Definition of Constipation

Constipation (from Latin constipare = to press together) is evacuating the bowel with difficulty, or less than three times a week. There is no need to have a bowel movement every day if someone does not feel the need for it.

Symptoms of Constipation

One or more of the following symptoms may be present in constipation:

  • straining or pain at passing the stool, feeling of incomplete bowel emptying;
  • hard and dry stool;
  • bloating – excessive gas in the gut;
  • coated tongue, bad taste, offensive breath, headache, fatigue, and loss of appetite and weight may follow.

Causes of Constipation

Constipation in adults is mostly a consequence of inappropriate food or stress. In infants it is almost always caused by congenital disorders. In children psychological factors are important. In old people inactivity is the main cause. Constipation may also be caused by a disease, medications or hospitalization.


Types of Constipation

Atonic constipation occurs due to loosen rectal muscles in old people, or as a consequence of irregular meals, less fibres in diet, postponing bowel evacuations, or prolonged use of laxatives, where nerves in an otherwise normal gut wall stop reacting on a food presence in the gut. Spastic constipation comes from irritation of intestines by foods, medicines, stress, like in irritable bowel syndrome (IBS), or in neurological disorders. Obstructive constipation is due to congenital rectal abnormalities, tumors, post-operative or post-inflammatory scars, or damaged pelvic nerves which prevent relaxation of external anal sphincter.

Gut Anatomy, Peristalsis and Digestion

The gut comprises of mouth, gullet (esophagus, 20-25cm), stomach (gaster), and bowel (intestine) (1). Small intestine (about 6m) parts are duodenum, jejunum and ileum, large intestine parts are cecum with appendix (few cm), colon (right-ascending, cross-transverse, left-descending and sigmoid; 130cm), and rectum (about 15cm). Last part of intestinal tube is anal canal (2.5-4cm) which ends with anal opening (anus). The time needed for food to pass the entire gut (gut transit time) varies widely among people and with different types of food (12-120 hours) (2).

The gut has its own nervous system. This means that no command from the brain or spine is needed for gut to work (it is needed for normal defecation though). When the food enters the gut, it distends its wall and excites the nerves within it; larger the food volume, more gut stimulation. Inner circular muscles’ segmental contractions cut the food and outer longitudinal muscles’ contractions propel it forward through the gut. This contraction pattern is called peristalsis. Peristalsis may be additionally stimulated via parasympathetic nerves (n. vagus coming from brain stem and sacral nerves coming from S2-4 segments of spinal cord) and depressed via sympathetic nerves (from thoracic segments). Psychological factors, exercise and some medications also influence the gut through these nerves. Pudendal nerve (from S2-4 segments) is responsible for sensibility of anal canal and voluntary contraction/relaxation of external anal sphincter (and muscles of pelvic floor), thus enabling fecal continence and act of defecation (3).

Digestion is mechanical and biochemical break down of ingested food into substances which can be absorbed into the blood.

In the mouth the food is chewed and proteins and lipids are partially digested. After conscious swallowing the food bolus enters into esophagus and from there a single peristaltic wave pushes it into the stomach.

In the stomach the food is grinded and some proteins are broken down by pepsin. Food may stay in the stomach for 4-5 hours; liquid go through first, acid, cold or hot food stays in the stomach longer. Carbohydrates leave the stomach first, then proteins follow, then fats.

In the small intestine, the major part of digestion takes place, and most nutrients, vitamins, minerals and some water are absorbed there. Fibres and other indigestible substances, bile components and remaining water enter the large intestine in the form of a dense liquid.

In the colon some additional water is absorbed. Slower the peristalsis, more water will be absorbed and harder, drier stool (also called feces) will be formed. Optimally, stool should be soft, sausage-shaped, and comfortable to pass. Bacteria, which are normally present in the colon, partially break down fibres and some gas (CO2, methane, ammonia) is formed as a result.

During, and up to 3-4 hours after the meal, continuous peristalsis is present in the gut. Between meals only occasional 5-10 minutes lasting peristaltic waves clear the stomach and small intestines. During sleep, for most people, peristalsis is pretty silent.

Entering of food bolus into a stomach triggers mass movements of the colon (gastro-colonic reflex) – this usually occurs 15-30 minutes (up to 1 hour) after the meal. These movements last for about 15 minutes and push the stool from previous meals from the left colon toward the rectum.

