Crohn's Disease – Symptoms, Treatment, and Course of This Chronic Inflammatory Bowel Disease

Crohn’s disease is a chronic inflammation of the gastrointestinal tract and, like ulcerative colitis, is classified as a chronic inflammatory bowel disease.

It is also known as Crohn’s regional enteritis, terminal enteritis, terminal ileitis, or scarring enteritis.

The disease usually progresses in flare-ups and is not contagious.

The entire gastrointestinal tract—that is, from the mouth to the anus—can be affected by Crohn’s disease. However, the disease most commonly manifests in the lower section of the small intestine, at the junction with the large intestine.

This is where the following develop:

• fistulas
• strictures, and
• ulcers in all layers of the intestinal wall

In contrast, ulcerative colitis occurs only in the large intestine and affects the intestinal mucosa exclusively at the surface level. In Crohn’s disease, deeper layers of the intestinal wall may also be affected by inflammation.

Depending on the affected section, doctors distinguish between:

• Crohn’s disease with ileocecal involvement: occurs when the terminal ileum and cecum are inflamed
• Crohn’s colitis: occurs when all or part of the large intestine is inflamed

Crohn’s Disease by the Numbers

Crohn’s disease is one of the most common chronic inflammatory bowel diseases:

• Out of every 100,000 people, approximately 120 to 200 have Crohn’s disease.
• In Central Europe, approximately 5.2 to 8.6 people per 100,000 develop Crohn’s disease each year.
• In Germany, about 5 people per 100,000 residents are newly diagnosed with Crohn’s disease each year.

In principle, the disease can occur at any age.

However, young adults between the ages of 15 and 35 are most commonly affected by Crohn’s disease. In about 15 to 25 percent of all those affected, the first symptoms appear before the age of 20, and in some cases even during infancy.

The activity of the disease often decreases with age.

Crohn’s disease occurs with roughly equal frequency in women and men.

Comparison of the effects of ulcerative colitis and Crohn’s disease © bilderzwerg | AdobeStock

The exact causes of Crohn’s disease are not known. However, given its tendency to run in families, it is believed that there is a genetic predisposition.

If a close relative already has Crohn’s disease, other family members face a risk that is about ten times higher.

Disorders of the immune system may also be responsible. These lead to pathological interactions with the intestinal wall and thus to inflammation.

Environmental factors also appear to play a role in the development of Crohn’s disease. For example, smokers and people from industrialized nations have a higher risk. Psychological factors (e.g., psychological strain, stress) do not influence the onset of the disease, but they do affect its course.

Diet, on the other hand, is not responsible for either the onset or the flare-ups of the disease.

Crohn’s disease is typically characterized by:

• cramping abdominal pain, usually in the lower right abdomen, and
• watery, sometimes mucous-containing diarrhea that lasts for several weeks and rarely contains blood.
• This is usually accompanied by a loss of appetite and weight loss. The symptoms are similar to those of ulcerative colitis.

The exact symptoms depend, among other things, on which part of the digestive system is affected by the inflammation. As a result, some people experience only mild symptoms, while others suffer from severe symptoms.

Furthermore, the symptoms can be nonspecific, especially at the onset of the disease. In children, Crohn’s disease can also manifest as slower growth and delayed onset of puberty.

Since inflammation can also occur outside the intestine, extraintestinal manifestations may occur.

These include:

• Pain in the knee or ankle
• Inflammatory skin changes
• Chronic fatigue (fatigue syndrome)

Crohn’s disease has a chronic, relapsing-remitting course, in which disease activity increases and then subsides.

Depending on the severity of the inflammation, doctors classify an acute Crohn’s disease flare-up into:

• mild
• moderate, or
• severe

Crohn’s disease can affect a single section or multiple areas of the digestive tract simultaneously.

The following sections are most commonly affected:

• Lower small intestine (terminal ileum): about 30 percent of cases
• The junction between the small intestine and the large intestine (ileocolon): about 40 percent of cases
• Large intestine and anal canal: about 25 percent of cases
• Other sections: about 5 percent of cases

Although Crohn’s disease is a chronic condition, it has little impact on patients’ life expectancy. The vast majority of patients can lead a largely normal life.

The following video shows the findings from a colonoscopy:

Depending on the extent and duration of the disease, complications may arise. However, this is relatively rare.

The occurrence of a complication can often be an indication for Crohn’s disease surgery.

