What is Crohn's disease?
Crohn's disease is a type of inflammatory bowel disease (IBD), which is very different to irritable bowel syndrome (IBS). Crohn’s may cause swelling of the tissues (inflammation) in the digestive tract, that can lead to abdominal pain, severe diarrhoea, tiredness, weight loss and poor nutrition.
Inflammation caused by Crohn's disease can involve any area of the digestive tract, and the areas of inflammation maybe a single continuous area or multiple segmental areas. This differs between individuals and can make it a more challenging condition to manage. The most frequently affected part of the gut is the small intestine.
Crohn's disease can cause painful and impact on activities, and sometimes may lead to serious complications.
Unfortunately, there is currently no cure for Crohn's disease, but treatments can greatly reduce patients’ symptoms and even bring about long-term remission. With treatment, many people with Crohn's disease can get on with their lives the vast majority of the time.
Signs and symptoms of Crohn's disease can range in their severity. They usually develop gradually, but sometimes will develop rapidly. There often long periods of time when there are no symptoms (remission).
During a flare up, symptoms typically include:
Abdominal pain and cramping
Blood in the stool
Reduced appetite and weight loss.
Pain or discharge near or around the anus due to inflammation from a connect between the bowel and the skin (fistula)
Other signs and symptoms
Crohn's disease can sometimes cause a range of symptoms outside of the gut including:
Inflammation of skin, eyes and joints
Inflammation of the liver or bile ducts
Iron deficiency (anaemia)
Delayed growth or sexual development, in children
When to seek help?
Medical advice should be sough it there has been a persistent change in bowel habit or there have been other symptoms of Crohn's disease, such as:
Cramping abdominal pain
Blood in the stools
Nausea and vomiting
Prolonged Diarrhoea (greater than two weeks)
Unexplained weight loss
Crohn’s Disease Diagnosis
Diagnosis is made by scans including CT and MRI, a colonoscopy which is the passage of a small camera into the back passage to inspect the bowel and is usually carried out under sedation. A biopsy may be taken at the time to confirm the diagnosis.
Endoscopic features of Crohn's (A,B) and ulcerative colitis (C,D) from Review: Colon Capsule Endoscopy in Inflammatory Bowel Disease Diagnostics 2022, 12(1), 149; https://doi.org/10.3390/diagnostics12010149
The precise cause of Crohn's disease remains unknown. Previously, diet and stress were implicated, but now it is believed these factors may only trigger bouts, but are not the underlying cause of, Crohn's disease. A combination of factors are likely to contribute to its development.
Immune system. It has been postulated that a virus or bacterium may bring about Crohn's disease; however, scientists have yet to identify such organisms as triggers. When the immune system tries to neutralise a bacterial or viral infection, an overactive immune response could result in the immune system attacking the body’s own cells in the digestive tract, too.
Heredity. Crohn's disease is more common in people who have family members with the disease, so genes are likely to play a role in the disease process, but are only part of the process as the majority people with Crohn's disease do not have a family history of the disease.
Risk factors for Crohn's disease may include:
Crohn's disease can occur at any age, but it is most likely to present for the first time in younger people. The majority of people who develop Crohn's disease are diagnosed before they reach the age of 30.
Although Crohn's disease can affect any ethnic group, white people have the highest risk of developing the disease, especially people of Eastern European (Ashkenazi) Jewish descent. However, the incidence of Crohn's disease is increasing among Black people who live in North America and the United Kingdom and in Middle Eastern migrants to the United States.
People are at higher risk of developing Crohn’s disease if they have a first-degree relative, such as a parent, sibling or child, with the disease. Roughly 1 in 5 people with Crohn's disease has a family member with the disease.
Cigarette smoking is the biggest controllable risk factor for developing Crohn's disease. Smoking is also associated with more-severe disease and an increased risk of having surgery. Quitting smoking can be an important lifestyle measure to help manage the disease.
Nonsteroidal anti-inflammatory medications.
Examples of these medications include ibuprofen, naproxen, diclofenac. While they do not cause Crohn's disease, they can lead to inflammation of the bowel that may exacerbate Crohn's disease.
Crohn's disease may lead to some of the following complications:
Crohn's disease can affect the full thickness of the gut wall. Over time, parts of the bowel can scar and narrow, which also called a stricture. This may obstruct the flow of digestive contents, which may have serious consequences. These strictures may require surgery to widen the stricture or sometimes to remove the diseased portion of your bowel. Sometimes such operations need to be carried out as an emergency in some cases of bowel obstruction.
Inflammation can lead to open sores (ulcers) anywhere in the digestive tract, including the mouth and anus, and in the genital or perineal area.
