A 23-year-old woman presents to the clinic complaining of bloody diarrhea, abdominal pain, and urgency that has progressively worsened over the past 6 weeks. She reports passing 5 loose, bloody stools per day, accompanied by crampy left lower quadrant abdominal pain that is partially relieved by defecation. She also notes a constant feeling of needing to pass stool. She denies any recent travel, sick contacts, or the use of antibiotics or nonsteroidal anti-inflammatory drugs. Her medical history is unremarkable. She is a non-smoker and works as a graphic designer. She takes no medications and has no known drug allergies.

She appears fatigued but is in no acute distress. She is afebrile. Her blood pressure is 112/72 mmHg, with a heart rate of 86 bpm and a respiratory rate of 14 breaths per minute.