Imaging description

A dominant pelvic cystic structure or fluid collection may be mistaken for the urinary bladder, as it can present with an identical appearance to the bladder on multiple images (Figure 73.1), on ultrasound, CT, or MRI. This apparent bladder is sometimes referred to as a “pseudobladder.”

Careful evaluation of the entire structure, and/or a high level of clinical suspicion leading to additional reformations or imaging, will usually help avoid this pitfall.

Importance

Mistaking a cystic structure for a distended urinary bladder can result in an erroneous diagnosis of bladder pathology, such as increased post-void residual secondary to bladder outlet obstruction [1]. This could result in inappropriate interventions such as Foley catheter or suprapubic catheter placement.

Moreover, a cystic mass mistaken for the urinary bladder can result in delayed identification of a pelvic cystic mass, such as a cystic ovarian carcinoma.

Typical clinical scenario

This potential pitfall arises when a large cystic mass is present in or near the pelvic midline, presenting with a similar or identical appearance to the bladder on many images. This may occur in studies performed specifically to evaluate the bladder, to evaluate for a pelvic mass, or for non-specific symptoms unrelated to the pelvis.