How Crohn’s Disease Is Diagnosed and Treated: Tests, Medications, and Surgery

Diagnosing Crohn’s Disease

Diagnosing Crohn’s disease can take time because its symptoms often resemble those of other digestive conditions. There is no single test that confirms the disease. Instead, healthcare providers use a combination of medical history, physical examinations, laboratory tests, imaging studies, and endoscopic procedures.

The goal is not only to identify Crohn’s disease but also to determine which part of the digestive tract is affected and how severe the inflammation is. This information helps guide treatment decisions.

An early and accurate diagnosis can reduce the risk of complications. It also allows treatment to begin before inflammation causes lasting damage to the intestines.

Medical History and Physical Examination

The diagnostic process usually starts with a detailed discussion of your symptoms and medical history.

Your healthcare provider may ask questions such as:

• When did your symptoms begin?
• How often do you have diarrhea?
• Have you noticed blood in your stool?
• Are you losing weight without trying?
• Does anyone in your family have inflammatory bowel disease?
• Do you smoke?
• What medications do you currently take?

A physical examination may include checking for:

• Abdominal tenderness
• Swelling or bloating
• Weight loss
• Fever
• Signs of dehydration
• Skin changes
• Joint swelling
• Anal fissures or fistulas

Laboratory Tests

Blood and stool tests cannot diagnose Crohn’s disease by themselves. However, they provide valuable information about inflammation, infection, and nutritional status.

Common Blood Tests

Stool Tests

Stool tests help rule out infections and measure intestinal inflammation.

They may check for:

• Bacterial infections
• Viral infections
• Parasites
• Blood in the stool
• Inflammatory markers such as fecal calprotectin

These tests help distinguish Crohn’s disease from infectious diarrhea and other gastrointestinal conditions.

Endoscopy

Endoscopy allows doctors to examine the digestive tract directly using a thin, flexible tube equipped with a camera.

This procedure can reveal:

• Inflammation
• Ulcers
• Bleeding
• Narrowed areas
• Tissue damage

Small tissue samples, known as biopsies, are usually collected during the examination. These samples are examined under a microscope to look for changes that support a diagnosis of Crohn’s disease.

Colonoscopy

A colonoscopy is one of the most important tests used to diagnose Crohn’s disease.

During the procedure, the doctor examines:

• The rectum
• The entire colon
• The end of the small intestine (terminal ileum)

A colonoscopy can identify:

• Ulcers
• Areas of inflammation
• Bleeding
• Skip lesions
• Narrowed sections of the intestine

Biopsies taken during the procedure help confirm the diagnosis and rule out other diseases.

Upper Endoscopy

If symptoms suggest involvement of the upper digestive tract, an upper endoscopy may be recommended.

This procedure examines:

• The esophagus
• The stomach
• The first part of the small intestine

Although Crohn’s disease is less common in these areas, inflammation can still occur.

Capsule Endoscopy

Capsule endoscopy uses a small camera inside a capsule that is swallowed like a pill.

As it travels through the digestive tract, the camera takes thousands of pictures.

This test is especially helpful for detecting inflammation in parts of the small intestine that cannot be reached with a standard endoscope.

It may not be suitable for people with suspected bowel narrowing because the capsule can become trapped.

Imaging Tests

Imaging studies provide detailed pictures of the intestines and surrounding tissues.

These tests help identify complications that cannot always be seen during endoscopy.

Common imaging tests include:

• CT scan
• CT enterography
• MRI
• MR enterography
• Abdominal ultrasound (in selected cases)

Doctors may use these tests to detect:

• Abscesses
• Fistulas
• Thickened bowel walls
• Intestinal narrowing
• Blockages

Complications of Crohn’s Disease

Crohn’s disease can cause complications when inflammation continues for a long time or becomes severe.

Some complications affect only the digestive tract, while others involve different parts of the body.

Regular medical care can reduce the risk of many of these problems.

