What is Truelove-Witts criteria for acute severe ulcerative colitis?

Truelove–Witts criteria for acute severe ulcerative colitis:

According to the Truelove–Witts criteria, acute severe ulcerative colitis will be diagnosed if the following parameters are met:

• ≥ 6 bloody stools/24 hours plus one or more of:
• Anemia [Hb < 100 g/L (< 10 g/dL)]
• Fever [T ≥ 37.8°C]
• Tachycardia [HR ≥ 90 beats/min]
• High inflammatory markers [ESR > 30 mm/in first hour (or equivalent C-reactive protein)]

Pathology of ulcerative colitis. (A) Endoscopic view of severe ulcerative colitis with ulceration and adherent mucopurulent material. (B) Total colectomy with pancolitis showing active disease, with red, granular mucosa in the cecum (left) and smooth, atrophic mucosa distally (right). (C) Sharp demarcation between active ulcerative colitis (bottom) and normal (top). (D) This full-thickness histologic section shows that disease is limited to the mucosa.

Sources: 

• Davidsons Principles and Practice of Medicine 23 edition; page: 817; Box: 21.53
• Step Up to MRCP Review Note for Part I & Part II by Dr Khaled El Magraby; page: 311
• Robbins Basic Pathology 10th Edition; page: 625; Fig: 15.30 (image)