Postoperative oliguria: cause

Prerenal

• Hypovolemia
• Low renal blood flow (hypotension, low cardiac output, excess renal vascular resistance due to high SVR or renal clot, dissection, etc.)
• Intraabdominal hypertension (high CVP decreases the pressure gradient across the kidneys)

Renal

• Acute tubular necrosis
• Contrast dye
• Tumor lysis
• Myoglobin
• Hemoglobin

Postrenal

• Obstruction of the ureters or urethra
• Catheter dysfunction