Bladder outlet obstruction can arise from a number of conditions affecting the urethra and/or bladder outlet but is most commonly encountered in elderly men due to prostate enlargement. 

Clinical presentation

Patients often present with difficulty in urination, retention, and urinary discomfort ^2,7.

Pathology

Obstruction can be caused by a wide range both functional and anatomical causes that varies by sex, a non-exhaustive list includes:

• anatomical

  • iatrogenic, e.g. anti-incontinence surgery (in females) ^6,7

  • mass lesions within the periurethral region

    • benign

      • in males: prostate enlargement (most common cause) ^1,7

      • in females: ovarian cyst, uterine fibroid ⁷

    • malignant, e.g. urethral cancer, vaginal cancer, cervical cancer ⁷

  • urethral strictures: more common in males than females ^1,7

  • pelvic organ prolapse ⁷

  • congenital urethral valves ¹

• functional

  • sphincteric dyssynergia

    • from neurogenic cause, e.g. multiple sclerosis, spinal cord injury ⁷

    • without neurogenic cause, i.e. primary bladder neck obstruction ⁷

  • sphincteric pseudodyssynergia

    • from dysfunctional voiding related to learned behaviour or pain syndromes ⁷

    • Parkinson disease ⁷

Radiographic features

On radiographic evaluation, the bladder wall appears thickened and trabeculated. Urinary retention is noted with increased post-void residual on sonographic or voiding studies.

Treatment and prognosis

The goal of treatment is to relieve the obstruction and prevent urinary tract infections and renal compromise. This can be done by either catheterisation or surgical intervention depending on the aetiology of the obstruction ².  

Differential diagnosis

On imaging consider:

• neurogenic bladder

• posterior urethral valves