Causes of Constipation?


There are several different aspects of constipation in IBS.

Colonic inertia

The contractile activity of the colon is quite complex.  For much of the time, it consists of contractions that mix the semi-solid products of digestion, bringing them into contact with bacteria and with the absorptive colonic epithelium or lining.  Then from time to time, especially first thing in the morning or after breakfast, peristaltic contractions move the contents on to the rectum where they will be expelled.   Failure of peristalsis is known as colonic inertia and may be related to increased activity in the sympathetic nerve supply to the colon.


Anismus is the term applied to paradoxical contraction of the anal sphincter which blocks attempts of defaecation.  People with anismus often feel like going but can’t manage it.  And the more they strain, the worse it gets.

Anismus may be corrected by Biofeedback Training.

Rectal Frustration

Have you ever felt you’ve wanted to go, but either not been able to or perhaps just managed to force out a hard pellet or two? Or have you passed a stool but still felt there was something left?  Rectal frustration may be caused by a combination of Anismus and exaggerated rectal sensitivity.

Faecal pellets (Type 1 on the Bristol Stool Scale) are often too small to expel with ease, but if the rectum is very sensitive, they can generate an urge to defaecate. Attempts to relieve the feeling by straining can often be counter productive as it tenses up the sphincter. It is often best to wait until the urge gets stronger or to take fibre products to bulk up the stool so that it is easier to pass.


“A good set of bowels is worth more to a man than any quantity of brains”
Josh Billing


Alternating diarrhoea and constipation

How can the same person have an illness that can cause constipation at one time and diarrhoea at another and alternate between the two? This is exactly what many people with IBS have though the timing of the different phases varies considerably.

There is no certain explanation. It might be related to fluctuations in stool consistency whereby the delivery of small regular volumes of fluid matter into a sensitive rectum leads to the frequent and often urgent passage of small amounts of liquid stool, whereas the frequent delivery of faecal pellets elicits a frustrated urge to defaecate.

Faecal consistency is related to alterations in the motility of the sigmoid colon. In diarrhoea the colonic motility is propulsive whereas in constipation it moulds the faeces into hard pellets. Thus alternating diarrhoea and constipation may imply rather subtle changes in the balance of sympathetic (obstructive) and parasympathetic (propulsive) tone in patients with enhanced bowel sensitivity.   This in turn may relate to changes in emotional expression;  alternating diarrhoea and constipation may therefore represent an ambivalent emotional state, where uncontrolled expression of feeling alternates with suppression and control of emotion.

Now listen to Tanya’s story below

Constipation in Women with Dr Nick Read 

Click here to view the video

Tanya's Story

Tanya's Story

Faecal impaction

Faecal impaction occurs when faeces accumulate in a distended rectum causing pelvic discomfort and difficulty in defaecation. It is much more common in childhood and in old age.

Infants may hold on to their faeces either because it is painful to poo or because they are resisting parental control. After a time the faecal mass gets so big and so large that it is impossible to get rid of it. Most cases of faecal impaction in childhood respond to the sensitive application of behavioural techniques and medicines to soften the stool and rarely continue in adulthood. Only occasionally is it due to a neurological disorder, such as short segment Hirshsprung’s Disease.

The elderly may retain faeces because of a combination of mental and physical infirmity, immobility and uncomfortable toilets.   Some may also have neurological impairment of pelvic floor function.

Other causes of Constipation

Constipation can be caused by any condition that impairs colonic propulsion and/or anal relaxation.

These include.

Some medications (e.g. painkillers, blood pressure tabs, antidepressants, etc).  If you have recently developed constipation, ask yourself whether you have started a new medication.

A diet deficient in fibre, fruit and vegetables.

Rarely, other diseases (e.g. thyroid conditions, neurological disease, and many others).

Age, infirmity, and not drinking enough fluid.

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