(1)   Post operatively it was noticed that a patient with diabetic nephropathy had blood urea nitrogen rapidly rising to 46mg/dL and creatinine to 3.4mg/dL. The most likely cause for this worsening is:

(a)    Hypotension during surgery

(b)   Hypertension during surgery

(c)    Uncontrolled sugars perioperatively

(d)   Prolonged urinary catheter preoperatively.

Answer: The answer is (a). The most common cause of worsening renal function post operatively is hypotension and hypoperfusion during surgery leading to acute tubular necrosis and acute renal failure. In this case it is likely to have precipitated an acute on chronic renal failure.