Signs and Symptoms of Irritable Bowel Syndrome (IBS)
Irritable bowel syndrome is characterized by recurrent abdominal pain associated with changes in bowel habits (stool frequency and/or consistency) in the absence of structural abnormalities, with symptoms typically present for at least 6 months. 1
Core Diagnostic Symptoms
Abdominal Pain
- Typically located in the lower abdomen, but can occur anywhere in the abdomen 2
- Often described as colicky or crampy 2
- Pain is relieved by defecation in many patients 1
- Pain episodes typically last 2-4 days followed by periods of remission 2
- Pain may be aggravated within 90 minutes of eating in approximately 50% of patients 1
Altered Bowel Habits
- Stool consistency changes: Hard stools, loose stools, or alternating between both 1
- Stool frequency abnormalities: Less than 3 bowel movements per week or more than 3 per day 1
- IBS subtypes based on predominant stool pattern:
- IBS with constipation (IBS-C): Hard stools >25% of time, loose stools <25% of time 1
- IBS with diarrhea (IBS-D): Loose stools >25% of time, hard stools <25% of time 1
- IBS with mixed patterns (IBS-M): Both hard and loose stools >25% of time 1
- Unclassified IBS (IBS-U): Neither loose nor hard stools >25% of time (approximately 4% of cases) 1
Supporting Symptoms
Gastrointestinal Symptoms
- Bloating and abdominal distension - very common and often reported as highly bothersome 1, 3
- Abnormal stool passage: Straining, urgency, or feeling of incomplete evacuation 1
- Passage of mucus in stools 1
- Morning bowel pattern: Repeated defecation in the morning with progressive loosening of stool consistency (sometimes called "morning rush") 1
- Overlap with functional dyspepsia in 42-87% of IBS patients: epigastric pain, nausea, vomiting, early satiety 1
Non-Gastrointestinal Symptoms
- Lethargy and fatigue 1
- Poor sleep 1
- Backache 1
- Headache 1
- Urinary symptoms: Frequency, urgency, nocturia, incomplete bladder emptying 1
- Dyspareunia in women 1
- Fibromyalgia is present in 20-50% of IBS patients 1
Behavioral and Psychological Features
- Stress-related exacerbation: About 60% of patients report that stress aggravates symptoms 1
- Frequent consultations for non-gastrointestinal symptoms 1
- Previous medically unexplained symptoms 1
- Anxiety and depression are common but not diagnostic 1
Diagnostic Considerations
Timing and Pattern
- Symptoms typically present for more than 6 months 1
- Most patients experience intermittent symptoms with flares lasting 2-4 days followed by remission 1
- Some patients may be "alternators" whose predominant subtype changes over time 1
Alarm Features (Require Further Investigation)
- Age >50 years at symptom onset
- Short history of symptoms
- Documented weight loss
- Nocturnal symptoms
- Family history of colon cancer
- Anemia
- Rectal bleeding
- Recent antibiotic use 1
Clinical Pearls
IBS is a diagnosis of inclusion based on characteristic symptoms, not merely a diagnosis of exclusion 1
Continuous abdominal pain (rather than intermittent) may suggest "functional abdominal pain" rather than IBS, which has poorer treatment outcomes 1
Painless bowel dysfunction should be classified as functional constipation or functional diarrhea, not IBS 1
The Rome III criteria define IBS as recurrent abdominal pain or discomfort at least 3 days per month in the last 3 months, associated with two or more of: improvement with defecation, onset associated with change in stool frequency, or onset associated with change in stool form 2
IBS-M is the most common subtype (44.1%), followed by IBS-C (27.9%) and IBS-D (26.3%) 3