Kidney ultrasound is a fast, safe way to check kidney size, blockage, stones, and bladder volume at the bedside. This guide gives seven clear, practical steps to improve your scans, plus common pitfalls, measurement tips, and when to get further imaging or help from SonoCare Ultrasound Scan Centre.
For a kidney ultrasound, use either a curvilinear (abdominal) probe or a phased array (cardiac) probe. The curvilinear probe gives a wider field and deeper penetration. The phased array probe fits between ribs and is useful when rib spaces are narrow. Set the machine to abdominal mode for optimal depth and gain. Keep frequency lower for deep patients and raise it for thin patients to improve resolution.
Have the patient lie flat with the arm on the scanned side raised above the head. This opens rib spaces and helps reach the retroperitoneal kidneys. For the right kidney, scan a little lower because it sits under the liver. For harder-to-see kidneys, try slight lateral decubitus or ask the patient to take a deep breath and hold to move the liver or spleen out of the way.
Orient the probe so the marker points toward the patient's head on longitudinal views. Scan in the mid to posterior axillary line around the 8th to 10th intercostal space. Identify the liver or spleen as anterior landmarks and Morrison pouch (hepatorenal recess) on the right. The cortex is the darker rim and the central sinus is echogenic. Consistent orientation reduces confusion when comparing sides.
Start with a longitudinal view to see the full kidney length and medullary pyramids. Then rotate 90 degrees for a transverse cross-section to measure width and assess the parenchyma. Sweep from superior to inferior and angle posteriorly to include the full pole-to-pole length. Save representative images: one long axis and one short axis for each kidney.
Normal adult kidney length is about 9 to 13 centimeters. A difference greater than 2 centimeters between sides is notable. Measure the longest pole-to-pole length on a longitudinal image and the greatest width on transverse views. For bladder volume use three dimensions: width, length, and height, then apply the formula bladder volume = 0.53 × width × length × height. Record measurements in cubic centimeters or milliliters.
Hydronephrosis shows as anechoic (black) dilation in the central sinus where the pelvis and calyces are. It ranges from mild calyceal separation to severe dilation that replaces most renal parenchyma. Stones are often bright echoes with an acoustic shadow behind them. Cysts are round, anechoic structures with well-defined walls and posterior enhancement. Document presence and degree of hydronephrosis and any shadowing that suggests a stone.
Common mistakes include misidentifying prominent renal sinus fat as pathology, missing hydronephrosis when only a single plane is scanned, and overcalling small echogenic foci as stones when they are vascular calcifications. If kidney size is small and echogenic, consider chronic kidney disease and recommend formal imaging or nephrology input. If point of care images show severe hydronephrosis, large bladder retention, or an unclear mass, escalate to SonoCare Ultrasound Scan Centre or radiology for full evaluation and Doppler studies.
Refer for a full renal ultrasound or CT when you find any of the following:
SonoCare Ultrasound Scan Centre offers formal renal ultrasound with expert sonographers and radiologist reporting if you need higher-resolution imaging or same-day scans. For urgent cases, contact SonoCare to arrange rapid assessment and follow-up.
SonoCare Ultrasound Scan Centre provides fast, reliable renal and bladder ultrasound services for patients and clinicians. Services include high-resolution imaging, expert sonographers, formal radiology reports, and same-day appointments for urgent cases. If bedside kidney ultrasound raises uncertainty, SonoCare can confirm findings, perform Doppler studies, and advise on next steps.
Kidney ultrasound can detect stones that are large or located in the renal pelvis, especially if they cast a clear shadow. Small stones and ureteric stones are often missed. CT remains the most sensitive test for suspected acute ureteric stones.
Normal adult kidney length is usually 9 to 13 centimeters and width 4 to 6 centimeters. A size difference greater than 2 centimeters between kidneys is significant and should prompt further evaluation.
Measure bladder width, length, and height on ultrasound. Apply the formula: bladder volume = 0.53 × width × length × height. Record the result in milliliters. This estimate guides decisions about catheterization for retention.
Severe hydronephrosis with acute kidney injury, uncontrolled pain, fever, or suspected obstructing stone often requires urgent urology or radiology referral. Mild hydronephrosis without symptoms can be followed with imaging and outpatient care.
Bedside kidney ultrasound is a valuable screening tool but does not replace formal imaging when detailed anatomy, Doppler, or definitive stone diagnosis is needed. Use it to triage, guide management, and decide on the need for referral to facilities like SonoCare Ultrasound Scan Centre.
Kidney ultrasound is an effective first-line tool for evaluating kidney size, hydronephrosis, stones, and bladder volume. Use the right probe, proper patient position, and both longitudinal and transverse views. Measure carefully, watch for common errors, and escalate when findings are severe or unclear. For confirmatory imaging and expert reports, SonoCare Ultrasound Scan Centre offers rapid, high-quality renal and bladder ultrasound services.
Japan