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Chronic constipation
- an evidenced based approach
Robert A. Baldor, MD, FAAFP
Professor, Family Medicine & Community
Health
UMass Medical School
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Learning Objectives
• by the end of the session, you will have a clear
understanding of the basic pathophysiology
related to chronic constipation
• …and develop an evidenced based approach
for the primary care diagnosis and treatment
of these chronic problems.
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Mrs Z.
• A 34-year-old white female who complains of
constipation; she hasn’t discussed it in the
past as “it’s embarrassing,” but states that
she has been constipated her entire life and
has tried a variety of OTC products without
much relief.
• She further reports that she is very active,
runs 4 days a week, that she always has a
bottle of water with her and tries to eat
salads regularly…..
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History
• Character of the problem
– Consistency
– Frequency
– Straining, bloating
– Diarrhea
• Medications
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Mrs. Z
• Doesn’t have much discomfort, but has to strain
and has hard stools along with blood occasionally
on TP – she tends to go about twice a week
• She will occasionally have diarrhea – but it seems
related to something she had eaten
• Takes Tums for her ‘bones’
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Constipation
No Clear Definition
A group of syndromes with similar findings
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Am College of Gastroenterology …
Unsatisfactory defecation, characterized
by infrequent stools and/or difficult stool
passage
Brandt 2005
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Pathophysiology…
• As food leaves stomach, gastroileal reflex
relaxes the ileocecal valve and digested
food (chyme) enters the colon
• Peristaltic contractions move chyme
through the colon
• Na+ actively absorbed - water follows
because of the generated osmotic gradient
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Normal Colonic Transit Time
• A meal reaches the ileo-cecal valve in 4 hours
…the sigmoid colon 12hours later
… then slows to the anus.
• Plastic pellets with a meal → 70% recovered
in 3 days; remainder in a week!
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Defecation
• Food distends the stomach, initiating the gastro-colic
reflex causing rectal contractions & a desire to go!
• ‘Urge to defecate’ occurs as rectal pressures ↑
• Defecation reflexes can be inhibited by voluntarily
contracting the external sphincter or facilitated by
straining
• Pelvic floor/anal sphincter dysfunction interfere
with normal defecation
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Most with primary constipation suffer
from which one of the following?
1. Slow colonic transit time
2. Pelvic floor/anal sphincter dysfunction
3. Functional – normal transit time and
sphincter function
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Most with primary constipation suffer
from which one of the following?
1. Slow colonic transit time
2. Pelvic floor/anal sphincter dysfunction
3. Functional – normal transit time and
sphincter function
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Secondary Constipation
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•
•
•
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Endocrine dysfunction (DM, hypothyroid)
Metabolic disorder (↑ Ca,↓ K)
Mechanical (obstruction, rectocele)
Pregnancy
Neurologic disorders (Hirschsprung’s,
multiple sclerosis, spinal cord injuries)
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Medication Effect
• Anti-cholinergic effects
– Antidepressants
– Narcotics
– Antipsychotics
• Calcium channel blockers
• Antacids (calcium, aluminum)
Mrs. Z taking Tums (ca carbonate) for osteoporosis - ca phosphate
(Posture) and ca citrate (Citracal) less constipating.
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IBS ? Rome III Criteria
• Symptoms at least 3 days/month of
recurrent abdominal pain or
discomfort associated with hard
constipated stools interrupted by brief
episodes of diarrhea …
Drossman Gastroenterology. 2006
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IBS Treatment
• Multiple RCTs with inconsistent results –
best evidence for treating IBS-C:
– Bulking agents
– Psychotropic agents
DARE review 2001
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Red flags
1.
2.
3.
4.
5.
Onset after age of 50
Hematochezia/melena
Unintentional weight loss
Anemia
Neurological defects
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Physical Exam
• Digital rectal examination
– Stool character
– Pain, anal tone
– Masses, fissures, hemorrhoids,
• Abdominal/gynecological exam
– Masses, pain
• Neurological exam
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Treatment – Behavioral
• Toileting program to take advantage of
natural reflexes
• Obey the urge
– Gastro-colic
– Defecation reflex
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Medications - Laxatives
•
•
•
•
•
•
Bulking agents
Stool softeners
Osmotic agents
Stimulants
Lubricants
Other
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Bulking Agents at the Grocery Store…
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•
•
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Vegetables
Fruits
Whole grain foods
Bran (hard outer layer of cereal grains)*
• Bloating and gas can be problematic
– Gradually increase intake to 25 grams/day
– Less fermentable fiber like wheat bran tends to be
better tolerated
* Limited evidence for effectiveness
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Food
Serving
Fiber (Gm)
All Bran® cereal
1/3 cup
10
Whole wheat bread
2 slices
4
Wheat bran muffin
medium
3
Brown rice
1cup
3
Apple/Pear
medium
4
Banana
medium
3
Dried figs
5
8
Prune juice
1 cup
3
Sunflower seeds
¼ cup
3
Baked potato w/skin
medium
4
Canned baked beans
½ cup
5
Chickpeas
½ cup
5
Lentils/ Kidney beans
½ cup
8
Corn
½ cup
2
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Bulking Agents at the Pharmacy…
• Moderate evidence
– Psyllium (Metamucil 2.5gms fiber/dose)
• Limited evidence
– Bran methycellulose (Citrucel 2gms fiber/dose)
– Polycarbophil (Fibercon)
Fiber needs to be accompanied by adequate
amounts of liquid to be useful - 8oz/2-3gms
of added fiber!
