Constipation
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Constipation is defined as having a bowel movement fewer than
three times per week. With constipation stools are usually hard,
dry, small in size, and difficult to eliminate. Some people who are
constipated find it painful to have a bowel movement and often
experience straining, bloating, and the sensation of a full
bowel.
Some people think they are constipated if they do not have a
bowel movement every day. However, normal stool elimination may be
three times a day or three times a week, depending on the person.
Constipation is a symptom, not a disease. Almost everyone
experiences constipation at some point in their life, and a poor
diet typically is the cause. Most constipation is temporary and not
serious. Understanding its causes, prevention, and treatment will
help most people find relief.
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Who gets constipated?
Constipation is one of the most common gastrointestinal
complaints in the United States. More than 4 million Americans have
frequent constipation, accounting for 2.5 million physician visits a
year. Those reporting constipation most often are women and adults
ages 65 and older. Pregnant women may have constipation, and it is a
common problem following childbirth or surgery.
Self-treatment of constipation with over–the–counter (OTC)
laxatives is by far the most common aid. Around $725 million is
spent on laxative products each year in America.
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What causes constipation?
To understand constipation, it helps to know how the colon, or
large intestine, works. As food moves through the colon, the colon
absorbs water from the food while it forms waste products, or stool.
Muscle contractions in the colon then push the stool toward the
rectum. By the time stool reaches the rectum it is solid, because
most of the water has been absorbed.
Constipation occurs when the colon absorbs too much water or if
the colon's muscle contractions are slow or sluggish, causing the
stool to move through the colon too slowly. As a result, stools can
become hard and dry. Common causes of constipation are
- not enough fiber in the diet
- lack of physical activity (especially in the elderly)
- medications
- milk
- irritable bowel syndrome
- changes in life or routine such as pregnancy, aging, and
travel
- abuse of laxatives
- ignoring the urge to have a bowel movement
- dehydration
- specific diseases or conditions, such as stroke (most common)
- problems with the colon and rectum
- problems with intestinal function (chronic idiopathic
constipation)
Not Enough Fiber in the Diet
People who eat a high-fiber diet are less likely to become
constipated. The most common causes of constipation are a diet low
in fiber or a diet high in fats, such as cheese, eggs, and
meats.
Fiber—both soluble and insoluble—is the part of fruits,
vegetables, and grains that the body cannot digest. Soluble fiber
dissolves easily in water and takes on a soft, gel-like texture in
the intestines. Insoluble fiber passes through the intestines almost
unchanged. The bulk and soft texture of fiber help prevent hard, dry
stools that are difficult to pass.
Americans eat an average of 5 to 14 grams of fiber daily,* which is short of the 20 to 35 grams recommended by the American
Dietetic Association. Both children and adults often eat too many
refined and processed foods from which the natural fiber has been
removed.
A low-fiber diet also plays a key role in constipation among
older adults, who may lose interest in eating and choose foods that
are quick to make or buy, such as fast foods, or prepared foods,
both of which are usually low in fiber. Also, difficulties with
chewing or swallowing may cause older people to eat soft foods that
are processed and low in fiber.
*National
Center for Health Statistics. Dietary Intake of Macronutrients,
Micronutrients, and Other Dietary Constituents: United States,
1988–94. Vital and Health Statistics, Series 11, Number 245. July
2002.
Not Enough Liquids
Research shows that although increased fluid intake does not
necessarily help relieve constipation, many people report some
relief from their constipation if they drink fluids such as water
and juice and avoid dehydration. Liquids add fluid to the colon and
bulk to stools, making bowel movements softer and easier to pass.
People who have problems with constipation should try to drink
liquids every day. However, liquids that contain caffeine, such as
coffee and cola drinks, will worsen one’s symptoms by causing
dehydration. Alcohol is another beverage that causes dehydration. It
is important to drink fluids that hydrate the body, especially when
consuming caffeine containing drinks or alcoholic beverages.
Lack of Physical Activity
A lack of physical activity can lead to constipation, although
doctors do not know precisely why. For example, constipation often
occurs after an accident or during an illness when one must stay in
bed and cannot exercise. Lack of physical activity is thought to be
one of the reasons constipation is common in older people.
Medications
Some medications can cause constipation, including
- pain medications (especially narcotics)
- antacids that contain aluminum and calcium
- blood pressure medications (calcium channel blockers)
- antiparkinson drugs
- antispasmodics
- antidepressants
- iron supplements
- diuretics
- anticonvulsants
Changes in Life or Routine
During pregnancy, women may be constipated because of hormonal
changes or because the uterus compresses the intestine. Aging may
also affect bowel regularity, because a slower metabolism results in
less intestinal activity and muscle tone. In addition, people often
become constipated when traveling, because their normal diet and
daily routine are disrupted.
