Causes of a child with chronic constipation

Full Answer Section

• Tests/Labs:

  • Rectal Biopsy: This is the gold standard for diagnosing Hirschsprung's disease. It involves taking a small sample of rectal tissue to look for the absence of ganglion cells.
  • Anorectal Manometry: This test measures the pressures in the anal sphincter muscles and rectum. In Hirschsprung's disease, there is often a lack of relaxation of the internal anal sphincter in response to rectal distension.
  • Contrast Enema (Barium Enema): This X-ray procedure can help visualize the colon and identify a narrowed segment (transition zone) suggestive of Hirschsprung's disease or anorectal malformations.
  • Abdominal X-ray: Can show signs of obstruction, such as dilated loops of bowel.
  • Sweat Chloride Test: This is the standard test for diagnosing cystic fibrosis.
  • Thyroid Function Tests (TFTs): Blood tests to measure TSH and free T4 levels to assess thyroid function.
  • Spinal Ultrasound or MRI: To evaluate for spinal cord abnormalities.
  • Trial of Elimination Diet (for Cow's Milk Protein Allergy/Intolerance): Removing cow's milk protein from the diet under medical supervision and observing for symptom improvement.
  • Upper Gastrointestinal (UGI) Series with Small Bowel Follow-Through: Can help evaluate intestinal motility in cases of suspected pseudo-obstruction.
  • Colonic Transit Studies: These studies track the movement of markers through the colon over several days to assess colonic motility.

b. Persistently narrow diameter stools.

This often suggests a structural narrowing in the distal colon or anorectal region.

• Possible Causes:

  • Anal Stenosis: A narrowing of the anal opening. This can be congenital or acquired (e.g., due to chronic inflammation or scarring).
  • Distal Rectal Stricture: A narrowing within the rectum, which can be congenital or due to inflammatory bowel disease (though less common in early childhood), previous surgery, or trauma.
  • Chronic Fecal Impaction: While not a primary cause of narrow stools, a long-standing impaction can sometimes lead to the passage of only thin stool around the impaction. However, this usually alternates with larger, hard stools or overflow incontinence.
  • Hirschsprung's Disease (short segment): In some cases, a very short affected segment might primarily lead to difficulty passing larger stools.

• Tests/Labs:

  • Careful Physical Examination: A thorough visual inspection and gentle digital rectal examination (if appropriate for the child's age and comfort) can often identify anal stenosis or a low rectal stricture.
  • Anorectal Manometry: Can sometimes reveal abnormalities in sphincter function or rectal compliance.
  • Contrast Enema (Barium Enema): This is crucial for visualizing the colon and rectum to identify any strictures or narrowing.
  • Flexible Sigmoidoscopy or Colonoscopy: Allows direct visualization of the rectum and distal colon and the possibility of taking biopsies if a stricture is identified to determine its cause.
  • Abdominal X-ray: May show fecal loading but is less specific for identifying structural narrowing.

c. Failure to gain weight/weight loss.

Constipation accompanied by failure to thrive (poor weight gain) or weight loss is a red flag and suggests an underlying systemic disease or a severe gastrointestinal issue affecting nutrient absorption.

• Possible Causes:

  • Cystic Fibrosis: Malabsorption due to pancreatic insufficiency is common, leading to poor weight gain and bulky, greasy stools (though constipation can also be a feature).
  • Celiac Disease: An autoimmune reaction to gluten can damage the small intestine, leading to malabsorption, diarrhea (though constipation can occur), and failure to thrive.
  • Inflammatory Bowel Disease (IBD): Crohn's disease and ulcerative colitis can cause inflammation in the digestive tract, leading to pain, diarrhea (more common), constipation, bleeding, and poor nutrient absorption.
  • Chronic Intestinal Pseudo-obstruction: Impaired motility can lead to poor absorption and nutritional deficiencies.
  • Severe Food Allergies/Intolerances: Multiple food allergies or severe intolerances can lead to inflammation and malabsorption.
  • Metabolic Disorders: Some rare metabolic conditions can affect digestion and nutrient absorption.
  • Hirschsprung's Disease with Enterocolitis: Severe inflammation of the colon in Hirschsprung's can lead to systemic illness and poor growth.
  • Underlying Systemic Illnesses: Chronic infections, immunodeficiencies, or other serious medical conditions can affect appetite and nutrient absorption.

