Imaging description

CT cystography (CTC) has replaced conventional fluoroscopic cystography for the evaluation of bladder rupture in trauma patients. The bladder is filled with diluted contrast using the Foley catheter to generate adequate distension. At our institution, we usually perform CTC immediately after venous phase CT scan by emptying the bladder, mixing 30 mL of iohexhol 350 mg/mL in a 500 cc bag of normal saline warmed to body temperature, connecting this to the Foley catheter using an intravenous “drip” set, and hanging the bag 40 cm above the symphysis pubis. We perform a low-dose CT scan through the pelvis after 350 mL of contrast has been administered, or contrast stops dripping, or when the patient cannot tolerate bladder distention. We routinely perform multiplanar reformations.

A markedly distended bladder (such as in a patient with chronic bladder outlet obstruction) may require considerably more than 350 cc of contrast to fill the bladder. If images do not demonstrate a distended oval-shaped bladder (e.g., a floppy bladder draping around adjacent structures) then the bladder is inadequately distended and has not been “stressed” adequately to evaluate for rupture.