Constipation

Introduction

One definition of constipation is fewer than three stools per week for women and five for men despite a high-residue diet, or a period of more than 3 days without a bowel movement, straining at stool more than 25% of the time and/or two or fewer stools per week, and straining at defecation and less than one stool daily with minimal effort.

• The American Gastroenterological Association defines constipation as difficult or infrequent passage of stool, at times associated with straining or a feeling of incomplete defecation.
• Constipation may be primary (occurs without an underlying identifiable cause) or secondary (the result of constipating drugs, lifestyle factors, or medical disorders). It is not a disease but a symptom of an underlying disease or problem.
• Constipation commonly results from a diet low in fiber, inadequate fluid intake, decreased physical activity, or from use of constipating drugs such as opiates. Constipation may sometimes be psychogenic in origin.

CLINICAL PRESENTATION

Drugs Causing Constipation Inhibitors of prostaglandin synthesis, Opiates, Antihistamines, Antiparkinsonian agents (e.g., benztropine or trihexyphenidyl), Phenothiazines, Tricyclic antidepressants, Antacids containing calcium carbonate or aluminum hydroxide, Barium sulfate, Calcium channel blockers, Clonidine Diuretics (non-potassium-sparing),Ganglionic blockers, Iron preparations Muscle blockers (d-tubocurarine, succinylcholine), Nonsteroidal anti-inflammatory agents, Polystyrene sodium sulfonate.

Signs and symptoms

• Infrequent bowel movements (less than 3 per week)
• Stools that are hard, small, or dry
• Difficulty or pain of defecation
• Feeling of abdominal discomfort or bloating, incomplete evacuation, etc. Alarm signs and symptoms
• Hematochezia
• Melena
• Family history of colon cancer
• Family history of inflammatory bowel disease
• Anemia
• Weight loss
• Anorexia
• Nausea and vomiting
• Severe, persistent constipation that is refractory to treatment
• New-onset or worsening constipation in elderly without evidence of primary cause

Physical examination

• Perform rectal exam for presence of anatomical abnormalities (such as fistulas, fissures, hemorrhoids, rectal prolapse) or abnormalities of perianal descent
• Digital examination of rectum to check for fecal impaction, anal stricture, or rectal mass

Laboratory and other diagnostic tests

• No routine recommendations for lab testing—as indicated by clinical discretion
• In patients with signs and symptoms suggestive of organic disorder, specific testing may be performed (i.e., thyroid function tests, electrolytes, glucose, complete blood count) based on clinical presentation
• In patients with alarm signs and symptoms or when structural disease is a possibility, select appropriate diagnostic studies:

1. Protoscopy
2. Sigmoidoscopy
3. Colonoscopy
4. Barium enema

TREATMENT

• Goals of Treatment: The major goals of treatment are to

(a) relieve symptoms;

(b) reestablish normal bowel habits; and

(c) improve quality of life by minimizing adverse effects of treatment.

GENERAL APPROACH TO TREATMENT

• General measures believed to be beneficial in managing constipation include dietary modification to increase the amount of fiber consumed daily, exercise, adjustment of bowel habits so that a regular and adequate time is made to respond to the urge to defecate, and increased fluid intake.
• If an underlying disease is recognized as the cause of constipation, attempts should be made to correct it. GI malignancies may be removed through a surgical resection. Endocrine and metabolic derangements are corrected by the appropriate methods.
• If a patient is consuming medications known to cause constipation, consideration should be given to alternative agents. If no reasonable alternatives exist to the medication thought to be responsible for constipation, consideration should be given to lowering the dose. If a patient must remain on constipating medications, more attention must be given to general measures for prevention of constipation.
• The proper management of constipation will require a combination of non-pharmacologic and pharmacologic therapies.

PHARMACOLOGIC THERAPY

• Lactulose is generally not recommended as a first-line agent for the treatment of constipation because it is costly and may cause flatulence, nausea, and abdominal discomfort or bloating.
• Sorbitol, a monosaccharide, has been recommended as a primary agent in the treatment of functional constipation in cognitively intact patients.
• Agents such as milk of magnesia (an 8% suspension of magnesium hydroxide) may be used occasionally (every few weeks) to treat constipation in otherwise healthy adults.
• Glycerin is usually administered as a 3-g suppository and exerts its effect by osmotic action in the rectum. As with most agents given as suppositories, the onset of action is usually less than 30 minutes.
• Lubiprostone (Amitiza) is approved for chronic idiopathic constipation and constipation-predominant IBS in adults. The dose is 24 mg capsule twice daily with food.