This document provides guidance on performing an ultrasound examination of the kidneys. It describes scanning the kidneys longitudinally and transversely to visualize the anatomy. Key aspects to assess include cortical echogenicity compared to the liver, presence of hypoechoic renal pyramids, and a smooth kidney surface. Proper patient preparation and transducer positioning are outlined. Common renal pathologies and anatomical variants that may be identified on ultrasound are also discussed.

1. USG EXAMINATION
TECHNIQUES of KIDNEY
JUSTIN JAMES

3. Longitudinal Plane Transverse Plane

5. A comprehensive examination of the renal tracts include assessment of the urinary
bladder and, in males, the prostate. The patient should fast a minimum of 6 hours.
• Longitudinally, scan along the subcostal region. Visualize the kidney inferior to the right
lobe of the liver (RT), or spleen (LT).
• Transverse. Scan from beyond the superior margin to inferior.
• Place the probe between iliac crest and the lower costal margin to examine in the
coronal plane
Upper pole of each kidney is best visualised using a high posterior intercostal approach.
Lower poles using a subcostal approach usually during a deep inspiration.
Location of transducer must be varied from anterior to lateral to posterior and the patients
position varied from supine to decubitus position.
If the kidney is obscured by the ribs,
1. Ask the patient to hold the hands above head
2. Lie on their side
3. Holld inspiration

6. • Cortical echogenicity is equal to or slightly less than that of the liver, and
substantially less than that of the spleen. Homogenous, except that of hypoechoic
pyramids.
• Pyramids are cone shaped hypoechoic structure.
• Cortex is slightly more echogenic than the pyramids
• Renal sinus is hyperechoic
• Surface smooth

7. Basic Hardcopy Imaging:
A renal series should include the following minimum images:
•Both kidneys with length measurements
•Right kidney along with liver for comparison
•Left kidney along with spleen for comparison
•Both kidneys transverse
• superior
• middle
• inferior
•Document the normal anatomy. Any pathology found in 2 planes, including measurements and any vascularity.

8. Patient preparation :
Begin with the patient supine. Each kidney may also need to be examined in the decubitus
position. Raise the ipsilateral arm above the patient’s head.
Role of Ultrasound
To identify the cause of:
•Flank pain
•Haematuria (frank or microscopic)
•Follow-up of previously identified pathology
•Classification of a mass (Solid V’s cystic)
•Post surgical complications
•Guidance of aspiration, biopsy or intervention
•Post injury
Limitations
• The mid to distal ureter is generally obscured by bowel gas.
• Small lesions at the upper pole of the kidney may be difficult to see due to refractive
edge shadowing.

9. Patient Preparation
Begin with the patient supine. Each kidney may also need to be examined in decubitus position. Raise the
ipsilateral arm above the patient’s head.
Equipment setup
• Highest frequency curved linear array probe possible. Start with 7MHz and work down to 2 or 3 for larger
patients.
• Pediatric and thin patients should be scanned with a higher frequency probe.
• Good color / power / Doppler capabilities when assessing vessels or vascularity of a structure.
What to Check ?
•Kidney size (should not be >1cm difference between sides)
•Cortico-medullary differentiation
•Cortex at least as hypoechoic as the liver
•Pyramids slightly hypoechoic relative to the cortex
•No Hydronephrosis
•Cortical thickness(not <10mm)
•Renal scarring(beware mistaking prominent lobulations as scars)

10. Common Pathology :
•Calculus
•Renal cyst
•Angiomyolipma
•Renal cell carcinoma
•Hydronephrosis
•Medullary sponge kidney
•Polycystic kidney disease

11. Anatomical Variants
Horse shoe kidney
A transverse ultrasound view across the midline
Longitudinal sagittal ultrasound view

12. Crossed ectopic kidney. The left kidney is fused to the
lower pole of the right kidney.

13. “baggy” extra-renal pelvis

14. An absent left kidney indicating agenesis and the right kidney is present and enlarged due to compensatory hypertrophy.

15. Fused pelvic kidney / ''cake kidney''

16. References :
1. RUMACK’s DIAGNOSTIC ULTRASOUND
2. Ultrasound teaching manual - Hoffer
3. https://ultrasoundpaedia.com/kidney-normal/