Gastrointestinal and hepatology · Moderate
This case is fictional and exists for study. It describes no real patient.
24 years · female
A 24-year-old female presents to the emergency department with a 2-week history of worsening bloody diarrhoea, opening her bowels 8 to 10 times daily. She reports crampy lower abdominal pain, rectal tenesmus, malaise, and an unintentional weight loss of 3 kg over the past month. She has no significant past medical history and takes no regular medications. On physical examination, she appears pale and acutely unwell. Abdominal examination reveals mild, diffuse lower abdominal tenderness without guarding or rebound tenderness. Digital rectal examination demonstrates mucous and frank blood in the rectal vault. Stool microscopy is negative for ova, cysts, and parasites.
Vital signs
- HR
- 102 bpm
- BP
- 110/70 mmHg
- RR
- 18/min
- Temp
- 38.1 °C
- SpO₂
- 98%
Examination findings
- Pale conjunctivae and dry mucous membranes
- Mild diffuse lower abdominal tenderness without peritoneal signs
- Frank blood and mucous present on digital rectal exam
Investigations
| Haemoglobin | 9.8 g/dL | reference: 12.0-15.5 |
| White blood cell count | 13.5 10^9/L | reference: 4.0-11.0 |
| Platelets | 450 10^9/L | reference: 150-400 |
| C-reactive protein (CRP) | 68 mg/L | reference: 0-5 |
Question 1 of 3
Which of the following is the most likely diagnosis?
Ulcerative colitis (UC) characteristically presents with rectal bleeding, bloody diarrhoea, tenesmus, and continuous colonic mucosal inflammation. According to Truelove and Witts criteria, severe UC is defined by ≥6 bloody stools/day with features of systemic toxicity (fever >37.8°C, heart rate >90 bpm, Hb <10.5 g/dL, or CRP >30 mg/L). Crohn's disease typically presents with non-bloody diarrhoea, skip lesions, transmural inflammation, perianal disease, and abdominal mass. Ischaemic colitis presents acutely in older adults with vascular disease as sudden abdominal pain followed by bloody diarrhoea. Irritable bowel syndrome does not cause fever, elevated CRP, anaemia, or overt bloody stools.
Teaching point: Truelove and Witts criteria classify acute severe ulcerative colitis by ≥6 bloody stools/day plus systemic features (fever, tachycardia, anaemia, or high CRP).
Question 2 of 3
Which of the following is the next best initial imaging investigation to evaluate for a life-threatening complication of this condition?
In acute severe ulcerative colitis, a plain abdominal radiograph is essential to assess colonic dilatation and rule out toxic megacolon (transverse colon diameter > 6 cm) or pneumoperitoneum. Full colonoscopy and barium enema are strictly contraindicated in acute severe colitis due to a high risk of bowel perforation. Abdominal ultrasound can show bowel wall thickening but is less sensitive and specific for detecting acute acute megacolon or free air compared to abdominal radiographs or CT.
Teaching point: Plain abdominal radiography is the initial test of choice to screen for toxic megacolon in patients presenting with acute severe ulcerative colitis.
Question 3 of 3
Which of the following is the most appropriate initial medical management step for this patient?
Patients meeting Truelove and Witts criteria for acute severe ulcerative colitis require urgent hospital admission and first-line treatment with high-dose intravenous corticosteroids (e.g., IV hydrocortisone 100 mg four times daily or IV methylprednisolone). Oral mesalazine and oral prednisolone are appropriate for mild-to-moderate flares managed in the outpatient setting, but are insufficient for severe flares. Infliximab or ciclosporin are rescue therapies indicated if there is inadequate response to IV steroids after 3-5 days.
Teaching point: First-line treatment for acute severe ulcerative colitis is intravenous corticosteroids (e.g., IV hydrocortisone).
Key learning points
- Acute severe ulcerative colitis is defined by Truelove and Witts criteria (≥6 bloody stools/day plus systemic toxicity signs including fever, tachycardia, anaemia, or raised CRP).
- Plain abdominal radiography must be performed early to rule out toxic megacolon (>6 cm transverse colonic dilatation) and perforation.
- First-line treatment for acute severe colitis is inpatient admission, IV fluid resuscitation, and high-dose intravenous corticosteroids (e.g., IV hydrocortisone).
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