Voiding cystourethrogram (VCUG), also known as micturating cystourethrogram (MCUG), is a specialized imaging technique used to assess the structure and function of the lower urinary tract, in particular, the bladder and the urethra. Passing urine is called micturating or voiding. This test is performed on both children and adults. It is most commonly used in children to detect urinary tract infections.

How Does the Urinary Tract Function Normally?

Urine is produced in two kidneys which drains down the tubes called ureters into the urinary bladder. Urine is stored in the bladder. The bladder contracts to pass the urine outside the body through the urethra when the bladder is full. While bladder contraction, the wall of the bladder squeezes the end of the ureter to prevent the backflow of the urine (valve mechanism). Normally urine should flow in one direction.

What Is Vesicoureteral Reflux?

If there is an abnormality in the valve mechanism, the urine flows backward into the lower part of the ureter, sometimes into the kidneys. This condition is called vesicoureteral or VU reflux.

What Are the Uses of Voiding Cystourethrogram (VCUG)?

The voiding cystourethrogram is used to assess the following conditions:

Persistent urinary tract infections.
Family history of urinary reflux (backflow).
Evaluate reflux after certain medical procedures.
Prior urethral infections, trauma, or surgery.
Urinary incontinence (loss of bladder control).
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Hypertrophy (enlargement) of the prostate.
Check for structural problems in the bladder and urethra.
Incomplete emptying of the bladder.
Birth defects with bladder and urethra.

How To Prepare for Voiding Cystourethrogram?

Children may be asked to take antibiotics before or after the test.
Inform the doctor about the medical condition or regular medicines taken.
Inform if breastfeeding. The doctor may ask to stop feeding 24 hours after the procedure as the contrast material may pass through the breast milk.

How Is the Voiding Cystourethrogram (VCUG) Taken?

During the VCUG procedure, the patient will have to remove underpants and wear the hospital gown.
After that, the patient will be asked to lie on his back on the X-ray table. Girls place their legs in the frog position. The nurse/technician puts on gloves and washes the area between the legs with soap and water. A thin, flexible tube called catheter coating with numbing gel will be inserted into the urethra (an opening from where the urine comes out of the body) and passed into the bladder. One may experience some discomfort while inserting the catheter. The tube will be safely taped in place so that it will not move during the procedure. Contrast material (a special dye) flows through the catheter into the bladder until it is completely filled. Urograffin 60 percent diluted with normal saline in 1:3 is used as a contrast material.
This contrast material shows the urinary tract as a bright white color on the X-ray. X-rays are taken from different angles. Using fluoroscopy, a special X-ray technique, the radiologist will get images of bladder filling and emptying. The patient may be asked to hold his breath for a few seconds during imaging to get better images. After that, the catheter is removed so that he can urinate. Images are taken while he empties his bladder.
Once the bladder is empty, a final X-ray is taken. This test usually takes about an hour.
After the procedure, the doctor may ask the patient to drink plenty of water to flush out the contrast materials from the body.

For a Child Patient:

The procedure is the same as the adult patients. For child patients, one of the parents or caretakers may be allowed to stay in the room. But they should wear a lead apron to avoid radiation exposure. Infants and young children may be wrapped in a blanket or other restraint to help them stay in position. When the bladder is full, the child will urinate on the X-ray table. Hence, a bedpan or absorbent pad may be used to catch the liquid contrast.

What Is a Choke Voiding Cystourethrogram?

In adult male patients, this study can be modified by getting the patient to void against resistance by using a penile clamp or compression of the distilled part of the penis. This enhances the visualization of the urethra by the artificial distension.

How to Calculate the Bladder Capacity?

Your age and weight are considered to determine the bladder capacity. Based on that, the contrast material will be used.

Linear Equations:

<1 year: Weight [kg] * 7 = capacity (mL).
<2 years: [age(years)+2]*30 = capacity (mL).
>2 years: [(age (years)/2+6]*30 =capacity (mL)⁶.

Non-Linear Equation:

[4.5*age (years)⁰˙⁴⁰ ]*30= capacity (mL).

What Are the Complications of Voiding Cystourethrogram?

Fever.
Pinkish or reddish urine.
Foul-smelling or cloudy urine.
Pain in the back below the rib cage on one side of the body (flank pain).

Some other complications are:

Blood in the urine after two days Skin rashes.
Nausea (urge to vomit) or vomiting.

Severe Allergic Reactions:

Low blood pressure.
Difficulty in breathing.
Swelling of the throat or other parts of the body.
Cardiac arrest.

What Are the Limitations of Voiding Cystourethrogram?

Pregnant women may be exposed to radiation during the procedure. Radiation may cause birth defects in the fetus in the womb.
Active or untreated urinary tract infection.
It cannot assess the obstruction of the flow of urine from the kidneys. Additional examinations are required in such conditions.
Hypersensitivity to contrast materials.

Conclusion:

Voiding cystourethrogram (VCUG) provides detailed information to assist doctors in preventing kidney damage by urinary infections. It allows the doctor to determine the treatment options, such as medication and surgery. The radiation exposure in this technique is low. VCUG is a minimally invasive procedure that does not require a hospital stay.