What Is Constipation?

Constipation is one of the most common symptoms complained of by older persons. Defecation less than three times a week or straining on defecation at least >25% of the time is defined as constipation.(1) There is a striking discrepancy between the definition of constipation based on a patient's perception and definition based on objective measures.(2) When asked to maintain a stool diary, it was noted that patients had been reporting three or more stools less per week. The older generation considers defecation every day a sign of good health. Constipation can be classified into two syndromes: functional and rectosigmoid outlet delay.(3)

Epidemiology

The prevalence of constipation is not known. A distinct geographic distribution exists in the USA that may suggest three global environmental factors: rural living, colder temperature and low socio-economic status.(4)

Risk Factors(5)

• Older Age
• African American
• Female
• Poor socio-economic status
• Less exercise
• Less education
• Low calorie intake

Diet and Constipation

It is not clear how diet and constipation are related. Constipation may occur in patients taking fewer calories.(6) It has been seen that dehydration may be the cause of constipation in some patients.(7) Fiber may be related to constipation.(8) Fiber is the name given to food derived from a plant source not digested by humans. Not all fruits and vegetables are a good source of fiber. Patients may be eating these foods thinking that they will provide them with adequate fiber. Foods with high fiber include 100% bran cereals, beans, peas, raspberries and broccoli. Fiber may lessen transit time in the colon but does not correct pelvic dysynergia.(9) For fiber to decrease transit time, the person needs to be physically active and drinking adequate amounts of fluid.

Laxative Abuse

A large number of people use laxatives. In the USA, $400 million are spent annually on different kinds of laxatives.(10) In patients on chronic laxatives, anatomic changes occur in the colon suggesting neuronal injury or damage to colonic longitudinal musculature, characterized by loss of austral folds.(4) Also, colonic transit time is increased.(11) Eventually, chronic laxative users may develop megacolon with megarectum and may have recurrent episodes of fecal impaction. There is a risk of acute distension and colonic perforation (Ogilivie's syndrome). Over time, there is decreased effectiveness of the laxatives and constipation may be aggravated. Stimulant laxatives should not be given for chronic use. On sigmoidoscopy, there may be spotty or diffuse dark pigmentation in laxative abusers called "Melanosis coli".

Causes and Presentation

Constipation is a symptom of many diseases. The patient should be interviewed to rule out all the organic causes of constipation. A history of bowel habits, stool frequency, consistency and straining should be recorded. Patients should be asked to maintain a stool record. Colon cancer may cause any kind of change of bowel motility in the elderly and may be accompanied by blood from the rectum. Decreased food intake should be explored. Hypothyroidism, hyperparathyroidism, depression, dehydration, scleroderma, Parkinsonism, CVA and diabetes mellitus are potentially treatable causes of constipation.

Pain, fever, urinary or fecal incontinence, diarrhea and/or delirium are findings that may occur in persons with fecal impaction. Impaired, bed-bound patients with neurological complications may develop volvulus, especially of the sigmoid colon. Presenting features may include sudden abdominal distention, cramping, vomiting, constipation or fecal incontinence.

Constipation may occur in an acutely hospitalized patient due to bed rest and altered dietary routines.

Drugs Causing Constipation

History of intake of the following medicines should be taken, as they are a common cause of constipation.

• Antacids
  • Aluminum hydroxide
  • Calcium Carbonate
• Anticholinergics
• Antidiarrheals
• Antiparkinson's
• Antidepressants
  • Tricyclics
  • Lithium
• Antihypertensives/Antiarrhythmics
  • Calcium channel blockers especially verapamil
• Metals
  • Bismuth
  • Iron (gluconate is better than sulfate)
  • Heavy metals
• Opioids
• Laxatives (used chronically)
• NSAIDs
• Sympathomimetics
  • Pseudoephedrine

Examination

Performing a large number of tests is costly and the benefits to the patients are unclear.(12) Therefore, a common sense and simple examination should be done first.

• A mini-mental examination will check the reliability of the history
• A geriatric depression scale should be checked to exclude depression.
• The oral cavity should be examined. Ill-fitting dentures or poor dentition may interfere with food intake, causing decreased intake of calories and constipation.
• The abdomen should be inspected for any surgical scars, palpated for tenderness, excessive stools or masses. The bowel sounds should be auscultated.
• On rectal examination, visually look for prolapse, fissures and hemorrhoids. Digital tone, tenderness, masses, contractility and impaction should be looked for.
• A thorough physical examination should be done to rule out Parkinsonism and autonomic neuropathy.

Investigations

Complete blood count, calcium, magnesium and a TSH will rule out anemia and rare metabolic disorders. An elevated BUN/creatinine ratio >20:1 may suggest dehydration.

