It is located below the bladder (the organ where urine is stored) and surrounds the upper portion of the urethra (the tube that carries urine out of the body)

The reasons are not entirely clear but ageing and hormonal changes appear to play an important role.

As the prostate gland increases in size it causes the gland to pinch against the urethra like a clamp on a garden hose.As a result it can lead to the following problems. It can put pressure on the urethra and slow down or cut off the flow of urine.The bladder wall becomes thicker and irritable leading to contraction of bladder even when it contains small amounts of urine, causing more frequent urination.Eventually, the bladder weakens and loses the ability to empty itself.

The size of the prostate does not always determine how severe the obstruction or the symptoms will be. Some men with greatly enlarged glands have little obstruction and few symptoms while others whose glands are less enlarged, have more blockage and greater problems.Sometimes a man may not know that he has any obstruction until he suddenly finds that he is unable pass urine at all called acute urinary retention.

Medical evaluation will include a
History
Physical examination
Preliminary tests.
The following universal symptoms chart helps you to evaluate your symptoms by yourself.- AUA SYMPTOM SCORE

Physical Examination
A physical examination helps your doctor evaluate your general health. Your doctor will also assess you prostate with a digital rectal examination, preformed by insuting a finger into the rectum and feeling the prostate to enable your doctor to detect an enlarged prostate or other abnormalities.

Laboratory Investigations
Urine investigations like urine culture to rule out urinary tract infection.PSA (Prostate specific antigen) blood test is used to detect abnormally high levels of a Protein substance in your blood that may indicate prostate cancer.

These test serve as a baseline for comparsion to future tests and to follow your response to treatment.

Uroflow :- Metering how quickly or slowly your urine flows can show a blockage. 

Ultrasound :- Ultrasound uses sound waves to create a two-dimensional image of your prostrate, bladder or kidneys.

To provide relief for your symptoms, medications may be needed to relax the muscles of your prostate to block hormones that cause prostatic growth, or to relax your bladder and improve continence.

There are two types of surgery to remove excess prostate tissue.
1. Trans-urethral resection of prostate (TURP)
a. Is the most commonly employed method.
b. During this procedure an instrument is inserted through the penis to sallow your doctor to see & remove any tissue blocking your urethra and bladder.

2. Open prostatectomy
a. May be done when a large amount of tissue must be removed or when the size, shape or position of the prostrate makes it necessary.
b. An incision is made in the abdomen or the area between the anus and scrotum and the excess tissue is removed.

1. Retrograde ejaculation - If during surgery the muscle that is involved in ejaculation may be cut, semen may travel backward into the bladder during an orgasm, instead of traveling out of the body through the urethra.

2. Infection.

3. Pneumonia
4. Blood clots
5. Excessive bleeding.
6. Impotence