Only a few studies, most of them with small patient numbers, have been performed to evaluate treatment for children with defecation disorders. Treatment of constipation is mainly based on empirical experience, rather than on placebo-controlled, randomized studies. The main reason for a consultation is interference with social activities of the child and its family because of the defecation problems (soiling and encopresis). They should be educated and the problem should be demystified.29 It should be stressed that the prevalence of constipation and soiling is quite common. The relationship between fecal impaction and overflow diarrhea should be explained with the help of drawings, and the involuntary nature of the loss of feces in the underwear made clear. The objective of this is to make parents start to feel more comfortable and decrease the feeling of shame in the child. The child and parents almost invariably accept a positive non-accusatory approach with relief. Organic versus functional disease should be explained clearly, once the history and physical examination have been evaluated and the diagnosis is made with confidence. It should be stressed that there is no need for further investigation. The therapy is stressful and might be long lasting. The child is the only one who is responsible for completing the treatment. Behavioral therapy (see below) is not generally recommended; if the treatment is successful, the behavior abnormalities usually normalize too. It is helpful to advise that a diary is kept to follow and gain insight into the therapeutic progress; it might also motivate the child. The child has to fill in the diary himself, and that enhances responsibility. It might also be linked to a reward system.30-33
Another simple general measure is toilet training to normalize defecation. It should be explained that the sensation of defecation must be felt by the child and, usually from the age of 4, will be admitted by the child when it is explained well. The treatment of the child should involve an instruction to attempt to defecate three times a day for 5 min after each meal. This should stimulate straining actively and the child should be able to place his feet on a footrest or on the ground (the younger ones usually need a footrest). This is important, to flatten the anorectal angle, facilitating fecal expulsion. Using this approach, the child will be forced to focus on its bowel function. The emptying of the rectum will reduce the risk of fecal soiling during the rest of the day. This approach is only successful in 50% of children with severe constipation referred to a tertiary hospital, without any added pharmacological treatment.
Fluid intake of children with constipation has been found to be slightly lower than normal,33 and so is energy intake, estimated in a prospective study to be around 100kcal/day lower. Fiber intake of children with constipation was also slightly lower than controls, but in 6 months after reinforcement we found that it could be increased in some by only around 9g while it was actually decreased in others up to 16 g. The total amount remained less than 20g and no child achieved 30g/day. There was no relation between fiber intake, colonic transit times and success in treatment. Therefore, while we would still recommend increasing fiber intake in constipated children, one might not expect much success in children from this intervention alone.34
No double-blind randomized study on oral or rectal laxatives has been performed in children with constipation, except for the use of cisapride.35 The effect of lactulose, one of the most widely used stool softeners, has not been investigated. An evidence-based treatment cannot be constructed. Almost all advice concerning the use of oral or rectal laxatives is currently based on clinical empirical experience.
The major aim of medical therapy is two-fold: to remove fecal impaction; and to prevent its recurrence by avoiding prolonged rectal distension.
The most convenient approach in the majority of cases is by daily enemas, better administered after returning from school, as it might take some time to induce defecation.36 The effect is mainly due to a sudden increase in rectal filling, which leads to a strong rectal contraction and reflex relaxation of the internal anal sphincter, often followed by a bowel movement. The advantage of an enema strategy is a direct effect on overflow incontinence and relief for the child and parents. Enemas have the effect of hyperosmosis and increased fluids in the colon; furthermore, they lubricate the feces and distend the colon. Enemas used in children may contain dioctyl sodium sulfosuccinate and sorbitol or phosphate. Also, oil enemas and tap water enemas can be used. Hyperphosphate enemas in children have some risk when the enema administration is not followed by defecation and might lead, through retention, to hyper-phosphatemia, subsequent hypocalcemia, hypokalemia and dehydration.37,38 Also, hypocalcemia might lead to tetany and cardiac abnormalities in children, which in practice it is mainly seen in treatment of Hirschsprung's disease prior to surgery. Enemas should contain a sufficient amount of fluid: under 2 years of age around 60 ml and above 2 years of age 120 ml. Usually, evacuation is achieved within 3 days with consecutive daily enemas. Otherwise, it should be continued until the fecal mass has been removed successfully. When soiling relapses or the defecation frequency does not normalize with adequate treatment with oral laxatives, enemas are added to long-term treatment on an individual basis, usually 2-3 times weekly. When this procedure for severe fecal impaction is unsuccessful, and also in children who are treated for constipation and have recurrent large impaction, intermittent nasogastric lavage treatment might be tried. A safe and efficient method to clean the intestine is the balanced electrolyte solution of non-resorbable polyethylene glycol. This solution is often well taken by the child and, if he cannot swallow the required quantity, nasogastric tubes might be used. The recommended volume varies between 14 and 40 ml/kg per h, not to exceed llitre/h, and treatment should be continued until clear fluid is excreted through the rectum, an effect usually reached within 24 h. This treatment gives some temporary relief, but is not a substitute for other treatment protocols.
The remaining initial treatment after desimpaction is achieved involves osmotic laxatives (lactulose, lactitol) at a dose of 1-6 g/kg body weight per day. The main function is to loosen stool consistency, and enhance the rectal sensation and urge of the child to defecate. The dose might be increased without any danger up to 20-40g daily. Side-effects are initially bloating, flatulence and increase of abdominal pain, but these symptoms usually disappear after the first 1-2 weeks. Therapy should be continued for at least 3-6 months until constipation has disappeared; the dose should be titrated individually. If this treatment is insufficient, recently polyethylene glycol has been shown to be effective in treating constipation in children at a dose of 0.8g/kg per day. It also functions as an osmotic laxative.39,40 It has fewer side-effects in terms of flatulence and abdominal pain, and its tasteless nature increases compliance. The effects are comparable to those of lactulose.
Another laxative is mineral oil, an emollient agent, at a dose of 1-3 ml/kg per day, whose main function is to keep the rectal walls lubricated. Disadvantages are anal oil seepage with coloring of the underwear, which is not removable with washing, and the risk of aspiration and chemical pneumonia in very young children, and in children with cerebral palsy or other causes of mental retardation. Milk of magnesia is a relatively non absorbable laxative, and can be given at a dose of 1 ml/kg per day. The treatment might be started at a higher dose, up to 3 ml/kg per day. Prokinetic agents, such as cisapride at a dose of 0.2mg/kg body weight three times daily, have some transient effect on constipation, but this drug is no longer available.
Stimulant laxatives such as bisacodyl, sodium picosulfate and senna alkaloids should be used with caution and have no advantage over osmotic laxatives. Biofeedback training has been shown to normalize defecation dynamics, but has no place in management, because it does not influence therapeutic outcome. Surgical colostomies for antegrade enemas have been successfully tried, but also have their complications; at present, indications are difficult to establish.
In functional non-retentive fecal soiling, biofeedback training showed a minor effect on treatment outcome.41 In this form of constipation, the main treatment is laxatives. Daily enemas in the morning might help to have a clean day, which might stimulate the defecation behavior. Oral laxatives usually worsen soiling and encopresis and should be avoided in these children with functional non-retentive fecal soiling.
Biofeedback training compared to conventional treatment
In a large cohort of 200 children who had conventional treatment and one arm of biofeedback training added, they did learn to normalize their defecation dynamics, but this normalization had no influence on outcome of treatment. Only in functional non-retentive fecal soiling did biofeedback have a modest effect in a sample of 100 tested children.
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