The most significant complications of Crohn’s disease occur in the intestines:

• Narrowing (stenosis)
• Intestinal obstruction: Depending on the cause, surgery for Crohn’s disease may be necessary
• Intestinal perforation: a life-threatening complication that requires immediate surgery for Crohn’s disease
• Fistulas (abnormal channels, usually between sections of the intestine or between the intestine and the skin)
• Fissures (tears, usually around the anus and in the anal canal)
• Abscesses (collections of pus, especially in the anal area)
• Conglomerate tumor (inflamed bowel loops that have adhered to one another)
• Malabsorption syndrome (nutrient deficiency)
• Intestinal bleeding: If blood loss can no longer be compensated for by blood transfusions, surgery for Crohn’s disease is necessary.

The most important complications of Crohn’s disease outside the intestine are:

• Kidney stones
• Gallstones
• Inflammation of the bile ducts
• Joint inflammation with joint pain
• Eye inflammation
• Skin changes (erythema nodosum)

The diagnostic process typically begins with a patient interview (medical history) regarding:

• Symptoms
• Medical history
• Family history

This is followed by a physical examination and additional tests.

During the physical examination, the doctor palpates the abdomen. The doctor checks for tenderness in the lower right abdomen and for areas of hardening. The doctor also examines the anus for fistulas and fissures.

Blood tests: Certain changes can be detected in the blood count.

The following symptoms are common:

• Anemia
• Elevated erythrocyte sedimentation rate (ESR) and white blood cell count
• Elevated C-reactive protein (CRP) level (indicates an acute inflammatory process)
• Low levels of folic acid, vitamin D, and vitamin B12

Some blood test results may indicate Crohn’s disease © Henrik Dolle | AdobeStock

A colonoscopy allows for visual examination of the colon and the collection of tissue samples from the mucosa. This enables doctors to confirm the diagnosis through histological examination.

An ultrasound examination (sonography) allows doctors to check whether the intestinal wall is thickened. Additionally, an upper endoscopy and other imaging procedures such as magnetic resonance imaging (MRI) may be necessary.

Since the causes of Crohn’s disease are unknown, the disease is incurable.

Therefore, treatment for Crohn’s disease primarily aims to:

• To halt the inflammatory process
• To relieve symptoms and
• To reduce the risk of complications

Depending on the severity and course of the disease, there are generally various treatment options available for Crohn’s disease:

• During an acute flare-up, medication is used (e.g., corticosteroids or specific anti-inflammatory drugs).
• In cases of recurrent flare-ups, long-term medication may also be necessary.
• Dietary changes for children and underweight patients
• Taking essential nutrients if a deficiency exists

In cases of complications such as fistulas or bowel obstruction, or if medication is ineffective, surgical treatment (Crohn’s disease surgery) is necessary.

Surgical Treatment for Crohn’s Disease

Surgery for Crohn’s disease is an important treatment option for patients with Crohn’s disease, as evidenced by the following figures:

For 80 percent of Crohn’s disease patients, the first Crohn’s surgery takes place approximately 10 years after the onset of the disease.

About 90 percent of Crohn’s disease patients will undergo Crohn’s disease surgery at least once in their lifetime.

The main reasons for Crohn’s disease surgery are:

• Intestinal obstruction (ileus)
• Intestinal perforation or
• Severe bleeding

Timely Crohn’s disease surgery can prevent symptoms and complications. During surgery, doctors remove as little of the small intestine as possible, as a recurrence (relapse) may occur.

The Goal of Crohn’s Disease Surgery

There are two types of Crohn’s disease surgery:

1. Emergency Crohn’s disease surgery
2. Elective Crohn’s disease surgery

Emergency Crohn’s disease surgery is necessary in life-threatening situations.

These include, for example:

• Stenoses (narrowing of the intestine) and
• intestinal obstruction (ileus)
• Peritonitis and
• bowel perforation

Elective Crohn’s disease surgeries are part of an individualized treatment plan and can be scheduled well in advance. Elective Crohn’s disease surgeries account for the vast majority of all surgeries performed for Crohn’s disease.

Indications for Crohn’s disease surgery

Surgery cannot cure the disease. Even after Crohn’s disease surgery, there is a risk of relapse (recurrence). Therefore, the doctor must assess the pros and cons of surgery for Crohn’s disease on a case-by-case basis.

