Evidence Checklist: Irritable Bowel Syndrome (IBS)

GI specialist evaluation documenting IBS diagnosis and symptom patternCritical

Gastroenterologist evaluation confirming IBS (diarrhea-predominant, constipation-predominant, or mixed subtype) with documentation of stool frequency, consistency (Bristol Scale), and abdominal pain pattern meeting Rome IV criteria.

Nexus opinion linking IBS to service ("at least as likely as not")Critical

A medical opinion connecting IBS to service-related factors including combat stress, PTSD (gut-brain axis), traumatic abdominal injury, antibiotic use during deployment, or infectious gastroenteritis acquired during service.

Colonoscopy or flexible sigmoidoscopy ruling out organic diseaseCritical

Colonoscopy or sigmoidoscopy report confirming absence of inflammatory bowel disease, malignancy, or other structural pathology — required to support the IBS diagnosis.

Treatment records (antispasmodics, dietary modifications, IBS-specific medications)

Records showing medications prescribed (dicyclomine, hyoscyamine, rifaximin, linaclotide) and dietary recommendations (low-FODMAP diet), documenting treatment need and severity.

Symptom diary documenting frequency, pain, and incapacitating episodesCritical

A personal log recording daily bowel habits, pain severity (1–10 scale), and episodes that forced you to restrict activities or stay home. The number of incapacitating episodes per year is a primary rating driver.

Buddy statement from spouse, family, or fellow service member

A written statement from someone who can describe observable symptoms and how your condition affects daily life.

Personal statement describing symptoms and functional impact

Your own written account of how this condition affects your daily activities, work, and relationships. Describe your worst days.

Completed DBQ Intestinal Conditions (other than Small or Large Intestine)Critical

Standardized form capturing IBS subtype, symptom frequency, incapacitating episode count, and weight/nutritional impact.

Service treatment records (STRs)Critical

Military medical records showing in-service treatment, complaints, or injuries related to this condition.