When the stool reaches the rectum, defecation reflex is triggered – internal anal sphincter relaxes, anal canal widens and external anal sphincter contracts. A person, with the help of sensory receptors in anal wall, can clearly distinguish among solid, liquid stool and gas. If a person decides to have a bowel movement, he/she can voluntary relax external anal sphincter and puborectal muscle, and contract chest and abdominal muscles to increase intra-abdominal pressure which helps to expel the stool out from the body. If no bowel evacuation is planned, contraction of external anal sphincter can be voluntary sustained and defecation reflex diminishes in 10-15 minutes. After this time stool may move back deeper in the colon and sometimes the next mass colon movement has to be awaited to fill the rectum. Stool can be voluntary expelled only from the rectum, not from deeper parts of the large intestine. Most of the time, the rectum is empty, and is filled only during mass colonic movements. Mass movements occur only 1-3 times a day, usually after the breakfast or after other big meal. Terms to describe the act of expelling stool: bowel movement, bowel evacuation, defecation, poo.

Food usually needs 1-3 days to pass the entire gut, and it spends the most of time in the colon. Test of bowel transit time: at certain time eat two big spoons of sweet corn with the meal, and then look for the peelings in the stool (probably won’t be in the first next stool).

Primary trigger of peristalsis is food. Other peristalsis stimulants: inappropriate food, bacterial toxins from spoiled food, psychological factors like fear, hormone thyroxine, salt, magnesium, poisons like insecticides, laxatives.

Peristalsis depressors: calcium (the role of dietary calcium in constipation is still debatable) and aluminium from food and medications, low blood potassium, magnesium, high calcium, increased sympathetic tonus (caused by anxiety, stress, caffeine, teine, taurine, drugs like cocaine), hormones adrenalin, progesterone and estrogen, medications like sedatives.

Milk, alcohol or soda may have either constipating or flushing effect on the bowel – it depends on a person.

Relieving Constipation

Acute constipation

Foods that Cause Constipation

In otherwise healthy person, constipation which starts suddenly, mostly results from:

  • skipped meal;
  • dry food: cookies, pastries, cereals without water…;
  • low-fibre food (heavy, sugarry/fatty foods): fast food, fried foods, red meat (beef, bacon, pork), potatoes (french-fry, chips, instant meshed potatoes -puree), cakes, nuts, sweets, chocolate….;
  • dairy (may cause diarrhea in some persons): milk, cheese, creams, ice-cream…;
  • alcohol, stress and travel may quickly constipate sensitive people.

Solution: If you feel you have a full rectum, take a time on toilet as necessary (up to 20 minutes) and try to expel stool with moderate straining. If no success, have a bulk vegetable meal with some hot soup or warmed mineral water with magnesium, or apricot juice – this may trigger mass colon movements. When you notice that rectum has been filled with the stool (within 30 minutes or so after the meal) try to evacuate the bowel. If not absolutely necessary, do not take any laxative. In the case of stress, do what you think is appropriate (take a rest, make necessary decision…).

When to Visit a Doctor?

In case of severe abdominal pain or distension, vomiting, rectal bleeding, raised temperature or general bad feeling, immediately visit a doctor, because of possible serious underlying process, like appendicitis. Constipation itself is not dangerous for health, but if despite appropriate food, symptoms of acute constipation persist for more than a week, an examination is recommended to find a cause.

Chronic Constipation

1. Foods that Relieve Constipation

Regular meals are the first condition for bowel regularity.

Dietary fibres retain water, thus keeping the stool bulky and soft. Only food containing certain amount of fibres will form enough stool to stimulate bowel evacuations.

Example of high fibre foods are vegetables and whole-grain bread (4). Low fibre foods are white bread, spaghetti, ice cream and other milk products, processed meat in fast food, etc. Foods with insoluble fibres in whole-grain breads, cabbage, and brown rice, fruits with edible seeds, lentils or wheat bran contain cellulose. Foods with soluble fibres in oat bran, apples, citruses, legumes contain pectin. The later diminish absorption of substances, responsible for creating cholesterol, and slow down absorption of glucose into the blood, so they are good for diabetics. The formula to choose the right high fibre food: the food should help toward regularity, should be tasteful, and shouldn’t cause excess gas.

