Constipation

Key Features

Essentials of Diagnosis

• Defined as two or fewer bowel movements per week or excessive difficulty and straining at defecation

General Considerations

Primary constipation

• Most cases cannot be attributed to any structural abnormalities or systemic disease

• Normal colonic transit time is about 35 hours; > 72 hours is significantly abnormal

• Defecatory disorders can occur with or without slow colonic transit

• Slow colonic transit

  • Commonly idiopathic but may be part of a generalized gastrointestinal dysmotility syndrome

  • More common in women, some of whom have a history of psychosocial problems (depression, anxiety, eating disorder, childhood trauma) or sexual abuse

• Patients may complain of

  • Infrequent bowel movements and abdominal bloating

  • Excessive straining

  • Sense of incomplete evacuation

  • Need for digital manipulation

  • Need for adopting a non-sitting (eg, standing) position during defecation

Causes of secondary constipation

• Systemic disease

  • Endocrine

    • Hypothyroidism

    • Hyperparathyroidism

    • Diabetes mellitus

  • Metabolic

    • Hypercalcemia

    • Hypokalemia

    • Uremia

    • Porphyria

  • Neurologic

    • Parkinson disease

    • Multiple sclerosis

    • Sacral nerve damage (pelvic surgery, tumor)

    • Paraplegia

    • Autonomic neuropathy

  • Medications

    • Opioids

    • Diuretics

    • Calcium channel blockers

    • Anticholinergics

    • Psychotropics

    • Calcium, iron

    • Nonsteroidal anti-inflammatory drugs

    • Clonidine

    • Cholestyramine

  • Structural abnormalities

    • Anorectal

      • Rectal prolapse

      • Rectocele

      • Rectal intussusception

      • Anorectal stricture

      • Anal fissure

      • Solitary rectal ulcer syndrome

    • Perineal descent

    • Obstructing colonic mass (cancer)

    • Colonic stricture

      • Radiation

      • Ischemia

      • Diverticulosis

    • Hirschsprung disease

    • Idiopathic megarectum

  • Slow colonic transit

    • Idiopathic: isolated to colon

    • Psychogenic

    • Eating disorders

    • Chronic intestinal pseudo-obstruction

  • Dyssynergic defecation

  • Irritable bowel syndrome

Demographics

• Occurs in 15% of adults and up to one-third of elderly adults

• More common in women

• Elderly are predisposed due to comorbid conditions, medical conditions, decreased mobility, medications, poor eating habits, inability to sit on toilet (bed-bound patients)

Clinical Findings

Symptoms and Signs

• Decreased appetite

• Nausea and vomiting

• Abdominal pain and distention

• Paradoxical "diarrhea"

• Firm feces palpable on digital rectal examination

Differential Diagnosis

• Inadequate fiber or fluid intake

• Poor bowel habits

• Irritable bowel syndrome

Diagnosis

• In healthy patients under age 50 without alarm symptoms, it is reasonable to initiate a trial of empiric treatment without diagnostic tests

• Further diagnostic tests should be performed

  • In patients aged 45 and older with no prior colonoscopy screening

  • In patients of any age with

    • Severe constipation

    • Hematochezia

    • Weight loss

    • Anemia

    • Positive fecal occult blood or fecal immunochemical tests

    • Positive family history of colon cancer or inflammatory bowel disease

    • No response to empiric treatment

Laboratory Tests

• Complete blood count

• Serum electrolytes

• Serum calcium

• Serum glucose

• Serum thyroid-stimulating hormone

• Fecal occult blood or fecal immunochemical tests

Imaging Studies

• Colonoscopy or flexible sigmoidoscopy and barium enema