Urinary bladder wall thickening

Urinary bladder wall thickening is a common finding and its significance depends on whether the bladder is adequately distended.

Radiographic features

Ultrasound

In both adults and children, the wall may be considered thickened on ultrasound if it measures ⁶:

• >3 mm when distended (>25% expected volume*)

• >5 mm when non-distended (<10% expected volume*)

* normal adult bladder volume is 300-400 mL ⁷

CT

Bladder wall thickness varies with volume, ultrasound cut-offs may not be applicable ⁸.

Differential diagnosis

If the bladder is not distended, then it is difficult to exclude artifactual thickening from a collapsed bladder

If the bladder wall is adequately distended, then a differential may be developed based on whether the bladder is diffusely thickened or focally thickened:

Diffuse bladder wall thickening

• bladder outlet obstruction

• neurogenic bladder

• infectious cystitis

• cystitis from radiation or chemotherapy

• ketamine associated lower urinary tract dysfunction ⁵

Focal bladder wall thickening

• urothelial cell carcinoma of the bladder (transitional cell carcinoma)

• artifact: blood products/clot

  • will not enhance on postcontrast CT or MRI; no vascularity on color flow Doppler

  • may be adherent to the bladder wall, like tumor, but clot is more likely to have a concave margin, unlike tumor

• other bladder neoplasm

  • squamous cell carcinoma of the bladder

  • adenocarcinoma of the bladder

  • bladder lymphoma

  • local invasion by adjacent tumor

  • small cell carcinoma of the bladder

  • bladder paraganglioma

  • bladder wall leiomyoma

  • neurofibroma/neurofibromatosis ^3,4

• cystitis: more commonly diffuse than focal, but may mimic a neoplasm

• adjacent inflammatory process (e.g. diverticulitis)

• cystitis cystica and cystitis glandularis

  • may mimic bladder cancer

• amyloidosis of the bladder: rare

• malacoplakia of the bladder: rare

• bladder endometriosis ²