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Irritable bowel syndrome

Irritable bowel syndromeDescription 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)

Irritable bowel syndromeDrug(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

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