Constipation is common in Western society. The frequency of constipation diagnoses depends on both the patient’s and the physician’s definitions of the problem. One bowel movement each day is what most patients consider normal. However, many physicians may accept two or three hard and dry stools a week as normal if this pattern is usual for the individual. Some experts believe that anyone who strains to defecate or does not effortlessly pass at least one soft stool daily is constipated. By this definition, constipation is very common.
Constipation may also be defined as a change in the person’s normal bowel pattern to less frequent or more difficult defecation. In this chapter, constipation is defined as straining with bowel movements or bowel movements that occur fewer than three times per week. The American College of Gastroenterology defines constipation as “unsatisfactory defecation characterized by infrequent stools, difficult stool passage, or both.” The Rome III criteria are generally used to define chronic functional constipation in adults, infants, and young children. They define chronic as the presence of these symptoms for at least 3 months. Constipation has been attributed to the deficiency of dietary fiber in the customary Western diet, which has replaced fiber with excessive ingestion of refined carbohydrates.
Constipation is usually not caused by a serious disease. In most patients it can be corrected by decreasing the amount of refined carbohydrates and increasing the amount of fiber ingested. It is particularly important for the examiner to ask whether the constipation is of recent onset and constitutes a change in previous bowel habits, since such findings may indicate serious disease.
The most common causes of constipation are laxative habit, diets high in refined carbohydrates and low in fiber, change in daily habits or environment, drug use, irritable bowel syndrome (IBS), and painful defecation due to a local anorectal problem. In many instances, it is important to differentiate IBS from chronic constipation. Pain or abdominal discomfort must be present to diagnose IBS. In many cases, multiple factors contribute to the patient’s constipation. Less common causes include bowel tumors, fecal impaction, pregnancy, and metabolic disorders (e.g., hypothyroidism, diabetes, hypercalcemia).
The common causes of constipation can be divided into three categories: simple constipation, disordered motility, and secondary constipation. Simple constipation usually results from a diet that contains excessive refined carbohydrates and is deficient in fiber. It may be influenced by environmental factors. Disordered motility, the next most common category, is seen with idiopathic slow transit (most common in elderly persons), idiopathic megacolon and megarectum (more common in children), irritable bowel syndrome, and uncomplicated diverticular disease. Secondary constipation can be a response to drugs (especially codeine, opiates, and calcium channel blockers); chronic use of laxatives; prolonged immobilization; and organic disease of the anus, rectum, or colon (anal fissures, strictures, and carcinoma).
Constipation is uncommon in neonates and is usually caused by anal fissures or feeding problems. It rarely results from congenital problems such as Hirschsprung’s disease. Cow’s milk occasionally causes constipation. In children the most common cause of constipation is a change in daily habits or environment. The earlier that constipation begins in childhood, the greater the likelihood of an organic cause.
Disorders of defecation in children are common, difficult to manage, and negatively perceived by the family. Approximately 85% to 95% of constipation in children is functional. In children ages 6 months to 3 years, it frequently results from some psychological cause. Early diagnosis of psychological causes of constipation in children facilitates treatment. For example, toilet training may have occurred recently, or constipation may have developed because the child had a condition, such as a rectal fissure, that caused painful defecation. Fearing painful defecation, the child suppressed the urge to defecate, perpetuating the production of hard, dry stools, which continued to irritate the rectal fissure.
In adults, most constipation is caused by dietary fiber deficiency or laxative habit. Laxative use is more common in women than men. Constipation is a common complaint in elderly persons, although 80% to 90% of patients older than 60 years have one or more bowel movements per day. Despite this fact, 50% of patients older than 60 years use laxatives. This apparent discrepancy may be a result of older persons’ greater preoccupation with bowel function in comparison with younger people. Constipation in elderly patients most often is caused by inappropriate diet, decreased activity, poor dentition, use of constipating medications, and impaired motility. Constipation ranks with joint pain, dizziness, forgetfulness, depression, and bladder problems as one of the major causes of misery in older patients.
Obstipation (regular passage of hard stools at 3- to 5-day intervals) and fecal impaction are most common in elderly patients. Some patients with fecal impaction have continuous soiling (liquid passing around hard stools), which they describe as diarrhea. Elderly patients who are confined to bed, drink small amounts of fluid, or take constipating drugs are particularly vulnerable to fecal impaction. Although fecal impaction is more common in elderly persons, the physician must be aware that it can occur in any patient subjected to sudden immobility, bed rest, or a marked change in diet or fluid consumption.
Tumors of the bowel are uncommon in children and young adults, but their frequency increases after age 40 years. In any patient older than 40 years who presents with recent constipation or a marked change in bowel habits, the physician must rule out carcinoma of the colon and rectum.
The most important factor in determining whether constipation should be investigated for a serious cause or treated symptomatically and by dietary modification is whether it is chronic or of recent onset. The second most important factor is the presence of alarm symptoms. Patients who have long-standing constipation and those whose constipation developed with a recent depressive illness, change in diet, recent debility, or ingestion of constipating medicine can be treated symptomatically. Their clinical status should be reassessed after a few weeks of appropriate therapy. Patients with unexplained constipation of recent onset or a sudden aggravation of existing constipation associated with abdominal pain, unexplained weight loss, passing of blood or mucus, a progressive decrease in the number of bowel movements per day, or a substantial increase in laxative requirements should be investigated even in the absence of abnormal physical findings. These patients should undergo colonoscopy. Constipation occurs in less than one third of patients with carcinoma of the colon and is less common than diarrhea in these patients.
Ribbon-like stools suggest a motility disorder. They can also be caused by an organic narrowing of the distal or sigmoid colon. A progressive decrease in the caliber of the stools suggests an organic lesion. If the patient complains of stools that have a toothpaste-like caliber, fecal impaction should be suspected.
Tumors of the descending colon are more common in older adults with right-sided lesions, increasing in frequency as the patient grows older. One third of colon cancers in patients older than 80 years are right sided, and fewer than half of these patients have altered bowel habits. They usually present late with an anemia or a palpable mass on the right side of the colon.