CT kidneys, ureters and bladder (protocol)

Computed tomography of kidneys, ureters and bladder (CT KUB) is a quick non-invasive technique for diagnosis of urolithiasis. It is usually considered the initial imaging modality for suspected urolithiasis in an emergency setting ¹.

Advantages

• quick
• easily accessible
• identification

  NB: This article is intended to outline some general principles of calcified renal tract calculi and their sequelae

• assessment of other causes of flank pain if negative for calculus disease

Disadvantages 

• exposure to ionizing radiation

Technique

Procedure 

protocol design. The actual procedurespecifics will vary depending on CT hardware and software, radiologists' and referrers' preference, institutional protocol/guidelines butprotocols, patient factors (e.g. allergy) and time constraints. 

Indications

• suspected urolithiasis 
• hematuria
• flank pain

Technique

• patient position
  • supine with their arms above their head
• scout
  • above the diaphragm to the below is a typical description:pubic symphysis 
• scan extent
  • above kidneys to below pubic symphysis 
• scan direction
  • caudocranial
• contrast injection considerations
  • non-contrast CT scanning is ideally performed on a multi-detector computed tomography (MDCT) scanner.
• supine or prone patient positioningscan delay
  • minimal scan delay
• ​respiration phase
  • ​inspiration

Practical points

• prone has the advantage of assessing stones near the VUJ which may have just passed
• some institutions may perform a limited pelvic scan in prone if the supine scan shows a calculus near the VUJ

Findings

• identification of calcified renal tract calculi size and position
• stone composition assessment with dual energy CT
• assessment of the sequelae of calculi
  • obstruction
  • infection
• assessment of other causes of flank pain if negative for calculus disease
• presence of further calculi at risk of obstructing