IRRITABLE BOWEL SYNDROME

IRRITABLE BOWEL SYNDROME – IBS

March 11, 2026

EARLIEST DESCRIPTIONS OF SYMPTOMS DEFINING IBS

1849 – W Cumming¹“The bowels are at one time constipated,at another lax, in the same person. How the disease has two such different symptoms I do not profess to explain. . . .”

Other historical terms – mucous colitis – colonic spasm – neurogenic mucous colitis – irritable colon – unstable colon – nervous colon – spastic colon – nervous colitis – spastic colitis1962 – Chaudhary & Truelove2 Irritable colon syndrome1966 – CJ DeLor3 Irritable bowel syndrome

HISTORICAL PERSPECTIVE

sufferers are women)²– condition not fatal

•Long dismissed as a psychosomatic condition¹ no clear etiology– affects predominantly women(~70% of

•Attitudes now changing

•Incidence and prevalence not extensively monitored in past

HALLMARK SYMPTOMS OF IBS

•Chronic or recurrent GI symptoms– lower abdominal pain/discomfort– altered bowel function (urgency,altered stool consistency, altered stool frequency, incomplete evacuation)– bloating

•Not explained by identifiable structural or
biochemical abnormalities

KEY FACTS ABOUT IBS

Up to 20% of the US population report symptoms consistent with IBS¹
The most common GI diagnosis among gastroenterology practices in the US²
One of the top 10 reasons for PCP visits³
Affects predominantly females (~70% of sufferers)⁴
The most common functional bowel disorder⁵
Can cause great discomfort, sometimes intermittent or continuous, for many decades in a patient’s life¹
Can significantly disrupt daily life²
Can have negative impact on quality of life²

Current treatment options– dietary modification– fiber supplements– pharmacologic agents– psychotherapy
Success of current treatment options in addressing multiple symptoms of IBS has been limited⁴

iBS Consultation pattern

DIRECT MEDICAL COSTS ASSOCIATED WITH IBS

BS results in an estimated $8 billion in direct medical costs annually¹
IBS sufferers incur 74% more direct healthcare costs than non-IBS sufferers¹
IBS patients have more physician visits for both GI and non-GI complaints²

PRODUCTIVITY BURDEN

Impact on work due to IBS

Patients with some missed workdays — 30%
Average number missed workdays* — 1.7
Patients who cut back some days — 46%
Average number days cut back* — 3

EVOLUTION OF MECHANISTIC HYPOTHESES IN IBS

Biopsychosocial Disorder–Psychosocial–Motility–Sensory–? Infectious

Prevalence 10%, Incidence 1-2% per Year
Disturbs QOL, Social Function, Healthcare Utilization

ENTERIC NERVOUS SYSTEM

Controls motility and secretory functions of the intestine
Semiautonomous– actions modified by parasympathetic and sympathetic nervous systems– may function independently
Contains many neurotransmitters, including 5-HT, substance P, VIP (vasoactive intestinal peptide), and CGRP (calcitonin gene-related peptide)

IBS: Current thinking on pathophysiology

Defects in the enteric nervous system may leadto the hallmark symptoms of IBS

Visceral hypersensitivity1 – Increased visceral afferent response to normal as well as noxious stimuli– Mediators include 5-HT, bradykinin, tachykinins, CGRP, and neurotropins
Primary motility disorder of GI tract² – Mediated by 5-HT, acetylcholine, ATP, motilin, nitric oxide, somatostatin, substance P, and VIP

PHYSIOLOGICAL DISTRIBUTION OF 5-HT

5-HT initiates peristaltic reflex mediated by the ENS

5-HTRECEPTOR EFFECTS

•Mediate reflexes controlling gastrointestinal motility and secretion
Mediate perception of visceral pain

COMPARISON OF PAIN THRESHOLDS OF IBS PATIENTS AND CONTROLS

COMPARISON OF PAIN THRESHOLDS

MAKE A POSITIVE DIAGNOSIS^1,2

HISTORY OF DIAGNOSTIC APPROACHES

1950s – Increased gut motility¹
1970s – Specific motility markers¹
1980 to 1999 – Symptom-based criteria¹–Manning criteria–Rome criteria
1999 – Rome II criteria²

IBS ROME II CRITERIA

At Least 12 Weeks, Which Need Not Be Consecutive, in the Preceding 12 Months, of Abdominal Discomfort or Pain That Has Two of Three Features:

1.Relieved with Defecation; and/or

2. Onset Associated with a Change in Frequency of Stool; and/or

3. Onset Associated with a Change in Form (Appearance) of Stool

RED FLAGS” MAY SUGGEST AN ALTERNATIVE OR COEXISTING DIAGNOSIS

DIAGNOSTIC TESTS—WHAT? WHEN? WHO?

If patient has typical features of IBS:

•If <50 years of age, order CBC, electrolytes, LFTs, screen stool for occult blood, and consider sigmoidoscopy.¹

•If ³50 years of age, order CBC, electrolytes, LFTs, and perform a colonoscopy or air-contrast barium enema with sigmoidoscopy.^1,2

DIFFERENTIAL DIAGNOSIS

Malabsorption¹
Dietary factors¹
Infection¹
Inflammatory bowel disease¹
Psychological disorders¹
Gynecological disorders²
Miscellaneous¹

CURRENT MANAGEMENT OF IBS

Establish a positive diagnosis¹
Reassure patient that there is no serious
organic disease or alarming symptoms¹
Success of current treatment options in addressing multiple symptoms of IBS has been limited²

CURRENT MANAGEMENT COMPONENTS OF IBS

Education
Reassurance•Dietary modification
Fiber
Symptomatic treatment
Psychological/behavioral options
Realistic goals

Laxatives and bulking agents

Symptomatic treatment—constipation

Increased dietary fiber or psyllium¹
Osmotic laxatives (MgSO₄, lactulose)²
Stimulant laxatives³
Some laxatives and bulking agents can exacerbate abdominal pain and bloating³

TRICYCLIC ANTIDEPRESSANTS AND SSRIS

Symptomatic treatment—pain

•Reserved for patients with severe or refractory pain

Multiple medications needed to treat multiple symptoms

A COMPREHENSIVE MULTICOMPONENT APPROACH

Treatment program is based on dominant symptoms and their severity and on psychosocial factors

Medical management
Diet
Psychological or behavioral options– psychotherapy– stress management

INITIAL MANAGEMENT OF IBS

Non-Traditional Remedies

Chinese Herbal Medicine –116 pts randomized to CHM did better than pts receiving placebo
Peppermint Oil–Relaxation of GI smooth muscle–Meta-analysis showed significant improvement of IBS symptoms
Acupunture
Probiotics
Antibiotics

Surgical Therapy for IBS

IBS symptoms may be attributed to:–Non-functioning gallbladder disease, chronic appendicitis, uterine fibroids, tortuous colon
IBS symptoms rarely improve after surgery
IBS patients 2 to 3 times more likely to undergo unnecessary surgery

Take Home Points

•IBS is a chronic medical condition characterized by abdominal pain, diarrhea or constipation, bloating, passage of mucus and feelings of incomplete evacuation

•Precise etiology of IBS is unknown and therefore treatment is focused on relieving symptoms rather that “curing disease”