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.[2]

Rome IV defines functional constipation separately for infants and children greater than 4 years of age[5]

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

1. History of excessive stool retention
2. History of painful or hard bowel movements
3. History of large-diameter stools
4. Presence of a large fecal mass in the rectum

In toilet-trained children, the following additional criteria may be used:

1. At least 1 episode/week of incontinence after the acquisition of toileting skills
2. History of large-diameter stools that may obstruct the toilet

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:

1. 2 or fewer defecations in the toilet per week in a child of a developmental age of at least 4 years
2. At least 1 episode of fecal incontinence per week
3. History of retentive posturing or excessive volitional stool retention
4. History of painful or hard bowel movements
5. Presence of a large fecal mass in the rectum
6. History of large diameter stools that can obstruct the toilet

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.[6]  Imaging studies may be helpful to rule out other suspected disorders but are not required to diagnose functional constipation.[7][8][9][10]. An X-Ray abdomen can help diagnose fecal impaction, especially in a child where the abdominal examination is difficult but not done routinely. 

Disimpaction

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.[11]

Maintenance Therapy

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.[9]

1. Osmotic Laxatives
   • Polyethylene Glycol (PEG) 3350 at 0.2-0.8g/Kg/day
   • Lactulose at 1- 3mL /Kg/day
   • Magnesium Hydroxide at 0.5-3mL/Kg/day
2. Stool Softeners
   • Docusate Sodium at 5mg/Kg/day
   • Mineral Oil (Lubricant) at 1-3mL/Kg/day
3. Stimulant Laxative for rescue therapy in addition or alone (duration <30days)
   1. Senna at 2.5-7.5mL/day
   2. Bisacodyl at 5-10mg/day

Non-Pharmacological

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.[9]

Red Flags concerning for an organic disorder :

• Systemic symptoms such as Fever, abdominal distention, weight loss or poor weight gain, decreased appetite, and bloody diarrhea
• Onset before one month of age
• Delayed passage of meconium
• Failure to thrive
• Intermittent diarrhea and explosive stools
• Abnormal neurological examination 1) Low tone, loss of cremasteric reflex, and decreased lower extremity reflexes.
• No response to treatment

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.[8]

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[12].

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.[12]

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.[2]

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.

• Family members should receive education and a written plan at their initial visit.  This information should be placed in their chart and reviewed at each subsequent visit
• Treatment plans should include:
  • Instructions for initial management, ongoing care, how to address relapses at home, and how/when to follow up for additional help and questions
  • Lifestyle changes including increasing daily activity, increase fluid intake (especially water) and increased fiber intake
  • Behavioral interventions including sitting on the toilet after the same meal each day and trying 5 to 10 minutes to have a bowel movement (for toilet-trained children)
  • Scheduled follow-up appointments: Generally every 3 to 4 weeks until bowel movements normalized, then every 3 to 6 months and as needed
• Nursing staff should be familiar with constipation plans and be able to access individual plans in patient charts and be able to answer questions related to these plans over the phone when families call.
• If medications are prescribed, pharmacists should assist in monitoring for complications and effectiveness, reporting to the team concerns.
• Using an interprofessional team approach to coordinate care and educate the family will result in the best outcomes. [Level 5]