Assessment
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➤ If feasible, discontinue medications that can cause constipation
before further testing (Strong; Low Quality of 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;
Moderate Quality of Evidence).
The key components of the rectal examination include:
• In the left lateral position, with the buttocks separated, observe the descent of the
perineum during simulated evacuation and the elevation during a squeeze aimed at
retention. The perianal skin can be observed for evidence of fecal soiling and the anal
reflex tested by a light pinprick or scratch.
• During simulated defecation, the anal verge should be observed for any patulous
opening (suspect neurogenic constipation with or without incontinence) or prolapse
of anorectal mucosa.
• The digital examination should evaluate resting tone of the sphincter segment and its
augmentation by a squeezing effort. Above the internal sphincter is the puborectalis
muscle, which should also contract during squeeze. Acute localized tenderness to
palpation along the puborectalis is a feature of the levator ani syndrome. Finally, the
patient should be instructed to integrate the expulsionary forces by requesting that
she or he "expel my finger."
• An examination should then be conducted to evaluate for a rectocele or consideration
be given to g ynecologic consultation.
Testing for Medical Causes
➤ In the absence of other symptoms and signs, only a complete blood
cell count is necessary (Strong; Low Quality of Evidence).
➤ Unless other clinical features warrant otherwise, metabolic tests
(glucose, calcium, sensitive thyroid-stimulating hormone) are not
recommended for chronic constipation (Strong; Moderate Quality of
Evidence).
➤ A colonoscopy should not be performed in patients without alarm
features (eg, blood in stools, anemia, weight loss) unless age-
appropriate colon cancer screening has not been performed (Strong;
Moderate Quality of Evidence).
➤ Anorectal manometry and a rectal balloon expulsion should be
performed in patients who fail to respond to laxatives (Strong;
Moderate Quality of Evidence).
➤ Defecography should not be performed before anorectal manometry
and a rectal balloon expulsion test (Strong; Low Quality of Evidence).
