Chapter 05 · Diagnosis & Testing

Diagnostics in Crohn’s Disease

Diagnosing Crohn’s involves a few different tests. Here’s what each one checks for — and how doctors measure how active the disease is.

There is no single medical test to diagnose Crohn’s disease. Diagnosis typically involves multiple appointments, tests, and procedures — each one giving a different piece of the puzzle.

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You probably won’t need every test listed here Your doctor will choose the ones that fit your symptoms. Each test shows a different part of the picture — together they help confirm if it’s Crohn’s and how active it is.

Interview & Physical Examination

💬 Conversation with your doctor

Reviewing your medical history, including family history
Questions about your general health and current symptoms
A physical examination

Lab Work

🩸 Blood work

Signs of inflammation in the body
Signs of anemia
Nutritional status (e.g., iron, vitamin D, vitamin B12)
Specific antibodies that can help distinguish Crohn’s from other inflammatory bowel conditions

🧪 Stool tests

Testing for infectious diseases (parasites, viruses, and bacteria)
Checking for signs of inflammation (fecal calprotectin)

Endoscopy with Biopsies

🔬 Gastroscopy with biopsies

Examining the esophagus, stomach, and beginning of the small intestines
Assessing disease location and severity
Collecting biopsies (tiny tissue samples)

🔎 Colonoscopy with biopsies

Examining the large intestines, rectum, and last part of the small intestines
Assessing the inflammation
Determining location and severity
Collecting biopsies (tiny tissue samples)

Imaging

📷 CT & MR Enterography

Both provide images of the small and large intestines and other organs of interest like the stomach
MR enterography is preferred due to lower radiation

💊 Capsule endoscopy

A procedure for examining the small intestines using a camera in a little capsule you swallow
Mainly used when doctors need a closer look at the small intestines, since this part is harder to reach with regular scopes

🌊 Ultrasound

Used to assess and monitor intestinal inflammation and wall swelling

🥛 Upper & Lower GI series with barium

Older imaging tests using a fluid called barium to examine the upper or lower part of the gastrointestinal tract
Less commonly used today, since MR enterography and ultrasound usually give better information with less radiation

PCDAI Score

Once Crohn’s is diagnosed, your doctor might calculate a Pediatric Crohn’s Disease Activity Index (PCDAI score) in patients under 19 to assess the severity of the disease and to help monitor disease activity over time. The PCDAI is grouped into four severity levels:

The four severity levels:

Remission Mild Moderate Severe

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Don’t try to score yourself The PCDAI is calculated by your doctor using your symptoms, physical exam findings, and lab results — so it gives a fuller picture than symptoms alone. If you’re curious about your own score, ask your medical team.

Factors included in the PCDAI score

If you’re curious, the score takes into account abdominal pain, the number of stools per day, your general well-being and daily functioning, weight, height, a physical abdominal examination, a perirectal examination, the number of extraintestinal symptoms, and specific laboratory results.

👉 A note for older teens: PCDAI is designed for patients under 19. As you transition into adult care, your doctor may start using the adult version — the CDAI (Crohn’s Disease Activity Index) — which measures similar things in a slightly different way.

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TeenHealthInsight is a health education website — not a substitute for medical advice. Any symptom or question that worries you should be brought to your doctor or gastroenterologist. If something feels off, reach out to your medical team.