Chronic Constipation

Introduction to Chronic Constipation

Figure X | Image courtesy of GI Society

Chronic constipation is defined as constipation lasting for more than 3 months. Constipation may be defined clinically as unsatisfactory defecation resulting from infrequent stools, difficult passage, hardness of stool, or feeling of incomplete evacuation. While it is normal to have a bowel movement anywhere from three times a day to three times a week, a patient experiencing chronic constipation has fewer than three spontaneous bowel movements per week often as result of hard or lumpy stool that is very difficult to pass.

Chronic constipation is a common disorder in adults older than 60 years, and is a frequent reason for their seeking medical care. Although constipation is rarely a life-threatening disorder, it can impair quality of life and carries a significant economic burden.

Treatment is usually empiric, using dietary changes and laxatives. Only if conservative measures fail should specialized testing be considered to define pathophysiologic subgroups, as this will influence treatment.

Definition and Classification

Although physicians frequently define constipation Opens in new window on the basis of frequency alone (less than 3 stools per week), patients are more likely to complain of unsatisfactory defecation and this is often influenced by cultural and social customs.

Symptoms include the type of stool (hard/lumpy), and subjective feelings such as excessive straining, feeling of incomplete evacuation, sense of difficulty passing stool, and the need for manual maneuvers during defecation. Chronic constipation is clinically distinguished from acute or intermittent constipation by the presence of symptoms for greater than three (3) months.

Table X1 \| Definitions of constipation by various gastroenterology society and groups
G society	Constipation	Constipation predominant IBS
AGA	Syndrome of bowel symptoms including difficult or infrequent passage of stool, hardness of stool, or a feeling of incomplete evacuation that may occur either in isolation or secondary to another underlying disorder (e.g., Parkinson’s disease)	Abdominal discomfort that is temporally associated with 2 of the following 3 symptoms: relief of discomfort after defecation, hard stools, or less frequent stools
ACG	Difficult stool passage that includes straining, a sense of difficulty passing stool, incomplete evacuation, hard/lumpy stools, prolonged time to stool, or need for manual maneuvers to pass stool. Chronic constipation is defined as the presence of these symptoms for at least 3 months	Abdominal pain or discomfort that occurs in association with altered bowel habits over a period of at least 3 months
Rome III	Must include two or more of the following: Straining during at least 25% of defecation Lumpy or hard stools at least 25% of defecations Sensation of incomplete evacuation at least 25% of defecations Sensation of anorectal obstruction/blockage at least 25% of defecations Manual maneuvers to facilitate at least 25% of defecations (e.g., digital evacuation, support of the pelvic floor) Fewer than 3 defecations per week Loose stools are rarely present without the use of laxatives Insufficient criteria for IBS Symptoms present for 6 months	Recurrent abdominal pain or discomfort at least 3 days per month in the past 3 months associated with 2 or more of the following: Improvement with defecation Onset associated with change in frequency of stool Onset associated with change in form (appearance) of stool Hard or lumpy stools 25% and loose (mushy) or watery stools <25% of bowel movements

The Rome Criteria have been used to attempt to identify homogeneous groups of patients for clinical trials investigating treatments for constipation (Table X1) but are less suitable for routing clinical use.

Constipation predominant IBS (IBS-C) should be considered in constipated patients with significant abdominal discomfort or pain although there is an overlap with functional constipation in clinical practice (Table X1).

Table X2 \| Secondary causes of constipation in the elderly
Mechanical	Neurologic disease
Colorectal cancer Anal fissure Rectal/anal stricture Rectocele (some) Pseudo obstruction Megacolon	Spinal cord lesion Stroke Parkinson’s disease Multiple sclerosis
Metabolic disturbances	Medications
Hypercalcemia Hypokalemia Hypothyroidism Uremia	Opiates Anticholinergics Calcium channel blockers Anticonvulsants Antidepressants Antispasmodics Antihistamines Non-steroidal anti-inflammatory drugs
Miscellaneous
Amyloidosis Scleroderma Heavy metal poisoning

Potentially treatable conditions which cause or exacerbate constipation should be considered in all patients with chronic constipation (Table X2).

