Differentiating inflammatory bowel disease (IBD) from other conditions, such as irritable bowel syndrome (IBS), can be challenging, particularly when symptoms are intermittent or mild. Careful assessment of alarm features, inflammatory markers, stool testing, and recent infectious or travel history can help identify patients who require gastroenterology (GI) evaluation.
Since IBS lacks certain inflammatory markers that may indicate a diagnosis of IBD, understanding the patient’s medical history, their symptoms, and using the correct testing early on is crucial.
Although IBD is most commonly diagnosed between 15 and 30 years of age and in older adults as well, it can present at any age and significantly impact quality of life. Studies show that early recognition and timely diagnosis are important because persistent intestinal inflammation can lead to progressive bowel damage and complications, including strictures, fistulas, abscesses, hospitalization, and surgery. Prompt referral allows earlier initiation of appropriate therapy and may improve long-term outcomes.
IBD red flags for primary care providers
Symptoms to watch for include:
- Persistent diarrhea over four weeks
- Blood or mucus in stool
- Waking up during the night to have a bowel movement (Nocturnal bowel movements)
- Unintentional weight loss
- Tenesmus (incomplete evacuation) or urgency
- Persistent abdominal pain
- Iron-deficiency anemia
- Fever or elevated inflammatory markers
- Perianal fistula, abscess, drainage
- Extraintestinal manifestations (arthritis, uveitis, erythema nodosum, pyoderma gangrenosum, and recurrent oral ulcers)
“Unlike ulcerative colitis (UC), Crohn’s disease (CD) sometimes may lack visible rectal bleeding, but consider it if there is weight loss, anemia, abdominal pain, and chronic diarrhea,” says gastroenterologist and IBD specialist Jalpa Devi, MBBS. “Extraintestinal features like arthritis, rash, recurrent oral ulcers, uveitis or scleritis, and a family history of IBD should further increase suspicion.”
Key differentiators from IBS
Although abdominal pain and altered bowel habits occur in both IBD and IBS, patients with IBD are more likely to have blood in the stool, nocturnal symptoms, weight loss, and extraintestinal manifestations like joint pain or skin rashes.
Important IBD mimics
IBD can mimic other conditions, such as:
- NSAID-induced enteropathy or colitis. Document the medication, dosage, and duration of use.
- Infectious gastroenteritis, such as Clostridioides difficile (C. diff)
- Recent antibiotic use, which can trigger acute diarrhea but may lack weight loss
- Chemotherapy-or immune checkpoint inhibitor-associated colitis or ischemic colitis
- Celiac disease
"Fecal calprotectin is a marker of intestinal inflammation but is not specific for IBD," adds Dr. Devi. "Elevated levels can also occur with gastrointestinal infections, NSAID use, ischemic colitis, colorectal neoplasia, and other inflammatory conditions. Results should always be interpreted in the context of the patient's history and clinical presentation."
Recommended initial evaluation
Laboratory tests:
- Complete blood count (CBC) with differential
- Comprehensive metabolic panel (including albumin and liver enzymes)
- C-reactive protein (CRP)
- Ferritin and iron studies
- Celiac serologies (Tissue transglutaminase IgA with total IgA) for chronic diarrhea without bleeding
- Stool tests for enteric pathogens, including C. diff.
- Fecal calprotectin stool test. This test differentiates IBD from IBS. A result over 250 strongly indicates inflammation and requires a gastroenterologist referral.
Fecal calprotectin
Fecal calprotectin is a noninvasive marker of intestinal inflammation that can help distinguish IBD from functional gastrointestinal disorders such as IBS. Results should be interpreted in the context of the clinical presentation because elevations may occur with gastrointestinal infections, NSAID use, colorectal neoplasia, and other inflammatory conditions. A normal result does not completely exclude IBD.
Imaging:
- Cross-sectional imaging is not routinely required before referral. A CT enterography or MR enterography may be appropriate. Use this rather than a simple abdominal CT scan with only IV contrast because it provides a clearer picture of the small and large bowel lumen to assess inflammation.
- Pelvic MRI with fistula protocol for suspected perianal abscesses or fistulas
Endoscopy:
- Colonoscopy with biopsies (even if mucosa looks normal, GI needs to take biopsies) remains the gold standard for diagnosing IBD. When clinical suspicion is high, referral for Gastroenterology evaluation should not be delayed while ruling out alternative diagnoses.
Refer to an IBD specialist
Refer a patient to an IBD specialist for any suspected IBD right away, especially those with confirmed IBD cases. In addition, refer for diagnostic uncertainty despite symptoms or with persistent symptoms with equivocal labs.
“IBD is a chronic disease with multi-organ involvement,” says Dr. Devi. “Early diagnosis and an individualized treatment plan can prevent complications like strictures, fistulas, and surgery. Management is complex, requiring a multidisciplinary team and avoiding unsafe practices like chronic steroid use.”
The gastroenterologists at the Frederick F. Paustian Inflammatory Bowel Disease Center understand the nuances of IBD symptoms, diagnosis, and timely treatment to help patients with IBD live life to the fullest.
To refer a patient to an IBD specialist:
Frederick F. Paustian Inflammatory Bowel Disease Center
4310 Emile St.
Omaha, NE 68105
402.559.0264
Please specify “suspected IBD” in the referral and include all prior notes, complete lab panels, stool tests, imaging, endoscopy reports, and pathology.