Abuse of Laxatives
The common belief that people must have a daily bowel movement
has led to self-medicating with OTC laxative products. Although
people may feel relief when they use laxatives, typically they must
increase the dose over time because the body grows reliant on
laxatives in order to have a bowel movement. As a result, laxatives
may become habit-forming.
Ignoring the Urge to Have a Bowel Movement
People who ignore the urge to have a bowel movement may
eventually stop feeling the need to have one, which can lead to
constipation. Some people delay having a bowel movement because they
do not want to use toilets outside the home. Others ignore the urge
because of emotional stress or because they are too busy. Children
may postpone having a bowel movement because of stressful toilet
training or because they do not want to interrupt their play.
Specific Diseases
Diseases that cause constipation include neurological disorders,
metabolic and endocrine disorders, and systemic conditions that
affect organ systems. These disorders can slow the movement of stool
through the colon, rectum, or anus.
Conditions that can cause constipation are found below.
- Neurological disorders
- multiple sclerosis
- Parkinson's disease
- chronic idiopathic intestinal
pseudo-obstruction
- stroke
- spinal cord injuries
- Metabolic and endocrine conditions
- diabetes
- uremia
- hypercalcemia
- poor glycemic control
- hypothyroidism
- Systemic disorders
- amyloidosis
- lupus
- scleroderma
Problems with the Colon and Rectum
Intestinal obstruction, scar tissue (adhesions), diverticulosis,
tumors, colorectal stricture, Hirschsprung's disease, or cancer can
compress, squeeze, or narrow the intestine and rectum and cause
constipation.
Problems with Intestinal Function
The two types of constipation are idiopathic constipation and
functional constipation. Irritable bowel syndrome (IBS) with
predominant symptoms of constipation is categorized separately.
Idiopathic (of unknown origin) constipation does not respond to
standard treatment. Idiopathic constipation may be related to
problems with intestinal function, including hormonal control,
nerve, and muscle problems in the colon, rectum, or anus.
Functional constipation means that the bowel is healthy but not
working properly. It is not caused by organic (occurring naturally
in the body) disease. Functional constipation is often the result of
poor dietary habits and lifestyle. It occurs in both children and
adults and is most common in women. Colonic inertia, delayed
transit, and pelvic floor dysfunction are three types of functional
constipation. Colonic inertia and delayed transit are caused by a
decrease in muscle activity in the colon. These syndromes may affect
the entire colon or may be confined to the lower, or sigmoid, colon.
Pelvic floor dysfunction is caused by a weakness of the muscles
in the pelvis surrounding the anus and rectum. However, because this
group of muscles is voluntarily controlled to some extent,
biofeedback training is somewhat successful in retraining the
muscles to function normally and improving the ability to have a
bowel movement.
Functional constipation that stems from problems in the structure
of the anus and rectum is known as anorectal dysfunction, or
anismus. These abnormalities result in an inability to relax the
rectal and anal muscles that allow stool to exit.
People with IBS having predominantly constipation also have pain
and bloating as part of their symptoms.
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How is the cause of constipation identified?
The tests the doctor performs depend on the duration and severity
of the constipation, the person's age, and whether blood in stools,
recent changes in bowel habits, or weight loss have occurred. Most
people with constipation do not need extensive testing and can be
treated with changes in diet and exercise. For example, in young
people with mild symptoms, a medical history and physical exam may
be all that is needed for diagnosis and treatment.
Medical History
The doctor may ask a patient to describe his or her constipation,
including duration of symptoms, frequency of bowel movements,
consistency of stools, presence of blood in the stool, and toilet
habits (how often and where one has bowel movements). A record of
eating habits, medication, and level of physical activity will also
help the doctor determine the cause of constipation.
The clinical definition of constipation is having any two of the
following symptoms for at least 12 weeks (not necessarily
consecutive) in the previous 12 months:
- straining during bowel movements
- lumpy or hard stool
- sensation of incomplete evacuation
- sensation of anorectal blockage/obstruction
- fewer than three bowel movements per week
Physical Examination
A physical exam may include a rectal exam with a gloved,
lubricated finger to evaluate the tone of the muscle that closes off
the anus (anal sphincter) and to detect tenderness, obstruction, or
blood. In some cases, blood and thyroid tests may be necessary to
look for thyroid disease and serum calcium or to rule out
inflammatory, metabolic, and other disorders.
