Overview
Definition:
Constipation clean-out, often referred to as disimpaction, is a process to rapidly evacuate hardened stool from the colon and rectum in children with severe constipation and fecal impaction
Polyethylene Glycol (PEG) is a widely used, safe, and effective osmotic laxative for this purpose, working by drawing water into the bowel lumen, softening stool, and promoting bowel evacuation
It is typically used in high doses for a short duration to achieve complete colonic emptying.
Epidemiology:
Constipation is a common pediatric complaint, affecting 3-5% of children in primary care settings and up to 30% in specialist clinics
Fecal impaction requiring clean-out is estimated to occur in about one-third of constipated children
This condition impacts quality of life for both the child and the family and can lead to significant healthcare utilization.
Clinical Significance:
Effective clean-out protocols are crucial for relieving symptoms of chronic constipation, such as abdominal pain, infrequent stools, and encopresis (involuntary defecation)
Improper or incomplete disimpaction can lead to a cycle of re-accumulation of stool, persistent symptoms, and potential long-term functional bowel disorders
Understanding appropriate PEG dosing is paramount for successful management and improving patient outcomes.
Clinical Presentation
Symptoms:
Abdominal pain, often diffuse and crampy
Infrequent, hard, large stools
Straining or pain with defecation
Fecal leakage or soiling (encopresis), especially in underwear
Loss of appetite
Nausea or vomiting
Palpable fecal mass in the abdomen
Rectal distension
History of withholding stool.
Signs:
Abdominal distension
Palpable fecal impaction on abdominal examination or digital rectal examination
Dilated rectum with palpable stool
Perianal skin irritation or excoriation due to leakage
Poor weight gain or failure to thrive in severe cases
Diminished anal tone (may be paradoxically increased due to overstretching).
Diagnostic Criteria:
Diagnosis of functional constipation requiring clean-out is typically based on clinical presentation and the Rome IV criteria for functional gastrointestinal disorders in children
These include: Two or more criteria met for at least 1 of the last 3 months: 1
Two or fewer defecations per week
2
At least one episode per week of fecal incontinence after the development of bowel control
3
History of retentive posturing or excessive volitional stool retention
4
History of painful or hard bowel movements
5
Large fecal mass in the rectum
6
History of large-diameter stools that may obstruct the toilet
Clean-out is indicated when there is evidence of significant fecal impaction and the child is symptomatic.
Diagnostic Approach
History Taking:
Detailed history of bowel habits, including frequency, consistency (using Bristol Stool Scale), pain, straining, and soiling
Duration of symptoms
Dietary habits (fiber, fluid intake)
Toilet training history
Previous treatments and response
Presence of red flags such as blood in stool, fever, weight loss, vomiting, abdominal distension, or a family history of GI malignancy or inflammatory bowel disease.
Physical Examination:
Abdominal examination: Assess for distension, tenderness, and palpate for fecal masses
Auscultate bowel sounds
Digital rectal examination (DRE): Assess rectal tone, presence and consistency of stool in the rectal vault
Perianal inspection: Look for skin irritation, fissures, or signs of leakage.
Investigations:
Generally, investigations are not required for uncomplicated functional constipation
Plain abdominal X-ray may be used to confirm fecal loading and assess the extent of impaction, particularly if the diagnosis is uncertain or there is suspicion of obstruction
However, its routine use is debated, and it does not typically alter management decisions in children with clear clinical signs
Laboratory tests (CBC, electrolytes, thyroid function) are usually reserved for cases with red flags or suspected underlying organic pathology.
Differential Diagnosis:
Hirschsprung disease (suspect with failure to pass meconium in the neonatal period, a narrow distal segment on DRE, and a paradoxical fecal impaction in older children)
Spinal cord abnormalities (e.g., tethered cord)
Metabolic disorders (e.g., hypothyroidism, celiac disease)
Rectal malformations
Medications causing constipation
Inflammatory bowel disease (rarely presents as pure constipation).
Management
Initial Management:
The primary goal of the clean-out phase is to rapidly evacuate the impacted stool from the colon and rectum
This is typically achieved using high-dose osmotic laxatives like Polyethylene Glycol (PEG)
The chosen protocol should be tailored to the child's age, weight, and tolerance, and it is crucial to ensure adequate fluid intake during the process.
