280 THE NATIONAL MEDICAL JOURNAL OF INDIA VOL. 11, No.6, 1998

Everyday Practice

Constipation

A. B. DEY

ABSTRACTConstipation is a common problem in day-to-day practice. Asthere are wide variations in normal bowel habits, there is nostandard definition. Altered colonic transit and disorders of theanorectal mechanism are the essential abnormalities In patientswho experience this symptom. While there are several organiccauses, functional disorders are by far the commonest cause ofconstipation. Clinical assessment should Include a careful history,eliciting information on lifestyle, diet and personality. Extensiveinvestigations are seldom warranted. Reassurance and long termtreatment with a wide range of laxatives provide symptomaticrelief.Nad Med J India 1998; 11:280-82

INTRODUCTIONConstipation is a common symptom in everyday practice affect-ing a large section of the general population. The prevalence ofconstipation is higher in children and the elderly. The perceptionof this symptom and the related health-seeking behaviour showswide individual variation. The term 'constipation' denotes infre-quent stools, no urge, difficulty in evacuating (small, hard, needsgreat effort), ineffective straining and a sense of incompleteevacuation. Most individuals would tend to associate severalother symptoms with constipation such as anal and perianal pain,abdominal discomfort, bloating, bad taste in the mouth, malaise,nausea and headache. Constipation has been defined as two ormore of the following symptoms present for at least 3 months:

1. Straining more than 25% of the time,2. Hard stools more than 25% of the time,3. Incomplete evacuation more than 25% of the time,and4. Two or less than two bowel movements in one week.'

This definition appears subjective but is practical, as a widevariation in normal bowel habit is observed in different popula-tions and within the same population consuming a similar diet.

AETIOLOGY AND PATHOPHYSIOLOGYConstipation results from disorders of colonic transit or anorectalfunction, which may be due to a host of known and unknownfactors. Some of these include a primary motility disturbance,drugs, systemic diseases and a number of local conditions affect-ing the gastrointestinal tract. For unknown reasons, women con-suming a similar diet tend to suffer more from constipation thanmen.' A hormonal basis for this difference in bowel habit has beeninvestigated but has not yet been substantiated.' Constipation is a

Department of Medicine, All India Institute of Medical Sciences, AnsariNagar, New Delhi 110029, India

© The National Medical Journal of India 1998

common complaint in the elderly, due to several factors includinga decrease in dietary intake, reduced mobility, weaker abdominaland pelvic muscles and greater use of analgesics. The stoolvolume varies from race to race; it is maximum in Africans andminimum in whites. The average stool volume in Indians is about300 g/day.' This racial difference is probably related to differentdietary habits. Dietary fibre has been thought to be a majordetermining factor in stool volume. However, studies have notshown any correlation between dietary fibre intake and stoolvolume in severely constipated and healthy subjects.Y Lack ofphysical and recreational activity has been reported to be moreoften associated with constipation. However, a direct comparisonof physical activity in constipated and non-constipated subjectshas not shown any major difference;" neither does exercise haveany effect on gut transit time and stool volume."

Several drugs can lead to troublesome constipation. The com-monly used drugs which cause constipation includeanti-depres-sants, antacids, sucralfate, calcium channel blockers, iron supple-ments, narcotic analgesics and codeine-containing preparations(Table I). Thus, knowledge of common drugs that produce thisside-effect is often reassuring for the patient.

Several physiological states and systemic diseases are knownto be associated with constipation (Table II). Nearly 40% ofwomen experience constipation at some time during pregnancywhich is more often due to hard stools than decreased frequency."Hypothyroidism associated with mild-to-moderate constipationis a common condition especially in the elderly. This conditionrarely if ever leads to a megacolon and readily responds to thyroidreplacement therapy.

Several diseases of the central and peripheral nervous systemcan be associated with constipation and often require intervention(Table III). The mechanism of constipation varies in each condi-tion and includes loss of conscious control of body functions incerebrovascular accident, upper motor neuron weakness in sacral

TABLEI. Drugs causing constipation

Antacids: calcium and aluminium compoundsAnalgesics AnticholinergicsAnticonvulsants AntidepressivesAnti-Parkinsonian drugs AntihypertensivesBarium sulphate DiureticsHeavy metals: arsenic, lead, mercury Iron supplementsLaxati ve abuse Muscle relaxantsOpiates

