What is a cystometrogram?

A cystometrogram (CMG) is a test to check your bladder pressure.  This will take place in the Urodynamic Suite which is based in the Urology Clinic at Freeman Hospital.

Why is it necessary?

The normal bladder stores urine and then releases it at a convenient time.  Your symptoms suggest that your bladder may not be working properly and this test helps us to find out why by measuring activity of the bladder as it fills and empties.  To do this we need to recreate your symptoms in the clinic by filling your bladder artificially.

Is any preparation needed?

It is important that you drink plenty of fluid (1 glass every hour) on the day of the test and the day after.  It is very helpful if your bladder is fairly full when you arrive and that you have emptied your bowels before you come for the test. 

If you think you may have a bladder infection you should let us know before the test. 

If there is a chance that you may be pregnant you must tell the nurse when you arrive so that we know not to use x-ray equipment.

You are welcome to bring your own dressing gown and slippers to the clinic to make yourself comfortable.

How is the test done?

The test takes between 20 and 40 minutes to perform.  On arrival you will be asked to change into a hospital gown.  Secure lockers are provided for you to store your clothes and belongings. 

If possible you then pass water into a special toilet to measure urine flow and empty your bladder.  Following this we may scan your bladder with an ultrasound machine to see if any urine is left.

You will then be asked to lie down on a couch.  The room will be empty except for the specialist nurse or doctor doing the test.  They will clean your genital area with a mild antiseptic and introduce a small amount of local anaesthetic jelly into your urinary passage.  This sometimes causes mild discomfort.

Following this a fine soft tube (catheter) will be gently passed up into the bladder.  This feels strange and may sting as it passes through but the feeling quickly wears off.  A second thin tube will then be inserted into our back passage to measure changes in your tummy during the test.  Again this gives a strange feeling which quickly goes away.

Once everything is in place your bladder will be gradually filled with saline (salty water).  Throughout the test a specialist nurse or doctor will be with you and will ask about your symptoms and how the bladder feels.  When your bladder starts to feel uncomfortable you will be asked to cough and strain, to look fro leaks or turn some taps on to stimulate your bladder.  You should try to hold on to your urine if possible at this point.

The table will be titled upright to let you stand or sit.  You may be asked to cough or strain again to look for any leakage.  You will then be left on your own so that you can pass the water into the special toilet.

During the examination we may take a few x-ray images of your bladder to record its appearance during the test.

The tubes will then be removed and you will be ready to get dressed and return home.  We may also ask you to perform some exercised (coughing, squatting and jumping) whilst wearing a special pad to record any leakage.  The doctor or specialist nurse may speak to you about the results before you go.

Will there be any problems afterwards?

Like many medical tests the CMG involves some discomfort and embarrassment and can seem undignified.  Throughout the examination professional, trained staff who understand your concerns will look after you and help minimise any discomfort.

After the test it will sting when you pass your water for a couple of days and you may experience a mild ache in the bladder, these symptoms should improve quickly.  You may also pass a little blood with the urine the first time you pass water.

About 5% of patients who have this test get a bladder infection (cystitis) afterwards.  If this happens the stinging will worsen and you may feel feverish.  If this occurs you should see your GP as soon as possible and explain the situation.  If you are at higher risk of getting an infection or are particularly concerned about the possibility you will be given a short course of antibiotics to take when you leave.

When will I be told about the results?

The doctor or specialist nurse doing the test will briefly explain the results and may organise some treatment straight away.  The findings of the test are always sent to your consultant who will then write to you or arrange for you to be seen in the out patient clinic to explain the findings and discuss your problems.

What if I have any other questions?

It is very important that you know the reason for the test and that you are happy for it to be performed.  If you have any queries you can ring the urodynamic secretary on (0191) 213 7039 who will give you confidential advice. 

Alternatively you can speak to your consultant’s secretary by ringing (0191) 233 6161 and asking to be put through to her directly.  She may be able to answer your question, get a doctor to speak to you or arrange a further outpatient appointment. 

You can also speak to the clinic staff when you arrive for the test.