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相關機轉:圖解藥理學28 laxatives 01
Constipation Evaluation and Management: AGA Position Statement

[節錄]

Major Recommendations 

Note: Although the overall classification of chronic constipation into 3 categories (i.e., normal transit, isolated slow transit, and defecatory disorders) and several recommendations in this version are similar to the prior version, there are 3 substantive changes. First, these guidelines recommend assessment of colonic transit at a later stage, that is, only for patients who do not have a defecatory disorder or patients with a defecatory disorder that has not responded to pelvic floor retraining. Second, the evidence supporting these recommendations has been evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system, in which the strength of recommendation is rated as strong or weak and the quality of evidence is rated as high, moderate, low, or very low. Third, therapeutic recommendations have been updated to include newer agents and delete certain older agents.

Clinical Evaluation

Clinical Assessment of Constipation

If feasible, discontinue medications that can cause constipation before further testing (Strong Recommendation, Low-Quality Evidence). A careful digital rectal examination that includes assessment of pelvic floor motion during simulated evacuation is preferable to a cursory examination without these maneuvers and should be performed before referral for anorectal manometry. However, a normal digital rectal examination does not exclude defecatory disorders (Strong Recommendation, Moderate-Quality Evidence).

Diagnostic Tests

What Tests Should Be Performed to Assess for Medical Causes of Constipation?

In the absence of other symptoms and signs, only a complete blood cell count is necessary (Strong Recommendation, Low-Quality Evidence).

Unless other clinical features warrant otherwise, metabolic tests (glucose, calcium, sensitive thyroid-stimulating hormone) are not recommended for chronic constipation (Strong Recommendation, Moderate-Quality Evidence).

A colonoscopy should not be performed in patients without alarm features (e.g., blood in stools, anemia, weight loss) unless age-appropriate colon cancer screening has not been performed (Strong Recommendation, Moderate-Quality Evidence).

Anorectal manometry and a rectal balloon expulsion should be performed in patients who fail to respond to laxatives (Strong Recommendation, Moderate-Quality Evidence).

Defecography should not be performed before anorectal manometry and a rectal balloon expulsion test (Strong Recommendation, Low-Quality Evidence).

Defecography should be considered when results of anorectal manometry and rectal balloon expulsion are inconclusive for defecatory disorders (Strong Recommendation, Low-Quality Evidence).

Colonic transit should be evaluated if anorectal test results do not show a defecatory disorder or if symptoms persist despite treatment of a defecatory disorder (Strong Recommendation, Low-Quality Evidence).

Medical Management

What is the Initial Treatment Approach for Constipation?

After discontinuing medications that can cause constipation and performing blood and other tests as guided by clinical features, a therapeutic trial (i.e., fiber supplementation and/or osmotic or stimulant laxatives) is recommended before anorectal testing (Strong Recommendation, Moderate-Quality Evidence).

Normal transit constipation (NTC) and slow transit constipation (STC) can be safely managed with long-term use of laxatives (Strong Recommendation, Moderate Quality Evidence).

Anorectal tests should be performed in patients who do not respond to these measures (Strong Recommendation, High-Quality Evidence).

Pelvic floor retraining by biofeedback therapy rather than laxatives is recommended for defecatory disorders (Strong Recommendation, High-Quality Evidence).

Surgical Treatment of Constipation

What Approaches Should Be Considered for Constipation Unresponsive to Initial Approaches?

When bowel symptoms are refractory to simple laxatives, newer agents should be considered in patients with NTC or STC (Weak Recommendation, Moderate Quality Evidence).

Anorectal tests and colonic transit should be reevaluated when symptoms persist despite an adequate trial of biofeedback therapy (Strong Recommendation, Low Quality Evidence).

A subtotal colectomy rather than continuing therapy with chronic laxatives should be considered for patients with symptomatic STC without a defecatory disorder (Weak Recommendation, Moderate-Quality Evidence).

Colonic intraluminal testing (manometry, barostat) should be considered to document colonic motor dysfunction before colectomy (Weak Recommendation, Moderate-Quality Evidence).

Suppositories or enemas rather than oral laxatives alone should be considered in patients with refractory pelvic floor dysfunction (Weak Recommendation, Low Quality Evidence).

[Definitions for Quality of Evidence and Strength of Recommendation – available online]

[Link to free full-text Guideline Summary at NGC online | Gastroenterology PDF]

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