TABLEII. Systemic causes of constipation

• Pregnancy• Metabolic

AmyloidosisHypercalcaemiaUraemia

• EndocrineHypothyroidismPanhypopituitarism

• Collagen vascular diseasesSystemic sclerosis

• Chronic obstructive airway disease

Diabetic ketoacidosisPorphyria

Hyperparathyroidism

Dermatomyositis

DEY: CONSTIPATION

TABLEIII. Neurological causes of constipation

• Central lesionsCerebrovascularaccidentParkinson'sdiseaseMultiplesclerosisCaudaequinalesions

• Peripheral lesionsAutonomicneuropathyAganglionosis(Hirschsprung's disease)Hyperganglionosis

CerebraltumoursShy-DragersyndromeSpinalcord lesions

Chagas' diseaseHypoganglionosisGanglionomatosis

and conus-cauda lesions of the spinal cord, and multifactorialmechanisms in Parkinson's disease, Peripheral neuropathies areassociated with delayed colonic transit due to loss of intestinalmotor function.

Obstructive and inflammatory lesions of the colon, rectum andanal canal are important causes of constipation, which oftenrequire surgical intervention. Most diagnostic investigations inconstipation are in fact directed at excluding any local potentiallycorrectable pathology. Table IV lists important gastrointestinalconditions causing constipation.

FUNCTIONAL CONSTIPATIONIn the majority of patients with constipation, no obvious cause canbe identified, even after clinical assessmenr and investigations.These patients are suspected to have functional disorders of thegastrointestinal tract. Several functional constipation syndromeshave been recognized.

The commonest variety of functional constipation in youngand middle-aged adults is the irritable bowel syndrome (IBS). Itis typically accompanied by lower abdominal pain or discomfort,passage of small hard stools often associated with mucus, a senseof incomplete evacuation and excessive straining. Associatedsymptoms include flatulence, abdominal distension, heartburn,nausea, dysphagia and backache. The pathophysiological basis ofthis condition is uncertain and colonic transit is usually normal inthese patients. Psychosocial factors may play an important role inIBS. Several psychiatric diseases such as personality disorders,anxiety, depression, hysteria and somatization are more frequentin IBS patients compared to non-IBS patients. However, their rolein the causation of constipation is not clearly understood. Mostsymptoms of IBS respond readily to dietary advice but recurrenceis common.

Other functional constipation syndromes include slow transittype of functional constipation which presents with infrequentbowel action. Stool in these patients is never loose and distensionof the gut does not occur. The outlet delay type is characterized bystraining with near-normal bowel frequency and requires digita-tion for relief. The faecal impaction type is characterized by theformation of a large faecal mass and soiling, and can be relievedby emptying the rectum. The pseudo-obstruction type is associ-ated with recurrent gaseous abdominal distension, pain and vom-iting along with constipation.

CLINICAL ASSESSMENT1. Assessment of constipation as a symptom requires a detailed

history of the time course (recent, chronic, since early child-hood), associated symptoms such as weight loss, presence ofblood, relationship with pain, presence of any neurologicaldisorder and symptoms of associated systemic disease. Ahistory of drug intake for other medical disorders, childbirth in

281

TABLEIV. Gastrointestinal causes of constipation

• Diaphragmatichernia• Duodenalstenosis• Gastriccancer• Cystic fibrosis• Colonic lesions

ExtraluminalTumoursHernia

LuminalTumoursDiverticulitisIschaemiccolitis

Colonic muscular diseaseMusculardystrophyAmyloidosis

• RectumTumoursUlcerativeproctitisInternalrectal prolapse

• Pelvic floorDescendingperineumsyndrome

• Anal canalAnal fissureStenosis

Chronicvolvulus

StricturesTuberculosisSurgery

MyotonicdystrophyFamilialvisceralmyopathy

StrictureRectocoele

HaemorrhoidsMucosalprolapse

women and a past history of chronic disabling disease oftenprovide clues to the aetiology of constipation. A generalassessment of the lifestyle, psychological state, diet and physicalactivity is of value in diagnosing functional constipation. Thephysical examination must include careful exclusion of systemicand neurological conditions. Digital examination of the rectumprovides information on anal sphincter tone, rectal prolapseand obstructive and painful lesions of the anal canal.

2. Investigations for constipation are often non-productive andnot cost-effective. The goal is to exclude a systemic or obstruc-tive/structural cause of constipation. Laboratory investigationsmust include haematological and biochemical tests includingthyroid function, serum calcium and tests directed at specificinflammatory, metabolic or neoplastic conditions that maycause delayed colonic transit. Flexible sigmoidoscopy, colono-scopy and barium enema help in excluding any colorectalpathology, while a barium meal follow through is indicatedwhen pseudo or true obstruction of the small bowed is suspected.

