Crohn Disease Basics

Crohn disease is a chronic inflammatory disorder in which immune-mediated injury can extend through the bowel wall and appear in separated segments. That combination of depth and patchiness explains why one patient may have diarrhoea and nutrient deficiency while another develops a narrowed lumen, abscess, or fistula. The clinical task is therefore twofold: recognise active intestinal disease and look for structural or systemic complications that change urgency. Symptoms alone do not establish the diagnosis or reliably measure severity. Objective testing maps the location and behaviour of disease and helps distinguish Crohn disease from infection, irritable bowel syndrome, and other causes of diarrhoea. Fever, tachycardia, marked pain or distension, vomiting, substantial bleeding, or rapid deterioration shifts the priority from routine assessment to urgent escalation. The 2019 Canadian Association of Gastroenterology guideline and Canadian product monographs are not interchangeable with the 2025 American College of Gastroenterology update, which is United States guidance. RPN medication administration and monitoring occur within the prescriber’s order, provincial scope, and employer policy.