Review Question - QID 109858

A 35-year-old man is found unconscious outside his home by a passing neighbor and is brought to the emergency department by ambulance. Cardio-pulmonary resuscitation is performed and the patient awakens but remains somnolent and confused. He is unable to answer questions or provide any medical history. His temperature is 98.2°F (36.8°C), blood pressure is 108/62 mmHg, pulse is 110/min and respirations are 20/min. He is somnolent and his pupils are round, symmetric, and reactive to light bilaterally. Fundoscopy is normal. The patient winces to palpation of the epigastric region and bilateral costovertebral angles. Initial labs are drawn and are shown below.

Serum:
Na+: 137 mEq/L
K+: 3.1 mEq/L
Cl-: 92 mEq/L
HCO3-: 6 mEq/L
BUN: 36 mg/dL
Glucose: 100 mg/dL
Creatinine: 1.7 mg/dL

Bladder catheterization is notable for mildly bloody urine and microscopic analysis is shown in Figure A. Which of the following is the most appropriate next step in management?