Functional constipation is a prevalent condition in childhood, about 29.6% worldwide. In the United States, represents 3% to 5% of pediatric visits and a considerable annual health care cost. Most children do not have an etiological factor, and one third continue to have problems beyond adolescence. Up to 84% of functionally constipated children suffer from fecal incontinence, while more than one-third of children present with behavioral problems primary or secondary due to constipation. Pathophysiology underlying functional constipation is multifactorial and not well understood. Factors that may contribute to functional constipation include pain, fever, dehydration, dietary and fluid intake, psychological issues, toilet training, medicines, and family history of constipation.
Chronic idiopathic constipation is characterized by lack of periodicity in defecating, difficulty or pain during defecation without an identifiable organic cause, such as physiological, anatomical, radiological, or histological. Even though this is a common problem in children, an underlying cause is identified in less 5% of cases.
Causes of constipation may be divided into following broad categories:
Constipation can occur in any age group starting from newborn to older people; overall, it is seen more commonly in females than males. Also, the non-white population has been reported to have a 30% higher prevalence than the white population.
The pattern and frequency of defecation depend on a child’s age. During neonatal period and early infancy, bowel movements can present more than 4 times per day, eventually trending down to 1 to 2 per day by toddler age. At this point, children usually have achieved voluntary control of their sphincter. Hence, there is a correlation between bowel movements and age.
The cause of constipation is multifactorial. The problem may arise in the colon or rectum or it may be due to an external cause. In most people, slow colonic motility that occurs after years of laxative abuse is the problem. In a few patients the cause may be related to an outlet obstruction like rectal prolapse or a rectocele. External causes of constipation may include poor dietary habits, lack of fluid intake, overuse of certain medications, an endocrine problem like hypothyroidism or some type of an emotional issue.
Rome IV criteria establish functional constipation when 2 or more of the following are present for at least one month for infants and children up to 4 years. For children older than 4 years of age, symptoms should last for at least 2 months:
Careful history and examination are usually sufficient to make a diagnosis. A thorough history is recommended as part of a complete evaluation of a child with constipation. However, the answer to which aspects of the clinical history are most pertinent are not defined. Paramount information includes the time after the birth of the first bowel movement, the period the condition has been present, the incidence of bowel movements, consistency and the size of the stools, whether defecation is painful, whether blood is present on stool or toilet paper, and if defecation is associated with abdominal pain. Also, is important to inquire about soiling, which can be mistaken for diarrhea in some parents. Medications can be associated with constipation, such as opiates, sucralfate, antacids, among others. A psychosocial history is important to evaluate family structure, the number of members living at home and child relationship to them, interaction with his peers and possibility of abuse.
The physical exam should include an assessment of “alarm” signs and symptoms (in other words, fever, abdominal distention, anorexia, nausea, vomiting, weight loss, or poor weight gain). Bloody diarrhea in an infant with constipation could be an indication of a diagnosis such as Hirschsprung disease. On abdominal examination, distention or a palpable “mass” may be appreciated in the lower abdomen. A rectal exam should be performed to identify the presence of impacted stool or intrarectal mass. Visual and digital anal inspection to ensure normal size and positioning of the anal opening and to assess for rectal prolapse.
The routine use of any specific imaging or laboratory test in the diagnosis of pediatric functional constipation is not recommended. However, when symptoms fail to improve with a conventional medical approach, the further diagnostic evaluation may clarify possible causes and help guide therapy. Such diagnostic tests include anorectal manometry, colonic manometry, colonic transit studies and imaging such as x-ray and ultrasound.
Anorectal manometry evaluates motor and sensory anorectal function to identify potential causes of constipation or fecal incontinence. Hirschsprung’s disease diagnosis is aid by this test, but gold standard diagnosis continues to be a rectal suction biopsy.
Colonic manometry consists of the colonoscopic insertion of a catheter throughout the length of the colon to measure segmental pressures. This diagnostic modality helps identify neurogenic and myogenic causes of constipation. There is no specific motility pattern is diagnostic of idiopathic constipation.
Colonic transit studies use radiopaque markers to assess the speed of intestinal transit. This can help identify anatomic sites of fecal retention and slow transit.
Overall, plain abdominal radiograph does not add to the history and physical exam. It may help to assess stool collection in the bowel when patients are obese, refuse a digital rectal exam, or when it is contraindicated. However, an abdominal radiograph is neither sensitive nor specific to diagnose constipation.
Management for constipation includes medical supervision, dietary instructions, behavioral changes and instructions regarding toilet training. A normal fiber intake, fluid intake, and physical activity level are recommended, and the routine use of prebiotics or probiotics is not recommended in the treatment of childhood constipation. The non-pharmacological intervention consists of demystification, explanation, and guidance for toilet training in those children with a developmental age of a least 4 years.
Laxatives represent first-line treatment for childhood constipation and, if an adequate regimen is implemented, they often have a symptomatic improvement. Consensus guidelines recommend daily polyethylene glycol (PEG) at a dose of 1 to 1.5 gm/kg per day for 3 to 6 days for initial fecal disimpaction, followed by a daily maintenance dose of 0.4 gr/kg per day for at least 2 months to prevent re-accumulation. A stimulant laxative should be added if PEG alone does not cause disimpaction after 2 weeks of treatment.
Biofeedback has improved defecation dynamics but does not affect constipation. Hence this approach has not been supported for management of idiopathic constipation in children.
Sacral nerve stimulation is a modality that has been used to treat refractory constipation, helping extrinsic neural control of large bowel and modulating inhibitory reflexes. This has improved the defecation frequency in some children with functional constipation, but effects last less than 6 months in a large group of patients.
Surgical management is reserved for patients with refractory to medical interventions. At least 10% of children with functional constipation referred to a pediatric surgeon will require an operation. The surgical treatment goal is to produce symptom alleviation. Surgical options may include anal procedures, antegrade enemas, colorectal resection, and intestinal diversion.
Before making the diagnosis of functional constipation, these possible etiologies should be excluded: anorectal malformations, pelvic/rectal masses, rectal prolapse, rectocele, dysfunctional voiding, pelvic floor dyssynergia, internal anal sphincter hypertonicity or achalasia. Colorectal conditions should be ruled out, including visceral myopathies or neuropathies, as well as Hirschsprung disease. Systemic conditions, psychosocial issues, drugs or toxins need to be identified. Other conditions to explore include spinal cord anomalies, cystic fibrosis, connective tissue disorders, hypothyroidism, DM, hypercalcemia, hypokalemia, Celiac disease, cow’s milk protein allergy.
Most pediatric patients are managed with medical therapy, and most of them will improve. However, at least 30% will persist to be symptomatic until adulthood. Factors that are associated with a worse prognosis are female gender, older age of onset, longer time between symptom presentation and starting therapy, and longer colonic transit time.
Constipation is seen in patients of all ages and the causes are diverse-hence the disorder is best managed in a multidisciplinary fashion. It is important to educate the patient on the importance of fiber in the diet. In addition, the patient must be told to refrain from using laxatives, drugs that cause constipation and participate in regular exercise. For those habituated to laxatives, a gastroenterology consult is necessary.
Once constipation is diagnosed, compliance with the diet and medical therapy is essential to reverse the disorder. However, in many people recurrence of constipation is common and this is chiefly due to lack of compliance with the diet. A significant number of people can become disabled because of chronic constipation, and the quality of life can be poor. A few patients who fail to respond to medical management may need to undergo total abdominal colectomy; however, patient selection is vital in order to get a good outcome. The most difficult patients are those addicted to laxatives, who will not change their lifestyle and continue to use a variety of laxatives.