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Column originally published Feb 3, 2004
Column last revised/updated on Sep 5, 2018

Severe Constipation And Soiling Requires Long-Term Treatment

Question: We are worried about our four-year-old son. He became constipated shortly after we started toilet-training him. He would hide behind the chair when he needs to have a bowel movement. Sometimes we see him dancing around or crossing his legs when he needs to go to the toilet. When he finally does, his stool is so large in size that it would plug up the toilet. In the last two months, we have seen some loose stool in his underwear. He said that he didn’t know it until after it had happened, and he would deny it even though all of us could smell it. We are concerned that the problem will get worse next year when he starts kindergarten. Can you please advise us what we can do to control this constipation problem?


From your description, your son developed constipation when you started toilet-training him. This problem has progressed over the past two years to the point when liquid stool starts to leak around the constipated stool. This is called encopresis, and is a serious consequence of long-standing constipation. Your son definitely recognizes his problem, although he doesn’t know how to help himself. The problem of passing gases (due to constipation) and the smell of encopresis will result in serious emotional trauma unless help is given to him very soon.

Constipation is the name used to describe infrequent bowel movements that are hard in consistency, and large in size or diameter.   The frequency of bowel movement, and the size and consistency of stool, varies depending on age and the kind of food consumed. Before going any further, I will discuss briefly about the function of our intestines so that you can understand how and why constipation happens.

When food is taken into the mouth and swallowed, it passes through a long tube called oesophagus, into the stomach. Some digestion occurs there in the stomach, but most of it happens in the small intestines. After digestion and absorption, whatever that remains from the ingested food is passed into the large intestine (also called the colon). The main function of the colon is to finish the absorption of nutrients and water. Inside the colon, food remnant is converted into stool to be eliminated through the anus.

Just above the anus is the part of colon called rectum. When about one tablespoon of stool enters the rectum, its wall is stretched and a signal is sent to the brain, which gives the child the urge to have a bowel movement. If the child sits at the toilet, relaxes the sphincter (the muscle that controls the opening of the anus), increases the abdominal pressure by holding his breath, and pushing down (this is called Valsalva manoeuvre), he will push the stool out of the rectum. This explanation sounds quite complex for something that is universal for all human beings, but understanding this can help to explain what happens in constipation.

For a young infant, the time it takes for milk to enter the stomach until it is eliminated as stool is only a few hours. Therefore, the stool in babies are often very soft and runny. There can be as many as 12 stools a day in breast-feeding infants, to as little as one to two stools in those fed with infant formula. However, by two to three months of age, some breast-feeding infants may not pass stool more often than once a week. This can be perfectly normal and doesn’t indicate constipation, as long as the stool is still soft, and the child is otherwise healthy.

As a child gets older, the transit time for food going through the intestines gets longer. In a two year old child, this can take 16 hours. The transit time for a ten-year-old child is about 24 hours. The longer the transit time, the more water is absorbed by the large intestines, and the stool would become firmer in consistency.

Older children who have no constipation often would have three or more bowel movements a week. They may skip a day here and there, and their stool is usually soft to firm, and not large in diameter. There should be no pain on defecation, and each time there should be a fairly good amount of stool.

On the contrary, a constipated child can have one or more bowel movements a day, although most of the time it is more infrequent. However, each bowel movement usually has a small quantity of hard stool. What is happening is that the child cannot empty the stool collected inside the rectum and the adjacent colon. Because the stool is hard, these children will only allow a small amount of stool to pass at each movement. As long as the pressure in the rectum is relieved, they would rather withhold the stool instead of tolerating the pain associated with defecation.

There are many causes of constipation. Sometimes it is not easy to find out what actually happened in a particular child. Constipation tends to happen when there is a change in the child’s life. An infant who is breast-fed from birth can become constipated when he is started on cow’s milk formula or homogenized milk. Changing from pureed food to table food can cause constipation in some children. Starting daycare and full-day school can be stressful enough for some to develop problem. However, the most common cause, as in your son’s situation, is toilet-training.

Why toilet-training causes constipation is not completely understood. It is possible that many children are not matured enough or emotionally ready when parents started the process. When they are still in diapers, and if the stool is fairly soft, it doesn’t take much effort for them to relax the sphincter and push the stool out. It is quite possible that with toilet-training, the anxiety causes the child to tighten the sphincter instead of relaxing it. Once the stool is held in the rectum, water is absorbed and the stool becomes more firm. When the child gets the signal to pass the stool, it would require much more straining than before. The longer the stool stays in the rectum, the more water is removed, the harder it gets. Hard stool will lead to pain on defecation, and further withholding of stool, setting up a vicious cycle that finally ends up in constipation.

