kidney stone CT scan preparation

Overview

A CT scan (computed tomography) is an imaging test that uses X-rays to create detailed pictures of the inside of your body. For kidney stones, it helps doctors see if you have stones, how big they are, and exactly where they are located. The scan is quick and painless, and it often helps guide treatment decisions.

CT scans are a common and reliable way to diagnose kidney stones, especially when symptoms are severe or other tests are not clear.

Anyone who has symptoms that suggest kidney stones may need a CT scan. This includes adults of all ages, and sometimes children, though other imaging tests like ultrasound are often used first in younger people.

Symptoms

Common symptoms

• Severe pain in your side, back, or lower belly that may come and go
• Pain when you urinate
• Blood in your urine (pink, red, or brown)
• Needing to urinate more often

Symptoms in children

• Children may have belly pain, nausea, or fussiness that is hard to explain
• They may also have blood in their urine or trouble urinating

Symptoms in older adults

• Older adults might notice less typical pain, such as vague discomfort in the abdomen
• They may also feel confused or have a fever without clear pain

Causes

Main causes

• Not drinking enough water, leading to concentrated urine
• A diet high in salt, sugar, or certain foods (like spinach, beets, or nuts) that can form stones
• Medical conditions such as obesity, diabetes, or gout that affect how your body processes minerals

Risk factors

• Family history of kidney stones
• Dehydration, especially in hot climates or after exercise
• Certain medications like diuretics (water pills) or calcium-based antacids
• Prior kidney stones – they often come back

When to see a doctor

See a doctor urgently if:

• If you have severe pain that does not go away or comes in waves
• If you have a fever, chills, or nausea that makes it hard to keep fluids down
• If you notice blood in your urine for the first time

Book a routine appointment if:

• If you have mild to moderate pain that comes and goes
• If you have had a stone before and want to check for new ones

Diagnosis

To diagnose kidney stones, doctors often start with a physical exam, a urine test, and sometimes an ultrasound. If these do not give enough information, they may order a CT scan, which gives a very clear picture of the kidneys and urinary tract.

Tests that may be done

• CT scan (sometimes called a 'CAT scan') of the kidneys and bladder
• Urine test to check for blood, infection, or stone-forming minerals
• Ultrasound, which uses sound waves to see stones (often used first in children or pregnant women)

What to expect at your appointment

Before the CT scan, you may be asked to drink a contrast liquid that helps stones stand out on the images. You will lie on a table that slides into a large, round scanner. The machine will take pictures while you hold your breath for a few seconds. The whole scan usually takes less than 10 minutes, and you will not feel anything. You can go back to normal activities right after.

Treatment

Treatment for kidney stones depends on their size, location, and how much pain they cause. Small stones often pass on their own with the help of fluids and pain relief. Larger stones may need medical or surgical treatment.

Self-care at home

• Drink plenty of water – aim for 2 to 3 litres a day unless your doctor tells you otherwise
• Use over-the-counter pain relievers like paracetamol or ibuprofen (always follow the label and ask your doctor if you have other health conditions)
• Apply a warm compress to the painful area to help relax muscles

Medical treatments

If the stone does not pass on its own, doctors can use several approaches without naming specific drugs or brands. For example, they may use sound waves to break up the stone (lithotripsy), a thin scope to remove it (ureteroscopy), or a tube to drain urine from the kidney. Your doctor will discuss which option is best for you.

When is surgery considered?

Surgery may be needed for very large stones, stones that block urine flow, or if other treatments have not worked. The most common surgery is called percutaneous nephrolithotomy, where a small cut is made in the back to remove the stone.

Living with this condition

After a kidney stone, it is important to stay hydrated and watch for signs of new stones. Most people return to normal life quickly once the stone passes or is treated.

Lifestyle tips

• Drink enough water so that your urine is light yellow or clear
• Limit salty foods and eat a balanced diet that includes fruits, vegetables, and whole grains
• Stay active – regular exercise can help prevent stones

Diet and exercise

Cut back on foods high in oxalate (like spinach, rhubarb, and beets) if you have calcium oxalate stones. Also reduce salt, which can make it harder for your kidneys to process minerals. A moderate amount of calcium from food (like dairy) actually helps prevent stones – it is calcium supplements that may increase risk. Stay active with walking or other gentle exercise to keep your body healthy.

Mental health and emotional wellbeing

Having a kidney stone can be very painful and stressful, and some people worry about it coming back. It is normal to feel anxious or frustrated. Talk to your doctor about your concerns, and do not hesitate to seek support from loved ones or a mental health professional if needed.

Prevention

Yes, many kidney stones can be prevented by simple lifestyle changes. The most important step is to drink enough water throughout the day. Eating a healthy diet low in salt and animal protein also helps. If you have had a stone before, your doctor may suggest specific dietary changes based on the type of stone you had.

Complications

If left untreated

• A stone that blocks urine flow can cause a kidney infection (pyelonephritis), which can be serious
• Prolonged blockage can damage the kidney or lead to loss of function
• Stones that are not treated may get larger and harder to pass later

Long-term outlook

The outlook for kidney stones is very good. Most stones pass or can be treated without lasting harm. With proper prevention, many people never have another stone. If you have had one, staying hydrated and following a healthy lifestyle can help keep your kidneys working well for years to come.

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