Extensive testing usually is reserved for people with severe
symptoms, for those with sudden changes in the number and
consistency of bowel movements or blood in the stool, and older
adults. Additional tests that may be used to evaluate constipation
include
- a colorectal transit study
- anorectal function tests
- a defecography
Because of an increased risk of colorectal cancer in older
adults, the doctor may use tests to rule out a diagnosis of cancer,
including a
- barium enema x ray
- sigmoidoscopy or colonoscopy
Colorectal transit study. This test shows how well food
moves through the colon. The patient swallows capsules containing
small markers that are visible on an x ray. The movement of the
markers through the colon is monitored by abdominal x rays taken
several times 3 to 7 days after the capsule is swallowed. The
patient eats a high-fiber diet during the course of this test.
Anorectal function tests. These tests diagnose
constipation caused by abnormal functioning of the anus or rectum
(anorectal function).
- Anorectal manometry evaluates anal sphincter
muscle function. For this test, a catheter or air-filled balloon
is inserted into the anus and slowly pulled back through the
sphincter muscle to measure muscle tone and contractions.
- Balloon expulsion tests consist of filling a
balloon with varying amounts of water after it has been rectally
inserted. Then the patient is asked to expel the balloon. The
inability to expel a balloon filled with less than 150 mL of water
may indicate a decrease in bowel function.
Defecography is an x ray of the anorectal area
that evaluates completeness of stool elimination, identifies
anorectal abnormalities, and evaluates rectal muscle contractions
and relaxation. During the exam, the doctor fills the rectum with a
soft paste that is the same consistency as stool. The patient sits
on a toilet positioned inside an x-ray machine, then relaxes and
squeezes the anus to expel the paste. The doctor studies the x rays
for anorectal problems that occurred as the paste was expelled.
Barium enema x ray. This exam involves viewing
the rectum, colon, and lower part of the small intestine to locate
problems. This part of the digestive tract is known as the bowel.
This test may show intestinal obstruction and Hirschsprung's
disease, which is a lack of nerves within the colon.
The night before the test, bowel cleansing, also called bowel
prep, is necessary to clear the lower digestive tract. The patient
drinks a special liquid to flush out the bowel. A clean bowel is
important, because even a small amount of stool in the colon can
hide details and result in an incomplete exam.
Because the colon does not show up well on x rays, the doctor
fills it with barium, a chalky liquid that makes the area visible.
Once the mixture coats the inside of the colon and rectum, x rays
are taken that show their shape and condition. The patient may feel
some abdominal cramping when the barium fills the colon but usually
feels little discomfort after the procedure. Stools may be white in
color for a few days after the exam.
Sigmoidoscopy or colonoscopy. An examination of
the rectum and lower, or sigmoid, colon is called a sigmoidoscopy.
An examination of the rectum and entire colon is called a
colonoscopy.
The person usually has a liquid dinner the night before a
colonoscopy or sigmoidoscopy and takes an enema early the next
morning. An enema an hour before the test may also be necessary.
To perform a sigmoidoscopy, the doctor uses a long, flexible tube
with a light on the end, called a sigmoidoscope, to view the rectum
and lower colon. The patient is lightly sedated before the exam.
First, the doctor examines the rectum with a gloved, lubricated
finger. Then, the sigmoidoscope is inserted through the anus into
the rectum and lower colon. The procedure may cause abdominal
pressure and a mild sensation of wanting to move the bowels. The
doctor may fill the colon with air to get a better view. The air can
cause mild cramping.
To perform a colonoscopy, the doctor uses a flexible tube with a
light on the end, called a colonoscope, to view the entire colon.
This tube is longer than a sigmoidoscope. During the exam, the
patient lies on his or her side, and the doctor inserts the tube
through the anus and rectum into the colon. If an abnormality is
seen, the doctor can use the colonoscope to remove a small piece of
tissue for examination (biopsy). The patient may feel gassy and
bloated after the procedure.
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How is constipation treated?
Although treatment depends on the cause, severity, and duration
of the constipation, in most cases dietary and lifestyle changes
will help relieve symptoms and help prevent them from recurring.
Diet
A diet with enough fiber (20 to 35 grams each day) helps the body
form soft, bulky stool. A doctor or dietitian can help plan an
appropriate diet. High-fiber foods include beans, whole grains and
bran cereals, fresh fruits, and vegetables such as asparagus,
Brussels sprouts, cabbage, and carrots. For people prone to
constipation, limiting foods that have little or no fiber, such as
ice cream, cheese, meat, and processed foods, is also important.
