Bladder outflow obstruction

BOO, difficulty urinating, lower urinary tract symptoms (LUTS), urinary incontinence

Bladder outflow obstruction (BOO) is where the flow of urine out of the bladder is restricted. We offer a range of innovative treatments for bladder outflow obstrcution, as well as exceptional personal care.

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What is bladder outflow obstruction?

Bladder outflow obstruction commonly causes symptoms affecting the flow of urine.

It is common in older men and is most often caused by an enlarged prostate, known as benign prostatic hyperplasia (BPH). However, there are other possible causes so further investigation is usually needed.

We offer a full range of diagnostic tests and treatment options so our team of urologists can identify the cause of any bladder outflow obstruction, as well as recommend appropriate treatment to manage your symptoms.


The most common cause of bladder outflow obstruction is prostate gland enlargement. The prostate gland sits just beneath the bladder and produces a fluid that becomes part of semen. 

With age, the prostate gland tends to gradually enlarge. It is estimated that half of men will have some benign enlargement of the prostate gland by the age of 65, increasing to 90% by the age of 90. 

This can put pressure on the urethra (the tube which empties the bladder), restricting the flow of urine. Bladder outflow obstruction can also be caused by any other factors that restrict urine flow. 

It is important to identify the cause so that you can receive appropriate treatment. Benign prostate enlargement is not the same as cancer, but cancer of the prostate or bladder can cause similar symptoms. 

Bladder outflow obstruction can also be caused by prostatitis (an infection of the prostate gland), bladder stones, scar tissue following injury or surgery or a birth defect. 

In women, bladder outflow obstruction is much rarer but may also be caused by a prolapsed bladder or uterus.


Symptoms of bladder outflow obstruction may include:

•    A weaker flow of urine than usual
•    Difficulty starting or stopping urinating
•    Straining whilst urinating
•    Feeling like your bladder is not emptying completely
•    Dribbling after urinating
•    Needing to urinate more often or more urgently
•    Waking up at night to urinate

If you have any of these symptoms, it is important to seek medical advice. 

Although often caused by benign prostate enlargement, it is important to rule out other possible causes that may require urgent treatment. 
If left untreated, benign prostate enlargement may also increase your risk of developing a urinary tract infection.


Our expert urologists will arrange the necessary tests and investigations to identify the cause of your symptoms. 

This will typically include a detailed medical history, examination of your bladder and a digital rectal examination (DRE) to check your prostate. 

To evaluate your symptoms in more detail, you may be asked to record the volume you drink and the volume of urine you pass over a 24-hour period as well as complete a questionnaire to help evaluate the impact of your symptoms on your daily life.

Further investigations may include blood tests including a PSA (prostate-specific antigen) test and scans, such as ultrasound or an MRI.


Treatment options for bladder outlet obstruction will depend on the cause and the severity of symptoms. If the cause is benign enlargement of the prostate and the symptoms are affecting your quality of life, you may be able to take drug treatments which either relax the muscle around the prostate or shrink the prostate. Bladder outflow obstruction can be associated with erectile dysfunction. 

If this is affecting you, you may be able to take phosphodiesterase type-5 inhibitors (such as sildenafil, or Viagra) to improve your erections.
If medication is not suitable for you, or you continue to have symptoms that impact your daily life, you may wish to consider surgery. 

We have a range of minimally-invasive surgical options available including Aquablation therapy, prostate artery embolization, Urolift and TURP (transurethral resection of the prostate gland). 

We also offer innovative treatments for benign prostatic hyperplasia such as iTIND, where a temporary implant is inserted on the urethra to improve symptoms, and REZUM, which uses heat energy to shrink the prostate gland.

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Speak to someone today about bladder outflow obstruction. Book an appointment or ask for advice.