Parents often report surprise and disappointment when their child starts to withhold bowel movements again following a cleanout. This is because they and, sometimes, their pediatrician who recommended the cleanout, do not know the difference between functional constipation (encopresis) and occasional or normal constipation.
Children who have encopresis have developed a "habit" of withholding, which is to automatically contract their anal sphincter to avoid a painful bowel movement whenever they feel bowel urgency. So, because withholding is a learned or habitual response to the feeling of having to poop, it will start again after a cleanout. Step#3 of my Six Step Program is the phase of treatment during which your child's association of pain with urgency is gradually extinguished together with the related habit of withholding.
Children with occasional or normal constipation do not have difficulty passing stool because they are withholding but because their stool has become dry and hard and it is very difficult for them to push out. Normal constipation comes and goes fairly quickly and is usually treated by increasing fiber, liquids and exercise but if continues more than a week or so may require the use of a laxative or even an enema to remove the dry stool in order to prevent the child from starting to withhold.