Constipation is a common digestive complaint characterized by infrequent and difficult bowel movements. It can be caused by factors within the colon like slow motility or blockages, or external factors like diet, medications, and medical conditions. Chronic constipation significantly reduces quality of life and may lead to complications like hemorrhoids, anal fissures, or impaction if left untreated. Treatment involves increasing fiber intake, hydration, exercise, stool softeners, and in severe cases newer medications or surgery to correct structural issues. With lifestyle changes and proper management, most patients' constipation can be effectively controlled.

1. Constipation
MEDSCAPE MAR 28, 2017
ANDREWS CN, STORR M. THE PATHOPHYSIOLOGY OF CHRONIC CONSTIPATION.
CANADIAN JOURNAL OF GASTROENTEROLOGY.2011

2. Background
 is the most common digestive complaint in the United States. It is a symptom rather than a
disease and, despite its frequency, often remains unrecognized until the patient develops
sequelae, such as anorectal disorders or diverticular disease.
 No widely accepted clinically useful definition of constipation exists. Health care providers
usually use the frequency of bowel movements (ie, less than 3 bowel movements per week) to
define constipation. However, the Rome criteria, initially introduced in 1988 and subsequently
modified twice to yield the Rome III criteria, have become the research-standard definition of
constipation.
 According to the Rome III criteria for constipation, a patient must have experienced at least 2
of the following symptoms over the preceding 3 months:
 Fewer than 3 bowel movements per week
 Straining
 Lumpy or hard stools
 Sensation of anorectal obstruction
 Sensation of incomplete defecation
 Manual maneuvering required to defecate

3. Background
 Acute or subacute constipation in middle-aged or elderly patients should
prompt a search for an obstructing colonic lesion. Acute constipation must
be carefully distinguished from ileus secondary to intra-abdominal
emergencies, including infections.
 Constipation is frequently chronic, can significantly affect an individual’s
quality of life, and may be associated with significant health care costs. It is
considered chronic if it is present for at least 12 weeks (in total, not
necessarily consecutively) during the previous year. Chronic constipation
may be associated with psychological disturbances, and the reverse is true
as well.

4. Pathophysiology
 Constipation is divided, with considerable overlap, into issues of stool
consistency (hard, painful stools) and issues of defecatory behavior
(infrequency, difficulty in evacuation, straining during defecation).
Although hard stools frequently result in defecatory difficulties, soft bulky
stools may also be associated with constipation, particularly in elderly
patients with anatomic abnormalities and in patients with impaired
colorectal motility.

5. Pathophysiology
 Constipation may originate primarily from within the colon and rectum or may originate
externally. Processes involved in constipation originating from the colon or rectum
include the following:
 Colon obstruction (neoplasm, volvulus, stricture)
 Slow colonic motility, particularly in patients with a history of chronic laxative abuse
 Outlet obstruction (anatomic or functional) - Anatomic outlet obstruction may derive
from intussusception of the anterior wall of the rectum on straining, rectal prolapse, and
rectocele; functional outlet obstruction may derive from puborectalis or external
sphincter spasm when bearing down, short-segment Hirschsprung disease, and damage
to the pudendal nerve, typically related to chronic straining or vaginal delivery
 Hirschsprung disease in children
 Chagas disease

6. Pathophysiology
 Factors involved in constipation originating outside the colon include poor
dietary habit (the most common factor, generally involving inadequate
fiber or fluid intake and/or overuse of caffeine or alcohol), medications,
systemic endocrine or neurologic diseases, and psychological issues.

7. Pathophysiology
 Constipation results in various degrees of subjective symptoms and is
associated with abnormalities (eg, colonic diverticular disease,
hemorrhoidal disease, anal fissures) that occur secondary to an increase in
colonic luminal pressure and intravascular pressure in the hemorrhoidal
venous cushions.
 Nearly 50% of patients with diverticular or anorectal disease, when asked,
deny experiencing constipation. On careful questioning, however, nearly all
of these patients report having symptoms suggestive of defecatory
straining or infrequency, mostly constipation related, although occasionally
diarrhea related in patients with irritable bowel or other chronic diarrheal
disorders.

8. Etiology
 The etiology of constipation is usually multifactorial, but it can be broadly
divided into 2 main groups: primary constipation and secondary
constipation.

9. Etiology
Primary
 Primary (idiopathic, functional) constipation can generally be subdivided
into the following 3 types:
 Normal-transit constipation (NTC)
 Slow-transit constipation (STC)
 Pelvic floor dysfunction (ie, pelvic floor dyssynergia)

10. Etiology
Primary
 NTC is the most common subtype of primary constipation. Although the
stool passes through the colon at a normal rate, patients find it difficult to
evacuate their bowels. Patients in this category sometimes meet the
criteria for IBS with constipation (IBS-C). The primary difference between
chronic constipation and IBS-C is the prominence of abdominal pain or
discomfort in IBS. Patients with NTC usually have a normal physical
examination.

