Acute pyelonephritis

This code represents an acute bacterial infection of the kidney and renal pelvis, often characterized by sudden onset of fever, flank pain, dysuria, and bacteriuria. It signifies an inflammatory process affecting the renal parenchyma and collecting system.

Use this code when documentation clearly indicates an acute infection of the kidney, such as "acute pyelonephritis," "acute kidney infection," or "acute pyelitis." Supporting documentation should include clinical findings like fever, CVA tenderness, and laboratory results consistent with infection (e.g., positive urine culture, elevated WBC count).

• Differentiate from chronic pyelonephritis (N11.-) which implies long-standing or recurrent infection with renal scarring.
• Always look for and code any associated urosepsis (A41.9) or septic shock (R65.20, R65.21) if documented.
• Specify laterality (e.g., N10.0 for unilateral, N10.9 for unspecified) if available in the medical record.