Unilateral small kidney

This code represents a congenital or acquired condition where one kidney is abnormally small in size. This can be due to hypoplasia (underdevelopment) or atrophy (wasting away) of the renal tissue, affecting only one side of the body.

Use this code when documentation clearly indicates a diagnosis of a small kidney affecting only one side. This diagnosis is often made based on imaging studies such as ultrasound, CT, or MRI, which measure kidney dimensions and assess renal parenchyma.

• Ensure documentation specifies "unilateral" to differentiate from bilateral involvement.
• Do not use for general kidney atrophy without explicit mention of small size.
• Consider additional codes for the underlying cause of the small kidney, if known (e.g., renal artery stenosis, chronic pyelonephritis).