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Digestive Disorders > IBD > Crohn's Disease

Crohn's disease diagnosis: The complete guide

Dr. Sarah Toler, CNM, DNP

Dr. Sarah Toler, CNM, DNP

Receiving a Crohn's disease diagnosis is often a difficult and lengthy process. Many people have symptoms of Crohn’s disease before they receive a diagnosis. Because symptoms vary greatly, Crohn's disease can be easily mistaken for irritable bowel syndrome or celiac disease.

People with Crohn’s disease experience abdominal pain, diarrhea, fatigue, and weight loss. Many people with Crohn's disease experience these symptoms to the extent that their quality of life is negatively impacted. To receive a diagnosis of Crohn’s disease, a person might receive an ultrasound, blood tests, and a colonoscopy, along with other tests.

What is Crohn's disease?

Crohn's disease, or Enterocolitis Regionalis, along with ulcerative colitis, is a chronic inflammatory bowel disease. Unlike ulcerative colitis, Crohn's disease can occur throughout the gastrointestinal tract, from the mouth to the anus, but most often it affects the end of the small intestine, or ileum, and the beginning of the large intestine, or colon. The entire intestinal wall is affected, including deeper layers.

The disease occurs in flare-ups. Smoking is associated with increased risk for developing Crohn’s disease. Physical activity is associated with decreased risk for Crohn’s disease. Crohn's disease is most often diagnosed by the age of 35.

What are the first signs of Crohn’s disease?

The first signs of Crohn's disease are severe, sometimes cramp-like abdominal pain, which is often located in the right lower abdomen. The right lower abdomen includes the section of the intestine that is most often affected by Crohn’s disease. There may also be diarrhea, with or without blood. Diarrhea or soft bowel movements that occur more than three times a day and at night are often signs of Crohn’s disease. Another symptom can be persistent nausea.

There may also be a slight increase in body temperature caused by the inflammatory process. In some cases, the symptoms include constipation and a bloated stomach. Many patients experience loss of appetite that can lead to weight loss.

In children, the disease manifests as a growth delay. Symptoms may include tender, reddish bumps in the subcutaneous fatty tissue on the legs, or erythema nodosum. The eyes or joints can also be inflamed.

In addition, fistulas and abscesses can occur in the anal area. Such anal fistulas are often the first sign of Crohn's disease.


How is Crohn's disease diagnosed?

Symptoms Ultrasound Blood test Stool test Colonoscopy (with tissue sample)
Stomach pain Thickened intestinal wall Increased white blood cells Increased calprotectin Ulcerations
Diarrhea Increased C-reactive protein Increased lactoferrin Stenoses
Nausea Increased blood

sedimentation rate

Examination for infections (suspicion of Clostridium difficile) Tissue changes

1. Consultation

The examining healthcare provider, usually a gastrointestinal specialist or gastroenterologist, first gathers a medical history including symptoms and triggers to differentiate other diseases. If the healthcare provider suspects Crohn's disease, they will carry out further diagnostics.

2. Physical examination

When palpating the abdomen, painful hardening of the right lower abdomen is often noticed. This suggests that the intestinal area is affected by the inflammation. With Crohn's disease, the intestine in the right lower abdomen is most often affected. Appendicitis is also manifested with pain when palpating the right lower abdomen, so this condition is often misdiagnosed.

3. Ultrasound

The healthcare provider can order an ultrasound of the abdomen to identify inflamed sections of the intestine. On ultrasound, the intestinal wall thickened by the inflammation will be visible. Abscesses and fistulas are connections between two organs or one organ with the surface of the body that does not exist naturally that are often present in Crohn’s disease. They are often seen on ultrasound.

4. Laboratory diagnostics

Blood and stool samples will be evaluated by the lab. Blood tests will evaluate complete blood count, blood chemistry, nutrient levels, and inflammatory markers. Stool specimens will be evaluated for bacteria and parasites.

Blood test

Nonspecific inflammation markers are often found in the blood. These include an increase in white blood cells, called leukocytosis, increased C-reactive protein, fibrinogen and an increased value of the sedimentation rate. Anemia can result from bleeding in the gastrointestinal tract and reduced iron or vitamin intake.

Stool test

In the stool sample, increased calprotectin values indicate inflammation of the mucosa. The lab also examines the stool for bacteria. Even if the blood values are normal, the intestine can still be inflamed. If the healthcare provider continues to suspect Crohn's disease, they may suggest a colonoscopy for further clarification.


During a colonoscopy, every section of the gastrointestinal tract is examined, since inflamed and non-inflamed sections of the bowel alternate in Crohn's disease. Ulcers may be visible in inflamed sections. The gastrointestinal specialist takes tissue samples and then has them examined for suspicion, which is called a biopsy.


Gastroscopy, or endoscopy, is an examination of the esophagus and stomach with a flexible instrument called a gastroscope. This procedure may be ordered to clarify whether upper sections of the digestive tract are affected by Crohn’s disease. These parts of the GI tract are often affected in children. This procedure may identify specific tissue changes called granulomas or giant cells.


Thickening of the intestinal wall and enlarged lymph nodes in the gastrointestinal tract can be visualized on an MRI scan. Possible fistulas can also be visualized on an MRI scan..

Crohn’s diagnosis for children

The upper part of the digestive tract, the stomach and esophagus, is usually more affected in children. Other, rather nonspecific complaints in children are loss of appetite and abdominal pain. There is often mild diarrhea and weight loss. Due to the poor absorption capacity of the intestine due to inflammation, children with Crohn’s disease are often small and enter puberty later.

Crohn’s flare-ups and remission

Since Crohn’s disease occurs in flare-ups, there are times when a person with Crohn’s disease is symptom-free, or in remission. During this time, the person is free of abdominal pain, diarrhea, or other symptoms. Inflammation values also normalize. Remission can also be determined using ultrasound or MRI. The duration of the remission varies from patient to patient. The healthcare provider may try to extend the remission with medication. When a flare-up lasts more than 6 months, the disease is referred to as chronic.

What happens after a Crohn’s diagnosis?

After a diagnosis of Crohn’s disease, the healthcare provider classifies the patient according to the Montreal classification to assess the prognosis and course of the disease. They take into account the age of the onset of the disease, the location of the inflammation in the gastrointestinal tract, and the biological behavior, like scarring or fistula formation.

A customized treatment plan is created, including changes in diet, medication, and possibly even surgical treatment. The aim is to achieve remission of the disease.

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Dr. Sarah Toler, CNM, DNP

Dr. Sarah Toler, CNM, DNP

Sarah Toler is a Certified Nurse Midwife, Doctor of Nursing Practice, and science writer. She focuses on improving women's health and access to health care by working with digital health platforms. Her area of expertise is mental health, particularly the physical manifestations of stress and anxiety.

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