Post-Renal AKI (e.g., Obstruction)

Post-renal acute kidney injury (AKI) arises from obstruction to the urinary tract that impedes urine outflow from the kidneys. This obstruction can occur anywhere along the urinary pathway—from the renal pelvis to the urethra. Common causes include kidney stones, enlarged prostate (benign prostatic hyperplasia), urethral strictures, tumors, or external compression from surrounding structures.

The blockage leads to increased hydrostatic pressure within the urinary tract, which in turn reduces the glomerular filtration rate (GFR), causing the accumulation of waste products like urea and creatinine in the bloodstream. Clinically, patients may present with flank pain, reduced urine output, hematuria, or a palpable bladder if the obstruction is lower.

Diagnosis involves imaging techniques such as ultrasound or CT scans, which help identify the site and cause of obstruction. Laboratory findings reveal elevated serum creatinine and blood urea nitrogen (BUN) levels.

Prompt intervention is crucial to prevent permanent kidney damage. Treatment includes relieving the obstruction through catheterization, stent placement, or surgical correction, depending on the underlying cause. With timely management, kidney function often recovers completely, highlighting the importance of early recognition and intervention in post-renal AKI.