Irritable bowel syndrome (IBS)

Criteria (Rome IV criteria for the diagnosis of irritable bowel syndrome):

• Recurrent abdominal pain on average
  • at least 1 day/week 
  • in the last 3 months
• Associated with two or more of the following criteria:
  • Related to defecation – either increase or improve pain
  • Associated with a change in the frequency of stool
  • Associated with a change in the form (appearance) of stool

• Common – prevalence 15-20%
• is a disorder of gut-brain interaction. 
• No anatomic cause can be found on laboratory tests, imaging studies, and biopsies. 
• Symptoms and Signs of IBS
  • begin in adolescence and the 20s
  • Onset in late adult life is also possible but less common. 
  • Symptoms are often triggered by food or by stress.

precipitate or aggravate GI symptoms by

• Physiologic factors
  • Increased intestinal sensitivity (visceral hyperalgesia)
    • hypersensitivity to normal amounts of intraluminal distention and heightened perception of pain in the presence of normal quantities of intestinal gas
  • Altered intestinal motility
    • slower colonic transit 🡪 constipation
    • faster colonic transit  🡪 diarrhoea
    • exaggerated gastro-colonic reflex 🡪 Postprandial abdominal discomfort 
  • Diet
    • Fat ingestion may increase intestinal permeability and exaggerate hypersensitivity. 
    • Ingestion of food high in 
    • fermentable oligosaccharides
    • disaccharides
    • monosaccharides
    • polyols

(Collectively called FODMAPs)

• Are poorly absorbed or only slowly absorbed in the small intestine  🡪 
• The unabsorbed carbohydrates, along with osmotically trapped water and electrolytes, enter the colon where they are rapidly fermented by bacteria to🡪  short-chain fatty acids and carbon dioxide, hydrogen and methane.
• FODMAPs increase small intestinal water volume and colonic gas production, with
• secondary effects on small and large intestine motility. 
• These factors may lead to symptoms of IBS, especially in those with visceral hypersensitivity and/or gastrointestinal motility abnormalities.
• Although lactose intolerance may be associated with IBS, fructose malabsorption,
• where some ingested fructose reaches the colon, is a physiological occurrence

• Hormonal fluctuations
  • Rectal sensitivity is increased during menses but not during other phases of the menstrual cycle. 
  • The effects of sex hormones on gastrointestinal transit are subtle.

• Psychosocial factors
  • Psychologic distress is common among patients with IBS, especially in those who seek medical care.
    • anxiety disorders
    • depression
    • somatization disorder
    • Sleep disturbances
  • However, stress and emotional conflict do not always coincide with symptom onset and recurrence. 
  • Some patients with IBS
    • May have learned aberrant illness behavior (ie, they express emotional conflict as a gastrointestinal complaint, usually abdominal pain). 
    • Refractory symptoms 🡪 should investigate for unresolved psychologic issues, including the possibility of sexual or physical abuse
• Severe Gastroenteritis episode may be associated
  • Antibiotics (Rifamaxin, Neomycin) have reduced symptoms in some cases
• Familial association
  • Risk increases 3 fold with Family History of Irritable Bowel Syndrome

Associated Conditions

• Gastroesophageal Reflux Disease
• Dysphagia
• Globus Hystericus
• Fatigue
• Non-cardiac Chest Pain
• Urologic dysfunction
• Gynecologic disease
  •  Chronic Pelvic Pain
• Fibromyalgia
• Chronic Fatigue Syndrome
• Temperomandibular joint syndrome
• Food Allergy
• Low-fiber diet

Differential diagnosis

• Lactose intolerance
• Drug-induced diarrhea
• Postcholecystectomy syndrome
• Laxative abuse
• Parasitic diseases (eg, giardiasis)
• Eosinophilic gastritis or enteritis
• Microscopic colitis
• Small intestinal bacterial overgrowth
• Celiac disease
• Bile acid diarrhea
• Early inflammatory bowel disease

Risk Factors: Psychosocial

• Anxiety Disorder
• Major Depression
• Somatization Disorder
• Sexual abuse or physical abuse
• Stressful life events
• Substance Abuse

Symptoms and Signs

• Abdominal discomfort
  • varies considerably
  • often located in the lower abdomen
  • steady or cramping in nature
  • may be related to defecation
  • Pain relieved with Defecation (52% of cases)

