Note: the information below is a general guide only. The arrangements, and the way tests are performed, may vary between different hospitals. Always follow the instructions given by your doctor or local hospital.
What is a cystourethrogram?
A cystourethrogram produces specialised X-ray pictures to help assess the structure and function of the lower urinary tract, in particular the bladder (‘cysto’) and urethra. Sometimes X-ray pictures are also taken while you urinate (pass urine). This is done to see whether urine flows away correctly from the bladder. This is called a voiding or micturating cystourethrogram.
How does the urinary tract work?
The urinary tract is a series of tubes and storage vessels that take the urine produced by the kidneys from inside the body to the outside. This includes the ureters, bladder and urethra. The ureters take urine produced by the kidneys to the bladder. The bladder stores urine until it is ready to be passed out. The urethra forms the passage between the bladder and the outside world. In men the urethra also carries sperm.
The urinary tract collects and stores urine and provides a passage for urine to be expelled from the body. The ureters are about 25-30 cm long and carry urine from the kidneys to the bladder. Although the ureters are thin tubes they have muscle within their walls. This helps to push urine towards the bladder.
The bladder is a hollow muscular organ. When empty it collapses on itself. As it fills with urine it becomes pear-shaped and rises into the abdominal cavity.
The bladder of an adult holds around 700-800 millilitres (mls) of urine.
Urination (passing urine) occurs by a combination of voluntary and involuntary muscle contractions. The wall of the bladder has special receptors which can tell if the bladder is stretched. When the amount of urine in the bladder reaches between 200-400 mls these receptors send signals to the spinal cord. These signals trigger a reflex (an involuntary action). Signals are sent back from the spinal cord to the bladder wall. These signals cause contraction of some of the bladder muscles and relaxation of others. This causes urination. Although emptying of the bladder is a reflex, we learn to control this voluntarily during childhood.
The ureter passes through the wall of the bladder at an angle. So, when the bladder contracts to pass urine, the wall of the bladder squeezes the end of the ureter to prevent urine being passed back up the ureter. In effect, this action works like a valve to stop backflow (reflux) of urine up the ureters.
What is a cystourethrogram used for?
A cystourethrogram may be done to help:
- Find the cause of repeated urinary tract infections.
- Look for injuries to the bladder or urethra.
- Find the cause of urinary incontinence.
- Check for structural problems of the bladder and urethra.
- Look for enlargement (hypertrophy) of the prostate or narrowing (stricture) of the urethra in men.
- Find out if urinary reflux is present.
A cystourethrogram is commonly used in children who have repeated urinary tract infections or other urinary problems. In some children, a problem with the junction of the ureters and bladder allows urine to flow backwards towards the kidneys instead of away from them.
This condition is called vesicoureteric reflux (VU reflux). In mild cases urine backs up into the lower ureter. In severe cases it can back up into a swollen kidney. Usually, children with this condition are born with it. Other causes include:
- Blockage to the bladder.
- Abnormal urination with very high pressure within the bladder.
- Incomplete emptying of the bladder.
- Urinary tract infections.
- Urinary tract infection may be the only symptom of the problem.
How does a cystourethrogram work?
Normally, soft, hollow structures such as the bladder and ureters are difficult to see on X-ray images. In a cystourethrogram a contrast agent is inserted into the bladder. This helps to produce useful pictures. Contrast is a type of dye that blocks X-rays. By blocking the X-rays, contrast dye makes the structures being examined bright white in colour. This helps to show the important areas by making them stand out against the black background on the X-ray picture.
A cystourethrogram also uses a special kind of X-ray technique called fluoroscopy. A fluoroscope is an X-ray unit attached to a television screen. The fluoroscope uses a continuous X-ray beam to make a sequence of images. These images are fed to a television-like monitor. This allows your doctor to watch as the contrast agent fills your bladder and to observe any problems or defects. If the images show the contrast entering the ureters, this suggests you have VU reflux. Your doctor may be able to assess how much of a problem this is by looking at the X-ray images.
What happens during a cystourethrogram?
You will be asked to lie on the X-ray table. Your genital area will be cleaned and draped with sterile towels. A thin hollow tube called a catheter will be inserted into your urethra (the opening through which you urinate). This might be a little uncomfortable but should not be painful. The catheter will gently be advanced into your bladder.
A small amount of the contrast dye will then be put into the bladder via the catheter. While this is happening your doctor will be looking at the images on screen. He/she will be able to see whether the dye enters the ureters.
You may be asked to change positions during the test to get different views of the bladder and urinary tract.
Finally, the doctor will take some pictures as you empty your bladder by urinating. You may feel embarrassed about having to urinate in front of other people. However, this is a routine test and the staff will want you to feel as relaxed as possible. You may feel a strong urge to urinate at other times during the test. This is normal, but it is important to try to wait until you are asked to do so.
What should I do to prepare for a cystourethrogram?
Your hospital should give you information on how to prepare for this test. There is usually very little preparation needed. You should not have the test if you have a urinary tract infection, so let the hospital know if you have any of the signs of an infection (see below for a list). Pregnant women should not have the test. So, let your hospital know if you are, or may be, pregnant. You should also advise the hospital if you are breast-feeding. They will let you know whether any special precautions need to be taken.
What can I expect after a cystourethrogram?
You may feel a burning sensation when you urinate and/or need to go to the toilet more often than usual for a short time. It is normal for your urine to have a pinkish tinge for a couple of days after the test.
Are there any side effects or complications from a cystourethrogram?
Most people have a cystourethrogram without any complications. Rarely, a person may have an allergic reaction to the contrast dye used. It is also possible, although uncommon, that damage to the bladder or urinary tract could be caused during injection of the contrast. The most common complication is a urinary tract infection.
You should contact your doctor if you have any of the following problems:
- Blood in your urine after two days.
- Pain in your lower abdomen (tummy).
- Signs of a urinary tract infection. These signs include:
- Pain or burning upon urination.
- An urge to urinate frequently, but usually passing only small amounts of urine.
- Dribbling or leaking of urine.
- Urine that is reddish or pinkish, foul-smelling, or cloudy.
- Pain in the back just below the rib cage on one side of the body (flank pain).
- Fever or chills.
- Nausea or vomiting.
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