Final answer:
The nurse should prioritize D. measuring the urinary output to assess for potential postoperative complications related to renal function and to maintain homeostasis.
Step-by-step explanation:
The nurse should first D. measure the urinary output. This is imperative given the report of decreased urinary output after surgery, which may indicate a potential postoperative complication such as bleeding or urinary retention.
Immediate assessment and quantification of urinary output can provide critical information concerning renal function and fluid balance.
A saturated perineal pad could be a sign of hemorrhage, making it essential to correlate with the urinary output and determine the source of excessive bleeding.
Ensuring adequate urinary output is crucial for preventing renal complications and maintaining homeostasis post surgery.