Urine retention due to an enlarged prostate, conceptual artwork. The prostate is a gland at the base of the bladder. Enlargement of the prostate, called hypertrophy, is very common in elderly men. As the gland surrounds the urethra, through which urine passes, the enlargement can obstruct the flow of urine. This is represented here by the heavy doors forming a barrier to the liquid behind them. Treatment is with surgical removal of all or part of the gland. The prostate normally produces seminal fluid, which forms much of the ejaculate.