Hydronephrosis

This code signifies the swelling of a kidney due to a build-up of urine, typically caused by an obstruction in the urinary tract. The accumulation of urine leads to distension and dilation of the renal pelvis and calyces, potentially impairing kidney function.

Apply this code when documentation clearly indicates the diagnosis of hydronephrosis, regardless of the underlying cause. This includes cases identified via imaging studies such as ultrasound, CT, or MRI showing renal pelvic and calycal dilation.

• Always attempt to code the underlying cause of the hydronephrosis if known and documented (e.g., ureteral calculus, stricture, tumor).
• Distinguish from hydroureter, which refers to dilation of the ureter; hydronephrosis specifically involves the kidney.
• Review imaging reports and physician notes for laterality (unilateral or bilateral) if specified, though this code does not differentiate.