include neuromuscular disorders, metabolic abnormalities, medications, insufficient diet, or mechanical factors obstructing the movement of stool. Constipation may be further defined as acute or chronic. Chronic constipation indicates that symptoms have been present for more than three months and typically dates back years. Acute constipation requires a more rapid investigation into the aetiology, including evaluation for structural abnormalities or recent medication changes. Patients with chronic constipation may initially be treated symptomatically with fibre and/or simple laxatives. Those not responding to usual treatments require further investigation to evaluate for evidence of slow‐transit constipation or dyssynergic defecation (also called pelvic outlet dysfunction). Although constipation commonly occurs in the setting of irritable bowel syndrome (IBS), new‐onset IBS occurs less frequently in older patients than younger ones. Specific criteria have been defined to aid practitioners in diagnosing constipation related to IBS. The Rome IV criteria are commonly used, with the most recent iteration in 2016.1
The Bristol stool chart can be used to objectively describe bowel habits and classify patients into the correct subtype to ensure correct diagnosis and treatment. The Bristol stool form scale (BSFS) was developed in the 1990s in the Bristol Royal Infirmary, England.2 The authors described seven types of stool:
Type 1: Separate hard lumps, like nuts (hard to pass)
Type 2: Sausage‐shaped, but lumpy
Type 3: Like a sausage but with cracks on its surface
Type 4: Like a sausage or snake, smooth and soft
Type 5: Soft blobs with clearcut edges (passed easily)
Type 6: Fluffy pieces with ragged edges, a mushy stool
Type 7: Watery, no solid pieces, entirely liquid
Figure 20.1 Illustration of the defecatory process.
Table 20.1 Anatomical distribution of changes associated with constipation.
| Central nervous system |
|---|
| Awareness of need to defecate |
| Cerebrovascular accident |
| Dementia Parkinson’s disease |
| Peripheral nervous system |
| Controls myogenic activity of puborectalis |
| Pudendal nerve injury |
| Enteric nervous system |
| Controls rectal sensory function, peristalsis, and internal anal sphincter |
| Parkinson’s disease |
| Desensitization (chronically distended rectum) |
| Diabetes mellitus |
| Skeletal muscle |
| Contraction/relaxation of puborectalis and external sphincter |
| Direct muscular damage (e.g. prior birth trauma, sphincterotomy) |
| Rheumatological disorders (e.g. scleroderma, reduced muscular strength) |
| Incoordination |
| Idiopathic |
The authors classified stool types 1 and 2 as being associated with constipation. The BSFS is a convenient way for patients to describe their bowel habits and is routinely used in clinical trials.2
Epidemiology, pathophysiology, and impact
Constipation has long been misunderstood as a common problem associated with ageing. The prevalence of self‐reported constipation, physician visits, and laxative use increase with ageing.3‐5 In contrast, reported stool frequency does not change with age.3,4 Challenges in defining the prevalence of constipation in elders relates to the variety of criteria used in different studies. Self‐reported constipation affects 27% of individuals age 65 and older, whereas only 17% of elders meet more stringent (e.g. Rome criteria) diagnostic criteria for chronic constipation.6 When adjusting for race and laxative use, odds ratios for fewer than three bowel movements per week in individuals age 70–79 and ≥80 were 0.61 (95% confidence interval [CI], 0.51–0.72) and 0.85 (95% CI, 0.68–1.03), respectively, compared with individuals <40 years of age.3 Thus, age alone is not an independent risk factor for reduced stool frequency. Likewise, little evidence exists to support low‐fibre diets, lack of fluid, or reduced exercise as contributing to constipation in the otherwise healthy older patient.7,8 Elderly women are two to three times more likely to report constipation than their male counterparts.9 Non‐whites and individuals of lower socioeconomic status report fewer stools.10 In community‐dwelling frail elders, up to 45% report constipation as a health concern.11 The prevalence is higher in nursing home residents, with 74% of people symptomatic of constipation and requiring laxatives.12 In older people, the development of constipation is often multifactorial and typically represents the effects of medications, reduced dietary fibre intake, immobility, and comorbid diseases.13 The traditional perception of constipation due to ageing no longer holds; the healthy older person is not predestined to develop constipation.
Elders reporting constipation more often describe straining and hard bowel movements than reduced stool frequency.3,14,15 Population‐based prevalence of constipation includes 40% of community‐dwelling adults over the age of 64.16 The presence of constipation is also associated with medication use, including beta blockers, calcium channel blockers, anticholinergic drugs, and opiates.17 Despite the lack of difference in risk factor–adjusted constipation rates between elders and younger individuals, elders more frequently use laxatives. Up to 50% of elderly women report the use of laxatives. Overall, 20–30% of community‐dwelling elders use laxatives on at least a weekly basis. In the United States, a systematic review of the economic burden of IBS and chronic constipation showed that per patient, between $1912 to $7522 per year was spent on medications, hospitalization, outpatient clinics, emergency visits, and laboratory tests.18 Most elders self‐treat with over‐the‐counter products; hence the economic impact of laxative use is probably considerably higher than this estimate.
The findings of similar stool frequency but increased defecatory difficulty parallel the reported physiological changes that occur in the digestive tract with ageing. Colon transit overall is generally well preserved with ageing in humans.19 Changes in pelvic floor function may contribute to defecatory difficulty, with older women demonstrating reduced opening of the anorectal angle and a greater degree of perineal descent compared with younger women.20 Pudendal neuropathy also occurs more commonly with ageing and may negatively affect pelvic floor function.21 Other factors correlated with constipation in ageing include reduced caloric intake, use of multiple medications, haemorrhoids, and pain in the abdomen.22,23 Many diseases that occur more commonly in elders also contribute to the development of constipation, such as diabetes mellitus, Parkinson’s disease, and stroke. Prior surgery may also affect bowel function in elders. In women over 50 years of age, hysterectomy results in prolonged colon transit time and greater complaints of constipation and straining than in controls.24 Since ageing alone has little influence on the development of constipation, when complaints