• Gaseousness
  • Excessive Flatulence or Eructation
  • Normal patients experience about 13 farts per day
  • Abdominal Distention (32% of cases)

• Altered bowel habits – Classified as diarrhea, constipation predominant or mixed
  • Diarrhea
  • Constipation
  • Scybalous stools (hard, pellet-like stools)
  • Mucus per Rectum (40% of cases)
  • Incomplete evacuation Sensation (69% of cases)

• Extraintestinal symptoms
  • Fatigue
  • Fibromyalgia
  • sleep disturbances
  • chronic headaches

Red flags

• Older age
• Weight loss
• Rectal bleeding
• Iron deficiency anemia
• Low albumin
• Family history of colon cancer, inflammatory bowel disease, or celiac disease
• Nocturnal diarrhea

Treatment

• require a holistic consultation. 
• positive diagnosis and reassuring explanation of irritable bowel syndrome should be delivered in an empathetic manner, while allowing time for the patient to discuss their concerns

• General lifestyle advice
  • regular exercise
• Diarrhoea – loperamide, cholestyramine, TCA, fibre
• Constipation – aperients, SSRI, Psyllium husk/soluble fibre
• Abdominal pain – peppermint oil, Buscopan, Mebeverine, Psycholgoical therapies (CBT), low dose TCA or SSRI eg. Citalopram 20mg daily

• Medicines
  • Mebeverine and hyoscine
    • Antispasmodic drugs have only modest effects in irritable bowel syndrome and have a limited role.
    • Although hyoscine has greater evidence for symptom relief, it is associated with significant adverse effects including constipation and dry mouth.
  • Peppermint oil
    • Peppermint oil acts as an antispasmodic through smooth muscle calcium channel antagonism.
    • A systematic review found that it significantly reduces symptoms compared with placebo
  • Antidepressants
    • Antidepressants can significantly reduce symptoms of irritable bowel syndrome
    • They are purported to work by manipulating visceral hypersensitivity and abnormal central pain sensitization 
    • It is important to advise patients that antidepressants are used for their neuropathic-pain-modulating effect, rather than for an antidepressant effect. Patients should take a low dose of the antidepressant every day for 4–6 weeks before assessing efficacy.
  • Tricyclics are ostensibly used for the diarrhoea subtype
    • due to their known adverse effect of constipation. 
  • SSRIs may be better used for the constipation subtype
    • due to their adverse effect of diarrhoea. 
  • Rifaximin
    • a non-absorbed antibiotic that modestly reduces symptoms of non-constipating irritable bowel syndrome compared to placebo
    •  Despite theoretical concerns of developing persistent bacteria that are resistant to rifaximin, studies have not demonstrated this to be the case.
  • Probiotics
    • Probiotics possibly have a role in irritable bowel syndrome but the dose and strain needed for benefit is not clear. 
    • Of the products available in Australia, the strains and doses are too varied to provide a meaningful recommendation based on evidence.

• Psychological Therapies
  • Some patients recognize that their symptoms arise or are aggravated by stress and anxiety. For these patients, offering psychological therapies as a direct method to treat irritable bowel syndrome is a reasonable solution. A carefully timed and formulated referral to a psychologist with expertise in functional gastrointestinal disorders improves the chance of a successful outcome. Treatments that are effective include:
  • Cognitive Behavioral Therapy (CBT)
    • Cognitive Restructuring: Identifying and challenging negative thought patterns and beliefs about IBS symptoms.
    • Behavioral Activation: Encouraging engagement in positive activities to improve mood and reduce stress.
    • Relaxation Techniques: Teaching relaxation exercises such as progressive muscle relaxation, deep breathing, and guided imagery to reduce anxiety and stress.
    • Problem-Solving Skills: Helping patients develop strategies to cope with specific IBS-related challenges.
    • Exposure Therapy: Gradual exposure to IBS-related fears or situations to reduce avoidance behaviors.
  • Multi-Component Psychological Therapy
    • Combining various psychological approaches, including CBT, relaxation techniques, and stress management, to address multiple aspects of IBS.
  • Dynamic Psychotherapy
    • Focuses on understanding and changing the underlying psychological conflicts and emotional issues contributing to IBS symptoms.
  • Gut-Focused Hypnotherapy
    • Hypnotic Induction: Inducing a state of deep relaxation and focused attention.
    • Gut-Focused Suggestions: Providing positive suggestions aimed at normalizing gut function and reducing symptoms.
    • Visualization: Using mental imagery to visualize the gut functioning smoothly and without pain.
    • Autogenic Training: Teaching patients self-hypnosis techniques to manage symptoms independently.
    • Hypnotherapy has been proven to reduce symptoms of IBS with sustained benefit for greater than five years. A recent Australian trial showed that gut-directed hypnotherapy is as effective as a low-FODMAP diet. Patients should be advised that hypnosis is not as theatrical as it is portrayed in popular culture. It usually incorporates CBT and relaxation exercises administered by a psychologically trained hypnotherapist, typically over 10 weekly sessions.

