Ultrasounds for Kidney Stone Detection

Kidney stones (also called renal stones) are estimated to affect one in ten people during their lifetime. The risk is about 9% for those assigned female at birth and 11% for those assigned male. These “stones” are actually crystals, formed from various materials or minerals, and found within the kidneys.

Even small kidney stones can be very painful when they pass from the kidneys through the urinary system, which is why some patients with this condition end up in the ER for treatment. This article will discuss how and why kidney stones form, who is at higher risk for developing them and how ultrasounds are used for diagnosing this condition.

 

What is a kidney stone?

A kidney stone forms from chemicals found within the patient’s urine, crystallizing into a stone-like formation that can often be jagged and sharp. There are different types of chemicals and substances that make up these stones and therefore different categories of kidney stones. Stones can range in size from as tiny as a grain of sand to as large as a golf ball, though this is rare. Technical names for these stones include nephrolithiasis or renal calculi.

Many patients may not even know they have a stone, as how symptomatic they become often depends on the stone’s size and location.. Some very small stones may move from the kidney and through the urinary tract without incident, being eliminated through the urine without the patient even realizing it. The sensation of discomfort with kidney stones commonly occurs when a larger stone moves through or gets trapped in the patient’s ureter, which is the tube that connects the kidney to the bladder and is how urine moves through the body.

Some stones may pass quickly, while others may take weeks to exit the body. Even small ones may create a great deal of discomfort, with severe pain and nausea frequently accompanying this condition. Because of this, it may be recommended that patients experiencing kidney stones consider seeking medical treatment.

 

 

What are the types of kidney stones?

There are four primary classifications of kidney stones, which vary depending on their chemical and mineral makeup:

• Uric acid stones: A common variant, this is often caused by eating animal proteins such as poultry, eggs, beef, fish and other such products. These foods contain purines, which are broken down by the body, producing uric acid, a waste product in the blood. If uric acid levels are too elevated, this type of stone may form.
• Calcium oxalate stones: This is the most common kidney stone variant and is caused when the substance oxalate (found in foods such as spinach and almonds) combines with calcium. Too much oxalate or not enough urine (such as from not drinking enough liquids) can cause these stones to form.
• Cystine stones: This type of variant tends to be hereditary, caused by a rare condition known as cystinuria. The disease causes the amino acid, cystine, to enter the urine, forming stones when concentrations get too high. Many patients with this condition have recurring kidney stones.
• Struvite stones: These are less common variants and often form due to urinary tract infections, which create struvite-producing bacteria due to the unnaturally alkaline conditions. Repeat infections can cause a very large stone, called a staghorn calculus, to form. This often requires surgical removal.

 

What causes kidney stones?

When there are too many minerals or chemicals in the urine and insufficient liquid to balance it out, crystals can form. These crystals may pick up other elements and become larger. For most people, these crystallizations don’t grow large enough to be noticed or are removed through urine flow.

Patients with larger crystals and insufficient liquid to eliminate them are more prone to stones. If the stone exits the kidney and moves through the urinary tract, it may get stuck, which is when kidney stone pain typically occurs.

 

What are the symptoms of a kidney stone?

Common symptoms of kidney stones may include:

• Blood in the urine or urine that appears cloudy
• Nausea and vomiting
• Chills and fever
• Pain with urination and/or frequent urination
• Severe pain on the side, abdomen or lower back

If the ureter gets blocked and urine can’t pass, it can lead to significant pain and pelvic pressure. Patients with urine blockage should seek medical attention.

It’s important to note that the presence of these symptoms doesn’t necessarily mean someone has a kidney stone, as there are many other conditions with similar symptoms. It’s a good idea to discuss any such issues with your doctor so they can investigate the diagnosis and next steps.

 

How are kidney stones diagnosed?

Here is a brief overview of common methods to diagnose kidney stones.

Urine and blood testing

While an imaging test is one of the first diagnostic steps, urine and blood tests are also common. These tests check for imbalances in the blood, such as uric acid or electrolyte levels. A urinalysis is also used to assess signs of infection, such as red blood cells, or to look for crystals.

CT scan

While this article primarily focuses on renal ultrasounds, computed tomography (CT) scans are also widely used for kidney stone detection. This technique uses low-dose X-ray technology to create images of internal structures, such as the ureters, kidneys and bladder. Unlike a standard X-ray, CT scans create several cross-sectional views, called slices, which are then combined to form more detailed images. They are very useful for determining the location and size of the renal stone, as well as evaluating the kidney and ureter for inflammation.

Ultrasound

A kidney stone renal ultrasound is also commonly used for diagnosis. This noninvasive imaging method uses high-frequency sound waves that bounce off organs and internal structures, echoing back to form images that can be captured and studied, such as to check for the presence of a kidney stone. While a CT scan may show a little more detail, a renal ultrasound is also commonly used. This is partly because ultrasounds are easier to schedule, less expensive for the patient and still a very effective way to diagnose stones.

Another reason for choosing ultrasounds over CT scans is that CT scans expose the patient to a small amount of radiation. While this exposure is low and considered safe, many physicians advise against unnecessary repeat exposure when possible. This means that if a patient has recurring kidney stones, such as cystine stones, repeat imaging will typically be done using a non-X-ray method, like a renal ultrasound.

 

How is an ultrasound for kidney stone detection performed?