Lifestyle Changes
Other changes that may help treat and prevent constipation
include drinking enough water and other liquids, such as fruit and
vegetable juices and clear soups, so as not to become dehydrated,
engaging in daily exercise, and reserving enough time to have a
bowel movement. In addition, the urge to have a bowel movement
should not be ignored.
Laxatives
Most people who are mildly constipated do not need laxatives.
However, for those who have made diet and lifestyle changes and are
still constipated, a doctor may recommend laxatives or enemas for a
limited time. These treatments can help retrain a chronically
sluggish bowel. For children, short-term treatment with laxatives,
along with retraining to establish regular bowel habits, helps
prevent constipation.
A doctor should determine when a patient needs a laxative and
which form is best. Laxatives taken by mouth are available in
liquid, tablet, gum powder, and granule forms. They work in various
ways:
- Bulk-forming laxatives generally are
considered the safest, but they can interfere with absorption of
some medicines. These laxatives, also known as fiber supplements,
are taken with water. They absorb water in the intestine and make
the stool softer. Brand names include Metamucil, Fiberall,
Citrucel, Konsyl, and Serutan. These agents must be taken with
water or they can cause obstruction. Many people also report no
relief after taking bulking agents and suffer from a worsening in
bloating and abdominal pain.
- Stimulants cause rhythmic muscle contractions
in the intestines. Brand names include Correctol, Dulcolax, Purge,
and Senokot. Studies suggest that phenolphthalein, an ingredient
in some stimulant laxatives, might increase a person's risk for
cancer. The Food and Drug Administration has proposed a ban on all
over-the-counter products containing phenolphthalein. Most
laxative makers have replaced, or plan to replace, phenolphthalein
with a safer ingredient.
- Osmotics cause fluids to flow in a special
way through the colon, resulting in bowel distention. This class
of drugs is useful for people with idiopathic constipation. Brand
names include Cephulac, Sorbitol, and Miralax. People with
diabetes should be monitored for electrolyte imbalances.
- Stool softeners moisten the stool and prevent
dehydration. These laxatives are often recommended after
childbirth or surgery. Brand names include Colace and Surfak.
These products are suggested for people who should avoid straining
in order to pass a bowel movement. The prolonged use of this class
of drugs may result in an electrolyte imbalance.
- Lubricants grease the stool, enabling it to
move through the intestine more easily. Mineral oil is the most
common example. Brand names include Fleet and Zymenol. Lubricants
typically stimulate a bowel movement within 8 hours.
- Saline laxatives act like a sponge to draw
water into the colon for easier passage of stool. Brand names
include Milk of Magnesia and Haley's M-O. Saline laxatives are
used to treat acute constipation if there is no indication of
bowel obstruction. Electrolyte imbalances have been reported with
extended use, especially in small children and people with renal
deficiency.
- Chloride channel activators increase
intestinal fluid and motility to help stool pass, thereby reducing
the symptoms of constipation. One such agent is Amitiza, which has
been shown to be safely used for up to 6 to 12 months. Thereafter
a doctor should assess the need for continued use.
- Serotonin agonists help the muscles in your
intestines work correctly when a slow-moving digestive system is
caused by low levels of serotonin. Serotonin is a neurotransmitter
found mostly in the digestive tract. One brand-name agent is
Zelnorm, which is prescribed for the short-term treatment of
chronic constipation in people less than 65 years of age.
People who are dependent on laxatives need to slowly stop using
them. A doctor can assist in this process. For most people, stopping
laxatives restores the colon's natural ability to contract.
Other Treatments
Treatment for constipation may be directed at a specific cause.
For example, the doctor may recommend discontinuing medication or
performing surgery to correct an anorectal problem such as rectal
prolapse, a condition in which the lower portion of the colon turns
inside out.
People with chronic constipation caused by anorectal dysfunction
can use biofeedback to retrain the muscles that control bowel
movements. Biofeedback involves using a sensor to monitor muscle
activity, which is displayed on a computer screen, allowing for an
accurate assessment of body functions. A health care professional
uses this information to help the patient learn how to retrain these
muscles.
Surgical removal of the colon may be an option for people with
severe symptoms caused by colonic inertia. However, the benefits of
this surgery must be weighed against possible complications, which
include abdominal pain and diarrhea.
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Can constipation be serious?