Medical Management:
Polyethylene Glycol (PEG) 3350, often formulated as PEG 3350 and electrolytes (e.g., MiraLAX, Laxido, PediaLAX), is the preferred agent
Dosing for clean-out is significantly higher than maintenance doses
Common protocols include: \n- Standard Pediatric Clean-Out Protocol: 1.5 grams of PEG per kilogram of body weight per day, divided into 2-3 doses, for 3-6 days, or until clear liquid stools are passed
The maximum daily dose typically ranges from 100-200 grams depending on age and size.\n- Example Calculation: For a 20 kg child, 1.5 g/kg/day = 30 g/day
This would be given as 10-15 grams per dose, 2-3 times daily
\n- Fluid Intake: Emphasize concurrent intake of clear fluids (water, clear juices, broths) to prevent dehydration, typically at least 100-150 mL/kg/day for younger children, and adequate intake for older children and adolescents
\n- Electrolyte Monitoring: While PEG 3350 alone is generally safe, formulations with electrolytes are often used to mitigate potential electrolyte imbalances, especially with very high doses or in children with underlying renal or cardiac issues
However, PEG 3350 alone is considered safe and effective, with careful attention to hydration
\n- Other agents: While PEG is preferred, sodium phosphate enemas or bisacodyl suppositories may be used for rapid rectal evacuation if PEG is not tolerated or effective, but require careful medical supervision due to risk of electrolyte disturbances.
Surgical Management:
Surgical management is rarely indicated for functional constipation
It is reserved for cases with underlying organic causes that cannot be corrected medically, such as severe Hirschsprung disease or structural anomalies, or for managing complications like fecalith impaction that is refractory to medical management
Procedures might include pull-through procedures for Hirschsprung's or surgical intervention for intussusception if it is a cause of obstruction.
Supportive Care:
Education for parents and child regarding the process, expected outcomes, and importance of compliance
Gradual reintroduction of a high-fiber diet and adequate fluid intake once the clean-out is complete
Establish a regular toileting routine
Consider behavioral interventions
Psychological support for children experiencing anxiety or shame related to encopresis.
Complications
Early Complications:
Gastrointestinal upset: Abdominal cramping, bloating, nausea, vomiting, and diarrhea (if doses are too high or administered too rapidly)
Dehydration if fluid intake is insufficient
Electrolyte imbalances (rare with PEG 3350, more concern with sodium phosphate preparations)
Perianal irritation from frequent loose stools.
Late Complications:
Failure of clean-out leading to recurrent impaction and symptoms
Development of anal fissures due to passage of hard stools
Development of encopresis due to over-distension of the rectum and loss of sensation
Psychological distress and social isolation for the child
Development of a cycle of withholding and avoidance of defecation.
Prevention Strategies:
Ensure adequate hydration during clean-out
Titrate PEG dose based on clinical response to achieve soft, loose stools without significant cramping or vomiting
Educate parents on recognizing signs of dehydration or excessive diarrhea
Gradual transition to maintenance therapy to prevent re-impaction
Address underlying behavioral factors contributing to withholding.
Prognosis
Factors Affecting Prognosis:
Adherence to the clean-out and maintenance regimen
Early diagnosis and intervention
Addressing behavioral and dietary factors
Parental education and support
Presence of underlying organic pathology (which would alter the prognosis significantly).
Outcomes:
With successful clean-out and appropriate maintenance therapy, the prognosis for resolution of symptoms and improvement in quality of life is generally good
The majority of children with functional constipation can achieve normal bowel function
However, chronic constipation can be a relapsing condition, requiring ongoing management.
Follow Up:
Regular follow-up with a pediatrician or pediatric gastroenterologist is essential
This allows for monitoring of the maintenance therapy, assessment of adherence, adjustment of diet and fluid intake, and reinforcement of toileting habits
Follow-up frequency will depend on the severity of symptoms and the child's response to treatment, typically ranging from monthly to every 3-6 months.
Key Points
Exam Focus:
Understand the definition and indications for constipation clean-out in pediatrics
Know the standard PEG 3350 dosing for clean-out (1.5g/kg/day up to max dose, usually divided BID/TID for 3-6 days)
Emphasize the importance of hydration and the role of PEG in osmotic action
Differentiate clean-out dosing from maintenance dosing
Recognize red flags that warrant further investigation.
Clinical Pearls:
Always calculate PEG clean-out doses based on weight
Ensure clear communication with parents about the expected duration, frequency of stools, and the goal of achieving clear, liquid stools
Offer flexibility in administration times if possible to improve adherence
Monitor for signs of dehydration closely
Transition to maintenance therapy is critical to prevent recurrence.
Common Mistakes:
Under-dosing PEG, leading to ineffective clean-out
Insufficient fluid intake during the clean-out phase, leading to dehydration or poor efficacy
Failing to transition to maintenance therapy, resulting in rapid relapse
Over-reliance on imaging (abdominal X-ray) without a clear clinical indication
Neglecting behavioral aspects and parental education.