Chronic constipation: Update on management

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Release date: May 1, 2017
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Managing chronic constipation involves identifying and treating secondary causes, instituting lifestyle changes, prescribing pharmacologic and nonpharmacologic therapies, and, occasionally, referring for surgery. Several new drugs have been approved, and others are in the pipeline.


  • Although newer drugs are available, lifestyle modifications and laxatives continue to be the treatments of choice for chronic constipation, as they have high response rates and few adverse effects and are relatively affordable.
  • Chronic constipation requires different management approaches depending on whether colonic transit time is normal or prolonged and whether outlet function is abnormal.
  • Surgical treatments for constipation are reserved for patients whose symptoms persist despite maximal medical therapy.



Chronic constipation has a variety of possible causes and mechanisms. Although traditional conservative treatments are still valid and first-line, if these fail, clinicians can choose from a growing list of new treatments, tailored to the cause in the individual patient.

This article discusses how defecation works (or doesn’t), the types of chronic constipation, the available diagnostic tools, and traditional and newer treatments, including some still in development.


Chronic constipation is one of the most common gastrointestinal disorders, affecting about 15% of all adults and 30% of those over the age of 60.1 It can be a primary disorder or secondary to other factors.

Constipation is more prevalent in women and in institutionalized elderly people.2 It is associated with lower socioeconomic status, depression, less self-reported physical activity, certain medications, and stressful life events.3 Given its high prevalence and its impact on quality of life, it is also associated with significant utilization of healthcare resources.4

Constipation defined by Rome IV criteria

Physicians and patients may disagree about what constitutes constipation. Physicians primarily regard it as infrequent bowel movements, while patients tend to have a broader definition. According to the Rome IV criteria,5 chronic constipation is defined by the presence of the following for at least 3 months (with symptom onset at least 6 months prior to diagnosis):

(1) Two or more of the following for more than 25% of defecations:

  • Straining
  • Lumpy or hard stools
  • Sensation of incomplete evacuation
  • Sensation of anorectal obstruction or blockage
  • Manual maneuvers to facilitate evacuation
  • Fewer than 3 spontaneous bowel movements per week.

(2) Loose stools are rarely present without the use of laxatives.

(3) The patient does not meet the criteria for diagnosis of irritable bowel syndrome.


Defecation begins when the rectum fills with stool, causing relaxation of the internal anal sphincter and the urge to defecate. The external anal sphincter, which is under voluntary control, can then either contract to delay defecation or relax to allow the stool to be expelled.6

Colonic muscles propel stool toward the rectum in repetitive localized contractions that help mix and promote absorption of the content, and larger coordinated (high-amplitude propagating) contractions that, in healthy individuals, move the stool forward from the proximal to the distal colon multiple times daily. These contractions usually occur in the morning and are accentuated by gastric distention from food and the resulting gastrocolic reflex.

Serotonin (5-HT) is released by enterochromaffin cells in response to distention of the gut wall. It mediates peristaltic movements of the gastrointestinal tract by binding to receptors (especially 5-HT4), stimulating release of neurotransmitters such as acetylcholine, causing smooth-muscle contraction behind the luminal contents and propelling them forward.


The American Gastroenterological Association7 classifies constipation into 3 groups on the basis of colonic transit time and anorectal function:

Normal-transit constipation

Stool normally takes 20 to 72 hours to pass through the colon, with transit time affected by diet, drugs, level of physical activity, and emotional status.8

Normal-transit constipation is the most common type of constipation. The term is sometimes used interchangeably with constipation-predominant irritable bowel syndrome, but the latter is a distinct entity characterized by abdominal pain relieved by defecation as the primary symptom, as well as having occasional loose stools. These 2 conditions can be hard to tell apart, especially if the patient cannot describe the symptoms precisely.

Slow-transit constipation

Slow-transit constipation—also called delayed-transit constipation, colonoparesis, colonic inertia, and pseudo-obstruction—is defined as prolonged stool transit in the colon, ie, for more than 5 days.9 It can be the result of colonic smooth muscle dysfunction, compromised colonic neural pathways, or both, leading to slow colon peristalsis.

Factors that can affect colonic motility such as opioid use and hypothyroidism should be carefully considered in these patients. Opioids are notorious for causing constipation by decreasing bowel tone and contractility and thereby increasing colonic transit time. They also tighten up the anal sphincters, resulting in decreased rectal evacuation.10


Next Article:

Serotonin syndrome

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