Skip to Main Content


The urinary system is very amenable to imaging with ultrasound. The liver and spleen provide windows through which the kidneys can be visualized. The bladder is located directly behind the pubic symphysis and is readily seen from the suprapubic approach, particularly when full. Ultrasound of the kidneys and bladder can play a vital role in the effective management of patients in the emergent and critical care setting. Focused renal and urinary ultrasound can determine the presence of hydronephrosis, directly visualize stones, and measure bladder volume. Ultrasound easily identifies renal cysts, and may identify masses or clots in the kidneys or bladder. Ultrasound may guide urinary procedures such as ensuring correct Foley catheter placement, and suprapubic bladder aspiration.


Focused renal ultrasound should be incorporated into the examination of any patient with undifferentiated flank or abdominal pain. Ureteral stones can be difficult to visualize because they are retroperitoneal, but the presence of hydronephrosis on the side of the pain is very specific for ureterolithiasis as the cause of the patient's symptoms. Patients with abdominal, back, or flank pain may also have more serious diagnoses such as abdominal aortic aneurysm or dissection, cholecystitis, ovarian torsion, ruptured ectopic pregnancy, and others. Bedside ultrasound may be helpful in diagnosing other causes of pain although other imaging modalities such as consultant-performed ultrasound or CT may be required if the diagnosis remains uncertain.


Bedside ultrasound evaluation of the urinary system should be performed in patients presenting with the following:


  • Acute renal failure
  • Abdominal pain or flank pain suspicious for renal colic
  • Back, abdominal, or pelvic pain of uncertain cause
  • Urinary retention
  • Palpable abdominal or flank mass
  • Renal trauma
  • Gross hematuria


Curvilinear Probe with a Frequency of 3.0–5.0 MHz


When imaging the kidneys and bladder, the curvilinear probe with a frequency of 3.0–5.0 MHz should be utilized. Alternatively, a phased-array probe with a frequency of 2.0–4.0 MHz can be used to visualize the kidneys through the intercostal spaces. Lower frequencies, which improve penetration, can provide better visualization in obese patients.


Tissue Harmonic Imaging


Another ultrasound machine setting that can be of particular use in renal imaging is tissue harmonics. Renal stones, which are often made up of calcium, block the penetration of the ultrasound beam and produce an acoustic shadow. Tissue harmonics enhance acoustic shadowing and may improve the identification of nephrolithiasis.




The sonographer should start with adequate depth in order to not miss abnormalities in the far field. This is important for findings such as free fluid around the bladder, which is easily missed if subtle. Once the far field is fully interrogated, the depth can be decreased in order to make sure the kidneys or bladder are taking up most of the screen.


Gain and Time-Gain Compensation


The overall gain can be adjusted in order to ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.


Create a Free MyAccess Profile

* Required Fields

Note: If you have registered for a MyAccess profile on any of the Access sites, you can use the same MyAccess login credentials across all sites.

Passwords must be between 6 and 40 characters long (no whitespace), cannot contain characters #, &, and must contain:
  • at least one lowercase letter
  • at least one uppercase letter
  • at least one digit

Benefits of a MyAccess Profile:

  • Remote access to the site off-campus on any device
  • Notification of new content via custom alerts
  • Bookmark your favorite content such as chapters, figures, tables, videos, cases and more
  • Save and download images to PowerPoint
  • Self-Assessment quizzes saved for quick review
  • Custom Curriculum access for both instructors and learners

Subscription Options

AccessAnesthesiology Full Site: One-Year Subscription

Connect to the full suite of AccessAnesthesiology content and resources including procedural videos, interactive self-assessment, real-life cases, 20+ textbooks, and more

$995 USD
Buy Now

Pay Per View: Timed Access to all of AccessAnesthesiology

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.