Crohn's disease

Question 1

What is Crohn’s disease?

Answer 1

Crohn’s disease = chronic granulomatous transmural inflammatory disease that can affect any part of the GI tract

Can involve any part, from mouth to perianal area
Seen usually in terminal ileum (40%) and perianal locations

Skip lesions = normal bowel mucosal found between diseased areas
Transmural infection often leads to fibrosis, and thus obstruction
Inflammation causes sinus tracts that burrow through and penetrate the serosa, producing fistulae and perforations

Question 2

What are the aetiology and risk factors of Chron’s disease?

Answer 2

Aetiology
Thought to be an interplay between environmental and genetic factors

Risk factors
Developed country
White ancestry
Age 15-40 or 60-80
FHx
Smoking (2x as likely)
Diet high in refined sugar
OCP
Deficiencies – especially zinc
Not breastfed
Infection - Measles, TB
NSAIDs

Question 3

What is the epidemiology of Crohn’s disease?

Answer 3

Annual incidence of 5-8 in 100,000 in UK
Prevalence of 50-80 in 100,000 in UK
Affects any age - Incidence peaks in teens or twenties

Highest incidence in northern climates and developed countries
Rise in incidence over past 60 years
Incidence equal to UC
Equal sex prevalence

Question 4

What are the symptoms of Crohn’s disease?

Answer 4

Abdominal pain - Crampy, Multiple causes: inflammation, fibrosis, bowel obstruction

Diarrhoea - Bloody or steatorrhoea (if ileum affected)

Bowel obstruction

Blood in stools

Fatigue

Weight loss - More common than in UC

Question 5

What are the signs of Crohn’s disease?

Answer 5

Perianal skin tags, fistulae and abscessess
Fever
Abdominal tenderness
Oral lesions
Clubbing
Signs of anaemia

Question 6

What are appropriate investigations for Crohn’s disease?

Answer 6

Bloods
FBC - Anaemia, leucocytosis, thrombocytosis
Iron studies, vit-B12, folate = Normal or low
Comprehensive metabolic panel (CMP)
Hypoalbuminaemia, hypocalcaemia, CRP and ESR Elevated

Stool testing - Absence of infection

Plain AXR - Small bowel/colonic dilation, calcification, sacroiliitis Small bowel barium follow through, Fibrosis and strictures, Deep ulceration (Rose thorn),Cobblestone mucosa

CT/MRI - Skip lesions, bowel wall thickening, inflammation, abscess, fistulae

Other investigations
US
Endoscopy with biopsy – colonoscopy, OGD, wireless capsule
Biopsy
Transmural inflammation
Infiltration of macrophages, lymphocytes, plasma cells
Immunology - pANCA negative, ASCA positive

Question 7

How can Crohn’s disease be managed?

Answer 7

Acute exacerbation
Fluid resuscitation
IV corticosteroids - induce remission
5-ASA analogues
Analgesia
PEN
Antibiotics
Surgery?

Long term
5-ASA analogues = sulfalazine, mesalazine (Useful for mild-to-moderate disease)
Immunosuppression = azathioprine, 6-mercaptopurine, methotrexate - induce and maintain remission (Used to reduce relapses)

Anti-TNF agents = infliximab, adalimumab - induce remission in severe active disease (Reserved for refractory cases)

Smoking cessation advice
Anti-diarrhoeals

Question 8

What are the possible complications of Crohn’s disease?

Answer 8

GI complications:
Haemorrhage, Sinuses, Strictures, Perforation
Fistulae – bowel, bladder, vagina
Toxic megacolon
Malignancy - 5% risk in 10 years of GI carcinoma
Malabsorption - Short bowel syndrome, Anaemia

Extra intestinal features
PSC
Hepatic steatosis
Liver abscess
Arthropathy
Kidney stones
Ocular
AS

Medicine side effects
Pregnancy complications
Methotrexate - Hepatotoxicity, Pulmonary fibrosis, Myelosuppression
Sepsis

Question 9

What is the prognosis of Crohn’s disease?

Answer 9

Chronic relapsing
2/3 will require surgery at some stage (2/3 will require at least one more after this)

10-20% experience prolonged remission
Only a modest decrease in life expectancy

Colon cancer is the leading cause of death
Mortality increases with duration of disease