With the fibres, enough fluid has to be drunk; otherwise they can literally stick in the bowel. Plain or mineral water seems to be appropriate; a good indicator of amount of fluid needed is thirst. Excessive fluid is absorbed before reaching the colon, and excreted by kidneys, so drinking a lot to heal constipation has no sense. Having a bottle of fluid on a reach of a hand through all of the day encourages drinking. For someone, who can’t, or may not drink a plenty of fluid, like heart patients, high-fibre diet is not appropriate. Children, who resist eating some rough fibre food, should not be forced with it. It may take few days to see the effect of fibres, and few weeks to achieve bowel regularity. Milk should be limited (but not totally removed from meals) at constipated children if it represents a main part of ingested fluid.

2. Activity

Lack of life activity and will to fight with problems may lead to tension, anxiety, frustration and depression. In all these states sympathetic activity is increased and peristalsis is depressed.

Activity may be physical work, thinking, care about others, sport, etc. Only activities which a person finds them meaningful may bring relief. The role of physical exercise in constipation is debatable. Vigorous sport strain may cause more stress then relief and may aggravate constipation.

During, and after the meal, the blood flow is redirected from skeletal muscles toward the gut to provide oxygen and nutrients needed for peristalsis. This means, the time after a major meal is a rest time and not a time for exercising.

3. Psychological Factors

Psychological disturbances are the most common cause of constipation in children. Having over-demanding parents or being neglected by them, worries about school, and bad self-estimation may all result in constipation – from increased sympathetic activity, or from deliberately holding back the stool as a way of protest. Anorexia nervosa and bulimia also come with constipation that may not necessary recover completely even after eating disorder is treated.

At children who were sexually abused, a paradoxical action of anal sphincter occurs: when rectum tries to push the stool out, anus closes. These types of constipation will hardly improve if causes or bad memories persist. Once a child becomes more independent in mind and can understand and accept what happened, he/she may be able to go beyond it. An experienced and caring advisor may be of great help.

Stress, like preparing for an exam, changing a job, death in the family, often cause transient constipation, but regular life and eating should continue, if possible. Depression slows down peristalsis, so regular activity is a must. Right life decisions bring results and hence hope. For an anxious person it may be of great help – maybe not so much to have a caring friend, but – to take care for a friend(s).

IBS

IBS (irritable bowel syndrome, spastic colon) is an increased sensitivity of the gut, usually colon, which reacts with strong, disorganized contractions on certain food or stress. Diarrhea, constipation or cramps may appear; usually one symptom predominates, varies in time and usually improves with age. Symptoms are relieved with each bowel movement. IBS is mostly the problem of young adults or teens. There are no structural changes found in the bowel, so it is obviously a psychosomatic disorder. Treatment is mostly based on changing of life style or attitudes. Appropriate food has to be found personally, and small portions may prevent abdominal cramps. Note: on March 30, 2007 Zelnorm, previously used in treatment of IBS and constipation, was discontinued in the US and Canada because of excess number of serious cardiovascular adverse events, including angina, heart attacks, and stroke.

Anismus

Anismus (dyschezia) is a term used for an inability to relax external anal sphincter after pelvic floor muscles relaxation. This might be provoked by “laboratory environment” where investigation is made, so it is uncertain if this is the real cause of constipation (5). In adults, biofeedback training may bring some transient relief, but the main causes still seem to be psychological.

4. Bowel Evacuation Habit

Children often neglect urge to bowel movement, because they don’t want to leave the game, or are embarrassed to use toilet outside of home. People often don’t take time to have bowel movements in the morning and then delay with it through the day. This way colon muscles slowly become resistant on urge to defecate, and they lost their tone. Learning to have bowel movements at certain hour every day, e.g. after the breakfast and at home may help to re-establish the regular peristalsis rhythm. Children may be awarded for regular visiting of toilet, not for success achieved though. This type of toilet training should be avoided at 2-3 years old children because it may have just the opposite effect.

Natural squatting position at defecating provides the largest abdominal pressure and optimal angle between rectum and anus to push out the stool. Instead of squat WC someone can use a 20-30 cm high footstool when sitting on usual “English” WC. Stepping on toes doesn’t help; feet must be in horizontal position.

5. Pregnancy and Constipation

In pregnant woman, hormone progesterone relaxes bowel muscles, thus slowing down peristalsis. Pressing of growing uterus on the rectum and worries may contribute to constipation. Iron supplements may irritate bowel if taken by mouth; doctor should say if the dose may be lowered, replaced with other one, or intravenous iron applied – the later should not cause constipation and bowel irritation. After delivery, tiredness, rest, perianal tears, anaesthetic are main causes of constipation. Enough sleep, avoiding unnecessary stress, high dietary fibres, and enough fluid and staying active is recommended. If this doesn’t help a bulk forming laxative containing Ispaghula husk or stool softeners may be tried. Mineral oil disturbs absorption of some vitamins and Castor oil may cause premature uterine contractions, so they should be avoided (6).