Sometimes ulcers can penetrate all the way through the gut wall, creating a fistula — an abnormal connection between two different areas that shouldn’t be connected. Fistulas can develop between the intestine, or between the intestine and the skin, or between the intestine and another organ. Fistulas are commonest around the anal area (perianal) and typically lead to openings in the skin.
When fistulas develop inside the abdomen, it may lead to infections due to bowel bacteria entering the blood stream, and collection of pus which are also called abscesses, which may require urgent drainage or surgery. Fistulas may form between loops of bowel or connect to the bladder or vagina, or through the skin, causing continuous drainage of bowel contents to the skin, or mixing with urine.
This is a small tear in the tissue lining the anus or in the skin around the anus where infections can occur. It can be painful and may lead to a perianal fistula.
Diarrhoea, abdominal pain and cramping may make it difficult maintain a healthy diet and the bowel may not to absorb enough nutrients to maintain nourishment. It's also common to develop anaemia due to reduced iron or vitamin B-12 absorption.
If Crohn's disease affects the colon (large bowel) it increases the risk of colon cancer. Colon cancer screening is undertaken in the general population in many countries In the USA this is between the age of 45 and 75 and in the UK it is undertaken between ha age of 60 and 74 as examples. In people with Crohn's disease affecting a large part of the colon screening needs to be intensified and a typical strategy, would be to start regular colonoscopies about 8 years after disease onset, at 1-to-2-year intervals. The risk is low at first but increases the longer patients have the condition. For example, after 10 years the risk is about 1 in 50, after 20 years the risk increases to about 1 in 10 and after 30 years the risk increases further to about 1 in 5.
Crohn's disease sufferers can develop a condition called hidradenitis suppurativa. This is a skin disorder characterised by deep nodules, and abscesses in the armpits, groin, under the breasts, and in the perianal or genital area.
Other health problems.
Crohn's disease can also cause problems outside of the gut. Among these problems are low iron (anaemia), osteoporosis, arthritis, gallbladder or liver disease and eye problems.
Some Crohn's disease medication are associated with a small risk of developing cancers such as lymphoma and skin cancers. They also increase the risk of having infections.
Corticosteroids can be associated with a risk of osteoporosis (weakening of the bones), cataracts, glaucoma (increased eye pressure), diabetes, weight gain, increased risk of infections and high blood pressure.
Blood clots. Crohn's disease increases the risk of developing blood clots in veins and arteries, leading to increased risk of DVT (deep vein thrombosis) or P.E (pulmonary embolism).
Crohn’s Disease Treatment
Currently there is no cure for Crohn's disease, unfortunately, but treatments can control or reduce the symptoms and delay disease relapses.
Medicines are the mainstay of treatments, but sometimes surgery may be needed.
Many people with Crohn's disease need to take steroids (such as prednisolone) on occasions. These can relieve symptoms by reducing inflammation in the gut – they take a few days or weeks to work and are usually taken as tablets and may need to be taken for a few months.
A liquid diet may help to reduce symptoms. This involves having nutritious drinks instead of the usual diet, for a few weeks. It relatively safe and has few side effects, but some people get side effects such as nausea, diarrhoea, or constipation.
Sometimes it is necessary to take medicines called immunosuppressants to reduce the activity of the immune system. Examples include azathioprine, mercaptopurine and methotrexate. These drugs can relieve symptoms if steroids on their own are not working. They can be used as a long-term treatment to help stop symptoms coming back. They can cause nausea, increased risk of infections and liver problems.
These are the most potent drugs and are used when other medication have failed. Examples of biological medicines used in Crohn's disease are adalimumab, infliximab, vedolizumab and ustekinumab. These are administered by injection or a drip into a vein every 2 to 8 weeks. They are given longer term. Side effects can include an increased risk of infections.
The most common operation is a bowel resection. This involves: Removing the section(s) of diseased bowel and stitching the healthy parts of bowel together. Sometimes an ileostomy is required (where motions come out into a bag) for a few months to let the bowel recover before it's reconnected.
Living with Crohn’s
There is an increased risk of infections like flu in patients receiving either: immunosuppressant medicines, such as azathioprine, methotrexate and mercaptopurine or biological medicines. such as adalimumab and infliximab. It's recommended to have the influenza vaccine every year and the one-off pneumococcal vaccination.
Most patients with Crohn’s disease will have a normal pregnancy and healthy baby. Some Crohn's disease medicines can harm an unborn baby, so patients should inform their doctor as soon as are aware of the pregnancy as their medication may need to be altered.
It may be harder to conceive during a flare-up, but fertility return to normal eventually. Some medicines can temporarily reduce sperm count.