Constipation resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mugilan Poongkunran M.B.B.S [2]

Definition

Constipation is a syndrome that is characterized by difficulty in passing stool, by infrequent bowel movements, by hard stool, or by a feeling of incomplete evacuation that occurs either in isolation or secondary to another underlying disorder.

Rome III criteria	Pharmacologic studies based criteria
Symptoms for ≥6 months and ≥2 of the following for the past 3 months: ● Straining during defecation ● Hard or lumpy stools ● Sensation of incomplete evacuation during defecation ● Sensation of anorectal obstruction/blockade during defecation ● Manual maneuvers to facilitate defecations with <3 defecations/week ● Absence of loose stools	Spontaneous bowel movements <3 per week and ≥1 of the following for at least 12 weeks during the past 12 months: ● Straining during more than one-fourth of defecation ● Lumpy or hard stools in more than one-fourth of defecation ● Sensation of incomplete evacuation in more than one-fourth of defecation ● Absence of loose stools or watery spontaneous bowel movements

Clinical subgroups	Definitions
Normal transit constipation	Normal transit constipation refers to constipation in patients with normal anorectal function and normal colonic transit, with or without abnormal colonic motor disturbances and abnormal (ie, reduced or increased) colonic sensations.
Slow transit constipation	Slow transit constipation refers to constipation in patients with normal anorectal function but slow colonic transit, with or without abnormal colonic motor disturbances and abnormal (ie, reduced or increased) colonic sensations.
Defecatory disorders (Outlet obstruction, obstructed defecation, dyschezia, anismus, or pelvic floor dyssynergia)	Defecatory disorders refer to constipation in patients with impaired rectal evacuation from inadequate rectal propulsive forces and/or increased resistance to evacuation during defecation, with or without structural disturbances like rectocele and intussusception, reduced rectal sensation, and slow colonic transit. Increased resistance to evacuation might follow high anal resting pressure (anismus) and/or incomplete relaxation or paradoxical contraction of the pelvic floor and external anal sphincters (dyssynergia).
Combination disorders	Combination disorders refer to patients with combination or overlap of disorders (eg, STC with defecatory disorders), perhaps even an association with features of irritable bowel syndrome.

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

• Atropine poisoning
• Hypokalemia
• Lead poisoning
• Opium poisoning
• Severe dehydration
• Spinal cord injury
• Superior mesenteric artery occlusion

Common Causes

• Hardening of the feces: Improper mastication, low dietary fiber, dehydration and medications (aluminium, calcium, diuretic, iron).
• Paralysis or slowed transit: Hypothyroidism, hypokalemia, injured anal sphincter, medications (loperamide, codeine, morphine, tricyclic antidepressants) and severe systemic illness due to other causes.
• Constriction, where part of the intestine or rectum is narrowed or blocked: Diverticulosis, pelvic masses and stenosis.
• Psychosomatic constipation: Functional constipation and irritable bowel syndrome.
• Smoking cessation
• Abdominal surgery and childbirth

Management

Diagnostic Approach

Shown below is an algorithm depicting the diagnostic approach of constipation in adults based on the American Gastroenterological Association (AGA) guideline.

Characterize the symptom: Constipation: ❑ Any desire to defecate but an inability to pass a stool ❑ Any need for straining to begin and/or to end defecation ❑ Any need for prolonged time to pass stool ❑ Any need for direct digital manipualtion to pass stool ❑ Any need for perineal or vaginal pressure to pass stool ❑ Any sensation of incomplete emptying of bowel ❑ Frequency of passage of stools ❑ Consistency of stools (hard or lumpy) ❑ Onset (sudden or gradual) ❑ Duration (chronic ≥ 3 months) ❑ Any use of laxatives to pass stool (what laxative, how often and what dosage) ❑ Any use of additional enemas or suppositories to pass stool Associated symptoms: ❑ Abdominal pain or abdominal discomfort: Onset associated with change in frequency of stool Onset associated with change in consistency of stool Any improvement with passage of stool Onset only during there act of straining Any persistance between bowel movements ❑ Abdominal distention ❑ Diarrhea (Onset, duration, pattern, alternating with constipation) ❑ Blood in stools ❑ Fever ❑ Nausea and vomiting ❑ Loss of appetite ❑ Loss of weight ❑ Fatigue Obtain a detailed history: ❑ Dietary history: Dietary pattern change, low fiber diet, food intolerance, dehydration etc ❑ Medications history: Opioid analgesics, antidepressants, anticholinergics, antispasmodics, antihypertensives, antihistamines etc ❑ Family history: Colorectal cancer, pelvic masses, neuromuscular diseases etc ❑ Systemic illness: Diabetes, hypothyroidism, gastrointestinal disorders, neuromuscular disorders etc ❑ Personal history: Smoking cessation, travel history etc ❑ Surgical history: Abdominal surgeries, childbirth, extended bed rest etc ❑ Trauma history: Spinal cord injury

