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Chapter 13.  Disorders of Elimination: Constipation

143

associated symptoms such as abdominal pain, vomiting, blood in the stool, withholding bowel movements, fever, and abdominal distention should be noted. The grading of bowel movements using an objective scale such as the Bristol stool scale may be useful confirming if the child is passing hard stools. Large diameter stools or stools which clog the toilet are a signs of constipation as well. The history should probe for possible organic causes of constipation such as hypothyroidism, botulism, medication side effects, or neurological causes as well as failure to thrive. As mentioned above there is a high incidence of concomitant bladder and bowel symptoms and thus the frequency of urination, presence of urgency, posturing, daytime or night-time incontinence, and urinary tract infections should be sought.

A physical exam should be performed with emphasis on the abdominal (palpable stool, tenderness, abdominal distention, rectal exam and anal position), neurological (reflexes, strength, anal wink and perineal sensation), and back exam (sacral dimple, lipoma, or hair tuft). Any suspicious neurological findings should lead to evaluation for a spinal cord abnormality such a tethered spinal cord. Plain abdominal films have been used to assess the fecal load and evaluate the spine for an occult dysraphism. There use is considered optional although many clinicians find them useful and objective in assessing for retained fecal load. Patients with no suspicious findings in the history and exam likely have functional constipation and should be treated.

13.4  Treatment of Constipation

Classically, the therapy for constipation has consisted of behavior modification (sitting to have a bowel movement for

5–10 min shortly after meals) and laxative therapy. The first step is bowel cleanout by disimpaction, which has traditionally been achieved with enemas but many practitioners now use oral laxatives and stool softeners with similar results. Once disimpaction is complete then the child is maintained on laxatives to keep the stools soft and allow the chronically

144 J.C. Austin

over distended rectum to regain its normal tone and function. There is evidence for the efficacy of laxative and stool softener therapy in constipation. No treatment is clearly superior. The most common treatments and their usual dosages are listed below.The use of other stool softeners such as docusate sodium has not been well studied in children and the efficacy is not known.

The therapy should be continued for the duration of at least 4–6 months before discontinuation with the goal of 1–3 bowel movements per day that are of a milkshake consistency during treatment. If the child has difficulty with fecal incontinence during therapy it needs to be ensured that they are adhering to the scheduled bowel evacuations and not trying to hold their stools. Of the following agents PEG 3350 is a safe and well tolerated choice to start with.

PEG 3350 (Miralax™, Glycolax): Effective dose for constipation has been reported in the 0.5–0.84 gm/kg/day given daily. Total dose may be divided in half and given twice daily which can help improve the stool consistency. The powder may be mixed with any good tasting fluids. The solution should be mixed with 17 gm of powder (filled to the mark inside the cap) into 240 mL (8 oz) and the appropriate amount of this dilution taken (i.e., a dose of 8.5 g would require drinking 120 mL (4 oz) of the solution). The mechanism of action of PEG 3350 is an osmotic agent which retains water in the stool to soften it and increase the frequency of bowel movement. The dose can be adjusted up or down every 3–5 day by an ounce until the desired stool consistency is reached.

Milk of magnesia (magnesium hydroxide): Effective dose for treating constipation is 1–2 mL/kg/day given in a single or divided into a twice daily dose. The maximum recommended amount is 60 mL/day. Compliance with daily doses is less than with PEG 3350. It can be mixed or flavored with applesauce, chocolate syrup, or other flavorings to improve the taste. Its laxative effect is due to a hyperosmotic effect drawing fluid into the stool and the stimulation of increased peristalsis in the small intestine.

Chapter 13.  Disorders of Elimination: Constipation

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Mineral oil: Dosage for children 6–12 years old is 5–15 mL/ day. After age 12 years 15–45 mL/day. Not recommended for younger children due to the risk of aspiration. The oil helps soften stools by coating them and the intestine to reduce the colonic absorption of water and lubricate hard stools to facilitate passage.

Lactulose: Supplied in a solution of 10 g/15 mL. The mechanism of action due to the synthetic disaccharide being degraded in the colon by bacteria producing lactic acid, acetic acid, and formic acid, which increase the osmotic pressure drawing water into the stool softening it.

Senna: A laxative that stimulates peristalsis and is available as both oral syrup (218 mg/5 mL) and a tablet (167 mg). For children 1–5 years of age the recommended dose is 2.5–5 mL of syrup (109–218 mg) given at bedtime. For children age 5–15 years old a dose of 5–10 mL of the syrup can be used initially. Alternatively 1–2 tablets can be given at bedtime. Senna should only be used short term.

13.5  Indications for Referral

Patients with constipation that is suspected to be due to an organic cause based on the history or physical exam should be referred for further testing which may include rectal manometry, barium enema, or spinal MRI. Patients with persistent symptoms after adequate treatment for 3–6 months should be referred to pediatric gastroenterologist.

Suggested Readings

1.Allen HA, Austin JC, Boyt MA, et al. Evaluation of constipation by abdominal radiographs correlated with treatment outcome in children with dysfunctional elimination. Urology. 2007;69:966-969.

2.Baker SS, Liptak GS, Colletti RB, et al. Constipation in infants and children. J Pediatr Gastro Nutr. 1999;29:612-626.

3.Chase JW, Homsey Y, Siggaard C, et al. Functional constipation in children. J Urol. 2004;171:2641-2643.

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4.Erickson BA, Austin JC, Cooper CS, Boyt MA. Polyethylene glycol 3350 for constipation in children with dysfunctional elimination. J Urol. 2003;170:1518-1520.

5.Hadjizadeh N, Motamed F, Abdollahzade S, Fafiei S. Associate of voiding dysfunction with functional constipation. Indian Pediatr. 2009;46:1093-1095.

6.Heaton KW, Ghosh S, Braddon FEM. How bad are the symptoms and bowel dysfunction of patients with the irritable bowel syndrome? A prospective, controlled study with emphasis on stool form. Gut. 1991;32:73-79.

7.Koff SA, Wagner TT, Jayanthi VR. The relationship among dysfunction elimination syndromes, primary vesicoureteral reflux, and urinary tract infections in children. J Urol. 1998;160:1019-1022.

8.Loening-Baucke V. Urinary incontinence and urinary tract infection and their resolution with treatment of chronic constipation of childhood. Pediatrics. 1997;100:228-232.

9.Loening-Baucke V, Pashenkar DP. A randomized, prospective comparison study of polyethylene glycol 3350 without electrolytes and milk of magnesia for children with constipation and fecal incontinence. Pediatrics. 2006;118:528-535.

10.Pashankar DP, Bishop WP, Loening-Baucke V. Long-term efficacy of polyethylene glycol 3350 for the treatment of chronic constipation in children with and without encopresis. Clin Pediatr. 2003;42:815-819.

11.Voskuil WP, Heijmans J, Heijmans HS, et al. Use of Rome II criteria in childhood defecation disorders: applicability in clinical and research practice. J Pediatr. 2004;145:213-217.