True about Hirschsprung’s disease is
First, the core concept here is Hirschsprung's disease. It's a congenital condition where the absence of ganglion cells in the myenteric and submucosal plexus of the distal colon leads to functional obstruction. The key is understanding the pathophysiology, clinical features, and diagnostic methods.
The correct answer must relate to a true statement about the disease. Common MCQ options might include things like associated genetic syndromes (like Down syndrome), the typical presentation in infants (Hirschsprung's is a common cause of neonatal intestinal obstruction), diagnostic methods (rectal biopsy showing absence of ganglion cells), or treatment (surgical resection of the aganglionic segment).
If the correct answer is D, then the options might be something like:
D. Rectal biopsy shows absence of ganglion cells in the affected segment.
To explain why D is correct: The hallmark of Hirschsprung's disease is the absence of ganglion cells in the affected part of the colon. This is confirmed by a full-thickness rectal biopsy, which is the gold standard diagnostic test. The biopsy should show no ganglion cells and an increase in the number of nerve fibers, which is a key histological finding.
Now, the incorrect options could be:
A. Caused by deficiency of acetylcholinesterase – No, Hirschsprung's is due to failure of neural crest cell migration, not enzyme deficiency.
B. Characterized by Hirschsprung's area with dilated bowel proximal to the narrowed segment – This might be a distractor. The aganglionic segment is actually narrow, with a dilated proximal segment.
C. Commonly associated with Turner syndrome – Turner syndrome is a chromosomal abnormality, but Hirschsprung's is more commonly associated with Down syndrome (Trisomy 21).
Clinical pearls: Remember the key diagnostic test (rectal biopsy) and associated conditions like Down syndrome. Also, note that the affected segment is aganglionic and narrow, not dilated. The treatment is surgical removal of the aganglionic segment.
Putting it all together, the correct answer is D because the absence of ganglion cells in the rectal biopsy is the definitive diagnosis. The other options either confuse the pathophysiology with another condition or mix up clinical features.
**Core Concept**
Hirschsprung’s disease is a congenital absence of ganglion cells in the myenteric and submucosal plexus of the distal colon, leading to functional obstruction. Diagnosis relies on histological confirmation of aganglionosis via rectal biopsy, often associated with Down syndrome (Trisomy 21).
**Why the Correct Answer is Right**
The hallmark of Hirschsprung’s disease is the absence of ganglion cells in the affected bowel segment, confirmed by full-thickness rectal biopsy. This test reveals not only absent ganglion cells but also hypertrophic nerve fibers due to unopposed acetylcholine activity. The aganglionic segment is typically narrow, while the proximal colon becomes dilated and hypertrophied over time.