Enfermedad de Crohn

What is inflammatory bowel disease or IBD?
‘Inflammatory bowel disease’ or IBD is a condition that causes ‘inflammation’ of the digestive system. Inflammation is the body’s reaction to an injury, infection or irritation and can cause redness, swelling and pain. IBD is a ‘chronic condition’, which means that it is life-long and ongoing. Although there is no cure at the moment, treatments are available that can help manage IBD. [1]

There are two common types of IBD, ‘Crohn’s disease’ and ‘ulcerative colitis’ or UC. While the symptoms may overlap, they can affect different parts of the digestive system.

What is ulcerative colitis?
Ulcerative colitis or UC causes a continuous stretch of inflammation in the inner lining of the colon. As well as inflammation, people with UC can also get ulcers on the lining of their colon, which can bleed and produce mucus. [2]

There are different types of UC named by how much of the large intestine is affected: [3]

• ‘Proctitis’ – only the rectum is inflamed.
• ‘Left-sided colitis’ – includes inflammation of the rectum and the left side of the colon.

‘Total colitis’ (also called ‘pancolitis’) – affects the whole colon. 

What is Crohn’s disease?
Crohn’s disease is a type of inflammatory bowel disease that can cause inflammation anywhere in the gut, but most often in part of the small intestines called the ‘ileum’ or in the large intestine (also known as the colon). [4] Unlike the continuous stretch of inflammation that occurs in patients with ulcerative colitis, inflammation in patients with Crohn’s disease is often patchy, with non-inflamed areas in between. [4, 5] In Crohn’s disease, the inflammation can spread deep into the layers of the intestine walls, in contrast to ulcerative colitis where inflammation is limited to the intestine wall surface. [5] Active Crohn’s disease can affect the body’s ability to digest food, take in nutrients and get rid of waste. [4]

What are the risk factors for IBD?
It is not known what causes Crohn’s disease or ulcerative colitis although there are several ‘risk factors’ linked to each. Some risk factors are:

• Genetics
  • Inheritance of genes that can make a person more likely to develop Crohn’s disease.
  • People who have a close relative (e.g. parent, brother/sister or child) with Crohn’s disease or UC have a higher risk of developing the conditions.
• An abnormal reaction of the immune system to bacteria in the intestines.
• Environmental factors – including viruses, bacteria, diet, smoking, stress and some medications. [3, 6]
• Living in urban areas (cities and towns) or in more developed countries in the northern hemisphere.
• Race – IBD is more common in Caucasians.
• Age – IBD is more likely to happen for the first time between the ages of 10 and 40, but can start at any age. [3, 7]

What are the symptoms of Crohn’s disease and ulcerative colitis?
The symptoms of both conditions can change a lot between patients, partly because of differences in how bad the inflammation is, and where it is. In both Crohn’s disease and UC there may be times when there are very few or no symptoms. There may also be times when the disease becomes more active and symptoms get worse. These are known as ‘flare-ups’. [2]

The most common symptoms of Crohn’s disease and UC include rectal bleeding (especially in UC), belly pain, diarrhoea, tiredness, feeling generally unwell, fever, mouth ulcers, loss of appetite, weight loss and anaemia (having a reduced number of red blood cells). [8]

People with Crohn’s disease can develop other problems like ‘strictures’ or ‘fistulas’. Strictures are areas of the bowel that have narrowed because of scar tissue from repeated inflammation and healing. Fistulas are abnormal channels or passageways that form between one internal organ and another, or to the outside surface of the body. [4]

In people with Crohn’s disease and UC, holes in the bowel wall (called ‘perforations’) can occur with very active inflammation or blockages, which can cause the contents of the bowel to leak through. A rare, life-threatening complication of UC is ‘toxic megacolon’, which is an extensive and severe build-up of digestive gases, making the colon swell up, and putting you at risk for infection and shock. [3,9]

Crohn’s disease and UC can also cause problems outside the digestive system. The most common are: [3, 4, 6, 7]

• Inflammation of the joints (‘arthritis’).
• Inflammation and redness in the eyes.
• Blistered, red or swollen patches of skin.
• Mouth sores.
• Weak bones (‘osteoporosis’).
• Kidney stones.

How is IBD diagnosed?
The doctor may first suspect a patient has IBD based on the symptoms they are having. Some of the tests that the doctor can use to confirm a diagnosis of IBD include:

• Blood tests or stool tests – routinely used to assess whether a person has inflammation in their body and whether this is because of a specific infection.
• ‘Endoscopy’ – a thin tube with a camera put through the anus (to view the rectum and colon) or through the mouth (to view the oesophagus and stomach). A patient may have an endoscopy if a blood or stool test suggests that they have inflammation.
• ‘Capsule endoscopy’ – a small capsule swallowed by the patient that contains a camera and light that takes photos of the inside of a patient’s digestive system. Less widely used than regular endoscopy and may not be appropriate for some patients due to disease location or narrowing of the intestines by stricturing.
• MRI, CT and ultrasound scans – used to look at the location of the patient’s IBD and how much of the bowel it affects, for example to see if they have any fistulas.

These tests may need to be done regularly to check how bad a person’s condition is and whether their treatments are working. [3, 4, 6]

What treatment options are available for IBD?
Crohn’s disease and ulcerative colitis are chronic conditions, which means that they are life-long diseases and cannot be cured. Treatments are available that can help to control the symptoms and inflammation. The aim of treatment is to control inflammation and to have no symptoms (reach ‘remission’) and then to keep having no symptoms with regular treatment to keep the disease under control (‘maintenance treatment’). [3, 6]

As the main cause of symptoms in IBD is inflammation, most therapies aim to reduce this. These are called ‘anti-inflammatory’ drugs and include corticosteroids, immunosuppressants and biological drugs. Patients may also be given a drug that targets a specific symptom, such as diarrhoea. If a person’s condition is particularly severe or they need a quick response, they may need to take more than one drug at the same time. This is called ‘combination therapy’ and can help some drugs to work better. [3, 10]

Surgery is also a treatment option for Crohn’s disease and UC. The most common operations in people with Crohn’s disease are to remove the strictures in the digestive system (a ‘stricturoplasty’) and to remove very inflamed sections of the intestines (a ‘resection’). [4]

Surgery is more common in UC, with up to 1 in 4 patients eventually needing surgery. Most commonly these people have very severe UC with regular flare-ups, and will often have pancolitis rather than the other types of UC. The most common surgery for UC is a total removal of the colon and rectum (a ‘proctocolectomy’) or the removal of part of the colon (an ‘ileal pouch-anal anastomosis’ [IPAA]). [11]

Clinical research is looking into new treatment options for patients with Crohn’s disease or ulcerative colitis who do not respond or who stop responding to the anti-inflammatory drugs that are currently available. [12, 13]