Classifying chronic constipation into three major groups (normal transit constipation, pelvic floor dysfunction, and slow transit constipation) is clinically useful for patients who do not respond to conservative measures and empiric laxatives.

Pelvic floor dysfunction, also called functional defecation disorder may be associated with inadequate propulsive forces and/or increased resistance to evacuation caused by incoordination of abdominal, rectal, and anal muscles resulting in inadequate or difficult emptying of rectum (Table X3).

Dyssynergic defecation, for example, is associated with inappropriate contraction of the puborectal muscle and the external anal sphincter (Type 1) or incomplete relaxation of the anal canal (Type 2) during defecation attempts. This disorder may occur with normal or slow colonic transit.

Pelvic floor dysfunction can result in secondary delayed colon transit which reverses with successful treatment of the defecatory disorder. The term slow transit constipation should be reserved for patients with slow transit of the colon and normal rectal evacuation, a distinction which is of considerable clinical importance.

Table X3 \| Functional defecation disorder definitions
Functional defacation disorders The patient must satisfy diagnostic criteria for functional constipation (Table X1) During repeated attempts to defecate must have at least 2 of the following: Evidence of impaired evacuation, based on balloon expulsion test or imaging Inappropriate contraction of the pelvic floor muscles (i.e., anal sphincter or puborectalis) or less than 20% relaxation of basal resting sphincter pressure by manometry, imaging, or EMG Inadequate propulsive forces assessed by manometry or imaging Criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis
Dyssynergic defecation Inappropriate contraction of the pelvic floor or less than 20% relaxation of basal resting sphincter pressure with adequate propulsive forces during attempted defecation
Inadequate defecatory propulsion Inadequate propulsive forces with or without inappropriate contraction or less than 20% relaxation of the anal sphincter during attempted defecation

Table X3 | Functional defecation disorder definitions

Functional defacation disorders

The patient must satisfy diagnostic criteria for functional constipation (Table X1)
During repeated attempts to defecate must have at least 2 of the following:

Evidence of impaired evacuation, based on balloon expulsion test or imaging
Inappropriate contraction of the pelvic floor muscles (i.e., anal sphincter or puborectalis) or less than 20% relaxation of basal resting sphincter pressure by manometry, imaging, or EMG
Inadequate propulsive forces assessed by manometry or imaging

Criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis

Dyssynergic defecation

Inappropriate contraction of the pelvic floor or less than 20% relaxation of basal resting sphincter pressure with adequate propulsive forces during attempted defecation

Inadequate defecatory propulsion

Inadequate propulsive forces with or without inappropriate contraction or less than 20% relaxation of the anal sphincter during attempted defecation

Treatment

In the elderly patients who are healthy, constipation should be treated in a manner similar to the general population.

Specifically, after appropriate tests are done, and if pelvic dyssynergia is not suspected based on clinical presentation or exam, an empiric and conservative approach should be taken. These empiric measures are safe and recommended by experts.

Management should begin with discontinuation of constipating medications if possible, exercise, establishment of a bowel routine, and a gradual increase in dietary or supplemental fiber.

Patients should be advised to heed the cell to stool, especially in the morning, and set a routine time each day to have a bowel movement. Except in the case of dehydration, there is no merit to increasing fluid intake beyond normal requirements, as it will serve only to increase urination.

An osmotic laxative such as polyethylene glycol (17 g daily, adjusted as needed) is an effective, inexpensive addition. If needed, a stimulant laxative or suppository (biscodyl) can be added several times a week or daily. Newer, more expensive prescription agents (lubiprostone, linaclotide) could be considered if response to nonprescription agents is unsatisfactory. Treatment failure should lead to consideration of a defection disorder and obtaining appropriate diagnostic tests.