Sigmoidoscopy may show diverticulosis, chronic polyps, ischemic stricture, extrinsic compression by pelvic tumor or melanosis coli.

If constipation has been there for less than two years or has changed, evaluate for cancer by colonscopy and colon transit study.

Complications from Constipation

• Fecal impaction is heralded by cramping lower abdominal and lower back pain. It is the result of prolonged exposure of the feces to absorptive forces of the colon.
• Stercoral ulcer is caused by pressure necrosis of mucosa due to fecal mass. This may present as bleeding from the rectum.
• Delirium
• Anal fissure may occur due to straining
• Megacolon may be due to chronic laxative abuse or may be idiopathic
• Volvulus, especially of the sigmoid colon
• Carcinoma of the colon(13)

Treatment

The Acute Case

A constipated patient should be admitted to the nursing home or hospital. Irritant laxatives (bisacodyl), water, Fleets enemas or polyethylene glycol are given to clear the bowels. If there is no response, increased fluid intake can be useful either by instilling fluids into the stomach (1-2 liters) or alternatively using a high tap water enema.

Chronic Situations

• Counsel patients that daily bowel movements and purging are not necessary for health.
• Bowel Training: Patients should have regular bowel movements; make use of postprandial gastrocolic reflex after breakfast; never resist the urge to defecate and spend at least 10 minutes for a bowel movement to occur.
• Regular exercise
• Diet: Prune juice has been shown to be beneficial.
• Biofeedback may be used in the long term if idiopathic constipation is not responsive to traditional methods.(14) However, success is related to the number of sessions and the patient's willingness to complete treatment.(15)
• Hydration: At least 1500 ml/day of fluids should be taken, increasing in summer.
• If life style modifications fail, then pharmacological therapy should be started.

Our treatment of choice is sorbitol (30-50 cc) at night. Lactulose will have similar effects. It is important to remember that this regimen can eventually lead to diarrhea. We have seen a number of patients whose diarrhea was cured by stopping the sorbitol! Stimulant laxatives should be used only intermittently but never long term. Sorbitol and psyllium are safe laxatives to use.(16) As compared to docusate sodium, phyllium is considered superior.(*) All laxatives may result in fluid depletion and electrolyte abnormalities (particularly hyperkalemia).

Bulk forming laxatives work by two methods. They are hydrophilic, increase stool mass and soften consistency and are metabolized by the colon bacteria to produce osmotically potent metabolites. They are contraindicated in mechanical obstruction.

Mineral oil impairs absorption of fat soluble vitamins. Patients with impaired gag and swallowing reflexes may aspirate mineral oils resulting in a lipoid pneumonia. Docusate produces mild side effects (cramping, rashes, nausea) but increases absorption and toxicity of other drugs like phenolphthalein, mineral oil and quinidine. There is little evidence that docusate is more useful than fluids.

Lactulose is not digested in the small intestine and colonic bacteria act on it to produce hydrogen and organic acids. This acidifies the colon, causes electrolyte changes and alters motility. Senna, aloe and cascara are absorbed in the intestine and excreted through the enterohepatic circulation into the colon. The active metabolite is emodine. They can damage the myenteric plexus permanently and cause melanosis coli, protein losing enteropathy and osteomalacia.

Phenolphthalein is a fat soluble stimulant and can lead to dermatitis, photosensitivity and Steven-Johnson's syndrome. It gives the stool and urine a pinkish color. This should never be used.

Castor oil inhibits glucose and sodium absorption. It stimulates water and electrolyte secretion via inhibition of sodium-potassium ATPase and increasing cyclic AMP. It can cause fluid and electrolyte disturbances and is not recommended.

Bisacodyl is not absorbed. It can cause electrolyte imbalance, decrease potassium, increase fluid and water and cause diarrhea.

Laxatives

• Bulk-forming
  • Bran
  • Psyllium preparations
  • Methylcellulose
  • Calcium polycarbophil
• Surfactant laxatives
  • Docusates
  • Poloxamers
  • Castor oil
• Stimulant
  • Diphenylmethane derivates
    1. Bisacodyl
    2. Phenophthalein
  • Anthraquinone derivates
    1. Senna
    2. Cascara
    3. Aloe
    4. Rheum (Rhubarb)
• Osmotic
  • Sodium phosphate
  • Magnesium sulfate
  • Milk of magnesia
  • Magnesium citrate
  • Sorbitol
  • Mannitol
  • Glycerine
  • Lactulose

Summary

Constipation is a frequent problem in older persons. Intestinal transit does not change with age. Treatable causes such as hypothyroidism and hypomagnesici should be excluded. Treatment consists in the first instance of fluids and, where appropriate, bulk forming laxatives, e.g., bran, and osmotic laxatives, e.g., sorbitol. This approach will solve the problem in the majority of patients. Stimulant laxatives should be avoided.