What is the characteristic complication of benign prostatic hyperplasia?

Benign prostatic hyperplasia (BPH) is characterized by the enlargement of the prostate gland, which can lead to a mechanical obstruction of the urethra. This obstruction is the result of the enlarged prostatic tissue compressing the urethra and inhibiting the normal flow of urine from the bladder.

As a consequence of this urinary obstruction, patients often present with symptoms such as difficulty initiating urination, a weak urinary stream, frequent urination (especially at night), and the feeling of incomplete bladder emptying. Over time, if the obstruction remains untreated, it can lead to more severe complications, such as chronic urinary retention and even acute kidney injury as a result of retained urine and increased bladder pressure.

While urinary incontinence, bladder stones, and acute kidney injury may occur in conjunction with BPH due to long-standing obstruction, they are not direct or primary complications of the condition. Instead, urinary obstruction is the hallmark feature that fundamentally characterizes the complications associated with benign prostatic hyperplasia, making it the correct answer.