• Physical and Behavioral Therapies
  • Pelvic floor dysfunction is underdiagnosed among patients with IBS, especially those with the constipation subtype. These patients either fail to relax the pelvic floor or paradoxically contract the pelvic floor muscles, causing obstructed defecation.
  • Biofeedback
    • Pelvic Floor Retraining: Through a technique referred to as biofeedback, physiotherapists with expertise can retrain patients to use their pelvic floor muscles appropriately. Patients are given visual or tactile awareness of involuntary bowel function to learn voluntary control.
    • Behavioral Aspects: Addressing behavioral aspects that contribute to symptoms, such as incorrect toileting posture, prolonged time spent in the toilet, and use of inappropriate cues to trigger the need to defecate, with exercises and biofeedback.
    • Selecting patients for this therapy is best determined by specialists with expertise in the diagnosis of IBS.

• Diet
  • Soluble fibre
    • Insoluble fibres are more likely to worsen abdominal pain and bloating
    • Soluble fibre such as Psyllium husk – improves constipation and bloating with the constipation subtype
  • eating smaller frequent meals
  • avoiding trigger foods
  • avoiding excess alcohol and caffeine. 
  • dietary manipulation should be supervised by a dietitian

• low-FODMAP diet
  • Low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.
  • Implementation
    • The diet is trialed for 4–8 weeks.
    • FODMAP-containing foods are gradually reintroduced after the trial period.
    • Tolerance to reintroduced foods is evaluated.
    • Only ‘culprit’ FODMAPs should continue to be restricted after repeated re-introduction.
  • Precautions
    • Long-Term Use: The long-term benefits and risks of low-FODMAP diets are not known.
    • Duration: Patients should not continue a strict low-FODMAP diet beyond the recommended trial period.
    • Nutritional Balance: Care should be taken to ensure a nutritionally balanced diet.
      • Wheat, rye, and legumes are FODMAP-containing foods and may be restricted.
      • Reducing or eliminating these food items may affect gut microbiota, but the significance of this effect is not yet known.
    • Concomitant Conditions: Nutritional deficiencies should be considered and addressed before starting the diet in patients with other conditions or dietary habits that increase the risk of deficiencies.
  • Reintroduction Phase
    • After the initial 4-8 weeks, foods containing FODMAPs are reintroduced one at a time.
    • Tolerance to each food is evaluated to identify specific triggers.
    • Only foods that consistently trigger symptoms (‘culprit’ FODMAPs) should be restricted long-term.
  • Adverse Effects
    • Reported Adverse Events: No adverse events have yet been reported.
    • Study Limitations: Clinical trials were powered for efficacy, not safety.
      • Participant numbers were small.
      • Duration of the dietary intervention was brief.
  • Clinical Considerations
    • Monitoring: Regular follow-up is necessary to monitor the patient’s nutritional status and symptom control.
    • Individualization: The diet should be tailored to individual patient needs and responses.
    • Support: Referral to a dietitian for guidance on implementing and maintaining a low-FODMAP diet is recommended.
  • Conclusion
    • The low-FODMAP diet is an effective strategy for managing diarrhea-predominant IBS.
    • Careful implementation and monitoring are essential to ensure nutritional adequacy and long-term safety.
    • The reintroduction phase is critical for identifying specific FODMAP triggers and minimizing unnecessary dietary restrictions.