Causes, Signs, and Symptoms of Constipation

Causes, Signs, and Symptoms of Constipation - Constipation is a commonly encountered medical condition in the United States for which many patients initiate self-treatment. One reason constipation continues to be a frequent problem in this country is lack of adequate dietary fiber. Another unfortunate problem is that many people have misconceptions about normal bowel function, and think that daily bowel movements are required for health and well being. Others believe that the lack of a daily bowel movement contributes to the accumulation of toxic substances or is associated with various somatic complaints. These misconceptions often lead to the inappropriate use of laxatives by
the general public.

Constipation does not have a single, generally agreed upon definition. When using the term, the lay public or healthcare professional may be referring to several difficult-to-quantify variables: bowel movement frequency, stool size or consistency, and such symptoms as the sensation of incomplete defecation. Stool frequency is most often used to describe constipation; however, the frequency of bowel movements used to define constipation is not well established.

Normal people pass at least 3 stools per week. Some of the definitions of constipation used in clinical studies include (a) less than 3 stools per week for women and 5 stools per week for men despite a high-residue diet, or a period of more than 3 days without a bowel movement; (b) straining at stool greater than 25% of the time and/or 2 or fewer stools per week; or (c) straining at defecation and less than 1 stool daily with minimal effort. These varying definitions demonstrate the difficulty in characterizing this problem. 

An international committee defined and classified constipation on the basis of stool frequency, consistency, and difficulty of defecation. Functional constipation is defined as two or more of the following complaints present for at least 12 months in the absence of laxative use: (a) straining at least 25% of the time; (b) lumpy or hard stools at least 25% of the time; (c) a feeling of incomplete evacuation at least 25% of the time; or (d) two or fewer bowel movements in a week. Rectal outlet delay is defined as anal blockage more than 25% of the time and prolonged defecation or manual disimpaction when necessary. 


Constipation is not a disease, but a symptom of an underlying disease or problem. Approaches to the treatment of constipation should begin with attempts to determine its cause. Disorders of the GI tract (irritable bowel syndrome or diverticulitis), metabolic disorders (diabetes), or endocrine disorders (hypothyroidism) may be involved. Constipation commonly results from a diet low in fiber or from use of constipating drugs such as opiates. Finally, constipation may sometimes be psychogenic in origin.24 Each of these causes is discussed in the following sections.

Constipation is a frequently reported problem in the elderly, probably the result of improper diets (low in fiber and liquids), diminished abdominal wall muscular strength, and possibly diminished physical activity. However, as previously stated, the frequency of bowel movements is not decreased with normal aging. In addition, diseases that may cause constipation, such as colon cancer and diverticulitis, are more common with increasing age.

The majority of cases of drug-induced constipation are caused by opiates, various agents with anticholinergic properties, and antacids containing aluminum or calcium. The inhibitory effects on bowel function are dose dependent, with larger doses clearly causing constipation more frequently. Opiates have effects on all segments of the bowel, but effects are most pronounced on the colon. The major mechanism by which opiates produce constipation has been proposed to be prolongation of intestinal transit time by causing spastic, nonpropulsive contractions. 

An additional contributory mechanism may be an increase in electrolyte
absorption. All opiate derivatives are associated with constipation, but the degree of intestinal inhibitory effects seems to differ between agents. Orally administered opiates appear to have greater inhibitory effects than parenterally administered products. Orally administered enkephalins (endogenous opiate-like polypeptides) are recognized to have antimotility properties.

Possible Causes of Constipation

GI disorders 
     Irritable bowel syndrome
     Upper GI tract diseases
     Anal and rectal diseases
     Anal fissures
     Ulcerative proctitis
     Volvulus of the bowel
     Helminthic infections
     Lymphogranuloma venereum
     Hirschsprung’s disease

Metabolic and endocrine disorders Diabetes mellitus with neuropathy
     Enteric glucagon excess

     Depressed gut motility
     Increased fluid absorption from colon
     Decreased physical activity
     Dietary changes
     Inadequate fluid intake
     Low dietary fiber
     Use of iron salts

Neurogenic causes 
     CNS diseases
     Trauma to the brain (particularly the medulla)
     Spinal cord injury
     CNS tumors
     Cerebrovascular accidents
     Parkinson’s disease

Psychogenic causes 
     Ignoring or postponing urge to defecate
     Psychiatric diseases

Drugs Causing Constipation
     Inhibitors of prostaglandin synthesis
     AntiParkinsonian agents (e.g., benztropine or trihexyphenidyl)
     Tricyclic antidepressants
     Antacids containing calcium carbonate or aluminum hydroxide
     Barium sulfate
     Calcium channel blockers
     Diuretics (non–potassium-sparing)
     Ganglionic blockers
     Iron preparations
     Muscle blockers (D-tubocurarine, succinylcholine)
     Nonsteroidal antiinflammatory agents
     Polystyrene sodium sulfonate

Clinical Presentation of Constipation

Signs and symptoms
• It is important to ascertain whether the patient perceives the problem as infrequent bowel movements, stools of insufficient size, a feeling of fullness, or difficulty and pain on passing stool. 
• Signs and symptoms include hard, small, or dry stools, bloated stomach, cramping abdominal pain and discomfort, straining or grunting, sensation of blockade, fatigue, headache, and nausea and vomiting.

Laboratory tests
• A series of examinations, including proctoscopy, sigmoidoscopy, colonoscopy, and barium enema, may be necessary to determine the presence of colorectal pathology.
• Thyroid function studies may be performed to determine the presence of metabolic and endocrine disorders


by Umaee
Source: Pharmacotherapy 7th
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