Radiographs of kidneys, ureter and bladder (KUB) have long been used in the follow-up of patients with ureteral stones to reassess stone position and surgical planning. Emergence of computed tomography (CT) as the gold standard for the diagnosis of ureteral stones has meant there is no baseline KUB radiograph to compare with on follow-up. The objective of this retrospective study was to establish whether the ability of urologists to determine a stone’s status on a follow-up outpatient KUB is improved by the presence of a baseline KUB (in addition to the CT) or whether the CT scout is sufficient. Theoretically, if the baseline KUB improves diagnostic accuracy, further imaging, e.g. ultrasound (US) or repeated CT could be avoided. Three experienced urologists independently assessed the imaging of two groups of patients: ‘KUB and CT (with scout)’ and ‘CT only (with scout)’ to answer Yes or No to the question of stone passage or migration. Of 154 stones assessed (74 in the KUB and CT group and 80 in CT group) KUB had greater sensitivity for stone detection than CT scout (60.4% vs. 43.5% respectively). Definitive assessment rates were higher in the baseline KUB and CT group. Additionally when the reviewers were asked to reassess stone outcome in the CT group, using their baseline KUB (originally blinded from the reviewers), the reviewers were able to do so definitively in an additional 16 cases. A baseline radiograph is helpful in interpreting subsequent radiographs, because it demonstrates the stone’s degree of radio-opacity, establishes bony anatomy, and demonstrates the pattern of calcified structures that can mimic stones. However, with increasing evidence for the use of digital tomosynthesis (DT) the role of KUB radiographs in the follow-up of such patients may be dwindling. Nonetheless, until DT gains further acceptance, a prospective study is warranted to confirm the benefit of a baseline KUB.
