Constipation is the passing of hard, dry bowel motions (stools) that may be infrequent or difficult to pass. The most common causes of constipation include a change in routine, not enough fibre in the daily diet, not enough fluids and lack of exercise.
See your doctor for diagnosis and treatment. It is important not to over-treat constipation with laxatives in place of seeking medical advice.
Food nutrients are absorbed in the small intestine. Waste is massaged down the length of the large intestine by waves of muscular contractions (peristalsis). Once the 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 faeces.
Water makes up about three quarters of faecal content, while the rest is composed of solids, including undigested fibre, intestinal bacteria and dietary fats.
Symptoms of constipation
The symptoms 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 hasn’t fully emptied
- bloated abdomen
- abdominal cramps.
In some cases, constipation is caused by more serious illnesses and events, including tumours and systemic diseases.
Lifestyle-related causes of constipation
Constipation can be caused by many different lifestyle factors that often work in combination, including:
- A change in routine – normal bowel motions depend on the regular and rhythmic contraction of the bowels. This is part of the body’s internal ‘clock’ and is often upset with changes in routine. This type of constipation is often seen in shift workers and travellers.
- Low-fibre diet – as fibre is indigestible, it adds bulk to the faeces, making it more easily pushed along the digestive tract. There are two broad types of fibre; soluble and insoluble. Soluble fibre helps to soften the faeces. Good sources of soluble fibre include legumes, fruits and vegetables. Insoluble fibre adds bulk to the faeces, helping it to move more quickly through the bowel. Good sources of insoluble fibre are in wheat bran, wholegrain breads and cereals.
- Insufficient water – the fibre in faeces will only plump up with water. Constipation can occur from a high-fibre diet if insufficient water is consumed.
- Lack of regular exercise – living a sedentary lifestyle or being restricted in movement due to a disability are common causes of constipation.
- A tendency to ‘put off’ going to the toilet – ignoring the urge to go means that more water will be extracted from the stools, making them difficult to pass. Regularly ignoring this urge may make the body less sensitive to normal signals to go to the toilet.
- Some medications – such as 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 that constipation is common during pregnancy.
- Advancing age – constipation is more common in the elderly. This is due to a number of factors, including reduced intestinal muscle contractions and reliance on regular medications.
- Illness – a period of illness, particularly an illness resulting in hospitalisation and bed-rest, typically results in constipation. Factors include 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, but may be overlooked.
Medical causes of constipation
Constipation is sometimes symptomatic of underlying medical problems, such as:
- ‘Slow transit’ – some people naturally pass motions less often than most people. It seems their bowel ‘pacemaker’ may be less active. These individuals are more likely to become constipated with minor changes in their routine.
- 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, haemorrhoids (piles) or a rectal prolapse.
- Rectocoele – the rectum pushes through the weakened rear wall of the vagina when the woman bears down or strains.
- Hernia – an abdominal hernia can reduce intra-abdominal pressure, which makes it more difficult to pass a motion.
- Abdominal or gynaecological surgery – a combination of change in routine, strange surroundings, post-operative pain and codeine-containing analgesics is a potent cause of constipation and often needs preventive care.
- Irritable bowel syndrome – characterised by abdominal pain, bloating, and either constipation or diarrhoea or alternating constipation and diarrhoea.
- Problems of the endocrine system – such as hypothyroidism, diabetes or hypopituitarism.
- Tumour – 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 are associated with an increased susceptibility to constipation.
Complications of chronic constipation
Some of the complications of chronic constipation include:
- Faecal impaction – the lower bowel and rectum become so packed with faeces that the muscles of the bowels can’t push any of it out.
- Faecal incontinence – an overfull bowel can result in involuntary ‘dribbling’ of diarrhoea.
- Haemorrhoids – constant straining to open the bowel can damage the blood vessels of the rectum.
- Rectal prolapse – the constant straining pushes a section of rectal lining out of the anus.
- Urinary incontinence – the constant straining weakens pelvic floor muscles. This makes the involuntary passing of urine more likely, especially when coughing, laughing or sneezing.
Diagnosis of constipation
The underlying reason for the constipation must be found. Diagnosis may include:
- medical history
- physical examination
- detailed questioning about medications, diet, exercise and lifestyle habits
Treatment for constipation
Treatment depends on the cause, but could include:
- Removal of the impacted faeces – which may involve enemas, stool softeners and a short-term course of laxatives.
- Dietary changes – such as increasing the amount of fibre in the daily diet. Dietitians generally recommend about 30g of fibre every day. Good sources of fibre 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 – liquids help to plump out faeces. However, it is important to restrict the intake of diuretic drinks such as tea, coffee and alcohol.
- Fibre supplements – these may be helpful if the person is reluctant or unable to include more wholegrain foods, fresh fruits or vegetables in their daily diet. As fibre supplements can 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 of regular exercise helps.
- Treatment for underlying disorder – such as surgery to repair an abdominal hernia, hormone replacement therapy for hypothyroidism, or anaesthetic cream and sitz (salt water) baths for an anal fissure.
- Laxatives – there are two main types: bowel stimulants and agents that increase the water content of the stool. Bowel stimulants increase bowel contractions, but may cause cramps. Agents that increase the water content may interfere with the absorption of water from the bowel, or swell or bulk up the stool with fluid. When used appropriately, laxatives can greatly relieve acute and chronic constipation. There is little evidence that chronic use of laxatives at appropriate doses will lead to a ‘lazy’ or ‘twisted’ bowel.
Where to get help
- Your doctor
- Dietitians Association of Australia Tel. 1800 812 942
Things to remember
- Most cases of constipation are successfully treated by eating a diet high in fibre, drinking more fluids and exercising daily.
- Complications of chronic constipation include haemorrhoids, faecal impaction and rectal prolapse.
- Over-the-counter laxatives are fine in the short term, but seek advice if the problem persists.
This page has been produced in consultation with and approved by:
Canberra Hospital - Gastroenterology Unit
Page content currently being reviewed.
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