Kidney Sonogram

Kidneys (Renal) Sonogram

Renal ultrasound, a noninvasive diagnostic examination, utilizes sound waves to generate images of the kidneys and bladder. This procedure is safe, painless, and does not involve radiation exposure. In this article, we will discuss the various aspects of renal ultrasound, including its purpose, preparation, procedure, and results interpretation. We will also explore the benefits, risks, and limitations associated with this imaging technique.

Several Common Indications for the Exam:

  • Flank Pain
  • Urinary tract infections
  • Hematuria (blood in urine)
  • Abnormal blood tests

How to prepare for your exam. Read More →

Introduction to Renal Ultrasound

A renal ultrasound, is a medical examination that employs high-frequency sound waves to create real-time images of the kidneys and bladder. It allows doctors to diagnose and treat various urinary conditions without exposing the patient to radiation. During the exam, a small probe called a transducer is placed on the skin, along with a gel that facilitates the transmission of sound waves into the body. These sound waves bounce off internal structures, and the returning echoes are collected by the transducer. 

In some cases, a Doppler ultrasound exam may be included as part of a renal ultrasound. Doppler ultrasound is a specialized technique that assesses blood flow within the body. It enables doctors to evaluate blood circulation in the kidneys and detect any potential issues.

Common Uses of Renal Ultrasound

Physicians typically order renal ultrasounds to examine the kidneys and bladder for various reasons. Ultrasound imaging can help identify:

  • Abnormal kidney size or location
  • Indications of kidney injury or damage, including infection
  • Kidney stones, cysts, or tumors, and any potential blockages affecting normal drainage
  • Bladder issues, such as urinary retention (inability to fully empty the bladder during urination)

In addition, renal ultrasound can guide a doctor during a kidney biopsy by assisting with needle placement. Doppler ultrasound may also be used to evaluate uncontrolled high blood pressure that does not respond to medication and lifestyle modifications.

Preparing for a Renal Ultrasound

Before undergoing a renal ultrasound, your doctor will provide specific instructions. You may be asked to drink 24 ounces of water prior to the exam to enhance bladder imaging. Additionally, you might be instructed not to eat or drink for several hours before the examination. It is essential to follow these guidelines to ensure optimal results.

Patient Experience During and After Renal Ultrasound

Renal ultrasound exams are typically painless, quick, and well-tolerated by patients. During the procedure, the technologist may ask you to take deep breaths and hold them for a few seconds to obtain clear images of your kidneys. If a Doppler ultrasound exam is being performed, you may hear pulse-like sounds that change in pitch as the blood flow is monitored and measured.

If your bladder is being examined, you may need to empty it after images have been taken with a full bladder. Additional images may be captured to assess how well your bladder empties. Ultrasound exams generally last approximately 30-45 minutes, and patients can typically resume their normal activities immediately afterward.

Benefits and Risks of Renal Ultrasound


  • Renal ultrasound is noninvasive, with no needles or injections required.
  • It is widely available, easy to use, and more affordable than most other imaging methods.
  • Ultrasound is extremely safe and does not employ radiation.
  • It provides clear images of soft tissues, which may not be visible on X-ray images.
  • Real-time imaging capabilities make ultrasound an ideal tool for guiding minimally invasive procedures, such as needle biopsies and fluid aspiration.
  • Renal ultrasound can identify and evaluate various kidney disorders without X-ray exposure.
  • Although some patients may experience brief discomfort during the exam, it is generally not painful.


  • Standard diagnostic ultrasound has no known harmful effects on humans.


Renal ultrasound is a safe, noninvasive, and reliable imaging technique that allows doctors to diagnose and treat various urinary conditions without exposing patients to radiation. Although there are some limitations to this method, its benefits far outweigh the risks, making it an invaluable tool in the management of kidney and bladder health. By understanding the procedure, its uses, and its results, patients can make informed decisions about their renal health and work with their healthcare providers to create a personalized care plan.