Examine the patient: ❑ General status: Pulse, blood pressure, respiratory rate, weight, thyroid ❑ Signs of dehydration: Decreased skin turgor, dry mucosa, thirst ❑ Perineal/rectal examination: Observe perianal skin for evidence of fecal soiling Observe anal verge for any patulous opening, prolapse of mucosa Observe the descent of the perineum during simulated evacuation Observe the elevation of perineum during a squeeze aimed at retention Evaluate the resting tone of the sphincter and puborectalis muscle Test anal reflex by a light pinprick or scratch Look for any rectocele, hemorrhoids, anal fissure etc ❑ Abdominal examination: Mass, distension, tenderness and bowel sounds ❑ Neurological examination: Neuropathy, spinal cord injury ❑ Cardiovascular and respiratory examination

Order tests: ❑ Complete blood count (CBC) ❑ TSH ❑ Serum calcium ❑ Serum glucose ❑ Creatinine When secondary causes are suspected: ❑ Colonoscopy ❑ Flexible sigmoidoscopy ❑ Barium enema ❑ Magnetic resonance imaging

Possible etiologies after initial evaluation

Irritable bowel syndrome(IBS)

Unknown etiology

Organic constipation (mechanical obstruction or drug side effect)

Constipation secondary to systemic disease

Rx for IBS

Dietary fiber supplementation and simple laxatives

Treat the underlying etiology

Treat the underlying systemic disease

Refractory constipation if there is no response to initial management

Therapeutic Approach

Shown below are algorithms depicting the therapeutic approaches of clinical subgroups of constipation in adults based on the American Gastroenterological Association (AGA) guideline.

Refractory Constipation

Chronic constipation who have not responded to a high-fiber diet and/or over-the-counter laxatives after organic disorders have been excluded

Order specific tests: ❑ Rectal Balloon Expulsion Test (BET) ❑ Anorectal Manometry (ARM) ❑ Barium, Scintigraphic, and Magnetic Resonance Defecography (BD) ❑ Colonic Transit Test (CTT)

Normal BET, ARM, BD, CTT

Abnormal CTT Normal BET, ARM, BD

Abnormal BET, ARM, BD Normal CTT

Abnormal BET, ARM, BD, CTT

Normal transit constipation

Slow transit constipation

Pelvic floor dysfunction

Combined slow transit constipation and pelvic floor dysfunction

Normal Transit Constipation

Normal transit constipation

Fiber ❑ Psyllium: 1 tsp up to 3 times daily OR ❑ Methylcellulose: 1 tsp up to 3 times daily OR ❑ Calcium polycarbophil: 2-4 tablets OD ❑ Insoluble fiber (wheat bran) is not preferred PLUS Saline laxative ❑ Milk of magnesia: 15-30 ml OD or BID

Response to treatment

Yes

No

Continue the same regimen

Add stimulant laxative ❑ Bisacodyl: 10 mg suppositories or 5-10 mg orally up to 3 times/wk OR ❑ Glycerin: Suppository OD

Response to treatment

No

Yes

Add hyperosmolar agents ❑ PEG: 8-32 oz once daily OR ❑ Lactulose: 15-30 ml OD or BID

