Examkin

Question

Difficulty: MediumPediatric Gastrointestinal Disorders

A 9-month-old male infant is brought to the pediatric clinic by his parents due to severe, chronic constipation and poor weight gain. The parents report that he has a bowel movement only once every 5 to 6 days, often requiring significant straining, and his abdomen frequently appears noticeably swollen. He was born at 39 weeks gestation and passed his first meconium at 50 hours of life. His diet consists of breast milk and age-appropriate pureed solids. His weight has fallen from the 45th percentile at birth to the 10th percentile currently. Vital signs are within normal limits for age. Physical examination reveals a distended, tympanitic abdomen. Upon digital rectal examination, there is increased anal sphincter tone and an empty rectal vault; withdrawal of the examining finger is immediately followed by an explosive expulsion of foul-smelling liquid stool and gas. Which of the following is the most accurate test to confirm the diagnosis in this patient?

  1. A
    Barium enema
  2. B
    Sweat chloride testing
  3. Suction rectal biopsyAnswer
  4. D
    Anti-tissue transglutaminase IgA antibody testing
  5. E
    Anorectal manometry

Answer

The most accurate test to confirm the diagnosis is a suction rectal biopsy.
The correct answer is suction rectal biopsy. This patient's presentation of delayed meconium passage, severe chronic constipation, failure to thrive, and a positive 'squirt sign' on digital rectal examination is highly suggestive of Hirschsprung disease. This condition occurs due to the failure of neural crest cells to migrate to the distal colon during embryonic development, leading to an aganglionic segment that remains tonically contracted and causes a functional obstruction. Although a barium enema is often the best initial imaging test to visualize a transition zone between the normal dilated colon and the narrowed aganglionic segment, the most accurate and definitive confirmatory test is a suction rectal biopsy. The biopsy must include the submucosa and will definitively show an absence of ganglion cells and the presence of hypertrophied nerve trunks.

Step-by-Step Solution

1
Analyze the clinical presentation.
The patient has chronic severe constipation, failure to thrive, a history of delayed meconium passage (>48 hours), and an explosive release of stool on digital rectal examination (the 'squirt sign').
Identifying the constellation of signs and symptoms is necessary to formulate the most likely underlying diagnosis.
2
Determine the most likely diagnosis.
The clinical picture is highly characteristic of Hirschsprung disease.
Hirschsprung disease is characterized by an aganglionic segment in the distal colon that fails to relax, leading to a functional obstruction.
3
Identify the most accurate diagnostic test.
While barium enema and anorectal manometry are useful initial tests, suction rectal biopsy is the definitive confirmatory test.
A biopsy provides histological proof of the absence of ganglion cells in the submucosa, which is the gold standard for diagnosis.

Key Concept

Hirschsprung disease is suspected in infants with delayed meconium passage, chronic constipation, and an explosive release of stool on rectal exam; the definitive diagnosis is established via suction rectal biopsy demonstrating absent ganglion cells.
Rate this question

Topics

Pediatric Gastrointestinal Disorders

More questions from this topic