Intestinal Strictures

Long-term inflammation may lead to scar tissue formation.

Scar tissue can narrow sections of the intestine, creating a stricture.

Symptoms may include:

• Cramping
• Bloating
• Nausea
• Vomiting
• Constipation
• Difficulty passing stool

Severe strictures may require endoscopic treatment or surgery.

Fistulas

A fistula is an abnormal tunnel that forms between two body structures.

Crohn’s disease may cause fistulas between:

• Two sections of the intestine
• The intestine and the bladder
• The intestine and the skin
• The intestine and the vagina
• Around the anus

Fistulas can become infected and often require medication, drainage, or surgery.

Abscesses

An abscess is a pocket of infection filled with pus.

Symptoms may include:

• Fever
• Severe pain
• Swelling
• Redness
• Fatigue

Abscesses often require antibiotics and drainage.

Malnutrition

Inflammation can interfere with nutrient absorption.

People with Crohn’s disease may become deficient in:

• Iron
• Vitamin B12
• Vitamin D
• Calcium
• Folate
• Zinc
• Magnesium

Poor nutrition can lead to fatigue, weakness, bone loss, anemia, and delayed growth in children.

Bowel Obstruction

Scar tissue and inflammation may partially or completely block the intestine.

Symptoms include:

• Severe abdominal pain
• Vomiting
• Bloating
• Constipation
• Inability to pass gas

A complete bowel obstruction is a medical emergency.

Increased Risk of Colon Cancer

People with Crohn’s disease affecting the colon for many years have a higher risk of colorectal cancer than the general population.

Because of this increased risk, healthcare providers often recommend regular surveillance colonoscopies after several years of disease, with the timing based on individual risk factors and disease extent.

Problems Outside the Digestive Tract

Crohn’s disease may also affect other organs.

Possible complications include:

• Arthritis
• Osteoporosis
• Kidney stones
• Gallstones
• Eye inflammation
• Skin disorders
• Liver disease
• Blood clots

Treating intestinal inflammation often improves these symptoms as well.

Goals of Treatment

There is currently no cure for Crohn’s disease.

Treatment focuses on:

• Reducing inflammation
• Relieving symptoms
• Healing the intestinal lining
• Preventing flare-ups
• Preventing complications
• Improving quality of life

Treatment plans vary depending on the severity of the disease, the location of inflammation, previous treatments, and overall health.

Medications for Crohn’s Disease

Several types of medications are available.

Each works differently to reduce inflammation or calm the immune system.

Aminosalicylates (5-ASA)

These medications reduce inflammation in parts of the digestive tract.

Examples include:

• Mesalamine
• Sulfasalazine

They are used less often for Crohn’s disease than for ulcerative colitis because their benefit in Crohn’s is limited and depends on the location of disease.

Corticosteroids

Steroids help reduce inflammation quickly during moderate to severe flare-ups.

Common examples include:

• Prednisone
• Budesonide
• Methylprednisolone

These medications are effective for short-term symptom control but are generally not used long term because they can cause significant side effects.

Possible side effects include:

• Weight gain
• Mood changes
• Increased blood sugar
• High blood pressure
• Bone loss
• Increased infection risk

Immunomodulators

These medications reduce immune system activity.

Examples include:

• Azathioprine
• 6-Mercaptopurine
• Methotrexate

They often take several weeks or months to become fully effective.

Regular blood tests are needed to monitor for side effects.

Antibiotics

Antibiotics are not routine treatment for Crohn’s disease itself.

However, they may be prescribed to treat:

• Abscesses
• Fistulas
• Certain bacterial infections

Examples include:

• Metronidazole
• Ciprofloxacin

Biologic Therapies

Biologic medications have transformed the treatment of moderate to severe Crohn’s disease.

They are made from living cells and target specific proteins involved in the inflammatory process.

Unlike older medications that suppress the immune system more broadly, biologics are designed to interrupt particular immune pathways.