Contraceptive pills containing progesterone may cause terrible constipation. Constipation may also be a part of premenstrual syndrome.

6. Constipation in Old People

Low activity, inefficient chewing, low fibre diet, dehydration, loosen rectal wall and depression cause constipation in aged. Active healthy old people are usually not constipated. If feces are hard, fluid intake should be increased. Besides fibres, old people should get enough calcium, other minerals, and vitamins (7).

7. Diseases and Constipation

Any heavy injury, dehydration, pain, chronic or acute disease, even cold or flu may lead to constipation, which may be aggravated by associated medications and bed rest. Dietary fibres, plenty of liquid, getting out from the bed every now and then, regular use of toilet and avoiding analgesics help.

Infant Constipation

In breast-fed infant, constipation is most often caused by congenital disorders like cystic fibrosis or Hirschsprung’s disease. First bowel movement is called meconium, it usually occurs in first 48 hours after birth, and consists of bile, water and dead intestinal cells; it should be soft and yellow-greenish. Meconium ileus means obstruction of ileum by hardened meconium. It is mostly seen in cystic fibrosis as absent first bowel movement, vomiting and belly distension. It can be diagnosed with x-ray contrast investigation and is usually successfully treated with enema. At Hirschsprung’s disease nerve cells are missing along the various length of the end part of the colon, so peristalsis is slowed or stops entirely. Accumulated stool may then lead to colon distension (megacolon) in the front part of the defect. Treatment is surgical removal of affected part of the colon. Sometimes first symptoms show up only later in life. Other rare causes of constipation in infants: diabetes insipidus, hypothyroidism, congenital anatomical defects of rectum and anus.

Some infants may strain and scream for up to 20 minutes before passing fairly normal stools. Problem is in uncoordinated defecating muscles and usually resolves in a few weeks (8).

Constipation in Children

In 1-18 years old children, constipation is mostly related to psychological factors, diabetes mellitus, gluten enteropathy (Celiac disease), spinal cord trauma or abnormalities etc. High fibre food should be introduced wisely without forcing. In more severe cases bulk-forming or osmotic laxatives should be tried and then withdrawn in few months after regular peristalsis is established. When rectum is chronically obstructed with feces, it may enlarge to form a megarectum. Children with a megarectum may not feel the stool, which may lead to soiling when a lot of stool accumulates. A stimulating/softening laxative, like docusate sodium may be tried. Enemas and suppositories should be avoided, since many children find them unpleasant or understand them as a punishment.

Crohn’s disease and ulcerative colitis are chronic inflammatory diseases, most often diagnosed between age of 10-40. Colonic and rectal ulcers may appear, bloody diarrhea and tiredness are common symptoms, and occasionally constipation is a problem. Treatment is with antiinflammatory drugs and high fibre diet, sometimes surgery is needed. There were many studies performed indicating strong relationship to psychological disorders in both diseases (9).

Diverticula are pouches which bulge out from large intestinal wall; they are usually a consequence of repeated and prolonged straining. They are mostly found in old people during gut investigation, and usually don’t cause problems. If they cause constipation, high fibre diet should be tried first. Infection with lower left abdominal pain and fever is treated with antibiotics. If repeated infections leave scars which block the passage of the stool, surgical removal of affected part of the colon is needed.

Painful anorectal processes, like hemorrhoids or anal fissura (tear) discourage bowel evacuation. Foreign bodies may be swallowed, like tooth pickers, or parts of medical instruments lost in the bowel and stub in rectal mucosa.

Colon polyps and cancer rarely cause constipation, and chronic constipation does not represent a risk for developing a colon cancer. Rare adenomatous familiar polyposis may be present with changed stool passage though.

To terminally ill patients who experience constipation as difficulty, a prophylactic stimulant laxative and a stool softener should be prescribed besides opioids, and fluid intake increased if possible. Fentanyl or methadone may also be tried as alternative to morphine.

Other abdominal causes of constipation: peptic ulcer, gastritis, appendicitis, biliary orrenal colic, liver cirrhosis, hepatitis, salpingitis, endometriosis, abdominal or groin hernia. Atherosclerosis of intestinal arteries diminishes blood supply to large intestine, big abdominal tumors press on the large intestine from outside.

