Scope of this summary
Adults with chronic or recurrent diarrhea, rectal bleeding, abdominal pain, weight loss, perianal disease or extraintestinal findings suggesting ulcerative colitis or Crohn disease. The cited 2025 ACG guidelines cover confirmed adult disease; this page extracts the diagnostic and safety steps and does not prescribe an advanced-therapy regimen.
The Bottom Line
- Suspect ulcerative colitis with hematochezia, increased stool frequency or urgency and Crohn disease with chronic diarrhea, pain, weight loss, obstructive symptoms, perianal disease or compatible extraintestinal manifestations.
- Exclude infectious causes at presentation, including Clostridioides difficile when colitis is suspected, before attributing symptoms or escalation solely to inflammatory bowel disease.
- Use fecal calprotectin as a noninvasive marker to help distinguish inflammatory disease from a disorder of gut鈥揵rain interaction and to support monitoring, while interpreting intermediate results and infection carefully.
- Confirm ulcerative colitis with ileocolonoscopy and biopsies from affected and unaffected mucosa; evaluate suspected Crohn disease with ileocolonoscopy plus small-bowel imaging when the phenotype requires it.
- Assess extent, severity, nutritional status, anemia and extraintestinal disease at diagnosis because these features influence urgency, prognosis, prevention and treatment selection.
Practical clinical workflow
1
Document duration, stool frequency, nocturnal symptoms, urgency, blood, weight, fever, travel, antibiotics, smoking, family history, perianal symptoms and joint, eye or skin features; examine abdomen and perianal region appropriately.
2
Order complete blood count, inflammatory and nutritional markers, stool infection testing and fecal calprotectin as indicated; use pregnancy testing and medication review when they affect imaging or treatment.
3
Refer for timely ileocolonoscopy with correctly distributed biopsies, avoiding a false diagnosis from endoscopic appearance alone; use cross-sectional enterography for suspected small-bowel Crohn disease or complications.
4
Classify likely phenotype and severity, initiate supportive and specialist-directed care, and assess vaccination, infection, thrombosis and cancer-prevention needs before immunosuppressive treatment.
5
Arrange urgent gastroenterology or hospital care for severe symptoms and longitudinal specialist care for confirmed disease rather than leaving the patient on repeated empiric steroids or antibiotics.
Safety boundaries and escalation
- Frequent bloody stool with systemic toxicity, tachycardia, fever, severe anemia, distention or tenderness can represent acute severe colitis or toxic megacolon and requires emergency hospital assessment.
- Severe focal pain, vomiting, obstruction, peritonism, abscess or complex perianal sepsis can signal penetrating or stricturing Crohn disease and needs urgent imaging and surgical collaboration.
- Do not start prolonged systemic corticosteroids before reasonable infection exclusion and a plan for objective diagnosis; corticosteroids are not maintenance therapy.
- Immunosuppressive and advanced therapies require tuberculosis, hepatitis, vaccination, malignancy and product-specific safety review under the current disease guideline and FDA label.
Localization
US endoscopy, enterography, laboratory and advanced-therapy access vary by health system and payer. The 2025 ACG ulcerative-colitis and Crohn-disease documents are source-specific and should be read with current FDA safety information.
Source documents
Use the linked source documents for complete recommendations, evidence grading, exclusions and implementation detail.
- American College of GastroenterologyACG Clinical Guideline: Management of Crohn's Disease in AdultsDOI 10.14309/ajg.0000000000003465 路 American Journal of Gastroenterology 120(6):1225-1264 路 published 2025-06-01 路 accessed 2026-08-20view source
- American College of GastroenterologyACG Clinical Guideline Update: Ulcerative Colitis in AdultsDOI 10.14309/ajg.0000000000003463 路 American Journal of Gastroenterology 120(6):1187-1224 路 published 2025-06-03 路 accessed 2026-08-20view source
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