CAUSES & CONDITIONS

Crohn’s Disease

Symptoms, types, diagnosis, and management — and how it relates to short bowel syndrome

Crohn’s disease is a chronic inflammatory bowel disease (IBD) characterized by systemic, transmural inflammation that can affect any part of the digestive tract, from the mouth to the anus.

Unlike some other inflammatory conditions, Crohn’s can present with “skip lesions” — areas of severe inflammation interspersed with patches of healthy tissue. Because it can damage multiple sections of intestine, it is one of the leading causes of Short Bowel Syndrome.

CLASSIFICATION
Five Types of Crohn’s Disease
1. Gastroduodenal Crohn’s

Location: Stomach and duodenum. Often misdiagnosed as peptic ulcer disease. Symptoms: loss of appetite, weight loss, nausea, upper-middle abdominal pain, vomiting.

2. Jejunoileitis

Location: Jejunum (mid small intestine). High risk of nutrient malabsorption and fistulas. Symptoms: severe cramps after eating, diarrhea, nutrient deficiencies.

3. Ileitis

Location: Ileum (final small intestine). Can impair vitamin B12 and folate absorption. Symptoms: diarrhea, cramping, sharp pain in the lower right quadrant.

4. Ileocolitis

Location: Ileum and colon together — the most prevalent form, often around the ileocecal valve. Symptoms: severe diarrhea, cramping, right lower quadrant pain, significant weight loss.

5. Crohn’s colitis (granulomatous colitis)

Location: Colon only. Differs from ulcerative colitis by skip lesions and frequent sparing of the rectum (UC is continuous and always involves the rectum).

CLINICAL PICTURE
Signs & Symptoms
Gastrointestinal symptoms

Diarrhea — frequent loose or watery stools; may contain dark blood if inflammation is extreme; typically less mucus/pus than UC
Abdominal pain — terminal ileum disease often causes sharp lower-right and periumbilical pain that intensifies after meals; colonic disease causes generalized crampy pain
Fever & night sweats — acute spikes or persistent low-grade fevers from systemic inflammation; fatigue and irritability are common
Extraintestinal symptoms

Systemic immune responses can affect other systems — sometimes before intestinal symptoms appear:

Eyes — redness, pain, inflammation (iritis/uveitis)
Joints — migrating arthralgia in larger joints (knees, ankles, elbows, wrists)
Skin — erythema nodosum (tender red nodules on shins/calves) and aphthous mouth ulcers

RISK
Causes & Risk Factors

Crohn’s is classified as idiopathic — the exact trigger is unknown. It involves an unregulated, overactive immune response in the gut wall.

Genetics

Tends to run in families. About 20–25% of patients have a close relative with IBD.

Demographics

Higher rates historically in Western, industrialized societies and certain ethnic groups; incidence has been rising globally across demographics.

Environment

Diet, industrial exposures, and altered gut microbiomes are studied as triggers for initial episodes or relapses.

DIAGNOSIS
Diagnostic Approach
Laboratory testing

Complete blood counts (anemia, elevated white cells) and stool cultures to rule out infectious colitis.

Imaging & endoscopy

Colonoscopy or sigmoidoscopy for direct visualization and biopsies. Barium enema may map strictures, narrowings, or fistulas.

MANAGEMENT
Treatment & Remission

There is no permanent cure. Treatment focuses on controlling acute inflammation, inducing and maintaining clinical remission, preventing complications, and protecting nutritional status.

Medical therapy

Anti-inflammatory medications, immunosuppressants, biologics, and nutritional support tailored to disease location and severity.

Surgery & short bowel risk

Repeated resections for strictures, fistulas, or refractory disease can lead to short bowel syndrome and intestinal failure. Intestinal rehabilitation and specialized centers play a key role when residual bowel length is limited.

When Crohn’s leads to extensive bowel loss, patients may need home parenteral nutrition and long-term support — the same pathways used for other causes of intestinal failure.

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Note
This information is for educational purposes only and is not a substitute for professional medical advice. Always consult your medical team for diagnosis and treatment decisions.