What Does an Ultrasound of the Bladder and Kidneys Show?

• Kidney ultrasound: Examines your kidneys using sound waves and detects abnormalities in the size, shape, and position of your kidneys, as well as defects in the kidney tissue. It allows your doctor to assess how well blood is moving to your kidneys.
• Bladder ultrasound: Detects abnormalities in the bladder such as bladder diverticula (pouches), bladder stones, and large tumors. According to the American Urological Association, bladder ultrasounds are generally used to determine how the bladder drains after urine by measuring the amount of urine that remains in the bladder after urination. If urine remains in the bladder, it could indicate an underlying issue, such as bladder dysfunction.

Images of your kidneys and bladder are created by a device called a transducer, which emits sound waves that echo from your kidneys. The rebounded sound waves are subsequently picked up by the transducer. These are converted into images of your kidneys on a screen.

Your doctor may replace the transducer with another device called a Doppler probe. This probe allows your doctor to hear the sound waves emitted by the transducer and detect how quickly blood flows through a blood vessel, as well as in which direction. A lack of sound or faint sound may indicate a barrier in the flow.

Because an ultrasound does not involve radiation or dyes, it is safe for both pregnant women and those who are allergic to contrast dye. 

Ultrasounds are also considered a noninvasive test. This means that they do not require an incision or a gadget that enters your body. In most cases, an ultrasound does not cause pain or discomfort. On average, one ultrasound takes up to 20-30 minutes.

Preparation

• You normally do not need to refrain from eating or drinking prior to the test. 
• In most cases, sedation is not required.
• In some cases, you may be asked to hold in your urine.
• The gel used on your skin during the test will not stain your clothing. While the gel may not be entirely removed from your skin after the procedure, it will wash off in the shower.

Procedure

• A kidney ultrasound can be performed as an outpatient procedure or as part of a hospital stay. The manner in which the test is performed differs depending on your condition. In general, however, a kidney ultrasound follows the following steps:
• You will be asked to take off any jewelry or other things that could interfere with the scan. It is possible that you will be asked to remove your clothing. In this case, you will be provided a gown to wear.
• You will be asked to lay on your stomach on an exam table, and you will be advised when to change positions if necessary.
• A transparent gel will be applied to the skin over the area to be examined. When applied, it may feel cool.
• The transducer will be pressed against the skin and moved over the area being analyzed.
• When a Doppler probe is used to examine blood flow, you may hear sounds which indicate the flow of blood.
• If your bladder is examined initially, the scan is performed on a full bladder; later you will be asked to empty your bladder to undergo more scans.
• When the test is over, the gel will be wiped away.