Irritable bowel syndrome

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

1. 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