Inflammatory bowel disease (ulcerative colitis) Quiz: Ace Your Exams

A 38-year-old man with a history of moderate-to-severe ulcerative colitis presents to the emergency department due to a three day history of severe diffuse abdominal pain and six episodes of bloody diarrhea daily. Past medical history is otherwise unremarkable. Temperature is 37.8 °C (100.0°F), blood pressure is 98/76 mmHg, pulse is 122/min, respiratory rate is 20/min, and oxygen saturation is 98% on room air. The patient appears ill and dehydrated. Abdominal examination is notable for diffuse abdominal tenderness on palpation without guarding, rebound, or rigidity. Digital rectal exam is significant for bright red blood. Laboratory results are significant for a hemoglobin of 8.5 g/dL (reference range: 13.5-17.5 g/dL), thrombocytosis, and an elevated C-reactive protein level. Stool studies are sent for infectious etiologies including C. difficile. Abdominal x-ray is significant for colonic wall thickening and loss of haustrations. There is no colonic dilatation seen on imaging. Which of the following is the most appropriate initial step in the management of this patient?