Diseases in lower chest like myocardial infarction, pneumonia, pleuritis may cause spasm of the transverse colon.

In diabetics the main cause of constipation are atherosclerotic arteries and damaged nerves which supply the gut. Gastrocolic reflex may be diminished or absent. Stool softeners in combination with stimulants (neostigmine, metoclopramide) are helpful (10). Fibres (soluble) are appropriate for those without nerve damage (11).

Neurological patients with brain or spinal cord injury, stroke, multiple sclerosis, cerebral palsy, hypotonia, peripheral neuropathy or Parkinson’s disease are often constipated (or incontinent). Intrinsic nervous system of the gut remains intact in all mentioned diseases. Problems are mostly related to defecation: recognizing the full rectum and relaxing or contracting external anal sphincter. In case of spastic sphincter, digital stimulation of anal canal may help to relax it. Main non-neurological causes are inactivity and drugs, such as anti-cholinergic drugs in Parkinson’s disease. Treatment of constipation should start early. General rules about diet and activity should be strictly considered and treatment adjusted on a personal basis. Rehabilitation programs led by physiatrists or specialized physicians and local support groups are right places to find help. There is also much online information for neurological patients available (12).

Hormonal diseases presented with constipation are rare and include under-active thyroid gland (hypothyroidism) with low thyroxine, hypophysis dysfunction (hypopituitarism) with multiple hormone dysfunction, and adrenal tumor pheochromocytoma with excessive adrenalin secretion.

Other causes: pernicious anemia, porphyria, uremia, lupus, scleroderma, vitamin B deficiency. Lead poisoning causes constipation and abdominal cramps.

Chagas disease, found mostly in both Americas, may lead to large intestine distension – megacolon (13). Parasite T. cruzi, transmitted by some bugs, destroys a part of nervous plexus in large intestinal wall causing its distension and thus slowing stool transit. Treatment is with anti-parasite drug benznidazole and eventual surgery. Megacolon may also develop as a complication of ulcerative or pseudomembranous colitis.

8. Constipation Caused by Medicines

Medicines which may constipate: antidepressants (like Paxil), sedatives (like Valium), opiates (like. morphine), antacids which contain calcium (like. Tums) or aluminium (like Dialume), diuretics (like Lasix), antiparkinsons (like Bromocriptine), anticonvulsants (like Diazepam), antispasmics (like atropine), some blood pressure medications (like Verapamil, diltiazem), anti-diarrhea drugs (like Loperamide or bizmuth), cough suppressants. Long term use of laxatives may diminish the tone of intestinal wall (hypotonic laxative colon – lazy colon).

Iron supplements taken by mouth are not well tolerated by some people and constipation was reported by some patients but recent studies have not confirmed this. Injections of iron may be tried instead of tablets.

Surgery with stress, anesthesia, prolonged bed-rest, changed food, hospital environment and pain cause constipation in majority of operated patients. Postoperative scars and adhesions inside or outside the intestine may represent an obstacle for stool passage. Barium retention during GI studies, irradiation of lower abdomen may cause transient constipation.
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References:

1. http://www.bowelcontrol.org.uk/constipation.html GUT ANATOMY – IMAGES
2. http://springerlink.com/content/l2814u5381xl1231/ GUT TRANSIT TIME
3. http://jnnp.bmj.com/cgi/content/full/74/1/13 GUT INNERVATION, NEURO DISEASE
4. http://gicare.com/pated/edtgs01.htm ABOUT FIBRES
5. http://gut.bmj.com/cgi/content/abstract/41/2/258 ANISMUS
6. http://americanpregnancy.org/pregnancyhealth/constipation.html CONSTIPATION IN PREGNANCY
7. http://eatwell.gov.uk/agesandstages/olderpeople/ DIET IN AGED
8. http://www2.kumc.edu/kupedigi/PDF/Dyschezia.pdf INFANT DYSCHEZIA
9. http://psychosomaticmedicine.org/cgi/content/abstract/66/1/79 IBD
10. http://ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=6670291&dopt=Abstract LAXATIVES IN DIABETES
11. http://diabetes.ca/section_about/fibre.asp FIBRES IN DIABETES
12. http://makoa.org/sci.htm ONLINE SUPPORT FOR NEUROLOGICAL PATIENTS
13. http://emedicine.com/med/topic327.htm CHAGAS DISEASE

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