CT imaging of the unusually shaped bladder.

In the CT evaluation of a cystic pelvic mass it is important to identify the urinary bladder and assess its relationship to the mass. Although this is generally an easy task, we have encountered cases where delayed opacification of the bladder created diagnostic difficulties. Following intravenous contrast medium infusion, patients with normal renal function may have unopacified bladders due to (a) delayed transit from kidney to bladder and (b) rapid CT imaging of the bladder before opacification can occur. If one is aware of these problems, diagnostic dilemmas may be reduced by obtaining delayed scans of the pelvis or by obtaining postvoid films. Two cases are presented to illustrate these points.