11. Etiology
Primary
 STC is characterized by infrequent bowel movements, decreased urgency,
or straining to defecate. It occurs more commonly in female patients.
Patients with STC have impaired phasic colonic motor activity. They may
demonstrate mild abdominal distention or palpable stool in the sigmoid
colon.
 Pelvic floor dysfunction is characterized by dysfunction of the pelvic floor
or anal sphincter. Patients often report prolonged or excessive straining, a
feeling of incomplete evacuation, or the use of perineal or vaginal pressure
during defecation to allow the passage of stool, or they may report digital
evacuation of stool.

12. Etiology
Primary
 Pelvic floor dysfunction is
characterized by dysfunction of the
pelvic floor or anal sphincter. Patients
often report prolonged or excessive
straining, a feeling of incomplete
evacuation, or the use of perineal or
vaginal pressure during defecation to
allow the passage of stool, or they
may report digital evacuation of stool.

13. Etiology
Secondary
 Secondary constipation
 Dietary issues that may cause constipation include inadequate water
intake; inadequate fiber intake; overuse of coffee, tea, or alcohol; a recent
change in bowel habit paralleled by changes in the diet; and ignoring the
urge to defecate. Reduced levels of exercise may play a role as well.
 Structural causes of secondary constipation include anal fissures,
thrombosed hemorrhoids, colonic strictures, obstructing tumors, volvulus,
and idiopathic megarectum

14. Etiology
Secondary
 Systemic diseases that may cause constipation include the following:
 Endocrinologic and metabolic disorders - Hypercalcemia,
hyperparathyroidism, hypokalemia, hypothyroidism, pregnancy, and
diabetes mellitus (constipation is the most common gastrointestinal
problem affecting the diabetic population)
 Neurologic disorders - Stroke, Hirschsprung disease, Parkinson disease,
multiple sclerosis, diabetic autonomic neuropathy, spinal cord lesion, head
injury, cerebrovascular accident, Chagas disease, and familial
dysautonomia
 Connective-tissue disorders - Scleroderma, amyloidosis, and mixed
connective-tissue disease

15. Etiology
Secondary
 Medications that may contribute to constipation include the following:
 Antidepressants (eg, cyclic antidepressants and monoamine oxidase inhibitors [MAOIs])
 Metals (eg, iron and bismuth)
 Anticholinergics (eg, benztropine and trihexyphenidyl)
 Opioids (eg, codeine and morphine)
 Antacids eg, (aluminum and calcium compounds)
 Calcium channel blockers (eg, verapamil)
 Nonsteroidal anti-inflammatory drugs (NSAIDs; eg, ibuprofen and diclofenac)
 Sympathomimetics (eg, pseudoephedrine)
 Many psychotropic drugs [7]
 Cholestyramine and stimulant laxatives (long-term use) - Although laxatives are frequently used to treat
constipation, chronic laxative use becomes habituating and may lead to the development of a dilated
atonic laxative colon, which necessitates increasing laxative use with decreasing efficacy
 Inadequate thyroid hormone supplementation

16. Etiology
Secondary
 Constipation may be of toxicologic origin, as with lead poisoning.
 Psychological issues (eg, depression, anxiety, somatization, and eating
disorders) may also contribute to the development of constipation.

17. Signs and symptoms
 According to the Rome III criteria for constipation, a patient must have
experienced at least 2 of the following symptoms over the preceding 3
months:
 Fewer than 3 bowel movements per week
 Straining
 Lumpy or hard stools
 Sensation of anorectal obstruction
 Sensation of incomplete defecation
 Manual maneuvering required to defecate

18. Signs and symptoms
 A constipated patient may be otherwise totally asymptomatic or may complain of 1 or
more of the following:
 Abdominal bloating
 Pain on defecation
 Rectal bleeding
 Spurious diarrhea
 Low back pain
 The following also suggest that the patient may have difficult rectal evacuation:
 Feeling of incomplete evacuation
 Digital extraction
 Tenesmus
 Enema retention

19. Signs and symptoms
 The following signs and symptoms, if present, are grounds for particular
concern:
 Rectal bleeding
 Abdominal pain (suggestive of possible irritable bowel syndrome [IBS] with
constipation [IBS-C])
 Inability to pass flatus
 Vomiting

20. Diagnosis
 An extensive workup of the constipated patient is performed on an outpatient basis and
usually occurs after approximately 3-6 months of failed medical management. Features
of the workup are as follows:
 Rectal and perineal examination should already have been performed but should be
repeated
 Laboratory evaluation does not play a large role in the initial assessment of the patient
 Imaging studies are used to rule out acute processes that may be causing colonic ileus
or to evaluate causes of chronic constipation
 In patients with acute abdominal pain, fever, leukocytosis, or other symptoms
suggesting possible systemic or intra-abdominal processes, imaging studies are used to
rule out sources of sepsis or intra-abdominal problems
 Lower gastrointestinal (GI) endoscopy, colonic transit study, defecography, anorectal
manometry, surface anal electromyography (EMG), and balloon expulsion may be used
in the evaluation of constipation

