Contents · 12 sections
In a nutshell. Inflammatory bowel disease (IBD) includes Crohn's disease (CD) and ulcerative colitis (UC). CD is transmural inflammation of any part of the GI tract (most commonly terminal ileitis); UC is superficial inflammation of the colonic mucosa extending proximally from the rectum. Diagnosis: colonoscopy with biopsy + MR enterography (for CD) + fecal calprotectin. Treatment: induction (corticosteroids, biologics) → maintenance (5-ASA, immunosuppressants, biologics); surgery for complications.
1. Definition and epidemiology
IBD is a group of chronic immune-mediated inflammatory GI diseases. Prevalence in Russia: UC 40–50/100,000, CD 10–15/100,000; increasing due to urbanization. Peak onset at 15–35 years with a second peak at 60 years. Etiology is multifactorial: genetics (NOD2, ATG16L1), dysbiosis, environmental factors (smoking is protective in UC and a risk factor in CD!).
2. Comparative characteristics of CD and UC
| Sign | Crohn's disease | Ulcerative colitis |
|---|---|---|
| Localization | Any part of the GI tract, most commonly the ileocecal region | Colon only, extending continuously from the rectum proximally |
| Depth | Transmural inflammation | Mucosa and submucosa |
| Segmental involvement | "Skip" lesions | Continuous |
| Macroscopy | Deep longitudinal ulcers, "cobblestoning" | Erosions, pseudopolyps, friable hyperemia |
| Histology | Sarcoid-like granulomas (30%) | Crypt abscesses |
| Leading symptom | Abdominal pain, non-bloody diarrhea, fistulas | Bloody diarrhea, tenesmus |
| Fistulas, strictures | Common | Rare |
| Smoking | Worsens | Paradoxically protective |
| Colorectal cancer risk | With colitis | High in pancolitis > 10 years |
3. Clinical manifestations
Crohn's disease
- Chronic diarrhea (usually non-bloody) > 6 weeks.
- Right lower quadrant pain.
- Perianal lesions (fistulas, abscesses, anal fissures) in 30%.
- Weight loss, fever.
- Fistulas (enteroenteric, enterovesical, cutaneous).
- Strictures with partial obstruction.
Ulcerative colitis
- Bloody diarrhea, mucus, pus.
- Tenesmus, urgency.
- Nocturnal urgency — a marker of activity.
- Left lower quadrant pain.
- Fever, weight loss in severe disease.
4. Extraintestinal manifestations (up to 40%)
- Musculoskeletal: arthritis (peripheral, axial — sacroiliitis, ankylosing spondylitis).
- Skin: erythema nodosum, pyoderma gangrenosum, Sweet's syndrome.
- Eyes: uveitis, episcleritis.
- Liver: primary sclerosing cholangitis (PSC, more common in UC).
- Thromboembolism — risk increases 3-fold during flares.
5. Diagnostics
- Colonoscopy with ileoscopy and biopsy — key method; biopsy of at least 2 fragments in 5 segments + 2 fragments from the ileum.
- Fecal calprotectin > 150 mcg/g — marker of inflammation, convenient for monitoring.
- CRP, ESR, CBC (anemia, thrombocytosis), albumin, ferritin.
- Stool analysis, stool culture, C. difficile toxins — to rule out infections.
- MR enterography — for CD: strictures, fistulas, small bowel activity.
- Intestinal ultrasound — screening for flares.
- Video capsule endoscopy — for isolated small bowel CD (rule out strictures!).
- Serology: p-ANCA (more common in UC), ASCA (more common in CD) — adjunctive.
6. Activity indices
- Truelove-Witts criteria for UC: mild, moderate, severe — based on stool frequency, blood in stool, temperature, ESR, hemoglobin.
- Mayo score (0–12) for UC — clinical + endoscopy.
- CDAI (Crohn's Disease Activity Index) — clinical score for CD.
- SES-CD — endoscopic index for CD.
- Histology — Geboes/Robarts score.
7. UC therapy
Remission induction
- Mild-to-moderate distal — mesalazine (5-ASA) topically (enemas, suppositories) ± orally 3–4 g/day.
- Moderate extensive — oral GCS (prednisolone 40–60 mg), MMX budesonide.
- Severe — IV GCS (hydrocortisone, methylprednisolone) + hospitalization; if no response after 3–5 days — infliximab or cyclosporine (rescue therapy).
Maintenance therapy
- Oral/rectal 5-ASA.
- Azathioprine/6-mercaptopurine for steroid dependence.
- Anti-TNF (infliximab, adalimumab), vedolizumab (anti-α4β7), ustekinumab, tofacitinib (JAK), upadacitinib.
8. CD therapy
- Mild ileocecal — budesonide 9 mg.
- Moderate — prednisolone + azathioprine for long-term control.
- Severe and perianal forms — biologics: infliximab, adalimumab (with/without immunosuppressants), vedolizumab, ustekinumab, risankizumab (anti-IL23).
- 5-ASA has low efficacy in CD — not routinely recommended.
- Strictures — endoscopic balloon dilation, resection.
- «Top-down» in high-risk patients — early initiation of biologics.
9. Surgery
- UC: indications — toxic dilation (toxic megacolon > 6 cm), perforation, massive hemorrhage, dysplasia/cancer, medical refractory disease. Surgery — colectomy with ileal pouch-anal anastomosis (IPAA).
- CD: indications — strictures, fistulas, abscesses, perforations; goal is strictureplasty and conservative resection. Postoperative recurrence in 50% at 10 years.
10. Complications
- Toxic megacolon (UC): life-threatening.
- Perforation, hemorrhage.
- Colorectal cancer (UC > 10 years, pancolitis, PSC) — screening colonoscopy every 1–3 years.
- Strictures, fistulas, abscesses (CD).
- Nutritional deficiency, osteoporosis, iron-deficiency anemia, B12 deficiency.
11. Pregnancy and IBD
- Active disease at conception — main prognostic factor.
- Most medications (5-ASA, azathioprine, anti-TNF) are compatible with pregnancy.
- Methotrexate, tofacitinib — contraindicated.
- Vaginal delivery, C-section — in case of perianal disease.
12. FAQ
Can IBD be cured?
No. The goal is long-term deep remission (clinical + endoscopic + histological). Colectomy in UC is theoretically «curative», but pouchitis may develop.
Why use biologics earlier?
The «top-down» strategy has shown superiority over «step-up» in high-risk patients (young age, deep ulcers, perianal CD): fewer surgeries and complications.
What is «deep» remission?
Clinical + endoscopic mucosal healing + normal calprotectin. Associated with a lower risk of relapse and surgery.
Should biologics be discontinued?
For most patients — no, 40–50% annual risk of relapse after discontinuation. Discontinuation may be attempted after prolonged deep remission.
Prevention of colorectal cancer?
Follow-up colonoscopy with chromoendoscopy every 1–3 years for UC > 8–10 years, pancolitis, PSC. Mesalazine reduces the risk.
See also: Liver cirrhosis · GERD · Immune cells · Glucocorticoids · Gastroenterology catalog · Clinical scales