constipation%20in%20adults%20-%20chronic%20functional
CONSTIPATION IN ADULTS - CHRONIC FUNCTIONAL
Constipation is an unsatisfactory defecation distinguished by difficult stool passage, infrequent stools or both.
Difficult stool passage may include straining, feeling of difficulty in passing stool, incomplete evacuation, lumpy/hard stools, prolonged time to defecate, need for manual maneuver to pass stool, abdominal discomfort and feeling of anorectal blockade.
Chronic constipation is considered when symptoms of constipation have existed ≥3 months.
Symptoms of chronic constipation may be due to dysfunction of intestinal motility, visceral sensitivity, anorectal musculature or the enteric nervous system.

Diagnosis

  • Thorough history and physical exam in many cases can rule out most secondary causes of constipation eg colonic diseases (anal fissure, hemorrhoids, cancer, proctitis, stricture), neurologic disorders (spinal cord lesions, parkinsonism), disturbances in metabolism (diabetes mellitus, hypothyroidism, hypercalcemia), drug side effects (antispasmodics, iron and calcium supplements), or other conditions (depression, immobility, cardiac disease)

Evaluation

  • If patient with chronic constipation does not respond to conventional therapy, he should be evaluated for:
    • Slow transit constipation
    • Pelvic floor dysfunction
    • Other evacuation disorders or disorders of anorectal musculature
  • Patient may also be referred for psychological evaluation for possible behavioral, biofeedback, or psychotherapy
    • Biofeedback is a technique wherein patients are taught to relax their pelvic floor muscles while straining; it is the cornerstone for pelvic floor dysfunction management

History

  • Current bowel regimen and pattern
    • Use of Bristol stool scale may help in better characterizing bowel habits and fecal consistency
  • Medication history including products used to relieve constipation or the use of opiates and codeine
  • Associated abdominal pain or distress that is less severe and not the main symptom as compared with irritable bowel syndrome (IBS)
  • Unusual postures on toilet to ease stool expulsion
  • Posterior vaginal pressure, perineum support or digitation of rectum to ease rectal release
  • Failure to discharge enema fluid
  • Pelvic floor dysfunction may be suggested by prolonged and excessive straining prior to elimination; when evacuatory defects are pronounced, soft stools or even enema fluid is difficult to pass; need for perineal or vaginal pressure or digital evacuation is also indicative
    • Evacuatory disorders do not respond well to laxatives
  • IBS may be suggested by history of bloating, predominant pain, or malaise
  • Inquire also on patient’s surgical history, diet and fluid intake, lifestyle and occupation

Physical Examination

  • Physical exam should be used to rule out diseases to which the constipation is secondary

Rectal Exam (Patient in left lateral position)

  • Inspection of perianal area to look for fissures, fistulas, external hemorrhoids
  • Determine extent of perineal descent while patient, at rest, bears down
    • Reduced descent may indicate inability to relax pelvic floor muscles during defecation
    • Excessive descent may show laxity of the perineum which may be caused by childbirth or several years of straining

Digital Exam of the Rectum

  • Check for fecal impaction, anal stricture or fissure, or rectal masses
  • Lax anal orifice may suggest neurologic disorder or trauma as the cause of impaired sphincter function
  • Inability or difficulty in inserting the finger into the anal canal may suggest elevated anal sphincter tone at rest or anal stricture
  • Spasm of pelvic floor may be suggested by tenderness at the posterior aspect of the rectum

Imaging

Anorectal Manometry with Balloon Expulsion

  • Provides measurement of internal and external anal sphincter pressure, relaxation of the internal anal sphincter during rectal distension and straining and rectal sensation to distension in patients with chronic constipation resistant to medical therapy
  • This may be the test of choice for outlet obstruction, pelvic floor dysfunction and for excluding Hirschsprung’s disease and psychogenic megacolon, may even be considered before a trial of laxatives in patients with a strong suspicion of pelvic floor dysfunction

Colon Transit Studies

  • Radiopaque markers are used to measure gastrointestinal (GI) transit
  • First test to consider when an outlet obstruction is not demonstrated by clinical and proctologic exams
  • Performed on patients with symptoms unresponsive to laxatives or 1st-line pharmacological treatment and if anorectal test does not demonstrate a defecatory disorder

Defecography

  • May be done if results with anorectal manometry and rectal balloon expulsion are inconclusive
    • May be performed with anorectal manometry in patients with suggestive obstructed defecation
  • Pelvic floor dysfunction is diagnosed by the observation of insufficient descent of the perineum and less-than-normal change in the anorectal angle
  • This test reveals structural abnormalities (eg rectocele and intussusceptions) and evaluates mobility of the pelvic floor and degree of rectal emptying
  • Echodefecography or magnetic resonance defecography may be preferred over videodefecography in order to avoid ionizing radiation
  • This test is operator dependent and has poor reliability

Electromyography of Anal Sphincter 

  • Used in diagnosing presence of paradoxical contraction of puborectalis muscle

Hydrogen Breath Test

  • Evaluates orocecal transit time in patients with colonic inertia

Specialist Referral

  • In patients presenting with constipation without alarm symptoms, there is not sufficient data to make recommendations for routine use of colonoscopy, flexible sigmoidoscopy, barium enema, thyroid function tests, serum calcium, etc
    • A complete blood count (CBC) may be done to evaluate chronic constipation in the absence of other signs and symptoms
    • Specific metabolic diagnostic tests (eg thyroid and renal function tests, fasting blood sugar) may be performed in patients with additional signs or symptoms of an organic disorder
  • Routine colon cancer screen tools are recommended in all patients >50 years old
    • >40 years in areas with high prevalence of gastric cancer
  • In a patient who presents with alarm symptoms or is >50 years of age, blood biochemistry, imaging studies or colonoscopy are needed to verify the diagnosis, exclude organic disease, and determine corresponding treatment
    • Flexible sigmoidoscopy and colonoscopy can identify lesions that narrow or occlude the bowel
  • Colonoscopy is preferred in patients with iron-deficiency anemia, positive guaiac stool test, or 1st-degree relative with colon cancer
    • Alternatively, barium enema and flexible sigmoidoscopy combined have the potential to reveal colonic dilation and strictures
  • If extracolonic and mechanical causes of constipation are ruled out with lab tests and colorectal imaging, then a complete physiologic evaluation may be useful, although the interpretation should be guarded as patient cooperation is critical
    • Eg anal manometry, balloon insertion, defecography and colonic transit studies
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