Bladder outlet obstruction: causes, symptoms and treatment

The bladder stores urine and then contracts to push it out through the urethra, the tube that carries urine out of the body. Bladder outlet obstruction describes anything that narrows or blocks this exit. The bladder then has to work harder, and may not empty fully.

The Bladder & Bowel Community explains that there are two main causes of urinary retention: obstruction to the flow of urine through the urethra, and a weak bladder muscle. Outlet obstruction is the first of these. Over time, a bladder working against resistance can struggle, and urine left behind can be a risk for infection.

The symptoms are rarely dramatic at first. A slightly slower stream or getting up once more at night is easy to put down to age. Because the changes are gradual, many people only realise how much has changed when something such as a urine infection or complete inability to pass urine forces the issue.

The cause depends largely on age and sex. The NHS describes the prostate as a small gland below the bladder that makes semen and controls the flow of pee from the bladder to the penis; if it enlarges it can press on the urethra and cause problems with peeing. This is most common in men over 50.

In women, the Bladder & Bowel Community names anterior or bladder prolapse as a common cause of difficulty passing urine. The NHS also lists scarring of the urethra among reasons for catheter use because of an obstruction. Other causes of urinary retention described by the charity include a weak bladder muscle, nerve problems such as Parkinson's disease or multiple sclerosis, and learned voiding dysfunction such as fear of using toilets outside the home.

The NHS lists the main symptoms of an enlarged prostate as problems with peeing, and they develop slowly and may gradually get worse as you get older. These symptoms apply to bladder outlet obstruction from other causes too.

• Difficulty starting to pee, or having to push or strain.

• A weak flow that stops and starts and takes longer than usual.

• Feeling you cannot fully empty your bladder.

• Dribbling pee after you have finished.

• Needing to pee more often or urgently, including at night.

The NHS says to see a GP if you have difficulty peeing or need to pee more frequently, and notes that the GP will be used to talking about these symptoms. It says to ask for an urgent GP appointment or get help from NHS 111 if you have blood in your pee, pain when peeing or you cannot pee at all.

The NHS stresses that these symptoms should be checked because they can sometimes be caused by other, more serious conditions such as prostate cancer, where finding it early may make it easier to treat. The Bladder & Bowel Community adds that while the bladder is not emptying properly, the residual urine can become infected.

A GP will usually ask about symptoms and may ask you to keep a record for at least 3 days of how much you drink and how often and how much you pee. The NHS lists tests such as testing a pee sample, a PSA blood test, a rectal examination to check prostate size and examination of the tummy and penis.

Specialist tests may include a urine flow test, in which you pee into a machine that measures how you pee, an ultrasound scan of the bladder, and a cystoscopy, which looks inside the bladder with a camera. The Bladder & Bowel Community also names urinalysis, uroflowmetry, urodynamics and cystoscopy as tests a healthcare professional may recommend, and suggests a bladder diary before the appointment.

Treatment depends on the cause and how much the symptoms bother you. For an enlarged prostate the NHS says that if symptoms are not causing many problems, lifestyle changes are tried first; with moderate or severe symptoms you may be offered medicines, and surgery if medicines have not helped or symptoms are severe.

The NHS says a urinary catheter is a flexible tube used to empty the bladder and collect urine in a drainage bag, inserted by a doctor or nurse. It may be intermittent, inserted and removed once the bladder is empty, or indwelling, staying in place for days or weeks. It can be put in through the urethra or through a small opening in the lower tummy, called a suprapubic catheter.

The NHS says the main problems with catheters are infections, and that the longer a catheter is used the greater the risk, as well as bladder spasms, leakage, blockage and urethral damage. Even so, you should be able to live a relatively normal life with one, including working, exercising and swimming. The Bladder & Bowel Community explains that some people can be taught intermittent self-catheterisation and that continence nurses and specialist physiotherapists can help.

A bladder that cannot empty properly is more prone to infection, and the Bladder & Bowel Community highlights that residual urine can become infected. The NHS includes blockages in the flow of urine, such as an enlarged prostate, among the causes of chronic kidney disease, and in its hydronephrosis page lists an enlarged prostate as a cause of a blockage that can swell the kidneys. Seeking help when symptoms start is the best way to avoid these problems.