Approach to postoperative acute kidney injury Quiz: Ace Your Exams

A 65-year-old man presents to the emergency department for lower abdominal pain and distension, and difficulty urinating. Two days prior he had knee replacement surgery. After the surgery, a foley catheter was placed and left for two days due to difficulty voiding. He was able to void without the foley catheter prior to discharge. The patient states that he usually wakes up 4 or 5 times during the night to urinate but has not been able to pass urine for over 24 hours since returning home. Past medical history includes hypertension and type 2 diabetes mellitus, managed with lisinopril and metformin. Temperature is 37.2°C (100.2°F), heart rate is 90/min, blood pressure is 139/85 mm Hg, respiratory rate is 18/min, and oxygen saturation is 97% on room air. Physical examination is significant for diffuse abdominal tenderness and distension. There is questionable right costovertebral angle tenderness. Digital rectal exam is significant for a boggy enlarged prostate. Laboratory evaluation is significant for a serum creatinine of 2.9 mg/dL, increased from a baseline of 0.9 mg/dL, and blood urea nitrogen of 45 mg/dL. White blood count is slightly elevated and urinalysis shows leukocytes and trace blood and is negative nitrates and leukocyte esterase. A foley catheter is placed with minimal urine output. Which of the following is the best next step in management?