Continue the same regimen

Response to treatment

Yes

No

Continue the same regimen

Adjust and change medications periodically

Slow Transit Constipation

Slow transit constipation

Fiber ❑ Psyllium: 1 tsp up to 3 times daily OR ❑ Methylcellulose: 1 tsp up to 3 times daily PLUS Saline laxative ❑ Milk of magnesia: 15-30 ml OD or BID PLUS Stimulant laxative ❑ Bisacodyl: 10 mg suppositories or 5-10 mg orally up to 3 times/wk

Response to treatment

Yes

No

Continue the initial therapeutic regimen ❑ Fiber ❑ milk of magnesia

Add hyperosmolar agent ❑ PEG: 8-32 oz once daily OR ❑ Lactulose: 15-30 ml OD or BID

Response to treatment

No

Yes

Repeat colonic transit test with medications

Continue the initial therapeutic regimen

Response to treatment

Normal

Delayed

Adjust medications as needed

Repeat BET and BD

Normal

Abnormal

Consider illeo rectal anastamosis or subtotal colectomy

Manage for pelvic floor dysfunction

Pelvic Floor Dysfunction

Pelvic floor dysfunction

Abnormal BET or BD ❑ Define rectoanal angle ❑ Define preineal descent ❑ Define rectal emptying High resting pressure ❑ Rule out anal fissure first Abnormal reflex ❑ Absence of rectoanal inhibitory reflex ❑ Rule out adult Hirschsprung's disease

Fiber ❑ Psyllium: 1 tsp up to 3 times daily OR ❑ Methylcellulose: 1 tsp up to 3 times daily PLUS Stimulant laxative ❑ Bisacodyl: 10 mg suppositories or 5-10 mg orally up to 3 times/wk OR ❑ Glycerin: Suppository OD

Biofeedback ❑ Anorectal and pelvic floor muscle activity are recorded by surface electromyographic sensors ❑ Patients are taught to increase intraabdominal pressure and relax the pelvic floor muscles during defecation ❑ Patients practice by expelling an air filled balloon or through external traction to a catheter attached to the balloon ❑ Patients are taught to recognize weaker sensations of rectal filling ❑ Patients are taught Kegel exercises

Response to treatment

Yes

No

Follow clinically

Repeat balloon expulsion test

Abnormal

Normal

Perform defecating proctogram

Manage as normal transit constipation

Normal

Abnormal

Reassess biofeedback + medications if needed

Define anatomic rectal defect

No response

Clinically significant

Insignificant

Consider surgery

Surgical repair and follow up

No surgery needed

Combined Pelvic Floor Dysfunction and Slow Transit Constipation

Combined pelvic floor dysfunction and slow transit constipation

Biofeedback PLUS Dietary fiber: Psyllium/methylcellulose PLUS Stimulant laxative: Bisacodyl PLUS Saline laxative: Milk of magnesia

Response to treatment

Yes

No

Perform colonic transit test without medications

Repeat balloon expulsion test

If delayed manage as slow transit constipation

If normal follow clinically

Abnormal

Normal

Perform defecating proctogram

Manage as slow transit constipation

Normal

Abnormal

Reassess biofeedback + add hyperosmolar agents (lactulose/PEG)

Define anatomic rectal defect

No improvement

No response

Clinically significant

Insignificant

Repeat colonic transit test on medications

Continue therapeutic regimen

Surgical repair and follow up

No surgery needed

Normal

Delayed

Adjust medications as needed

Consider surgery

Consider surgery if no improvement

Do's

• Do begin evaluation of constipation with a detailed history and physical examination that includes a rectal examination.
• Do perform a colonoscopy in patient's presenting with the recent onset of constipation without an obvious explanation, hematochezia, weight loss of ≥10 pounds, a family history of colon cancer or inflammatory bowel disease, anemia and positive fecal occult blood test.
• Do perform a trial of conservative management of lifestyle and dietary modification in patients without any of the above alarm symptoms.

Dont's

• Dont use insoluble fiber like wheat bran for the intial managment of constipation in adults.

References

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