Functional constipation is a common problem in childhood, with an estimated prevalence of 3% worldwide. Constipation is defined as functional constipation FC if there is no underlying organic cause, which is the case in up to 95% of children. It can be seen in healthy children one year and older and is particularly common among preschool-aged children . Most individuals have bowel movements at regular intervals, and although the frequency varies from person to person, stools should pass without significant straining or discomfort. Functional constipation is often described as difficult or infrequent bowel movements/ deviation from normal frequency, painful defecation, the passage of hard stools, and/or sensation of incomplete evacuation of stool. It is often not caused by any underlying systemic cause or anatomical defect. It is usually multifactorial to include environmental conditions, stress, diet, coping skills, and social support.
It is commonly seen in preschool children, especially around the time of toilet training. Although specific individuals may be more prone to constipation than others, a common cycle of events or triggers often lead to functional constipation.
FC is a common childhood issue with varying prevalence across geographic regions. In Europe (including children), prevalence is estimated to be between 0.7% and 12% while in North and South America, it is (including infants–adolescents) between 10% and 23 percent. It varies from 0.5% to 29.6% in Asia.
Holding stools rather than emptying the colon leads to stool accumulation. The colon removes water from stool, making it harder and more challenging to pass. As stool continues to accumulate, the smooth muscles in the intestinal walls are stretched and become less effective. The cycle of stool holding, removal of water from the stool, and stretching of the smooth muscles in the intestine, results in hard stools that are large and painful to pass, causing further stool holding. If this becomes a more chronic condition, a patient’s rectum fills with a hard stool on an ongoing basis, and they begin to lose the sensation of having to have a bowel movement. Soft stool often leaks around the harder “plug,” resulting in encopresis.
Functional constipation is a clinical diagnosis based on history and physical exam. History should include information about the frequency and consistency of stools, associated issues, and the duration of symptoms. Parents will often describe stools that are small and hard “like little pebbles,” while others describe infrequent, large bowel movements that are “so big I can’t believe it came out of him.” A history of bright red blood in the stool associated with large, hard bowel movements may indicate rectal fissures from passing hard bowel movements. A history of additional symptoms including weakness, abdominal pain, vomiting, and urinary symptoms can suggest organic causes for constipation. Lower extremity weakness should raise concerns of a neurologic cause. Abdominal pain, vomiting, enuresis, and encopresis can accompany functional constipation but should prompt additional questions and close attention to the examination of the abdomen. The past medical history should include questions about neurologic abnormalities, surgeries, and any chronic conditions like hypothyroidism, Hirschsprung disease or cystic fibrosis that may contribute to difficulty passing stool. Social and developmental history may suggest concerns about lead intoxication.
A thorough head to toe physical exam is necessary. General examination should include growth parameters and vitals. Exophthalmos, lid lag, and abnormalities on the thyroid exam may suggest hypothyroidism. The abdominal exam may reveal a palpable fecal mass, indicating fecal impaction. Look for abdominal distention as it could indicate prune belly syndrome, an abdominal mass, or other significant abnormality. Significant pain with palpation of the abdomen may require additional evaluation for appendicitis, ovarian torsion, or other acute abdominal processes. The back, especially the lumbar region, should be evaluated closely for midline defects, hair tufts, hemangiomas, dimples, or other abnormalities that could suggest underlying myelomeningocele. The anus should undergo an evaluation to assure it is patent and normally placed. A rectal exam, although not routinely indicated - may be helpful to confirm hard stool in the rectal vault, rule out presacral masses, and to assess rectal tone. Abnormal strength, reflexes, sensation, or muscle mass of either or both lower extremity.
Rome IV defines functional constipation separately for infants and children greater than 4 years of age
In infants up to 4 years of age:
Must include 1 month of at least 2 of the following i2 or fewer defecations per week
In toilet-trained children, the following additional criteria may be used:
For Children > 4 years of age
Must include 2 or more of the following occurring at least once per week for a minimum of 1 month with insufficient criteria for a diagnosis of irritable bowel syndrome:
After appropriate evaluation, the symptoms cannot be fully explained by another medical condition.
