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Crohn’s Disease

Crohn's Disease

Etiological Agents

  • Infective agents:
    • Mycobacterium paratuberculosis
    • Enteroadherent E. coli (EAEC)
  • Inflammatory mediators:
    • IL-1, IL-2, IL-8, and TNF-alpha are the most common (MC) inflammatory mediators.
  • Genetic Factors:
    • Altered genes: NOD2, IL23R, and ATG16L1.
    • Loci found on chromosomes: 16q, 5q, 19p, 7q, 3p.

Clinical Features

  • Most common symptom (MC): Intermittent and colicky abdominal pain.
  • MC location of pain: Lower abdomen.
  • MC complication: Obstruction and perforation.
  • MC site of massive GI bleed: Duodenum.

Perianal Disease in Crohn's

  • Occurs in:
    • 25% with Small Bowel Crohn's.
    • 41% with Ileocolitis.
    • 48% with Colonic Crohn's.
  • Only perianal disease as presentation: 5% of cases.

Extraintestinal Manifestations

  • Occurs in 30% of patients.
  • MC extraintestinal symptoms: Skin lesions.

Diagnosis of Crohn's Colitis vs Ulcerative Colitis

Parameter Crohn's Colitis Ulcerative Colitis
Symptoms and Signs
Diarrhea Common Common
Rectal Bleeding Less common Almost always
Abdominal Pain (cramps) Moderate to severe Mild to moderate
Palpable Mass At times No (unless large cancer)
Anal Complaints Frequent (>50%) Infrequent (<20%)
Radiologic Findings
Ileal Disease Common Rare (backwash ileitis)
Nodularity, Fuzziness No Yes
Distribution Skip areas Rectum extending upward and continuously
Ulcers Linear, cobblestone, fissures Collar-button
Toxic Dilation Rare Uncommon
Proctoscopic Findings
Anal Fissure, Fistula, Abscess Common Rare
Rectal Sparing Common (50%) Rare (5%)
Granular Mucosa No Yes
Ulceration Linear, deep, scattered Superficial, universal

Crohn's Disease Investigations

Barium Radiographic Studies

  • Cobblestone appearance on barium studies.
  • Kantor string sign: Long lengths of narrowed terminal ileum.

MRI

  • MRI is superior to CT in detecting:
    • Intestinal strictures.
    • Ileal wall enhancement.

Capsule Endoscopy

  • A positive test is defined by the presence of three or more ulcers in the absence of NSAID use.

Serological Markers

  • Perinuclear antineutrophil cytoplasmic antibody (pANCA).
  • Anti-Saccharomyces cerevisiae antibody (ASCA):
    • ASCA is used to differentiate Crohn's Disease (CD) from Ulcerative Colitis (UC).

Stool Markers

  • Stool lactoferrin:
    • An iron-binding protein found in the secretory granules of neutrophils.
    • Sensitivity: 83%.
    • Specificity: 93%.
  • Fecal calprotectin:
    • A protein released by squamous cells in response to inflammation.
    • Sensitivity: 67%.
    • Specificity: 71%.

Medical Management of Crohn's Disease

  • Sulfasalazine:
    • Not effective in isolated small bowel Crohn’s disease.
  • Prednisone:
    • Used in moderate to severe disease.
    • Not useful for maintenance therapy.
    • IV administration in severe disease, only if there is no abscess.
  • Controlled ileal release Budesonide:
    • Effective for Crohn’s disease.
  • Antibiotics:
    • Helpful in treating septic complications and perianal Crohn's disease.
  • Immunosuppressive Agents:
    • Azathioprine (AZT), 6-Mercaptopurine (6-MP), Methotrexate (MTX), and Tacrolimus (FK-506):
      • Used for maintenance and treatment of severe disease.
  • Infliximab:
    • Effective in 2/3 patients for perineal fistula closure.
  • Natalizumab:
    • Acts against α4 integrin.
  • Vedolizumab:
    • Binds to α4β7 integrin and blocks MadCAM-1.
  • Ustekinumab:
    • Inhibits IL-12.

Surgical Management of Crohn's Disease

  • Surgery required in 70% of patients within 15 years after diagnosis.
  • Ankylosing spondylitis and hepatic complications do not improve after surgery.
  • Laparoscopic surgery is preferred.
  • Minimal segmental resection is the key principle.
  • Acute ileitis: Bowel resection should not be performed.

Indications and Surgical Options

  • Most common (MC) indication for surgery: Intractability.
  • Treatment of choice: Segmental resection & reanastomosis.
  • Stricturoplasty: Involves a longitudinal incision and transverse closure.

Genitourinary Complications

  • Occur in 1/3 of patients.
  • MC urologic complication: Ureteral obstruction.

