Table 1. Symptom Criteria for Constipationa
|Irritable Bowel Syndrome (IBS)|
|Criteria fulfilled for the last 3 months with symptom onset ≥6 months prior to diagnosis.|
|Recurrent abdominal pain, on average, ≥1 day per week in the last 3 months, associated with ≥2 of the following criteria:|
|IBS with predominant constipation (IBS-C):|
|More than one-fourth (25%) of bowel movements with Bristol stool form types 1 or 2 and less than one-fourth (25%) of bowel movements with Bristol stool form types 6 or 7.|
|Alternative for epidemiology or clinical practice: Patient reports that abnormal bowel movements are usually constipation (like type 1 or 2 in the picture of Bristol Stool Form Scale (BSFS), see Figure 1A).|
|Functional Constipation (FC)b|
|FC is a functional bowel disorder in which symptoms of difficult, infrequent, or incomplete defecation predominate. Patients with FC should not meet IBS criteria. Although abdominal pain and/or bloating may be present, they are not predominant symptoms. Symptom onset should occur ≥6 months before diagnosis, and symptoms should be present during the last 3 months.|
|General Definition of Constipation|
|Prolonged and excessive straining before elimination|
|Need for perineal or vaginal pressure to allow stools to be passed or direct digital evacuation of stools|
|Diagnosis requires anorectal tests (manometry, rectal balloon expulsion, or defecography [barium or MRI]) suggestive of a defecatory disorder|
|Normal transit constipation (NTC)|
|Normal colonic transit and anorectal functions|
|Slow transit constipation (STC)|
|Slow colonic transit and normal anorectal functions|
|Some patients may have combination or overlap disorders (eg, STC with defecatory disorders), perhaps even associated with features of irritable bowel syndrome.|
b For research studies, patients meeting criteria for OIC should not be given a diagnosis of FC because it is difficult to distinguish between opioid side effects and other causes of constipation. However, clinicians recognize that these 2 conditions might overlap.
GRADE Strength of Recommendations and Implications
|Grade||Implications of strong and conditional (weak) |
- 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 gynecologic 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).
- Defecography should be considered when results of anorectal manometry and rectal balloon expulsion are inconclusive for defecatory disorders (Strong; Low Quality of 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; Low Quality of Evidence).