray is generally recommended when a doctor is unable to diagnose the cause of a reported abdominal pain.