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Stool Softeners – Limited Evidence
• Contain docusate (Colace), an anionic
detergent with hydrophilic and hydrophobic
ends that improves the ability of water to mix
with and soften the stool
• Helpful to soften stools to make defecation
easier (post-op, childbirth)
• Helpful for hemorrhoids or anal fissures
• ↑ dose if no effect is seen after a week
– 40-400mg daily QD-QID
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Stimulants (Irritants)
• Irritate bowel, causing muscle
contractions
– often in combination with ducosate
– work in 8-12 hrs (try qhs, increase to BID)
• Senna/ducosate (Senokot-S, Ex-lax - max 4/d)
• Bisacodyl/ducosate (Dulcolax, Correctol- max
30mg/d)
• Casanthranol/ducosate (Peri-colace – max 2/d)
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Stimulant Suppositories …
• Contain bisacodyl/ducosate (Dulcolax)
• Glycerin suppositories also believed to
have their effect by irritating the rectum
• Insertion of the suppository into the
rectum may itself stimulate a bowel
movement
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Osmotic Laxatives
• Polyethylene glycol - PEG (good evidence)
– 17 grams daily
• Saccharines – lactulose (moderate evidence)
– flatulence, bloating, cramping
– 15 - 120 ml qhs
• Sorbitol (effective as lactulose in elderly men*)
– less bloating than lactulose
– 15 - 120 ml qhs
• Magnesium salts (MOM)
– avoid in renal insufficiency, best for acute treatment
* Lederle. ACP Journal Club, 1991.
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A Closer Look at Polyethylene Glycol - good
evidence for use
• PEG: Large, chemically inert polymer, with
substantial osmotic activity
– Bowel flora unable to metabolize
– Pulls water into colon to soften and increases
fecal bulk (takes 2-4 days to work)
– First used in a balanced electrolyte solution for
colon cleansing (Golytely)
– PEG 3350 (Miralax) or with electrolytes
(Movical)
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Lubricant Laxatives
• Contain mineral oil (15-45 ml/day)
• Short-term use only
– Binds fat-soluble vitamins
– May decrease absorption of some drugs
• Avoid lubricants in those at risk for
aspiration (lipid pneumonia)
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Lubiprostone (Amitiza)
• Selective Chloride channel activator
↑ secretion of Cl- ions into small bowel; Na+
and water follow, resulting in a softer,
bulkier stool
• 24 mcgs BID
• Nausea is common (32%)
• Avoid use in pregnancy, breast-feeding
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Methylnaltrexone (Relistor)
• Methyl group reduces lipidophilic properties
of the opioid antagonist naltrexone - ↓ ability
to cross blood-brain barrier
• Peripherally Acting Mu-Opioid Receptor (PAMOR) antagonist
• Indicated for palliative care
• For short-term use (< 4months)
• Side effects - abdominal pain and flatulence
Other, Non-FDA Approved Agents, Act to
Decrease Transit Time
• Misoprostol (Cytotec 100-200mcg QID)
– a prostaglandin increases colonic motility1
• Colchicine (0.6mg qd - tid)
– neurogenic stimulation ↑ colonic motility 2
1.Roarty. Alimen pharm & Therapeutics. 1997
2. Verne. Am J. Gastroenterology. 2003, Frame J ABFP, 1998
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A Practical Approach…
R/O treatable secondary causes..
Am Gastroenterological Assn (AGA) guidelines:
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•
CBC, Glucose, TSH, calcium, creatinine
Sigmoid/colonoscopy if red flags are present.
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Address Immediate Concerns
• Bloating/discomfort/straining
– Osmotic agent like PEG
• Post-op, childbirth, hemorrhoids, fissures
– Stool softener to make defecation easier
• Stimulants and suppositories acutely
• Manual disimpaction as needed
then approach the chronic condition….
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Start with Lifestyle Changes …
• Exercise, increase fluids and fiber to 25
grams/day over a period of 6 weeks.*
– Fiber must be accompanied by sufficient fluid
– Initial approach – fruits and vegetables
– Add commercial bulking agents
• Obey the ‘Urge’!
• For children trial of rice vs cow’s milk
* Uncontrolled studies support fiber for normal transient
constipation. Am J Gastroenterol. 1999; G Nutr 4/2010
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If No Improvement…
• Add osmotic laxative
– adjust dose slowly until stools are soft
– take several days to work
– caution if CHF or renal insufficiency
• Add stimulant laxatives
• Lubiprostone
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Trial of Other Agents…
• Misoprostol (Cytotec)
• Colchicine
Refractory to empiric approach .…
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Pursue Diagnostic Evaluation
• Colonoscopy if not indicated sooner ….
• Barium enema for obstruction/megacolon
• Radiopaque Sitz-Markers to measure transit time
– markers ingested, KUB in 5 days
– retention >20% markers indicates slow transit
– markers seen exclusively in distal colon/rectum
suggests pelvic floor dysfunction
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Referral to evaluate defecation….
• Balloon expulsion
• Defecography using a barium paste.
• Anorectal manometry with a rectal
catheter
• Biofeedback with artificial silicon stool
• Surgery rarely indicated
Enck. Dig Dis Sci. 1993
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Summary….
• Constipation - unsatisfactory defecation, with
infrequent stools, difficult stool passage or both
• Functional constipation (normal transit time and
sphincter function) seen most often
• Work-up is necessary in the presence of red flags
– onset >50 yrs; hematochezia/melena; unintentional weight
loss; anemia; neurological defects
• Best evidence for effectiveness is for osmotic agents
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Long-term Laxative Concerns…
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•
•
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No evidence for addiction
No evidence for tolerance
No evidence for dependence
No evidence for harm from stimulant use,
melanosis coli may develop, but it is a benign
condition
Muller-Lissner. Am J Gastroenterology. 2005
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The End!
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