CT Cystography

Indications

• Suspected bladder rupture: pelvic trauma with gross hematuria or pelvic ring fracture
• Postoperative leak (post-prostatectomy or cystectomy anastomosis, bladder repair)
• Suspected vesical fistula (vesicocolic, vesicovaginal)

Patient prep

• Foley catheter in place; drain the bladder before instillation
• Prepare dilute intravesical contrast: ~25-30 mL of 300-350 mgI/mL iodinated contrast in 500 mL saline (3-5% solution)
• Instill retrograde by gravity drip until adequate distension — target ≥300 mL (≥250 mL minimum) or patient tolerance
• Clamp the catheter for the distended acquisition

Contrast

Technique

• Baseline pelvis acquisition before instillation when leak conspicuity may be confused by prior IV contrast excretion
• Distended-bladder acquisition covering at least the pelvis (kidneys through symphysis if ureteral injury also in question)
• Optional post-drainage acquisition — small posterior extraperitoneal leaks can hide behind a distended bladder
• 120 kV; 2-3 mm axial with coronal/sagittal reformats
• Passive bladder filling from excreted IV contrast is NOT sufficient to exclude rupture — retrograde distension is required

Series / Sequences

Key points

• Adequate distension (≥300 mL) is the sensitivity of the exam — an under-filled bladder falsely excludes rupture
• Distinguish intraperitoneal rupture (contrast around bowel loops/paracolic gutters — surgical) from extraperitoneal (perivesical/prevesical space — usually managed with catheter drainage)
• Properly distended CT cystography matches conventional fluoroscopic cystography for sensitivity and adds pelvic fracture detail in the same exam
• For the fluoroscopic version see the Cystogram protocol

References