Historically less than 2-3 bowel movements/week; Excessive difficulty straining at defecation
Rome III for functional constipation: see below under Diagnostic Studies
Dyschezia: difficulty in defecating
5-30% of population report symptoms; Prevalence increases with age
Causes
Example
Idiopathic/Functional
Chronic idiopathic: Impaired colonic transit, IBS
Structural
Colonic or anorectal: cancer, stricture
Metabolic/Endocrine
Hypokalemia, Hypercalcemia, Hypocalcemia, Uremia, Hypothyroid, DM
Collagen vascular disorders
Scleroderma, Amyloidosis
Inherited muscular disorders
Familial visceral myopathy
Colonic disorders
Colonic inertia
Enteric neuro disorders
Hirschsprung’s, Chronic intestinal pseudo-obstruction
Nonenteric neuro disorders
Parkinson’s, Spinal cord injury, MS, Scleroderma (fibrotic/non-contractile)
Anorectal disorders
Anal stricture, Rectocele
Psychological
Anorexia nervosa
Medications
Opiates & antihypertensives such as calcium channel blockers (most common causes), antacids (calcium, aluminum), anticholinergics, antispasmodics, anticonvulsants, antidepressants, diuretics, iron
Classification based upon transit time:
Normal transit constipation: perception of disordered evacuation; Fiber supplementation may help
Slow transit constipation: malfunction of neural network; i.e. infection, endocrine, drug, scleroderma; Fiber may worsen
Obstructive defecation: mechanical; i.e. Hirschsprung’s, Pelvic floor dysfunction; Fiber may worsen
Anorectal dysfunction:
Anismus/spastic pelvic floor syndrome: spasticity of levator ani, abnormal angulated rectoanal axis; Functional problem
Impaired rectal sensation: decrease in urge to defecate
Megarectum: long-term fecal impaction, often seen in children, physically/mentally impaired elderly; Occasionally with neuro disorder
Rectocele: stool directed away from anal canal into rectocele during straining, leading to retention of feces in pouch
The colon absorbs approximately 100 mL of fluid and 1 mEq of sodium and chloride from 1,500 mL of chyme daily
If necessary, the absorptive capacity can increased to 5-6 L and 800-1000 mEq of sodium and chloride per day
Healthy subjects: average mouth-to-cecum time is 6 hrs, average transit through right, left and sigmoid colon is 12 hrs each (36 hrs total)
Normally:
First sensing in rectum via stretch receptors in the muscularis propria initiate a spinal reflex arc: relaxation of internal anal sphincter
Then relaxation of striated muscles of pelvic floor (puborectalis, pubococcygeus), rectoanal angle opens from 90 to 130°
Final relaxation of external anal sphincter and passage of stool, often with concomitant diaphragm & abdominal muscle contractionRelated posts:
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