Situation: A 32-year-old woman with ulcerative colitis is admitted for a flare. She has 8 bloody stools a day, a temperature of 38.2 °C, a heart rate of 104/min, and a hemoglobin of 9.8 g/dL (98 g/L). Stool tests for Clostridioides difficile and other pathogens are pending. How should the nurse classify the severity of this flare?

By the Truelove and Witts criteria, a flare is severe when there are 6 or more bloody stools a day plus at least one sign of systemic toxicity: heart rate over 90/min, temperature over 37.8 °C, hemoglobin below 10.5 g/dL (105 g/L), or raised inflammatory markers. She meets the stool count and has three toxicity signs. None of the thresholds in the other options apply.

Severity classification in ulcerative colitis flare

The correct classification is severe, based on the Truelove and Witts criteria. These criteria define a severe flare as the presence of 6 or more bloody stools per day plus at least one sign of systemic toxicity. This patient has 8 bloody stools daily, which already meets the stool-count threshold, and she also demonstrates three additional markers of systemic toxicity: fever of 38.2 °C (above the 37.8 °C threshold), tachycardia at 104/min (above the 90/min threshold), and hemoglobin of 9.8 g/dL (below the 10.5 g/dL threshold). The combination of a high stool frequency with any systemic toxicity sign places the flare in the severe category, not moderate.

The distractors in the other options reflect incorrect thresholds or irrelevant parameters. A temperature below 38.5 °C does not make the flare moderate, because the Truelove and Witts criterion for fever is 37.8 °C, not 38.5 °C. Similarly, a hemoglobin above 8 g/dL is not a valid cutoff for severity classification; the criterion is a hemoglobin below 10.5 g/dL. Blood pressure is not part of the Truelove and Witts severity criteria, so a normal blood pressure does not downgrade the classification.

Key point! The Truelove and Witts criteria use a two-part structure: a stool-frequency threshold plus any one systemic toxicity marker. Meeting the stool count alone is not enough; the systemic sign is what moves the classification from moderate to severe.

The pediatric literature reinforces the same conceptual framework. In children, severe disease is defined by a Pediatric Ulcerative Colitis Activity Index above 65 and/or 6 or more bloody stools per day, plus at least one of the following: tachycardia, fever, anemia, or elevated erythrocyte sedimentation rate, with or without systemic toxicity ^[3]. This mirrors the adult criteria and confirms that the combination of stool frequency and systemic signs is the core of severity assessment.

The clinical significance of correctly identifying severe disease is substantial. Acute severe ulcerative colitis is a life-threatening gastroenterological emergency requiring urgent intervention and close monitoring for therapeutic response. Approximately 30% of patients with acute severe ulcerative colitis do not respond to corticosteroids and require rescue therapy . Early identification of severe disease allows timely escalation of treatment, which is critical because delayed recognition increases the risk of colectomy and other complications .

Severity marker	Truelove and Witts threshold	This patient	Meets criterion?
Bloody stools per day	6 or more	8	Yes
Heart rate	Over 90/min	104/min	Yes
Temperature	Over 37.8 °C	38.2 °C	Yes
Hemoglobin	Below 10.5 g/dL	9.8 g/dL	Yes

Watch out! Do not wait for all toxicity markers to be present before classifying as severe. The criteria require the stool count plus only one systemic sign. This patient has three systemic signs in addition to the stool count, making the severe classification unambiguous.

The pending stool tests for Clostridioides difficile and other pathogens do not affect the severity classification. Infectious colitis can coexist with or mimic a UC flare, and identifying an infectious trigger is important for treatment planning, but the severity of the current presentation is determined by the clinical criteria, not by the pending microbiology results. Severity classification guides the intensity of initial management, including intravenous corticosteroids and consideration of rescue therapy, while pathogen testing guides additional antimicrobial treatment if indicated.