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Ultrasound signs of normal kidney and ureters
Last reviewed: 04.07.2025
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Ultrasound signs of a normal kidney
Measurements taken during ultrasound examination generally have lower values than the same parameters obtained during radiography: they are more accurate.
Both kidneys should be approximately the same size in adults; a difference in kidney length of more than 2 cm is pathological.
- Length: up to 12 cm and not less than 9 cm.
- Width: A width of 4-6 cm is considered normal, but may vary slightly depending on the scanning plane.
- Thickness: up to 3.5 cm, but may vary slightly depending on the scanning plane.
- The central echo complex (renal sinus) has high echogenicity and normally occupies about 1/3 of the kidney. (The renal sinus includes the pelvis, calyces, vessels and fat.)
In newborns, the kidneys are 4 cm long and 2 cm wide.
The renal pyramids are hypoechoic zones with unclear boundaries: in the projection of the medullary layer, the pyramids are surrounded by a more echogenic renal cortex. It is easier to visualize the pyramids in children and young adults.
When examining the kidneys, the following structures must be identified:
- Renal capsule. It is visualized as a bright, smooth echogenic line around the kidney.
- Cortex. It is slightly less echogenic than the liver, but more echogenic than the adjacent renal pyramids.
- Medullary layer: It contains hypoechoic renal pyramids that can be mistaken for renal cysts.
- Renal sinus (fatty tissue, collecting system and vessels of the renal hilum). This is the internal part of the kidney, it has high echogenicity.
- Ureters. Normal ureters are not always visible: one can only guess where they exit the kidney in the hilum. They can be single or multiple, often visualized in the frontal section.
- Renal arteries and veins. They are best visualized in the hilum area. They may be multiple and may enter the kidney at different levels.
Warning: Renal pyramids may be mistaken for renal cysts and tumors. Adjust the sensitivity level of the device.
Ultrasound signs of the adrenal glands
The adrenal glands are not easily visualized with ultrasound. The best position is with the patient supine, scanning as for the inferior vena cava and the patient lying on the side (this produces frontal plane views). The adrenal glands are superior and medial to the kidneys. If they are visualized, they are most likely pathologically enlarged, except in infants.