Sometimes constipation can lead to complications. These
complications include hemorrhoids, caused by straining to have a
bowel movement, or anal fissures (tears in the skin around the anus)
caused when hard stool stretches the sphincter muscle. As a result,
rectal bleeding may occur, appearing as bright red streaks on the
surface of the stool. Treatment for hemorrhoids may include warm tub
baths, ice packs, and application of a special cream to the affected
area. Treatment for anal fissures may include stretching the
sphincter muscle or surgically removing the tissue or skin in the
affected area.
Sometimes straining causes a small amount of intestinal lining to
push out from the anal opening. This condition, known as rectal
prolapse, may lead to secretion of mucus from the anus. Usually
eliminating the cause of the prolapse, such as straining or
coughing, is the only treatment necessary. Severe or chronic
prolapse requires surgery to strengthen and tighten the anal
sphincter muscle or to repair the prolapsed lining.
Constipation may also cause hard stool to pack the intestine and
rectum so tightly that the normal pushing action of the colon is not
enough to expel the stool. This condition, called fecal impaction,
occurs most often in children and older adults. An impaction can be
softened with mineral oil taken by mouth and by an enema. After
softening the impaction, the doctor may break up and remove part of
the hardened stool by inserting one or two fingers into the
anus.
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Hope Through Research
The National Institute of Diabetes and Digestive and Kidney
Diseases Division of Digestive Diseases and Nutrition supports basic
and clinical research into gastrointestinal conditions, including
constipation. Researchers are studying the anatomical and
physiological characteristics of rectoanal motility and the use of
new medications and behavioral techniques, such as biofeedback, to
treat constipation.
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Points to Remember
- Constipation affects almost everyone at one time or
another.
- Many people think they are constipated when, in fact, their
bowel movements are regular.
- The most common causes of constipation are poor diet and lack
of exercise.
- Other causes of constipation include medications, irritable
bowel syndrome, abuse of laxatives, and specific diseases.
- A medical history and physical exam may be the only diagnostic
tests needed before the doctor suggests treatment.
- In most cases, following these simple tips will help relieve
symptoms and prevent recurrence of constipation:
- Eat a well-balanced, high-fiber diet that
includes beans, bran, whole grains, fresh fruits, and
vegetables.
- Drink plenty of liquids.
- Exercise regularly.
- Set aside time after breakfast or dinner for
undisturbed visits to the toilet.
- Do not ignore the urge to have a bowel movement.
- Understand that normal bowel habits vary.
- Whenever a significant or prolonged change in
bowel habits occurs, check with a doctor.
- Most people with mild constipation do not need laxatives.
However, a doctor may recommend laxatives for a limited time for
people with chronic constipation.
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For More Information
International Foundation for Functional Gastrointestinal
Disorders
P.O. Box 170864
Milwaukee, WI 53217
Phone:
1–888–964–2001 or 414–964–1799
Fax: 414–964–7176
Email: iffgd@iffgd.org
Internet: http://www.iffgd.org/
American Gastroenterological Association
National
Office
4930 Del Ray Avenue
Bethesda, MD 20814
Phone:
301–654–2055
Fax: 301–654–5920
Email: info@gastro.org or webmaster@gastro.org
Internet: http://www.gastro.org/
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The U.S. Government does not endorse or favor any specific
commercial product or company. Trade, proprietary, or company names
appearing in this document are used only because they are considered
necessary in the context of the information provided. If a product
is not mentioned, the omission does not mean or imply that the
product is unsatisfactory.
National Digestive Diseases Information Clearinghouse
2 Information Way
Bethesda, MD 20892–3570
Email: http://digestive.niddk.nih.gov/about/contact.htm
The National Digestive Diseases Information Clearinghouse (NDDIC)
is a service of the National Institute of Diabetes and Digestive and
Kidney Diseases (NIDDK). The NIDDK is part of the National
Institutes of Health of the U.S. Department of Health and Human
Services. Established in 1980, the Clearinghouse provides
information about digestive diseases to people with digestive
disorders and to their families, health care professionals, and the
public. The NDDIC answers inquiries, develops and distributes
publications, and works closely with professional and patient
organizations and Government agencies to coordinate resources about
digestive diseases.
Publications produced by the Clearinghouse are carefully reviewed
by both NIDDK scientists and outside experts. This publication was
originally reviewed by Michael Camilleri, M.D., Mayo Clinic
Rochester.
This publication is not copyrighted. The Clearinghouse encourages
users of this publication to duplicate and distribute as many copies
as desired.
NIH Publication No. 06–2754
February 2006
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