Description of Medical Condition
Altered bowel habits, abdominal pain, gaseousness, in the absence of organic pathology (divided into four types):
- Alternating diarrhea with constipation
- Diarrhea predominant
- Constipation predominant
- Upper abdominal bloating and discomfort
System(s) affected: Gastrointestinal
Genetics: Unknown, but more common in families of patients
Incidence/Prevalence in USA:
- Unknown, but 50% of gastrointestinal visits, and second to upper respiratory infection as cause for lost workdays
- At least 15% of population (uncommon in children and early teens)
Predominant age:
- Late 20′s, rarely in late teens
- If overage 40, other disease more likely
Predominant sex:
- Female > Male (2:1) in the US
- In other parts of the world — Male > Female
Medical Symptoms and Signs of Disease
- All present in most patients but not with every episode
- Abdominal pain, usually lower quadrant, relieved by defecation
- Mucus in stools
- Constipation
- Diarrhea
- Distention
- Upper abdominal discomfort after eating
- Straining for normal consistency stools
- Urgency of defecation
- Feelings of incomplete evacuation
- Scybalous stools
- Nausea, vomiting (rarely)
- Rome II criteria: 12 weeks or more in past 12 months of abdominal bowel pain or discomfort that has 2 out of 3:
– Relieved by defecation
– Onset associated with change in frequency of stool
– Onset associated with change in form of stool
What Causes Disease?
Unknown but patients show some gut motility abnormalities with increased response to stress and stimulants, and increase in the 3 cycles/ minute smooth muscle contractions. Up to 1/3 of patients develop IBS after an episode of gastroenteritis.
Risk Factors
- Other members of the family with the same or similar gastrointestinal disorder
- History of childhood sexual abuse
- Sexual or domestic abuse in women
Diagnosis of Disease
Differential Diagnosis
- Inflammatory bowel syndromes
- Lactose intolerance
- Infections (Giardia lamblia, Entamoeba histo-lytica, Salmonella, Campylobacter, Yersinia. Clostridium difficile)
- Diverticula
- Cathartic use
- Magnesium containing antacids
- Celiac sprue
- Pancreatic insufficiency
- Depression
- Somatization
- Adenocarcinoma of the colon
- Villous adenoma
- Endocrine tumors
- Hypo/hyperthyroidism
- Diabetes mellitus
- Radiation damage to colon or small bowel
Laboratory
- As needed to rule out other pathology OESR
– CBC
– Stool for ova, parasites and culture
Drugs that may alter lab results: N/A
Disorders that may alter lab results: N/A
Pathological Findings
All labs normal except for sigmoidoscopy
Special Tests
Not needed for diagnosis
Imaging
- Barium enema, if indicated is usually normal
- Small bowel series
Diagnostic Procedures
Sigmoidos copy (often normal), can show spasm that reproduces pain and increase mucosal folds
Treatment (Medical Therapy)
Appropriate Health Care
Outpatient
General Measures
- Heat to abdomen can help
- Biofeedback may help
- Reduce stress
Activity
As normal
Diet
- Increase fiber — may make some patients worse
- Avoid — large meals; spicy, fried, fatty foods; milk products, carbohydrates
Patient Education
- Many materials available nationally and locally
- Stress the organicity of the disease versus any psycho-social interpretation
- Teach patient to avoid problem stimulants
Medications (Drugs, Medicines)
Drug(s) of Choice
- Use from among this list according to need or response
- Bulk producing agents — psyllium (Metamucil) products 1 tbsp bid or tid
- Constipating agents (if diarrhea is significant) — loperamide (Imodium) 4 mg initial dose, then 2 mg after each unformed stool or diphenoxylateatropine (Lomotil) 2.5-5.0 mg (1-2 tablets) after each unformed stool
- Antispasmodics/anticholinergics/sedatives
- dicyclomine (Bentyl) 10-20 mg bid to qid
- chlordiazepoxide-clidinium (Librax) 1 or 2 ac and qhs
- hyoscyamine (Levbid) 0.375 mg bid
- phenobarbital-scopolamine-hyoscyamine-atropine (Donnatal) 1 or 2 tablets ac and hs
- amitriptyline (Elavil) 25-50 mg qhs
- 5-HT4 receptor agonist — tegaserod (Zelnorm) 6 mg bid for 4-6 weeks in patients with prominent constipation, may repeat course once (for women only)
- Antiflatulents — simethicone (Mylicon) 2 or 4 tablets pc and hs
- Lactose intolerance — lactase (Lactaid) capsules or tablets; 1-2 tablets prior to ingesting milk products
Contraindications: Refer to manufacturer’s profile of each drug
Precautions: Refer to manufacturer’s profile of each drug
Significant possible interactions: Refer to manufacturer’s profile of each drug
Alternative Drugs
N/A
Patient Monitoring
As needed for symptoms
Prevention / Avoidance
See Diet
Possible Complications
N/A
Expected Course / Prognosis
• No progression to cancer or inflammatory disease
• Expect recurrences, when under stress, throughout life. Frequency lessens as age increases.
Miscellaneous
Associated Conditions
- Migraine
- Bladder frequency
- Nocturia
- Urgency
- Fecal incontinence
- Fibromyalgia
- Dyspareunia
- Depression
- Stress incontinence
Age-Related Factors
N/A
Pediatric: N/A
Geriatric: N/A
Pregnancy
Anecdotal information implies that irritable bowel syndrome gets worse in pregnancy. But there are no increased risks to fetus or mother.
Synonyms
- Mucous colitis
- Spastic colon
- Irritable colon
International Classification of Diseases
564.1 Irritable bowel syndrome
See Also
Other Notes
Must not give patients the impression that this is a psychiatric illness
Abbreviations
IBS = irritable bowel syndrome