21. Diagnosis
 Large stool mass in hepatic flexure of
colon.

22. Diagnosis
 Large stool mass in hepatic flexure of
colon

23. Diagnosis
 Pseudo-obstruction secondary to
fecal impaction

24. Diagnosis
 Distended transverse colon

25. Diagnosis
 Distended rectum

26. Management
 Initial treatment measures for constipation include manual disimpaction
and transrectal enemas. A well-lubricated gloved finger might be required
in patients with lower anorectal impactions. These initial measures are then
followed by elective evaluation of the causes of constipation.
 Medical care should focus on dietary change and exercise rather than
laxatives, enemas, and suppositories, none of which really address the
underlying problem.
 The key to treating most patients with constipation is correction of dietary
deficiencies, which generally involves increasing intake of fiber and fluid
and decreasing the use of constipating agents (eg, milk products, coffee,
tea, alcohol).

27. Management
 Medications to treat constipation include the following:
 Bulk-forming agents (fibers; eg, psyllium): arguably the best and least
expensive medication for long-term treatment
 Emollient stool softeners (eg, docusate): Best used for short-term
prophylaxis (eg, postoperative)
 Rapidly acting lubricants (eg, mineral oil): Used for acute or subacute
management of constipation
 Prokinetics (eg, tegaserod): Proposed for use with severe constipation-
predominant symptoms
 Stimulant laxatives (eg, senna): Over-the-counter agents commonly but
inappropriately used for long-term treatment of constipation

28. Management
 Newer therapies for constipation include the following:
 Prucalopride (not approved in the United States), a prokinetic selective 5-
hydroxytryptamine-4 (5-HT4) receptor antagonist that stimulates colonic
motility and decreases transit time
 The osmotic agent lubiprostone is FDA approved for constipation caused by
IBS and opioid-induced constipation in adults with chronic, noncancer pain
 Linaclotide and plecanatide are guanylate cyclase C (GC-C) agonists; they are
indicated for chronic idiopathic constipation. Additionally, linaclotide is
indicated for constipation caused by IBS in adults
 Several peripherally-acting mu-opioid receptor antagonists (PAMORA) have
been approved by the FDA for opioid-induced constipation in adults with
chronic noncancer pain and/or for palliative care (eg, naloxegol,
methylnaltrexone, naldemedine)

29. Complications
 Difficulty in defecation may cause substantial discomfort, abdominal
cramping, and a general feeling of malaise.
 Actual or perceived constipation typically results in self-medicating with
various laxatives. Although laxatives may correct the acute problem,
chronic use of these agents leads to habituation, necessitating ever-
increasing doses that result in drug dependency and, ultimately, a
hypotonic laxative colon. Melanosis coli from prolonged laxative use is an
incidental finding at endoscopy.
 Acute or chronic episodes of straining may cause acute or chronic
hemorrhoidal disease

30. Complications
 The passage of hard stools may result in an acute anal fissure, which is a
painful tear in the anoderm that may bleed. The regular passage of hard
stools and the painful anal spasms during defecation that impinge the
hard stools against the fresh wound prevent the anal fissure from healing.
 Constipation may be one cause of pelvic floor damage in women.
 The chronic pressure effect of hard stools against the anterior rectal wall
when the patient strains during defecation is believed to cause solitary
rectal ulcers. This is usually a self-limiting process and responds to
treatment of constipation. In adults, surgical or gastroenterologic
consultation may be required to differentiate benign solitary rectal ulcers
from rectal malignancy.

31. Complications
 Other complications of constipation may include the following:
 Fecal impaction
 Bowel obstruction
 Fecal incontinence
 Stercoral ulceration/perforation
 Megacolon
 Volvulus
 Rectal prolapse
 Urinary retention
 Syncope
 Fistula in ano

32. Prognosis
 Most active patients do well with medical management and appropriate
dietary management. Recurrence depends on the patient’s long-term
compliance with therapy. A small percentage of patients are quite
debilitated as a result of constipation. Some patients with functional
(primary or idiopathic) constipation (ie, colonic inertia) require total
abdominal colectomy with ileorectal anastomosis.
 After a careful preoperative workup that includes physical and
psychological assessment, patients with outlet obstruction generally
respond well to surgical correction and have a good prognosis.

33. Prognosis
 Dyskinesias of the pelvic floor musculature and of the sphincter
mechanism may be managed via biofeedback therapy, but the results are
mixed.
 Patients who are chronically dependent on increasing doses of self-
prescribed laxatives are perhaps the most difficult patients to treat. Most
such patients can be treated with a combination of fiber, water, and
osmotic agents (eg, polyethylene glycol ,sorbitol). However, the need for
increasing doses of laxatives and the intermittent use of other agents
becomes problematic.
 In rare situations in which patients are virtually refractory to laxatives, total
abdominal colectomy may be performed after careful workup.
Postoperatively, these patients often experience a greatly improved quality
of life. A careful preoperative evaluation and a detailed informed consent
discussion are required.