Types of Stricturoplasty

  • Small Segment Strictures:
    • Heinecke Mikulicz
    • Judd
    • Moskel-Walske-Neumayer

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  • Long Segment Strictures:
    • Finney
    • Jaboulay
    • Michelassi

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Perianal Crohn's Disease

  • Common manifestations: Fissures & fistulas.
  • Occurs more frequently in colonic Crohn's.
  • Medical management is the primary approach.
  • Drugs used in treatment:
    • Azathioprine (AZT)
    • 6-Mercaptopurine (6MP)
    • Infliximab
  • Wide excision of abscess or fistulas is not indicated.
  • Non-cutting setons are used for management.
  • Fissures:
    • Usually lateral, relatively painless, large, and indolent.
    • Often respond to conservative management.

Duodenal Crohn's Disease

  • Occurrence: 1-5% of Crohn's patients.
  • Most common site: Duodenal bulb.
  • Operative intervention is uncommon.
  • Gastrojejunostomy (GJ) is the procedure of choice (No duodenal resection).

Key Points in Crohn's Disease

  • 80% of patients will require surgery at some point in their lifetime.
  • Symptomatic recurrence after surgery varies from 40% to 80%.
  • Smoking cessation is the only clearly modifiable risk factor.
  • High death rates are associated with wound complications.
  • Gastrointestinal cancer remains the leading cause of disease-related death in patients with Crohn's disease.

MCQs for Revision

1. All are most commonly involved inflammatory mediators in the etiology of Crohn's disease except?

A) IL-1

B) IL-2

C) IL-8

D) IL-5

Correct Answer: D) IL-5

(IL-1, IL-2, and IL-8 are the most commonly involved inflammatory mediators in Crohn's disease)

2. The most common extraintestinal manifestation of Crohn's disease is?

A) Arthritis

B) Ankylosing spondylitis

C) Uveitis

D) Primary sclerosing cholangitis (PSC)

Correct Answer: A) Arthritis

(Arthritis is the most common extraintestinal manifestation of Crohn's disease)

3. All are used in the diagnosis of Crohn's disease except?

A) Stool lactoferrin

B) Fecal calprotectin

C) ANCA

D) AMA

Correct Answer: D) AMA

(AMA is not used in the diagnosis of Crohn's disease, whereas ANCA, stool lactoferrin, and fecal calprotectin are used)

4. All are true regarding the medical management of Crohn's disease except?

A) Sulfasalazine is not effective in isolated small bowel Crohn's

B) Treatment with infliximab results in perineal fistula closure

C) Ustekinumab, a humanized IgG1 monoclonal antibody that inhibits α4β7 integrin

D) Natalizumab, a recombinant humanized monoclonal antibody against α4 integrin

Correct Answer: C) Ustekinumab, a humanized IgG1 monoclonal antibody that inhibits α4β7 integrin

(Ustekinumab inhibits IL-12, not α4β7 integrin. Vedolizumab targets α4β7 integrin)

5. All are true regarding the surgical management of Crohn's disease except?

A) 70% of patients will require surgical resection within 15 years after diagnosis

B) Laparoscopic surgery is better

C) Genitourinary complications occur in up to 1/2 of patients

D) Minimal segmental resection is key

Correct Answer: C) Genitourinary complications occur in up to 1/2 of patients

(Genitourinary complications occur in up to 1/3 of patients, not 1/2)

6. All are true regarding perianal Crohn's except?

A) More common with colonic Crohn's

B) Medical management is key

C) Cutting setons used

D) Fissures are usually lateral, relatively painless

Correct Answer: C) Cutting setons used

(Non-cutting setons are used in perianal Crohn's disease)

7. All are true about duodenal Crohn's except?

A) Seen in 1-5% of patients

B) Most common in the duodenal bulb

C) Operative intervention is common

D) Gastrojejunostomy is the procedure of choice

Correct Answer: C) Operative intervention is common

(Operative intervention is uncommon in duodenal Crohn's disease)

8. All are components of the Vienna classification of Crohn's disease except?

A) Age

B) Severity

C) Behaviour

D) Location

Correct Answer: B) Severity

(Age, location, and behaviour are components of the Vienna classification of Crohn's disease, not "location" specifically)

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9. Truelove-Witts criteria is used for classification of?

A) Crohn's disease

B) Radiation proctitis

C) Rectal prolapse

D) Ulcerative colitis

Correct Answer: D) Ulcerative colitis

(Truelove-Witts criteria is used to classify the severity of Ulcerative colitis)

10. Ram Horn's sign is seen in?

A) Ulcerative colitis

B) Crohn's disease

C) Carcinoma colon

D) Celiac disease

Correct Answer: B) Crohn's disease

(Ram Horn's sign is typically seen in Gastric Crohn's disease)

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11. Which of the following is not a characteristic feature of Crohn's disease?

A) Granular mucosa

B) Non-caseating giant cell granuloma

C) Skip lesions

D) Transmural involvement

Correct Answer: A) Granular mucosa

(Granular mucosa is more characteristic of Ulcerative colitis)

12. Resection of bowel segment is more appropriate in Crohn's disease in all of the following except?

A) Active inflammation

B) Long segment strictures involving multiple segments

C) Concern for malignancy

D) Presence of large phlegmon

Correct Answer: A) Active inflammation

(Resection is generally avoided in active inflammation of Crohn's disease)