Once constipation starts, the stool not only gets harder, it also gets larger in size and diameter, over-stretching the wall of the rectum and colon above. Stretching the wall reduces the contracting power of the muscle in the intestine, which is important in pushing the stool forward towards the rectum. This is similar to blowing a balloon: once the balloon is stretched, it doesn’t get back to its original size. This is why treatment of constipation requires a long maintenance phase so that the colon has a chance to recover its original calibre and muscle tone.

The first step in the treatment of constipation is to clean out the bowel and eliminate all the stool that has been collected. This often takes several days, and can be done either at home or in the hospital. It may involve enemas (instilling a liquid into the rectum) or taking a laxative by mouth. Sometimes, if the constipation is very severe, the doctor may have to pass a tube through the nose into the stomach in order to instil a medicine that can break up the very hard and constipated stool.

Once the evacuation process is finished, the child needs a maintenance program that prevents constipation from recurring. It has taken months or years for constipation to establish, it will take a long time for the intestine to regain the muscle strength. The child needs to have one or more soft bowel movements a day, everyday.

There are many things that can help. At the beginning, it may be wise to reduce dairy products like cow’s milk and cheese. It has been recognized that the high fat content in dairy products can reduce gut motility and promote constipation. Once the constipation is well under control, dairy products can be slowly increased.

Some sugars that cannot be digested by our intestines are very helpful, because they can reduce water absorption by the colon, and prevent the stool from getting too dry and hard. These sugars include fructose and sorbitol that are found in prune juice. Lactulose, a sweet liquid made with two molecules of lactose that our body cannot digest, is available in pharmacy and can be very effective for those children who won’t take prunes or prune juice.

Extra fibre is also very important in the maintenance phase of treatment. The best source of fibre is in fruits and vegetables. Many children need extra encouragement when it comes to this food group, but parents can set a good example at home. The benefits of fruits and vegetables extend beyond the bowel. There are lots of excellent nutrients and vitamins. Research has shown that they can also prevent certain cancers.

Children with constipation can benefit from extra fibre available in whole wheat cereal and bread, as well as supplements like Metamucil or fibre pills. Some children are more receptive of pills instead of drinking a glass of Metamucil. Parents have to try different things to find out which is going to work.

Most of the time, mild laxatives are necessary at least initially to maintain regular bowel movements. They do not cause ‘lazy bowel,’ contrary to many people’s belief. Mild laxatives allow the child to have consistent daily bowel movement that is fairly soft. This will prevent withholding of stool in the rectum and lower part of large colon, and allow it to return to its normal calibre and muscle tone. With time, laxatives can be slowly reduced and stopped, but this likely will take many months.

Management of constipation requires lots of patience from the parents and physicians. Most of the time, failure of treatment is because of inadequate evacuation of constipated stool, inadequate medicine during the maintenance phase, or stopping the medicine too quickly. It is important to recognize that constipation is a chronic problem, it has been going on usually longer than the parents recognize, and it will take a long time to correct.

In addition to medicine, it is also important to work on a regular bowel habit. The best time to sit a child at the toilet is shortly after a meal, when the intestines are most active. It is important to provide a calm environment, and encourage the child to relax the anus and increase the abdominal pressure. With adequate medicine and regular toilet time, the constipation problem can be overcome.

I should mention here that it is important to provide a footstool at the toilet for your son, so that his feet can rest on firm ground, in order to apply the abdominal pressure effectively. If he is afraid of the large hole in the toilet seat, you can give him a small potty, or place a toilet seat insert so that he doesn’t have to worry about falling into the toilet. Using stars and stickers on the calendar to chart successful bowel movements can give you child the additional encouragement.

Rarely, children with constipation require counselling by trained psychologists. If all the treatment plans that I have discussed here are not effective, further assessment by a doctor specialized in gastroenterology would be necessary.

I hope you can work with your doctor to help your son and prevent him from a life-long misery of constipation.

[Note to Readers: In recent years, we have successfully used polyethylene glycol, also called PEG, in long-term treatment of constipation.  Please read more recent columns on this topic.]