Children with history and exam consistent with functional constipation may not require any specific testing. Children who do not respond to treatment, who have an atypical history, or concerns on physical exam may require additional information or referral to a specialist. A TSH can screen for hypothyroidism, and a lead level can be helpful if lead intoxication is a concern. Hirschsprung disease is always a consideration, especially in very young, persistent, or atypical cases. A contrast enema can help with the diagnosis, and referral for a possible biopsy is also an option that will more definitively exclude the diagnosis of Hirschsprung's disease. Imaging studies may be helpful to rule out other suspected disorders but are not required to diagnose functional constipation.. An X-Ray abdomen can help diagnose fecal impaction, especially in a child where the abdominal examination is difficult but not done routinely.
The first phase of treatment is to empty the hard stool from the colon, also known as disimpaction. Removal of the impacted, hard stool allows the colon to begin returning to normal size and function. In the past, manual removal, suppositories, and enemas were common methods during this phase of treatment. Polyethylene glycol (PEG 3350) has become the first treatment of functional constipation due to its efficacy, safety profile, and because it is well tolerated. There are variations in the amount of PEG 3350 recommended for the cleanout phase of the treatment regime, but a reasonable dose would be 1 to 1.5 grams per kilogram PEG 3350 mixed with 6 to 8 oz. water or juice. Significantly higher doses have been used, especially in the hospital setting. Patients should be encouraged to drink this over 3 hours, if possible. If there has not been a significant response to this treatment, the patient can repeat the dose the next day. If there is no response after two days of treatment, or if there is significant abdominal discomfort, persistent vomiting, or any other concerns, the family should present for follow up and re-evaluation.
In the second phase of treatment, the goal is to keep the stool very soft, preventing re-accumulation of hard stool while the colon returns to normal size and function. Drugs in this phase are oral medications.
Normal fiber and fluid intake are recommended for children with constipation, along with an average amount of physical activity. There is no evidence to support the routine use of intensive behavioral protocolized therapy program or biofeedback in addition to conventional treatment. There is no evidence to suggest the use of prebiotics or probiotics in the treatment of constipation.
Adequate fluid intake is essential, as is age-appropriate activity. Children who are toilet trained should be encouraged to sit on the toilet and try to have a bowel movement for 5 to 10 minutes at the same time of day, every day, after the same meal; this will take advantage of the gastro-colic reflex and reduce the risk of constipation by “training” the child to have a bowel movement every day. A follow-up appointment should occur in 1 to 3 weeks to assess the efficacy of the treatment, as well as to consider necessary changes in the plan of care.
The differential diagnosis of constipation includes anatomic abnormalities like anal atresia and presacral masses, metabolic conditions like hypothyroidism, cystic fibrosis, and lead intoxication, and neurologic conditions including meningomyelocele and Hirsprung disease. Toxins like botulinum toxin (sometimes found in honey) and medications like opiates can cause constipation as well. In older children, irritable bowel syndrome is also a consideration.
Red Flags concerning for an organic disorder :
In most cases, a thorough history and physical exam will rule out most of these conditions. A history of lower extremity weakness or loss of bladder continence raises concern for a neurologic cause. Children who are less than one-year-old, who are not growing well, or who do not respond to treatment often warrant additional testing. The physical exam should devote special attention to the abdominal exam and lower extremity neurologic exam. A spinal exam should look for signs of neural tube defects like hemangiomas and large dimples with hair tufts in the midline. The anus should be inspected to ensure it is normal in appearance and location. A rectal exam can be uncomfortable but can assess rectal tone, the presence of hard stool in the vault, and the presence of a large presacral mass. Growth curves should be reviewed,, looking for signs of growth failure or changes in the growth curve.
Lubiprostone is a locally acting ClC-2 chloride channel activator that increases fluid secretion into intestines and is helpful in improving constipation. It is the US Food and Drug Administration approved for adults but not in children as of yet.
Prucalopride is a prokinetic agent that facilitates colonic motility and movement.This also improves bowel function and constipation related symptoms, but had only been tested in adults and not recommended in pediatric at this time.
Among patients referred to pediatric gastroenterologists, 50% will recover (3 or more bowel movements per week without fecal incontinence) and be without laxatives after 6-12 months. Approximately an additional 10% are well while taking laxatives, and 40% will still be symptomatic despite the use of laxatives.
Successful treatment of functional constipation requires a team approach. Family members, health care providers and the patient all have to play their part in the treatment of functional constipation and to prevent complications like encopresis and recurrent abdominal pain.
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