If you’re having kidney problems, your doctor will probably order tests to figure out what’s wrong. One of the first tests they may order is an ultrasound scan. Ultrasounds are quick and safe. They use sound waves to make pictures of the inside of your body.

For kidney cancer, an ultrasound can help doctors find a tumor, learn more about it, and figure out next steps. Ultrasounds can also be used after treatment to check if the kidney cancer has recurred (come back). In this article, we’ll explain how ultrasounds help with kidney cancer diagnosis and treatment, what doctors look for, and what to expect during and after the test.

How an Ultrasound Works

An ultrasound uses sound waves to create pictures of the inside of your body. These sound waves are too high-pitched to be heard by the human ear. When the waves bounce off your organs, like your kidneys or bladder, they create pictures on a screen. Different types of tissue — such as solid tumors, healthy kidney tissue, or fluid-filled cysts — reflect the sound waves in different ways. This helps doctors see what’s going on inside your body without surgery.

What To Expect During a Kidney Ultrasound

Most of the time, you don’t need to do much to get ready for a kidney ultrasound. You can usually eat and drink normally unless your doctor gives you other instructions. Sometimes, you may be asked not to eat or drink anything after midnight the day before your test.

Your doctor may also want to check how well your bladder empties. This is done with a post-void residual urine test. For that test, you might need to drink 30 to 32 ounces of water about an hour before the test and wait to use the bathroom until after the scan. A full bladder helps the doctor get clearer images and see how well your bladder is working.

During a kidney ultrasound, you’ll lie down on an exam table. An ultrasound technician will put a slippery gel on your skin over the area being checked. This helps the sound waves move better. Then, they’ll move a small device called a transducer over your skin. It may feel a little cool or like gentle pressure, but it shouldn’t hurt. The whole test usually takes about 20 to 30 minutes.

When Doctors Use Ultrasound for Kidney Cancer

Doctors may order a kidney ultrasound if you have symptoms that could be signs of kidney cancer. Possible symptoms of kidney cancer can include:

• Blood in your urine
• Lower back pain on one side
• A lump on your side or lower back
• Unintended or unexplained weight loss
• Loss of appetite
• Anemia (low red blood cell count)
• Fatigue
• A fever that doesn’t go away and isn’t caused by an infection

Your doctor will probably start with a physical exam, urine tests, and blood tests to see how well your kidneys are working. If the results of these tests suggest there could be kidney problems, an ultrasound is usually one of the first imaging tests they’ll order.

An ultrasound can help show if a lump is a simple cyst (fluid-filled sac) or a solid tumor. Cysts are usually harmless. Solid tumors could be renal cell carcinoma — the most common type of kidney tumor — or another type of kidney cancer.

Doctors may also use ultrasound to guide a needle during a biopsy. In a biopsy, doctors remove a small piece of tissue from the kidney and study it under a microscope. This helps confirm whether the mass is cancer, what type it is, and how fast it may grow. This information can confirm a cancer diagnosis and help doctors guide cancer treatment decisions. If you already have a kidney cancer diagnosis, a kidney ultrasound can help track changes in the tumor.

Can Ultrasound Alone Diagnose Kidney Cancer?

An ultrasound is very good at showing if something looks unusual in the kidney, like a tumor or cyst. It can show if a lump is solid — which is more likely to be cancer — or filled with fluid, which is usually a harmless cyst. But an ultrasound alone can’t confirm whether a mass is definitely kidney cancer. At the very least, other imaging tests are needed.

Other imaging tests might include a CT scan or MRI. These tests give a clearer, more detailed look at the tumor and the area around it. Sometimes, special types of CT scans or MRIs — known as CT angiography or MRI angiography — are used to get a better picture of the surrounding blood vessels.

In some cases, a biopsy is also part of the diagnostic process. A biopsy helps doctors confirm if the mass is cancer. A biopsy can also tell them the exact type of cancer — such as renal cell cancer or a type of urothelial carcinoma — and how fast it might grow.

What Doctors Look For on an Ultrasound

When doctors use an ultrasound to check for kidney cancer, they’re looking for several things. First, they check the size, shape, and texture of the kidney. A healthy kidney looks smooth and even, while a kidney with cancer may have a lump or an area that looks different from the rest.

Doctors may also use a special tool called Doppler ultrasound to see how much blood is flowing to a tumor. Cancer tumors often grow their own blood vessels to feed themselves, so seeing extra blood flow can be a warning sign.

During the procedure, your doctor will also check nearby areas, like the bladder, ureter (the tube that connects the kidney to the bladder), adrenal gland, and nearby lymph nodes. This helps them see if the cancer might be spreading to nearby organs.

What Happens After an Ultrasound

Once your doctor reviews the images from your ultrasound, they’ll go over the results with you. If anything looks concerning, your doctor may order more tests. These might include a kidney biopsy, more imaging tests — like an MRI or CT scan — or kidney function tests.

Kidney function tests use blood and urine tests to check how well your kidneys are working. They can show how well your kidneys remove waste, balance fluids, and filter your blood. These tests are especially important if you already have kidney disease, high blood pressure, or symptoms like swelling or fatigue. The results can help your doctor understand your overall health and decide on the best cancer treatment, if needed.

Treatment Plan and Follow-Up After an Ultrasound

After your ultrasound scan and follow-up tests, your doctor will work with you to create a treatment plan based on your test results. If the tumor is small and hasn’t spread, you may not need surgery right away. In some cases, doctors recommend active surveillance — also known as “watch and wait.” In other cases, treatment may involve surgery, like a nephrectomy (removal of one or both kidneys).

If the cancer has spread to other parts of the body, you may need more advanced cancer care, like immunotherapy, radiation, or targeted therapy. No matter your treatment plan, follow-up care is essential. You’ll likely need regular imaging tests, blood work, and checkups to track your health and how well the treatment is working.

If you’ve been diagnosed with kidney cancer, you don’t need to face it alone. Connect with other people on the same journey by joining a kidney cancer support group, either in person or an online community like MyKidneyCancerTeam.

Talk With Others Who Understand

On MyKidneyCancerTeam, people with kidney cancer and their loved ones come together to ask questions, give advice, and share their stories with others who understand life with kidney disease.

Have you been diagnosed with kidney cancer? What tests led to your diagnosis? Share your story in the comments below, or start a conversation by posting on your Activities page.