Treatment of fecal impaction entails manual disimpaction, enemas, and perhaps oral laxatives, usually polyethylene glycol. In contrast to chronic constipation, treatment of chronic megacolon includes a low fiber diet in addition to aggressive laxative use to prevent fecal impactions.

If symptoms of megacolon are intractable and disabling, if sigmoid volvulus is not responsive to attempts to untwist the bowel or recurs, or if there is a cecal volvulus, surgery should be performed. If anal sphincter function is intact, this entails a sub subtotal colectomy with ileorectal anastomosis; alternatively, a Hartmann’s pouch could be performed.

Medical Treatment of Functional Constipation

Bulking Agents

Bulking agents are organic polymers that increase stool bulk and consistency, thereby increasing colon motility and shortening colon transit time.

Included in this category are natural soluble fiber (psyllium, ispaghula), insoluble fiber (bran), and synthetic fibers such as methylcellulose and calcium polycarbophil. Fiber-rich foods include fruits, vegetables, nuts, bran, and beans.

Published studies of fiber in chronic constipation have generally been small, poorly designed, assessed for relatively short periods of time, and have not used rigorous definitions such as Rome criteria to select patients. However, fiber is recommended as a first line therapy for constipation because of its good safety profile, low cost, and other potential health benefits.

Prunes (50 g prune/6 g fiber once to twice daily), which improve stool frequency and consistency and decrease straining, are a good alternative to fiber for those who like them. Common side effects include bloating and flatulence, which occur more often with insoluble fiber and may be less common with synthetic fiber. Bowel obstruction occurs rarely.

The effect of fiber supplementation is gradual and may take several weeks. Patients should also be warned about the side effects of increased bloating and flatulence although these may subside after several days to weeks; alternatively, patients can try a different fiber supplement.

To minimize side effects, fiber should be increased slowly, about 5 g daily every 1–2 weeks according to tolerance and improved symptoms. Bulking agents are ineffective in patients with slow transit constipation and dyssynergic defecation and often make symptoms worse.

Stool Softeners and Probiotics

Stool softeners (docusate) act as detergents to allow water to permeate stool, thereby softening it. Although FDA approved for treatment of occasional constipation, there is insufficient evidence for use in chronic constipation.

Preliminary data suggests that Bifidobacterium lactic, Lactobacillus casei, and Escherichia coli Nissile may improve stool frequency and consistency in constipation, but data and safety profiles are limited and probiotics should be considered investigational at the present time.

Stimulant Laxatives

Stimulant laxatives increase intestinal motility by inhibiting water absorption and stimulating the mysenteric plexus. Bisacodyl is included in this category, as are casto oil and anthraquinones (senna, casecara sagrada, rhubarb, frangula, and aloe).

Sodium picosulfate is a diphenylmethane laxative closely related to bisacodyl. It is available in the USA only in a combined form with magnesium oxide marketed as a colonoscopy prep (Prepopik, Ferring Pharmaceuticals Inc., Parsippany, NJ) and is currently available only in Europe. Although older studies were poorly designed by today’s standards, several high quality recent clinical trials of bisacodyl and picosulfate have demonstrated improved stool frequency and quality of life.

Stimulant laxatives may be used up to but not more than once daily, in addition to or instead of a daily osmotic laxative. Side effects of stimulant laxatives include abdominal cramps, diarrhea, and, very frequently, electrolyte abnormalities. Hepatotoxicity has been reported with senna and cascara sagrada, although this may be dose related.

Melanosis coli is a dark brown pigmentation of the colon mucosa seen in patients who chronically use anthraquinones, and is more prominent in the proximal colon. Colonic bacteria convert these laxatives to compounds that induce apoptosis of colon epithelial cells. Macrophages ingest and convert the compound to a black pigment called lipofuscin. Melanosis coli is functionally inconsequential; it occurs after months of use and may take months to resolve after discontinuation. It is not associated with the development of colon cancer. There is no evidence that stimulant laxatives cause permanent damage to either the colonic musculature or enteric nervous system.

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