Differential diagnosis of pediatric bladder outlet obstruction

• Posterior urethral valves
• Genitourinary rhabdomyosarcoma of bladder or prostate or vagina
• Sacrococcygeal teratoma
• Constipation

Approach to the differential diagnosis of bladder outlet obstruction:

• Cross sectional imaging can be extremely helpful in determining the level of the bladder outlet obstruction and thus its etiology:
  — Bladder due to rhabdomyosarcoma
  — Prostate due to rhabdomyosarcoma
  — Vagina due to rhabdomyosarcoma
  — Posterior urethra due to posterior urethral valves
  — Presacral mass due to sacrococcygeal teratoma or constipation