Published online by Cambridge University Press: 05 July 2015
‘This is an unenhanced low-dose CT scan of the kidneys, ureter and bladder in axial/coronal/sagittal view.’
AAir: perforation from GI or urinary system
BBlood: high-density haemorrhage from tumour, trauma or obstruction
CCalcifications: renal, collecting system, ureteric, bladder calculi, prostate calcification
DDilatations: renal or ureteric obstruction
• Site – horseshoe or ectopic kidney
• Size – masses, obstruction (calculi), reflux
• Content – stones, staghorn calculi
• Site – on psoas: mass/lesion
• Size – obstruction:
• unilateral = calculi, ureteric or bladder tumour, stricture from previous surgery
• bilateral = bladder outflow obstruction
• Air (dark): trauma, instrumentation or fistula to bowel (e.g. Crohn' s disease) or infection
• Calcification of wall: schistosomiasis, TB infection, post radiation
• Retroperitoneal and peritoneal spaces
• The 3 Fs – fat inflammation, fluid collection (e.g. urinoma) and “fast” (acute) haemorrhage
• Prostatic calcification may be detected on a KUB radiograph and is usually a sign of chronic inflammation
• Bowel dilatation
• Free fluid, collection or air
• ‘ Dirty fat ’ around other organs, e.g. liver, gall bladder, pancreas
The scan is specifically an unenhanced ‘grainy’ low-dose scan looking for calculi.
CT KUB scans are good for artefacts – e.g. stents, calcifications and air – but lack of contrast limits diagnosis of solid organ pathology.
However, ‘dirty’ -looking fat or fluid around solid or hollow organs suggests inflammation, which requires a post-contrast scan.
If a ureteric cancer is suspected CT IVU should be requested (a delayed phase post-contrast scan). Contrast fills the renal pelvis, ureter and bladder, highlighting any mass or filling defects.
The commonest findings in exams are calcifications and secondary signs of obstruction (hydronephrosis or hydroureter).