MSFinals-6798

You are asked to review a middle-aged man, following an admission for lower abdominal pain. The patient has a distended abdomen and has not passed urine for eight hours. He is very uncomfortable and has a large palpable bladder extending above the pubic symphysis. A digital rectal examination is performed, which reveals an enlarged, smooth prostate. Urinalysis is unremarkable, and he remains systemically well. He describes increasing difficulty with voiding and poor stream over the past six months, but no other symptoms.
What is the most likely underlying cause for his urinary retention?