Constipation

Constipation is medically defined as passing infrequent bowel motions (stools), fewer than three per week. However, people may also experience the passage of hard or dry stools as constipation.

Occasional constipation is extremely common and may follow a change in routine (such as travel), a change in diet, a brief illness such as a respiratory infection, or medications such as antibiotics or analgesics. Chronic constipation, present for more than a few weeks, is rarely due to a life-threatening condition. However, if it does not respond to simple measures, see your doctor.

How the bowel works#

Food nutrients are absorbed in the small intestine. Waste is moved along the length of the large intestine by waves of muscular contractions (peristalsis). Once excess water is removed, the waste is temporarily stored in the rectum. The anus is a muscular ring (sphincter) that can be opened at will to allow the removal of feces.

Water makes up about three-quarters of fecal content, while the rest is made up of solids, including undigested fiber and intestinal bacteria.

Symptoms of constipation#

Symptoms of constipation include:

• needing to open the bowels less often than usual
• hard, dry stools that may be painful to pass
• straining to pass the motion
• having to sit on the toilet for much longer than usual
• the sensation afterwards that the bowel has not fully emptied
• a bloated abdomen
• abdominal cramps

In some cases, constipation is caused by more serious illnesses and events, including tumors and systemic diseases.

Lifestyle-related causes of constipation#

Constipation can be caused by many lifestyle factors that often work in combination, including:

• A change in routine – normal bowel motions depend on the regular, rhythmic contraction of the bowels. This is part of the body’s internal ‘clock’ and is often upset by changes in routine. This type of constipation is often seen in shift workers and travelers.
• A low-fiber diet – fiber is indigestible, so it adds bulk to the feces, making it easier to push along the digestive tract. There are two broad types of fiber: soluble and insoluble. Soluble fiber helps to soften the feces, and good sources include legumes. Insoluble fiber adds bulk to the feces, helping it move more quickly through the bowel; good sources include wheat bran and wholegrain breads and cereals.
• Insufficient water – the fiber in feces only plumps up with water, so constipation can occur from a high-fiber diet if not enough water is consumed.
• Lack of regular exercise – a sedentary lifestyle, or being restricted in movement due to a disability, is a common cause of constipation.
• A tendency to ‘put off’ going to the toilet – ignoring the urge to go means more water is extracted from the stools, making them difficult to pass. Regularly ignoring this urge may make the body less sensitive to normal signals.
• Some medications – narcotics (particularly codeine), antidepressants, iron supplements, calcium-channel blockers (antihypertensives, particularly verapamil) and non-magnesium antacids are known to slow bowel movements.
• Pregnancy – the action of hormones, reduced activity and the pressure of the growing uterus against the intestines mean constipation is common during pregnancy.
• Advancing age – constipation is more common in older people, due to factors including reduced intestinal muscle contractions and reliance on regular medications.
• Illness – a period of illness, particularly one resulting in hospitalization and bed-rest, typically causes constipation. Factors include a change in routine, shyness, reduced food intake, pain (especially after abdominal surgery), and pain-relief medication such as morphine. Short-term treatment with laxatives is often required.

Medical causes of constipation#

Constipation is sometimes a symptom of underlying medical problems, such as:

• Disordered defecation – an important cause of chronic constipation, caused by insufficient forward contractions of the lower bowel (anorectum), or by increased resistance in the lower bowel. Straining is a very common symptom.
• Slow transit – the bowel ‘pacemaker’ may be less active, so these people are more likely to become constipated with minor changes in routine.
• Irritable bowel syndrome – characterized by abdominal pain, bloating, and either constipation or diarrhea, or alternating constipation and diarrhea. People with this condition may have features of slow transit, disordered defecation, or both.
• Anal fissure – a tear in the lining of the anus (anal mucosa); the person may resist going to the toilet for fear of pain.
• Obstruction – the rectum or anus may be partially obstructed by, for example, hemorrhoids (piles) or a rectal prolapse.
• Rectocele – the rectum pushes through the weakened rear wall of the vagina when the woman bears down or strains.
• Hernia and abdominal or gynecological surgery – associated with an increased susceptibility to constipation.
• Problems of the endocrine system – such as hypothyroidism or diabetes.
• Tumor – pain while trying to pass a stool could be a symptom of rectal cancer.
• Diseases of the central nervous system – such as multiple sclerosis, Parkinson’s disease or stroke.

Complications of chronic constipation#

• Fecal impaction – the lower bowel and rectum become so packed with feces that the muscles cannot push any of it out.
• Stercoral ulcer – impacted stool can erode the lining of the lower bowel; these ulcers can cause significant bleeding or bowel perforation.
• Fecal incontinence – an overfull bowel can result in involuntary ‘dribbling’ of diarrhea.
• Hemorrhoids and rectal prolapse.
• Urinary incontinence – the involuntary passing of urine becomes more likely, especially when coughing, laughing or sneezing.

Diagnosis of constipation#

The underlying reason for the constipation must be found. Diagnosis may include:

• a careful medical history to determine the type of disorder
• detailed questioning about medications, diet, exercise and lifestyle habits
• a physical examination, including examination of the anal canal and rectum
• a trial of simple laxatives, as the outcome helps with accurate diagnosis of the cause
• referral to a specialist in disorders of defecation, who may perform simple tests of anorectal function or anorectal manometry (pressure measurements of the rectum and anus)
• colonoscopy in those with alarm symptoms or aged over 50 with new onset of constipation

Treatment for constipation#

Treatment depends on the cause, but could include:

• Stopping or changing medications that can cause constipation.
• Removal of impacted feces – which may involve enemas, stool softeners and a short-term course of laxatives.
• Dietary changes – such as increasing the amount of fiber in the daily diet. Dietitians generally recommend about 30g of fiber every day. Good sources include wholegrain cereals, fruits, vegetables and legumes. The intake of foods such as milk, cheese, white rice, white flour and red meat should be restricted, because they tend to contribute to constipation.
• More fluids – it is important to drink plenty of water and to limit diuretic drinks such as tea, coffee and alcohol.
• Fiber supplements – these may help if the person is reluctant or unable to include more wholegrain foods, fresh fruits or vegetables in their diet. As fiber supplements can sometimes aggravate or cause constipation, always check with your doctor or dietitian when using them.
• Exercise – one of the many benefits of regular exercise is improved bowel motility. Ideally, exercise should be taken every day for about 30 minutes. People with a condition that affects mobility need to be as active as possible each day, as every little bit helps.
• Treatment for an underlying disorder.
• Laxatives – bulk-forming laxatives swell or bulk up the stool with fluid.

Chronic constipation that has not responded to a trial of fiber supplementation can be safely treated long term with laxatives. There is little evidence that long-term use of laxatives at appropriate doses leads to a ’lazy’ or ’twisted’ bowel. Disordered defecation that does not respond promptly to fiber and laxatives may require suppositories or enemas and pelvic floor ‘retraining’ by biofeedback therapy, offered by centers specializing in anorectal disorders. Slow transit constipation that has not responded to simple laxatives may be treated with medications that increase the speed of stool transit.

Key points#

• In some cases, constipation is caused by more serious illnesses and events, including tumors and systemic diseases.
• A sedentary lifestyle, or being restricted in movement due to a disability, is a common cause of constipation.
• Constipation is more common in older people.
• Short-term treatment with laxatives is often required during illness.
• Pain while trying to pass a stool could be a symptom of rectal cancer.

Where to get help#