However, the following are generally considered indications for Crohn’s disease surgery:

• Treatment-refractory Crohn’s disease (medication is not sufficiently effective): elective indication
• Incomplete/chronic intestinal obstruction that cannot be treated: elective indication
• Complete intestinal obstruction: emergency indication
• Diagnosed precancerous lesions (low-grade intraepithelial neoplasia): elective indication
• Toxic megacolon (dilatation of the colon with harmful accumulations of intestinal contents): urgent indication
• Perforation (rupture of the bowel): emergency indication
• Severe intestinal bleeding: urgent indication
• Peritonitis (inflammation of the peritoneum): emergency indication

In the following cases, the physician should postpone Crohn’s disease surgery for as long as possible:

• In cases of abscesses
• In cases of fistulas
• In cases of conglomerate tumors

Diagnostic Tests Before Crohn’s Disease Surgery

If Crohn’s disease surgery is planned, the following tests are performed beforehand:

• Colonoscopy
• Ultrasound and radiological evaluation of the small intestine
• Determination of certain laboratory values

The preoperative diagnostic workup for Crohn’s disease should answer the following questions:

• Is it actually Crohn’s disease (or could it be ulcerative colitis or another chronic inflammatory bowel disease)?
• What is the pattern of involvement, or how has the disease spread?
• Is there a typical indication for Crohn’s disease surgery?

A colonoscopy is one of the key diagnostic tests performed prior to Crohn’s disease surgery © phonlamaiphoto | AdobeStock

Procedure for Crohn’s Disease Surgery

The most common procedures for Crohn’s disease surgery are:

• bowel resection (removal of sections of the bowel),
• Removal of fistulas, and
• drainage of abscesses

Surgery for Crohn’s disease is performed only on the affected section of the intestine. Experience has shown that radical Crohn’s disease surgeries—that is, the removal of large sections of the intestine—are detrimental and should therefore be avoided. Doctors will only operate on an inflamed area if it is causing symptoms.

Occasionally, scar tissue or adhesions can cause narrowings (stenoses) in the intestine. This prevents the passage of intestinal contents. In such cases, removal of the affected section of the intestine is necessary.

Surgery for Crohn’s disease in cases of stenosis involves the minimal removal of the narrowed segment of the intestine. For short narrowings (strictures), plastic dilation is sometimes sufficient without doctors having to remove the intestinal tissue itself.

By restoring unrestricted stool passage (stricturoplasty), the inflammation heals and the patient becomes symptom-free.

Fistulas from the intestine to the bladder (enterovesical fistulas) and fistulas that end blindly in the retroperitoneal space can be dangerous.

These can affect other organs (e.g., the urogenital tract). They can also lead to dangerous collections of pus in the body (abscesses). After the diseased sections of the intestine are removed, the fistula usually heals quickly.

Doctors can either puncture an abscess or drain the fluid using a drainage tube.

Emergency Surgery for Crohn’s Disease

Fortunately, true emergencies are rare in Crohn’s surgery. They account for just under 5 percent of all surgical procedures.

Indications for emergency surgery include:

• bowel perforation (resulting from severe inflammation or following a colonoscopy),
• Severe intestinal bleeding
• Acute severe inflammation, and
• Sudden complete bowel obstruction (ileus)

In all these situations, doctors must always act immediately. The outcomes are somewhat worse than with elective Crohn’s disease surgeries.

However, with proper medical care for Crohn’s patients, emergency surgeries should be the exception!

Surgery for Crohn’s disease is performed by a specialist in visceral surgery or a specialist in general surgery.

What exactly is Crohn’s disease?

Crohn’s disease is a chronic inflammatory bowel disease affecting the entire digestive tract. Crohn’s disease is a chronic inflammatory condition that can affect any part of the intestine and is also known as Crohn’s disease. Like ulcerative colitis, it is classified as an inflammatory bowel disease.

What are the common symptoms of Crohn’s disease?

A typical symptom of Crohn’s disease is chronic, recurring diarrhea. This is often accompanied by abdominal pain, weight loss, and fatigue. During active phases of Crohn’s disease, fistulas, abscesses, or strictures may develop. Some patients with Crohn’s disease also develop symptoms outside the intestines.

How is Crohn’s disease diagnosed?

Crohn’s disease is diagnosed through clinical examination, laboratory tests, and imaging studies. A colonoscopy to evaluate the intestinal mucosa and intestinal wall is essential. If Crohn’s disease is suspected, diagnostic testing is performed in accordance with clinical guidelines. The diagnosis of Crohn’s disease also takes into account other intestinal diseases, such as ulcerative colitis.

What is the treatment for Crohn’s disease?

Treatment for Crohn’s disease depends on the severity of the condition and the current flare-up. The goal of treatment is to control inflammation and prevent complications. Medication with anti-inflammatory drugs or TNF-α inhibitors is commonly used. In severe cases, surgery may be necessary. Treatment for Crohn’s disease is tailored to the individual.

What role do causes and risk factors play in Crohn’s disease?

The exact causes of Crohn’s disease are not fully understood. Genetic factors, immune system dysregulation, and environmental factors are considered risk factors. The development of Crohn’s disease is understood to result from the interaction of several factors. The risk of Crohn’s disease is increased in individuals with a family history of the condition. With consistent treatment, life expectancy in Crohn’s disease is generally not significantly reduced.