Several physiological tests are available. These includemeasurement of whole gut and colonic transit time, defaecatingproctography, anorectal pressure measurement and measure-ment of rectal sensation to distension. However, their value inclinical practice is limited.

MANAGEMENTGeneral measuresReassurance regarding the benign nature of the symptoms andinformation on its widespread prevalence in the general popula-tion is often effective in individuals with functional constipation.Advice on setting aside an unhurried time and the need to respondto the defaecatory urge must be emphasized. Regular physicalexercise, high roughage diet (high fibre diet from vegetables andcereals) and increase in water intake are of proven value.

Untreated chronic constipation is associated with several com-plications which include haemorrhoids, anal fissure, rectal pro-lapse, stercoral ulcer, melanosis coli, faecal impaction, ischaemiccolitis, colonic volvulus, colonic perforation, syncope, faecal

282 THE NATIONAL MEDICAL JOURNAL OF INDIA VOL. II, No.6, 1998

incontinence and urinary retention. Some of these complicationsare potentially life-threatening. Thus, for symptomatic relief aswell as prevention of complications, laxatives and purgatives arewidely used in clinical practice and are among the most frequentlyprescribed drugs, especially in the elderly. Psychological supportand treatment are usually required in psychiatric patients withconstipation.

LaxativesThree major groups-bulk laxatives, osmotic laxatives and stimu-lant laxatives-are commonly used in clinical practice (Table V).Each of these has a specific mechanism of action and purpose.When the effect is needed within 24 hours, stimulant laxatives areuseful whereas for a long term effect, bulk laxatives are preferred.For intermediate duration of use, osmotic laxatives are recom-mended. Many preparations with a combination of the threegroups of laxatives have been tried in controlled trials as cheaperand effective options.'?" Other medical measures include:

1. Cholinergic prokinetic drugs: Cisapride not only reduces thelaxative requirement but also leads to sustained improvementeven after the drug has been stopped. 12

2. Unabsorbed fluid for colonic perfusion: Polyethylene-glycolelectrolyte solution 13 as a nasogastric infusion or drink, normalsaline whole gut irrigation combined with intravenous fruse-mide and metocloproparnide are useful in the elderly. 14

3. Alteration of colonic bacterialflora by antibiotics: Oral vanco-mycin (250 mg four times a day for 4 weeks)."

4. Enemas and suppositories which work by rectal distensionand/or stimulation and also by faecal softening.

5. Behavioural therapy and relaxation of striated muscles of thepelvic floor during simulated defaecation coordinated with arise in intra-abdominal pressure.

Surgical managementSeveral invasive and surgical procedures have also been used forthe management of intractable constipation. These include colec-tomy with or without a permanent stoma and division of the analsphincter. These procedures are seldom required in the manage-ment of constipation, especially in patients with slow colonictransit.

Laxative dependenceDependence on laxatives develops in a number of patients follow-ing prolonged use. Abrupt withdrawal of the drug leads toconsiderable delay in the next bowel movement, which somepatients find unacceptable and resort to another dose of the drug.The best method for withdrawal is to start a bulk purgative a fewdays before stopping the stimulant laxative. The bulk laxative isthen withdrawn either by decreasing the dose or as an alternateday regimen.

CONCLUSIONConstipation is a common complaint in clinical practice. Thedefinition of this symptom is largely dependent on the patient'sperception of his state of health, health-seeking behaviour andfood habits. Disorders of colonic transit and anorectal function

TABLEV. Classification of laxatives

• BulkMethyl cellulosePolycarbophilPlant gum

• StimulantBisacodylCasanthranolPhenolphthalein

• HyperosmoticLactulose

• EmollientDocusate sodiumDocusate potassium

• LubricantsMineral oil

• SalineMagnesium citrateMagnesium sulphate

Malt soup extractPlantago seed (psyllium)

Cascara sagradaDanthronSenna

Glycerine

Docusate calcium

Magnesium hydroxideSodium phosphate

due to known and unknown causes are the common abnormalitiesresponsible for constipation. Though a majority of patients havefunctional constipation, some may have an underlying systemicor metabolic disease or a structural defect. Investigations forconstipation are usually directed at excluding treatable and cor-rectable pathology. Symptomatic treatment with any of the threegroups oflaxatives, depending on the patient's need and reassur-ance usually suffice.

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