Virtual Medical Centre

Crohn's Disease (Inflammatory Bowel Disease)

• What is Crohn's Disease?
• Who gets Crohn's Disease?
• Predisposing Factors
• Progression
• Probable Outcomes
• How Will Crohn's Disease Affect Me?
• Clinical Examination
• How is Crohn's Disease Diagnosed?
• How is Crohn's Disease treated?
• Crohn's Disease References
• Drugs/Products Associated with Crohn's Disease

What is Crohn's Disease?

Crohn's disease is a chronic and relapsing inflammatory disorder that can affect any part of the gastrointestinal tract, from the mouth to the anus, as well as other organs of the body. Crohn's disease is a type of inflammatory bowel disease. Ulcerative colitis is also part of this category and shares some similar clinical features as Crohn's disease. However, ulcerative colitis only affects the large intestine. Crohn's disease involves all three layers of the bowel wall (inner lining, muscular layer and outer lining). To contrast, ulcerative colitis only involves the mucosa (inner lining). The patterns of intestinal involvement in Crohn's disease are divided into large bowel alone (colonic) (25%), small and large bowel (ileocolic) (40%), and small bowel alone (30%). The duodenum is rarely involved (only 2%). The main pathological features of Crohn's disease are ulcers (shallow and deep), connection of the bowel lumen with surrounding structures (fistulae) and scar tissue leading to narrowing of the bowel lumen (strictures causing lumen obstruction). The extra-intestinal structures involved in Crohn's disease can be local or systemic. Local involvement can occur when fistulae are present, such as between the bowel and the vagina or the bladder. Systemic extra-intestinal manifestations include:

• Skin
• Mucous membranes: shallow ulcers of the mouth and vagina
• Eyes: inflammation of the iris (iritis)
• Joints: painful and inflamed large joints (arthralgia and arthritis).
• Liver/gallbladder: chronic active liver inflammation (hepatitis) and scar tissue damage with liver dysfunction (cirrhosis), gallstones.

Who gets Crohn's Disease?

Crohn's disease is an important cause of morbidity in Australia and affects approximately 50 people per 100 000 of the population. The incidence is set to increase even further in future years. The disease is most common in adolescents and young adults with up to 60% of patients being diagnosed before 25 years of age. However, Crohn's disease can occur at any age. Females are affected slightly more than males.

Predisposing Factors

The cause of this disease is unknown but various genetic and environmental factors are thought to have a role. There is evidence for a genetic component, in that siblings of Crohn's patients are 20-35 times more likely to develop Crohn's. Smoking, as well as a higher sugar content in the diet may increase the risk. An elemental diet improves symptoms. Crohn's disease is more common in Western societies and more common in Caucasians compared to black-skinned populations. Infection with a type of bacteria or virus has been proposed but largely unproven in clinical trials.

Progression

The disease usually manifests between 20 and 40 years of age, being rare before 10 or after 60. Crohn's disease typically follows a chronic and recurrent course. However, many patients remain well and have an almost normal lifestyle. If you have extensive disease you will have more frequent exacerbations and require multiple hospital admissions. Inflammation of the lining of the gut causes symptoms of diarrhoea which may be streaked with blood or mucus if the colon is involved. It is usually an episode of severe abdominal pain which will cause you to present to hospital. Involvement of the small intestine disrupts its normal functions of breaking down and absorbing food. This means the body may have trouble absorbing all the nutrients it needs. With time, Crohn's disease can lead to malnutrition and iron deficiency anaemia. In children in particular this can lead to growth retardation and even delays in puberty. Extension of the inflammation throughout the thickness of the bowel wall can lead to a number of other complications as the bowel becomes stuck down to nearby organs. This can cause:

• Adhesions- These are fibrous thickenings or scarring which can make future surgery in the abdomen difficult.
• Perforation (rupture of the bowel wall) and abscess formation.
• Fistulae- Connections can develop between diseased bowel and other hollow organs such as the stomach, rectum, bladder, uterus, vagina or even skin. This can cause additional complications such as faecal vomiting, passage of faeces via the vagina or severe urinary tract infection.

Chronic and extensive Crohn's disease is associated with an increased risk of adenocarcinoma of the colon.