Do I Really Need a CT Scan for Kidney Stones?

Passing a kidney stone is an unforgettable experience. And not in a good way. 

If you have a history of multiple kidney stones, you know the second you have another one. Some people are able to skip a trip to the emergency room (ER) with hydration and medication at home. But sometimes, no matter how hard you try, a trip to the ER is unavoidable. 

And if you’ve been to the ER for a kidney stone before, you know what to expect — a potentially long wait to see a healthcare provider, some blood tests, and a CT scan.  

But did you know that some people might be able to dodge the time and expense of a CT scan while dealing with a kidney stone? If you have kidney stones, here’s what you need to know about bypassing that CT scan and going straight to treatment. 

Why would your healthcare provider order a CT scan for kidney stones? 

A healthcare provider orders a CT scan to make sure a kidney stone is actually causing your pain. 

Imaging studies, like CT scans, are the most precise way to diagnose kidney stones. Blood and urine tests, along with your symptoms, all provide helpful clues. But only an imaging study can show, without a doubt, that you have a kidney stone.

A CT scan uses X-rays to take thousands of tiny images of the inside of your body. Computer software assembles these images so healthcare providers can see detailed views of your organs and bones. By ordering a CT scan, your healthcare provider can confirm that you don’t have another medical condition that’s causing your pain. 

A CT scan isn’t the only imaging study that can diagnose kidney stones. An ultrasound can also be used to diagnose kidney stones. Ultrasounds don’t use radiation, so they’re safer than CT scans. But ultrasounds aren’t always available, and the results depend on the skill of the ultrasound technician. Many healthcare facilities rely on CT scans for these reasons. 

When is it a good idea to get a CT scan for a kidney stone?

In some cases, healthcare professionals recommend a CT scan for kidney stones:

• First-time symptoms: If you have symptoms of a kidney stone but you’ve never been diagnosed with one before, you will likely need a CT scan. That’s because when you have never had one before, this increases the chance that something else is causing the pain. Studies show that 33% of people who went to the ER for what they thought was a first-time kidney stone actually ended up having something else. 

• Older adults: People who are over 50 years old might need a CT scan if they have symptoms of kidney stones. That’s because other medical conditions become more common as you get older. Certain types of cancers and abdominal aortic aneurysms can cause pain that can mimic kidney stone pain. Your healthcare providers will use a CT scan to make sure you don’t have one of these conditions. 

• Worsening symptoms: Most stones pass on their own, and then the pain goes away. If your kidney stone pain isn’t getting better or you have a fever, however, you might need a CT scan. That’s because these things can mean that your kidney stone is stuck or is leading to an infection. Larger stones are less likely to pass on their own, so knowing the exact size and location can help your provider know if additional treatment is needed. Larger stones are also more likely to block the flow of urine and lead to an infection, which also requires further treatment. 

Is a CT scan always necessary for kidney stones?

If you’re younger than 50 years old and you’ve had kidney stones before, the American College of Emergency Physicians says that you can skip the CT scan. Research shows that in this situation, a CT scan doesn’t help a healthcare provider make a diagnosis or change the course of treatment.

Similar findings were made in a larger, ongoing effort by the American Board of Internal Medicine called the Choosing Wisely campaign. The campaign aims to understand when additional testing is truly helpful. When it came to CT scans for kidney stones, experts involved in the campaign reviewed data to see which people benefited from CT scans and which didn’t. 

For younger people who previously had kidney stones, CT scan results didn’t change how healthcare providers decided on treatment. And the CT scans weren’t improving people’s care or their health outcomes. These people could avoid getting multiple CT scans. 

Since that recommendation was made in 2012, the group has been doing more research to see if other people can skip CT scans. In the future, more people may be able to forego a CT or get an ultrasound to diagnose kidney stones instead. 

What are the benefits of avoiding an unnecessary CT scan?

There are two major benefits to avoiding unnecessary CT scans: less radiation exposure and lower medical costs. 

CT scans use radiation. Even though newer CT machines use lower doses of radiation, it’s still a good idea to avoid unneeded radiation. An average CT scan of your abdomen and pelvis (which is what you get for kidney stones) exposes you to 7.7 millisieverts of radiation. That’s the same amount of radiation you’d be exposed to from the sun over the course of 2.5 years. Excessive radiation exposure has been linked to many health conditions, including cancer and cardiovascular disease. 

CT scans are also expensive. Depending on your insurance coverage and where the scan is performed, a CT scan can cost anywhere from $270 to $5,000 or more. Since you’re likely seeking emergency care for your kidney stone, you can expect the cost to be on the higher end because emergency rooms charge more for imaging studies than a typical outpatient imaging center. You might receive a bill from the radiologist, too. This is the doctor who actually looked at your CT scan to see if you had a kidney stone. 

The good news is you have new protections in the No Surprises Act if you receive emergency care. Most emergency care claims must be charged at the lower in-network rates. So speak up if you think you got a surprise bill instead of paying it right away. 

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Written by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

Reviewed by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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