Inflammatory Bowel Disease

This refers to chronic, relapsing inflammation of the bowel, which is thought to be associated with an abnormal immune response to gut flora.

It classically presents in the younger population with two key symptoms: bloody diarrhoea and abdominal pain.

It is subdivided into two disorders which share similar symptoms.

Ulcerative colitis (UC)

This disease is associated with recurrent inflammation of the colon which involves part or all the colon and rectum. The involvement is continuous, rather than in patches and never proximal to the ileocecal valve.

Inflammation leads to bleeding mucosa, pseudopolyp formation and ulcers which extend into the lamina propria.

It can lead to toxic megacolon and colon cancer and is also associated with primary sclerosing cholangitis.

Crohns disease

This is a disease which causes recurrent inflammation anywhere along the GI tract.

It is especially seen in the terminal ileum, resulting in malabsorption of vitamin B12.

It causes inflammation which traverses the whole thickness of wall and is not continuous (skip lesions).

Lymphoid aggregates form, giving granuloma formation with goblet cells.

It is also associated with stricture formation which can lead to bowel obstruction.

It can lead to malabsorption, colon cancer, fistula formation and osteoporosis.

Smoking increases the risk of developing Crohn’s.

Colonoscopy shows a “cobble-stone” appearance of mucosa and rose-thorn ulcers.

General symptoms

Increased bowel frequency

Rectal bleeding (more in UC)

Mucus like rectal discharge

Abdominal pain

Tenesmus (urge to defecate)

Fever, malaise, weight loss

Anal disease (more in Crohn’s)

Whilst there are the general symptoms, certain symptoms are more common in Crohn’s disease compared to ulcerative colitis.

Key tests

Blood tests – raised inflammatory markers, e.g., CRP and ESR

Stool test and culture – this is required to exclude an infective cause

Faecal calprotectin – this is a marker for gut inflammation which is raised

There are also a host of imaging techniques which can be used:

Flexible sigmoidoscopy – used in the acute setting to assess lower GI inflammation

Abdominal X-ray – used in the acute setting to check for toxic megacolon

Colonoscopy – a more definitive investigation providing a view of the large bowel

CT scan/MRI small bowel – this is used to assess small bowel inflammation

Capsule endoscopy – in situations when the MRI is not clear, this involves swallowing a camera which takes photos of the gut tube to show intramural inflammation

Acute management

In moderate UC flares, can use topical or oral aminosalicylates before steroids

For Crohn’s and severe UC flares, IV steroids (hydrocortisone) are usually required

This can then be switched to oral steroids on a weaning regimen

If not settling despite steroids, may require biologics, e.g., infliximab rescue therapy

If toxic megacolon, strictures or persistent inflammation, consider surgery

Chronic management

Ulcerative colitis

If mild, topical mesalazine anti-inflammatories

If persistent, increase to immunosuppressive drugs, e.g., azathioprine

If uncontrolled despite immunomodulators, then biological therapy

For recurrent flare, consider surgery, total colectomy is curative

Crohn’s

If mild, first-line is immunosuppressants (e.g., azathioprine, mercaptopurine)

If persistent/severe, consider biological therapy (e.g., infliximab, adalimumab, vedolizumab, ustekinimab)

For repeat flares, may require surgery to resect the inflamed patch of bowel