Your doctor suspects you have a kidney stone. Maybe you’ve been dealing with that sharp, cramping pain in your lower back or side, or perhaps you noticed some blood in your urine. Whatever brought you in, the next step your doctor will likely take is imaging and an X-ray is often one of the first tools they reach for.
If you’ve never been through this before, it’s completely normal to have questions. What exactly does an X-ray show? Will it hurt? Is it even the right test for kidney stones?
Can an X-Ray Actually Detect Kidney Stones?
Yes , but with an important caveat. A standard abdominal X-ray, often called a KUB (which stands for Kidneys, Ureters, and Bladder), can detect kidney stones, but only certain types.
About 80% of kidney stones are made of calcium oxalate or calcium phosphate. These calcium-based stones are dense enough to show up clearly on an X-ray as small, bright white spots. If your stone falls into this category, an X-ray can give your doctor a reasonably good picture of where it is and how large it is.
However, uric acid stones which make up roughly 5–10% of cases are not visible on a standard X-ray. They’re essentially transparent to X-ray beams. The same goes for certain other stone types like cystine or struvite, which may only show up faintly or not at all depending on their density.This is why your doctor may not stop at an X-ray alone.
What Happens During the X-Ray?
The procedure itself is quick and painless most people are in and out in under 10 minutes.
You’ll be asked to lie flat on an exam table or stand in front of an imaging plate. The technician will position the machine over your abdominal area and ask you to stay still and sometimes hold your breath for a second while the image is taken. That’s really it. No needles, no dye (unless your doctor orders a contrast study), and no discomfort beyond whatever pain you’re already dealing with from the stone itself.
The images are usually reviewed by a radiologist, and your doctor gets the results fairly quickly sometmthin the same appointment.
Why Your Doctor Might Order a CT Scan Instead
Here’s where things get a little more nuanced. While X-rays are a reasonable starting point, a low-dose CT scan (specifically a non-contrast CT of the abdomen and pelvis) has become the gold standard for diagnosing kidney stones. And for good reason.
CT scans can detect virtually all types of kidney stones regardless of their composition. They also give a much more precise picture of the stone’s exact location, size, and whether it’s causing any blockage in the urinary tract. This information matters a lot when deciding between watchful waiting, medication, or a procedure like lithotripsy.
So if your X-ray comes back inconclusive, or if your symptoms are severe, don’t be surprised if your doctor follows up with a CT scan. It’s not that something was missed it’s just that CT provides a fuller picture.
What Your Doctor Is Looking For
When reviewing your imaging, your doctor is trying to answer a few key questions. How big is the stone? Stones smaller than 5mm often pass on their own. Larger ones especially those above 10mm are much less likely to pass without intervention. Where exactly is it sitting? A stone stuck at the ureter junction causes far more symptoms than one still sitting quietly in the kidney. And is there any sign of infection or kidney damage? These are urgent concerns that change the treatment plan entirely.
After the X-Ray What Comes Next
Once the imaging confirms a kidney stone, your doctor will walk you through your options based on size, location, and how you’re feeling. Many smaller stones are managed with plenty of fluids, pain relief, and time. Larger or more stubborn stones may need shock wave therapy, ureteroscopy, or in rare cases, surgery.
The X-ray or CT is just the beginning of that conversation. It gives both you and your doctor something concrete to work with, which is always a good starting point.
If you’re experiencing severe pain, fever, or are unable to urinate, seek medical attention immediately don’t wait for a scheduled appointment.
