Hirschsprung Disease Flashcards
Define Hirschsprung Disease.
Absence of ganglion cells from myenteric (Auerbach) + submucosal (Meissner’s) plexuses; begins at rectum + spreads proximally for a variable distance (75% rectosigmoid), ending at normally innervated, dilated colon
Explain the embryology and pathophysiology of Hirschsprung Disease.
Parasympathetic neuroblasts fail to migrate from the neural crest to the distal colon
Developmental failure of parasympathetic Auerbach + Meissner plexuses (Lack PS innervation)
Affected bowel has only sympathetic innervation
Uncoordinated peristalsis: hypertonicity + lack of appropriate relaxation in response to proximal distension
Narrow/contracted segment of bowel- functional obstruction
Stool stasis proximally.
3 risk factors for Hirschsprung Disease
Male 4:1
Chromosomal abnormalities: Down’s (Trisomy 21)
FHx (Men IIA association)
Summarise the epidemiology of Hirschsprung Disease?
1/5000 live births
Accounts for 20% of all neonatal obstruction.
90% present in neonatal period + 95% before 1st year.
What is the neonatal presentation of Hirschsprung Disease?
- Failure to pass meconium in 1st 24–48 hours
- Acute intestinal obstruction; abdo distension, poor feeding, bilious vomiting
- Severe life-threatening enterocolitis.
What is the infantile presentation of Hirschsprung Disease?
Chronic constipation with abdo distension
Intermittent abdo pain + fever during episodes of retained faeces
Failure to thrive.
What are the signs of Hirschsprung Disease?
Abdo distension with dilated loops of bowel.
PR: empty rectal vault, then explosive ‘gush’ of gas + stool
Septic signs if associated enterocolitis.
What are appropriate investigations for Hirschsprung Disease?
AXR: dilated bowel (exclude atresia as ddx)
Contrast enema: demonstrate short transition zone + rectal diameter similar/ equal to sigmoid colon (CI: perforation)
Rectal suction biopsy: GOLD
Describe the findings on rectal sucction biopsy in Hirschsprung Disease.
Absence of ganglion cells in Auerbach + Meissner plexuses
Increased acetylcholinesterase stained nerve endings
Hypertrophied nerve trunks in lamina propria + muscularis propria.
What are the positives and negatives of rectal suction biopsy?
+ve: bedside, highly accurate, no GA
-ve: must provide abx coverage, good decompression (no washouts for 24hrs post-procedure), risk of perforation, bleeding + inadequate sample
What is the initial management for Hirschsprung Disease?
Broad spectrum IV abx
NGT insertion
Rectal washouts (~15ml/kg TDS). If this fails (rare) may require a colostomy to decompress colon.
What is the definitive treatment for Hirschsprung’s disease?
Surgery: removal of distal aganglionic segment with pull-through of proximal normal ganglionic bowel.
Swenson, Soave, + Duhamel procedures
What is the prognosis of Hirschsprung Disease?
Non-adequately treated enterocolitis 80% mortality.
Post-op: good, many acquire faecal continence. Dependent on extent of aganglionosis.
What are complications associated with Hirschsprung Disease?
Hirschsrpung associated enterocolitis (HAEC)
Surgical complications: Constipation, enterocolitis, perianal abscess, faecal soiling + adhesions
What other causes of neonatal abdominal distension may be in the differential with Hirschsprungs disease?
Intestinal Atresia: congenital malformation resulting in complete obstruction
Meconium ileus: distal SB impacted by meconium leading to abdo distension + failure to pass.
Meconium Plug syndrome: failure to pass meconium but Sx resolve after passage of plug
Intestinal malrotation: midgut volvulus presenting with bilious vomiting + abdo distension.
