Inflammatory Bowel Disease: Diagnosis and Clinical Management

What Is Inflammatory Bowel Disease?

Inflammatory bowel disease (IBD) is a term that encompasses two distinct chronic conditions: Crohn disease (CD) and ulcerative colitis (UC). Both are characterized by chronic inflammation of the gastrointestinal tract mediated by a dysregulated immune response.

Crohn disease may affect any segment of the digestive tract, from mouth to anus, with transmural inflammation (full thickness of the wall) and skip distribution. Ulcerative colitis affects the colon and rectum exclusively, with inflammation limited to the mucosa and continuous distribution starting from the rectum.

IBD affects about 7 million people globally, with rising incidence in industrializing countries, including Brazil. Peak onset occurs between 15 and 35 years, although the disease can arise at any age. IBD significantly impacts quality of life and requires long-term multidisciplinary follow-up.

Pathophysiology

IBD results from the interaction among genetic susceptibility, environmental factors, microbiota dysbiosis, and intestinal epithelial barrier dysfunction. More than 240 genetic susceptibility loci have been identified, including variants in genes for autophagy (ATG16L1), pathogen recognition (NOD2), and immune regulation (IL23R).

In Crohn disease, the immune response is predominantly mediated by Th1/Th17 cells, with excessive production of TNF-alpha, IL-12, IL-23, and IL-17. In ulcerative colitis, the Th2/Th9 response predominates (with Th17 contribution per recent data), with production of IL-5, IL-13 and altered NK-T cell function.

Environmental Factors

Tobacco use has a paradoxical effect: it is a risk factor for Crohn disease but protective in ulcerative colitis. Childhood appendectomy protects against UC. NSAID use, antibiotics in childhood, Westernized diet, and stress are other implicated environmental factors.

Intestinal dysbiosis — reduced microbial diversity, with decreased Firmicutes (especially Faecalibacterium prausnitzii) and increased Proteobacteria — is a consistent finding in IBD, although it is not clear whether it is cause or consequence of inflammation.

Symptoms

Clinical presentation of IBD depends on the location, extent, and severity of inflammation. The disease evolves with periods of activity (flares) alternating with periods of remission.

Diagnosis

IBD diagnosis is based on the combination of clinical, laboratory, endoscopic, histologic, and radiologic findings. No single test confirms the diagnosis — it is an integrated diagnosis.

Ileocolonoscopy with biopsies is the fundamental test. Fecal calprotectin (fecal inflammatory marker) is useful for screening and monitoring — elevated values (more than 250 mcg/g) have high sensitivity for intestinal inflammation. MR enterography assesses the small intestine in Crohn disease.

IBS vs. IBD: The Most Important Distinction in Practice

Irritable bowel syndrome (IBS) is the main differential diagnosis for IBD — both cause abdominal pain and altered bowel habits. The fundamental distinction is the presence or absence of inflammation: IBD shows rectal bleeding, fever, weight loss, elevated inflammatory markers (CRP, ESR), and increased fecal calprotectin (>150 µg/g). In IBS, all these markers are normal. Fecal calprotectin is the screening biomarker of choice — a normal result practically excludes active IBD.

Coexistence of IBS and IBD in the same patient is possible — patients with IBD in remission may have residual functional symptoms that meet IBS criteria. In this case, calprotectin elevation during symptomatic episodes distinguishes IBD relapse from overlapping functional symptoms. Empirically treating active IBD as IBS may result in progression of intestinal injury — correct distinction is fundamental.

Intestinal Tuberculosis: Critical Differential Diagnosis for Crohn Disease

Intestinal tuberculosis is the main differential diagnosis for Crohn disease with ileocecal involvement — and the distinction has critical therapeutic implications: immunosuppressants used in Crohn (corticosteroids, thiopurines, biologics) can be fatal in untreated tuberculosis. Evening fever, night sweats, history of pulmonary TB, positive PPD or IGRA, contact with a tuberculosis patient, and origin from an endemic region are important clues.

Colonoscopy in intestinal TB shows transverse "shirt-collar" ulcers and preferential involvement of the ileocecal valve. Biopsy with AFB (acid-fast bacilli) culture is the confirmatory standard, but culture takes weeks. Granulomas with caseous necrosis on histology are highly suggestive of TB. In doubtful cases, empirical anti-TB treatment for 2-3 months with endoscopic reassessment may be necessary before starting immunosuppression.

Drug-Induced Colitis and Colorectal Neoplasia: Diagnoses That Guide Management

NSAIDs are a frequent and underestimated cause of colitis — producing colonic erosions and ulcers that mimic IBD on endoscopy and histology. The most important clues are the temporal relationship between NSAID initiation and symptoms, and improvement with discontinuation. Other associated medications: antibiotics (C. difficile colitis), ipilimumab and other immunotherapies (immune-mediated colitis), mycophenolate, and some chemotherapies.

Colorectal neoplasia must be excluded in any patient with rectal bleeding and altered bowel habit, especially over age 45-50. Colonoscopy with multiple biopsies distinguishes IBD from colorectal cancer, which can present similarly. Important: patients with long-standing IBD have increased risk of colorectal neoplasia — periodic endoscopic surveillance is part of the IBD follow-up protocol.

Treatment

The goal of modern IBD treatment has evolved from clinical control of symptoms to mucosal healing (endoscopic remission), which is associated with better long-term outcomes. The treat-to-target strategy — treating until objective targets are reached — guides therapeutic decisions.

Acupuncture as Treatment

Acupuncture is studied as a complementary therapy in IBD, with proposed mechanisms that include modulation of the inflammatory response (reduction of TNF-alpha, IL-1beta, IL-6), regulation of the intestinal neuro-immune axis via the vagus nerve, and modulation of the intestinal microbiota.

Experimental studies in animal models of colitis show that acupuncture and moxibustion can reduce intestinal inflammation and promote mucosal repair. Activation of the cholinergic anti-inflammatory reflex (vagal pathway) is a plausible mechanism — vagal stimulation inhibits the release of pro-inflammatory cytokines by intestinal macrophages.

It is fundamental to emphasize that acupuncture does not replace pharmacologic treatment of IBD. Its role is complementary, potentially helping to control symptoms such as pain, fatigue, and anxiety, and possibly contributing to inflammatory modulation as an adjunct. Patients with IBD should maintain regular follow-up with a gastroenterologist.

Prognosis

IBD is a chronic condition requiring long-term treatment, but with therapeutic advances of the last two decades, most patients achieve sustained clinical and endoscopic remission. Life expectancy is practically normal with adequate treatment.

In Crohn disease, about 50% of patients will require surgery in the first 10 years, although rates are decreasing with earlier use of biologics (top-down strategy). Postoperative recurrence is frequent and requires medical prophylaxis.

In ulcerative colitis, the risk of colectomy at 10 years is 10-15% with modern treatment. Long-standing extensive UC (more than 8-10 years) increases the risk of colorectal cancer, requiring regular surveillance colonoscopy with chromoendoscopy.

Myths and Facts

When to Seek Help

IBD requires regular follow-up with a gastroenterologist. Some situations during follow-up require urgent attention.