Crohn’s disease

Although any part of the gut from the mouth to the anus can be affected it tends to affect the ileum (the last part of the small intestine) more commonly. The inflammation affecting the lining of the gut can be patchy or spread along quite a part of the gut. There could be several patches of inflammation at the same time with normal bowel in between. The inflammation tends to affect the entire thickness of the bowel leading on to strictures or narrowing of the lumen of the bowel and fistula formation which are holes in the wall of the bowel.

Cause


The cause is unknown. The body's own immune system seems to be attacking the body. Relatives with Crohn's disease are more prone to develop the condition. This means there could be a genetic predisposition. Smoking could increase the risks to crohn's disease and the disease tends to be more severe in smokers.

Symptoms

  • Diarrhoea or loose stools mixed with blood, mucus or pus is the most common symptom. It can vary from mild to severe diarrhoea. Tenesmus which is a feeling of going to the toilet and nothing to pass is fairly common.
  • Pain is common and could be localised to the right lower quadrant of the abdomen which could be mistaken for appendicitis. But in appendicitis the pain is more severe and pain is initially at the umbilicus before it passes down to the right lower quadrant.
  • Tiredness, fever, loss of appetite which could lead to weight loss.
  • Blood in stools due to bleeding from the ulcers in the gut.
  • Anaemia due to loss of blood in the stools.
  • Mouth ulcers
  • Anal fissures which are cracks around the opening of the anus.
  • When large parts of the bowel are involved one could become very unwell.
  • Malnourishment – when nutrients and vitamins are unabsorbed.


Crohn's disease can affect joints causing arthritis, eyes causing iritis and uveitis etc.

Progression

Crohn's disease is a chronic and relapsing condition which means symptoms could flare up (relapsing) and remitting (no symptoms). The flare ups could be mild or severe.

Diagnosis

  • A focussed history of bloody diarrhoea
  • A focussed clinical examination
  • Endoscopy – a fibre optic cable is passed down the stomach to visualise the oesophagus, stomach and duodenum and biopsies taken off the wall of the gut. Which are then studied under a microscope for certain types of cells.
  • Colonoscopy – a fibre optic cable is passed up the anus and the colon and the ileum are visualised and biopsies taken for study under a microscope.
  • Barium meal – barium coats the lining of the bowel and x rays are then taken to study the lining of the bowel.
  • Barium enema – barium is passes up the anus and x rays are taken to study the lining of the colon.
  • Abdominal CT scan.
  • MRI scan.
  • General blood test to look for anaemia.


Treatment

Aim of the treatment is to treat symptoms and prevent flare ups.
  • In mild cases no treatment might be needed
  • Steroids such as prednisolone or budesonide act by reducing inflammation. 7 in 10 cases are controlled with about 4 weeks of therapy. Steroids have side effects such as weight gain, high blood pressure, thinning of bones, risk of diabetes etc; hence it should be used at the lowest dose needed to control symptoms. Steroids can be used as enemas when the disease is localised to the colon or large bowel. Steroids are injected through the vein in severe cases.
  • Immunomodulators such as azathioprine, methotrexate, and mercaptopurine are used in selected cases when steroids are not tolerated.


Monoclonal antibodies such as infliximab or adalimumab can be used which are antibodies to certain toxic chemicals or cytokines secreted in the body during inflammation such as the tumour necrosis factor (TNF).

  • Aminosalicylate drugs such as sulphasalazine, mesalazine, olsalazine, and balsalazide. Their exact mode of action is unknown. Mesalazine is the most commonly used.
  • Antibiotics are needed for any infections developing such as an infected perianal fistula.
  • Surgery is needed to remove any severely affected section of the bowel and the cut ends are joined together.


Surgery is also needed for repair of any fistulas, strictures and drain any abscesses.
  • Iron tablets might be needed for anaemia
  • Vitamins and nutritional supplements are needed when a large portion of the bowel is resected.
  • Painkillers for any painful complications and flare ups.


Complications

Since the inflammation in crohn's disease is transmural which means the whole thickness of the bowel is affected, complications can be quite severe if the flare ups are frequent or severe.

  • Stricture – inflammation in the wall of the bowel might cause scarring which can cause a rigid narrowing of the bowel causing obstruction.
  • Fistula – the inflammation can cause abnormal openings and channels to form between two sections of the small bowel or a channel could form between small bowel and the large bowel. Passages could also form between the gut, bladder or uterus when surgery is needed to remove the abnormal.
  • Perforation – perforation in the small or large bowel could cause the contents to leak and cause inflammation which is serious.
  • Osteoporosis – thinning of the bone occurs due to insufficient absorption of nutrients from the gut.
  • Colon cancer – patients with crohn's disease carry an additional risk of cancer developing.


General precautions

It's important that certain drugs used for crohn's disease especially methotrexate be stopped as it could have an adverse effect on the developing foetus. Additional folate supplements might be needed during pregnancy.

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