Anti-TNF Medications

These drugs block tumor necrosis factor (TNF), a protein that promotes inflammation.

Examples include:

• Infliximab
• Adalimumab
• Certolizumab pegol

These medications can reduce inflammation, heal the intestine, and help maintain remission in many patients.

Integrin Receptor Antagonists

These medications prevent certain immune cells from entering inflamed intestinal tissue.

Examples include:

• Vedolizumab
• Natalizumab

Because they act more selectively, some have a lower impact on the rest of the immune system.

Interleukin Inhibitors

These biologics target proteins called interleukins that contribute to inflammation.

Examples include:

• Ustekinumab
• Risankizumab

These medications may be recommended when other treatments have not been effective or are not well tolerated.

Biosimilar Medications

Biosimilars are highly similar versions of approved biologic medications.

They provide comparable effectiveness and safety while often lowering treatment costs.

Many healthcare systems now use biosimilars as part of routine Crohn’s disease treatment.

Monitoring Treatment

Regular follow-up appointments help determine whether treatment is working.

Monitoring may include:

• Blood tests
• Stool tests
• Colonoscopy
• MRI or CT scans
• Symptom assessment
• Weight monitoring

The aim is not only to reduce symptoms but also to achieve healing of the intestinal lining whenever possible.

Surgery for Crohn’s Disease

Medication can control Crohn’s disease for many people, but surgery is still needed in some cases.

Surgery does not cure the disease because inflammation can return in other areas of the digestive tract.

However, surgery can improve quality of life and treat complications that cannot be managed with medication alone.

Reasons Surgery May Be Needed

Surgery may be recommended for:

• Bowel obstruction
• Severe bleeding
• Fistulas
• Abscesses
• Perforation
• Cancer or precancerous changes
• Disease that does not respond to medication

Common Surgical Procedures

Bowel Resection

The surgeon removes the damaged portion of the intestine and reconnects the healthy ends.

This is one of the most common operations for Crohn’s disease.

Strictureplasty

Instead of removing part of the intestine, the surgeon widens a narrowed section.

This preserves bowel length, which is especially important for people who have had multiple surgeries.

Drainage of Abscesses

Infected fluid collections may need to be drained before additional treatment can continue.

This may be done using imaging guidance or surgery.

Fistula Repair

Complex fistulas sometimes require surgery in addition to medication.

The specific procedure depends on the location and severity of the fistula.

Recovery After Surgery

Recovery time depends on the type of surgery performed.

Many people notice significant symptom improvement after surgery.

Recovery usually includes:

• Pain management
• Gradual return to eating
• Walking soon after surgery
• Follow-up appointments
• Continued medication when appropriate to reduce the risk of recurrence

Lifestyle changes, including avoiding smoking, may also help improve long-term outcomes.

Key Takeaways

• Crohn’s disease is diagnosed using a combination of medical history, laboratory tests, imaging, endoscopy, and biopsies.
• Colonoscopy with tissue biopsy remains one of the most important tools for confirming the diagnosis.
• Long-term inflammation can lead to complications such as strictures, fistulas, abscesses, bowel obstruction, and malnutrition.
• Treatment aims to control inflammation, achieve remission, heal the intestinal lining, and prevent complications.
• Medications include corticosteroids, immunomodulators, biologics, and other therapies chosen based on disease severity and location.
• Biologic therapies have significantly improved outcomes for many people with moderate to severe Crohn’s disease.
• Surgery can treat complications and improve quality of life, but it does not eliminate the underlying disease.

References

The information in this guide is based on evidence and patient education resources from the following organizations:

1. Mayo Clinic. Crohn’s Disease: Symptoms and Causes.
2. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Crohn’s Disease.
3. Cleveland Clinic. Crohn’s Disease.
4. Johns Hopkins Medicine. Crohn’s Disease.
5. WebMD. Crohn’s Disease Overview.