Here are some steps to expect for a kidney stone ultrasound procedure:

1. Most abdominal or renal ultrasounds require the patient to arrive with a full bladder, when possible. This improves sound wave transmission and helps lift organs into better viewing angles.
2. You will be asked to lie on the exam table while a conductive gel is applied to the skin over your kidneys. A handheld device called a transducer is used to create the sound waves for the ultrasound. The ultrasound technician will slowly move it across the kidney region, capturing images.
3. You will likely be asked to hold your breath for short periods of time, as it can help obtain specific views. You may also be asked to adjust your position for similar reasons.
4. Many ultrasounds involving the kidney and bladder will have you empty your bladder halfway through the appointment, then return afterward for additional imaging. This allows the doctor to assess your urinary system with and without a full bladder.
5. After the scan, you may return to your usual activities.

 

How to prepare for a kidney stone ultrasound

Here are some tips that may help you prepare for an ultrasound for kidney stone detection:

• If you’re especially nauseous, consider informing your doctor in advance: Nausea and vomiting are common, and some patients may find it difficult to drink enough water for a full bladder. It may be helpful to let your doctor or the ultrasound facility know in advance so that possible solutions can be discussed.
• Bring your requisition or ultrasound orders: The imaging clinic may already have these, but it could save you time at check-in if they don’t.
• Bring your health card or insurance card: Additionally, bring your identification, as this is commonly required.
• Review any preparatory instructions in advance: Examples include full bladder preparation or directions to the facility.
• Wear a two-piece outfit: Some ultrasound facilities may require a hospital gown for the scan. However, most will simply adjust the patient’s shirt to access the kidney area. Wearing something comfortable is also helpful, and it’s best to avoid wearing metallic items if possible.

 

Getting your results

Turnaround times for imaging results can vary widely depending on the facility and your doctor’s availability. Often, patients wait a week or more and receive their results during a follow-up appointment. With PocketHealth, you don’t have to wait as long—your results are securely accessible as soon as the report is available, allowing you to review them often before your follow-up visit.

Your imaging results are interpreted by a radiologist—an expert in medical imaging—who carefully reviews your ultrasound and provides a detailed report of any findings. This report is then sent to your referring doctor, who, with a deeper understanding of your medical history, can offer further insights and recommendations.

To better understand your imaging reports, Report Reader provides clear, straightforward definitions for medical terms. Simply tap or click on any underlined words to reveal their meaning. This is paired with illustrations and highlights of anatomy in your imaging to help you better understand your results and prepare for follow-up appointments.

 

 

What do abnormal results look like on a kidney stone ultrasound?

Some abnormal results that may suggest the presence of a stone include:

• Renal calculus: This is another term for a kidney stone.
• Measurements and location: If a stone is detected, the ultrasound will likely provide an estimate of its size and location within the ureter.
• Hydronephrosis: This term refers to swelling in the kidney and ureter, which can occur if a kidney stone obstructs normal urine flow. The scan results may indicate whether the swelling is mild, moderate or severe.
• Hyperechoic: Hyperechoic is an imaging term indicating that the stone appears brighter or white on the ultrasound compared to the surrounding areas. This means it is producing many echoes and reflecting more sound waves. This specification helps categorize certain findings, such as renal stones.

 

Frequently asked questions

Here are some common questions regarding kidney stones and diagnostic ultrasounds.

What are the risk factors for kidney stones?

There are many factors that may increase the risk of developing kidney stones for some patients, including:

• Eating excess protein-rich foods and animal products
• Regular use of vitamin C supplements
• A diet high in sugars and sodium
• Not drinking enough liquids
• A family history of renal stones
• Intestinal or stomach surgeries, such as gastric bypass
• Some medications, such as calcium-based antacids or anti-seizure medications
• Underlying health conditions, such as diabetes, cystic fibrosis, gout and more

Can kidney stones cause complications?

While many patients experiencing kidney stones have no lasting issues after they pass, there are some cases where complications may occur, such as:

• Hydronephrosis: When the renal stone blocks the ureter, it can cause urine to build up in the kidney, leading to inflammation and swelling.
• Urinary tract infections: UTIs may occur as a result of a kidney stone.
• Kidney infections: Also called pyelonephritis, symptoms include fever, chills and back/side pain.
• Chronic kidney disease (CKD): Chronic kidney disease occurs when there is permanent kidney damage due to various underlying conditions, including recurring kidney stones that may have caused kidney damage by obstructing the ureter. Fortunately, this is uncommon.

How accurate is an ultrasound for kidney stones?

While a kidney stone ultrasound procedure may not be quite as detailed as a CT scan, it is still a valuable and accurate method to detect stones and assess the ureters, bladder and kidneys.

Are kidney stone ultrasounds safe?

An ultrasound for kidney stone detection is considered a safe procedure with no radiation exposure or invasive methods. Some patients may find having a full bladder for the appointment uncomfortable, especially if they are already experiencing pain or discomfort. In these cases, discussing options with your doctor or the imaging technician may provide alternatives.

 

Take control of your health with PocketHealth

PocketHealth makes it simple to keep track of your kidney scans. All of your vital imaging is in one secure location and can be accessed online anytime. Reports can also be easily shared with other physicians in your care team, if needed. Additionally, it makes it easy to track health changes over time, such as with repeat imaging like ultrasounds. When used in conjunction with your medical provider’s professional advice, it is a powerful tool for organizing and understanding your imaging results and your health.

PocketHealth MyCare Navigator gives personalized insights into your health and identifies any recommended follow-up steps. This feature can also generate individualized questions to ask your doctor based on the findings in your report, ensuring you make the most of your consultation. A kidney stone diagnosis may feel overwhelming, but working closely with your providers can give you the best chance of managing your condition and protecting your kidney health.