• Tests/Labs:

  • Weight and Height Measurements with Growth Charts: To document the pattern of growth.
  • Stool Studies: To evaluate for fat malabsorption (fecal elastase for pancreatic function, quantitative fecal fat), inflammatory markers (calprotectin), and infection (ova and parasites, bacterial culture).
  • Celiac Disease Serology: Blood tests for tissue transglutaminase (tTG) IgA antibodies and total IgA levels. If positive, an upper endoscopy with small bowel biopsies is needed for confirmation.
  • Inflammatory Markers (Blood): ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein) can indicate inflammation.
  • Albumin and Prealbumin Levels (Blood): Markers of nutritional status.
  • Electrolyte Panel (Blood): To assess for imbalances due to malabsorption.
  • Complete Blood Count (CBC): To look for anemia or signs of infection/inflammation.
  • Thyroid Function Tests (TFTs): Hypothyroidism can affect growth.
  • Sweat Chloride Test: To rule out cystic fibrosis.
  • Upper Endoscopy with Small Bowel Biopsies and Colonoscopy with Biopsies: To visualize the lining of the digestive tract and obtain tissue samples for histological examination, especially if IBD or celiac disease is suspected.
  • Food Allergy Testing: Skin prick tests or blood tests (specific IgE) may be considered if food allergies are suspected.
  • Metabolic Screening: Depending on other clinical features, specific tests for metabolic disorders may be indicated.

d. Abdominal distention.

Significant abdominal distention in a child with chronic constipation suggests a large amount of stool buildup or potentially a more serious underlying issue causing bowel obstruction or impaired motility.

• Possible Causes:

  • Severe Fecal Impaction: The most common cause of abdominal distention in chronic constipation.
  • Hirschsprung's Disease: The aganglionic segment prevents stool from moving forward, leading to a buildup of stool and gas proximal to the affected area.
  • Chronic Intestinal Pseudo-obstruction: Impaired motility can cause a functional obstruction with accumulation of gas and fluids.
  • Volvulus or Intussusception (Less Likely in Chronic Constipation Alone): These are acute conditions involving bowel twisting or telescoping, but chronic partial obstruction could present with distention.
  • Large Abdominal Mass: Although rare, a tumor could cause obstruction and distention.
  • Ascites (Fluid in the Abdominal Cavity): While not directly caused by constipation, underlying conditions leading to ascites could also present with altered bowel habits.

• Tests/Labs:

  • Abdominal X-ray: This is usually the first-line investigation to assess the degree of fecal loading and look for signs of bowel obstruction (e.g., dilated loops of bowel, air-fluid levels).
  • Physical Examination: Palpation of the abdomen can reveal a large fecal mass.
  • Contrast Enema (Barium Enema): Can help identify a transition zone in Hirschsprung's disease or other structural abnormalities causing obstruction.
  • Abdominal Ultrasound or CT Scan: May be needed to further evaluate for masses, fluid collections, or signs of pseudo-obstruction.
  • Colonic Transit Studies: To assess colonic motility and identify areas of slow transit.
  • Rectal Biopsy and Anorectal Manometry: To evaluate for Hirschsprung's disease if suspected.
  • Blood Tests: Electrolytes to assess for dehydration, inflammatory markers if considering IBD, and other tests depending on the suspected underlying cause.

It is crucial to remember that a thorough history, detailed physical examination, and careful consideration of the child's overall clinical picture are essential in guiding the selection and interpretation of these tests. Often, a combination of tests is needed to reach an accurate diagnosis. Consulting with a pediatric gastroenterologist is highly recommended for children with chronic constipation, especially when accompanied by red flag symptoms like those listed above

Sample Answer

a. Constipation present since birth or early infancy.

This suggests a possible congenital or structural anomaly or a very early onset functional issue.

• Possible Causes:

  • Hirschsprung's Disease: This is the most significant concern. It's a congenital condition where nerve cells (ganglion cells) are missing in a segment of the large intestine (colon). This prevents peristalsis (the wave-like muscle contractions that move stool), leading to a functional obstruction and constipation from birth.
  • Anorectal Malformations: These are birth defects where the anus and rectum haven't developed properly. This can range from minor issues to complete absence of an anal opening.
  • Cystic Fibrosis: While primarily a respiratory disease, cystic fibrosis can affect the digestive system, leading to thick, sticky mucus that can cause meconium ileus at birth (failure to pass the first stool) and chronic constipation later in infancy.
  • Hypothyroidism (Congenital): A deficiency in thyroid hormone can slow down metabolism and bowel motility from birth.
  • Spinal Cord Abnormalities: Conditions affecting the spinal cord present at birth (e.g., myelomeningocele) can disrupt bowel innervation.
  • Cow's Milk Protein Allergy/Intolerance: In some infants, this can manifest with constipation, though it often presents with other symptoms like vomiting, diarrhea, and eczema.
  • Chronic Intestinal Pseudo-obstruction (Rare): This involves impaired intestinal motility without a mechanical obstruction. It can be congenital.