Rome V Bowel Disorders: Updated Diagnostic Framework for Disorders of Gut–Brain Interaction

Corsetti et al., Gastroenterology, 2026

 

Bowel disorders—previously referred to as functional bowel disorders—are among the most common gastrointestinal conditions worldwide. These disorders significantly affect quality of life, healthcare utilization, and productivity across all demographic groups.

 

In this Rome V update, Corsetti et al. present a revised diagnostic framework for bowel disorders based on advances in epidemiology, pathophysiology, clinical evaluation, and treatment since the publication of Rome IV in 2016. The updated classification aims to support clinicians in making more accurate diagnoses and delivering more individualized patient care.

What Are Rome V Bowel Disorders?

Rome V defines bowel disorders as chronic gastrointestinal conditions characterized by symptoms such as abdominal pain, bloating, distension, and abnormal bowel habits. These conditions are now classified into six main categories:

 

1. Irritable bowel syndrome (IBS)
2. Chronic constipation (CC)
3. Functional diarrhea (FDr)
4. Functional abdominal bloating/distension (FAB)
5. Unclassified bowel disorder (U-BD)
6. Opioid-induced constipation (OIC)

 

Although opioid-induced constipation has a clear pharmacologic cause, it is included due to its frequent overlap with other bowel disorders and similar clinical presentation.

Irritable Bowel Syndrome: Updated Diagnostic Criteria

IBS remains one of the most common disorders of gut–brain interaction. Under Rome V, IBS is defined as recurrent abdominal pain or discomfort associated with changes in bowel habits, with symptoms present for at least three months and onset at least six months before diagnosis.

 

Several important changes were introduced compared with Rome IV:

• Abdominal discomfort has been reintroduced as a diagnostic symptom alongside pain.
• The symptom frequency threshold has been adjusted to ≥3 days per month.
• Continuous abdominal pain is excluded to distinguish IBS from centrally mediated abdominal pain syndrome.
• Symptoms solely related to menstruation are excluded from IBS diagnosis.

 

IBS continues to be classified into four subtypes based on the Bristol Stool Scale:

• IBS with constipation (IBS-C)
• IBS with diarrhea (IBS-D)
• IBS with mixed bowel habits (IBS-M)
• IBS with unclassified bowel pattern (IBS-U)

 

Global prevalence estimates suggest approximately 4.3% of adults meet criteria for IBS, with higher prevalence among younger adults and women.

Chronic Constipation: Terminology and Diagnostic Updates

Rome V replaces the term functional constipation with chronic constipation (CC), reflecting a broader shift away from the “functional” terminology.

 

Chronic constipation is characterized by symptoms such as:

• Infrequent bowel movements
• Straining during defecation
• Hard stools
• Sensation of incomplete evacuation

 

Symptoms must occur for at least three months with onset six months before diagnosis, and patients must not meet criteria for IBS.

 

Global prevalence estimates range between 10% and 15%, making chronic constipation one of the most common bowel disorders worldwide.

Functional Diarrhea and Functional Abdominal Bloating

Rome V also refines diagnostic definitions for other bowel disorders.

 

Functional diarrhea is defined as recurrent loose or watery stools without an identifiable organic cause and without the abdominal pain characteristic of IBS.

 

Functional abdominal bloating and distension refers to recurrent abdominal fullness, pressure, or visible abdominal distension that predominates over other gastrointestinal symptoms.

 

Both conditions share pathophysiological features with IBS, including altered gut motility, microbiota changes, and gut–brain axis dysregulation.

A Positive Diagnostic Approach to Bowel Disorders

A key emphasis of Rome V is that clinicians should make a positive diagnosis based on symptom criteria, rather than relying on extensive testing to exclude organic disease.

 

In patients meeting diagnostic criteria and without alarm features, only selective testing is recommended.

 

Potential investigations may include:

 

• Inflammatory markers such as CRP.
• Fecal calprotectin to exclude inflammatory bowel disease.
• Targeted testing for conditions such as celiac disease when clinically indicated.

 

This approach can reduce unnecessary investigations while providing reassurance to patients.

Understanding the Multifactorial Pathophysiology of Bowel Disorders

Rome V emphasizes that bowel disorders should be understood through a biopsychosocial model, where multiple mechanisms interact to produce symptoms.

 

Proposed contributors include:

• Altered gastrointestinal motility.
• Visceral hypersensitivity.
• Immune activation.
• Changes in intestinal permeability.
• Gut microbiota alterations.
• Dysregulation of gut–brain signaling.

 

Environmental factors such as gastroenteritis, diet, stress, and psychological factors may also trigger symptom onset or exacerbations.

 

Implications for Clinical Management

Management strategies for bowel disorders should be individualized based on the patient’s predominant symptoms.

 

Recommended treatment approaches include:

• Lifestyle and dietary modifications (including fiber or low-FODMAP diets).
• Pharmacologic therapies targeting constipation or diarrhea.
• Neuromodulators for pain-predominant symptoms.
• Microbiome-directed therapies such as probiotics or antibiotics.
• Brain–gut behavioral therapies such as cognitive behavioral therapy or gut-directed hypnotherapy.

 

A strong patient–provider relationship and shared decision-making are considered central to successful long-term management.

Key Takeaways From the Rome V Update

The Rome V classification provides an updated framework for diagnosing and managing bowel disorders based on recent advances in clinical and translational research.

 

Key updates include:

• A revised diagnostic framework for bowel disorders.
• Reintroduction of abdominal discomfort into IBS criteria.
• Updated terminology such as chronic constipation.
• Emphasis on positive diagnosis and targeted testing.
• Recognition of bowel disorders as disorders of gut–brain interaction.

 

These updates aim to improve diagnostic accuracy, support more individualized treatment strategies, and enhance patient care for individuals living with these common gastrointestinal conditions.