Hirschsprung's disease Flashcards
Definition
Aganglionosis->partial or complete obstruction due to tonically contracted lumen
When does it present
Usually within first year of life.
Cingenital associations
Down syndrome
Anorectal rarely
Why misdiagnosis of Hirschsprungs and anorectal
Most patients born with anorectal malformations with present with a degree of constipation
Chromosomal abnormality
Associated with deletion in long arm xsome 10
Key features in pathological diagnosis
Absence of ganglion cells
Hypertrophic nerve
Increased acetylcholinesterase
Pathohysiology
arrest in the craniocaudal migration of the neuroenteric ganglion cells from the neural crest into the upper gastrointestinal tract, down through the vagal fibres, and along the distal intestine-> ganglion cells are missing from the Auerbach myenteric plexus, the Henle plexus, and at the Meissner plexus->para/sympathetic affected, uncoordinated contraction.
Response of muscle
Spasm, lack of propulsive peristalsis and mass contraction->lack relaxation of bowel/internal sphincter
Develops megacolon
Presentation in neonate
Failure to pass meconium in first 48 hours
Billous vomiting
Enterocolitis
Explosive passage of liquid and foul stools
Abdominal distension
Fever
Failure to thrive
Presentation in older children
Chronic constipation
Strong risk factor
Downs syndrome
Investigations
Plain abdominal xray
Contrast enema
?rectal biopsy
Findings on abdominal xray
Air fluid level
Distended bowel loops
Findings in enema
Narrowed distal colon with dilation of proximal
Findings on biopsy
Absence of ganglion cells Thickened non-myelinated nerves \+Acetycholinesterase -ve NADP neurons \+ACh nerve bundles
Differentials
Meconium plug CF with meconium ileus Hypothyroidism Chronic constipation Cerebral injury
Management of typical without enterocolitis
Bowel irrigation
Definitive surgery
Management of typical with enterocolitis
Bowel irrigation
IV antibiotics
Decompression by colostomy
Definitive surgery
Management of total colonic aganglionosis
Ileostomy
Definitive surgery
Short segment disease
Resection
Bowel irrigation
IV antibiotics
When may there be occassional passage of stool w/ diarrhea
When only a few centremetres of the rectum are affected
What are the three surgical procedures for repair
Swenson rectosigmoidectomy
Duhamel retrorectal transanal pullthrough
Soave endorectal pullthrough
Describe the surgery for repair
Remove the denervated segment and bring to the unaffected anus
Short term risks of operation
Normal operative and anaesthetic risks
Anastomosis leak/breakdown
Complications (6)
Recurrent enterocolitis Constipation Stricture Prolapse Epianal abscess Fecal soiling
What is the most important complication and why
Enterocolitis, major cause of mortality
Outline the post-operative monitoring (3)
Observe for enterocolitis (diarrhea and fever)
Receive follow up until toilet trained
Soiling after toilet training needs medical treatment
What is an important cause and management if enterocolitis persists beyond 1 year
Anatomical cause
May need to redo the pull through procedure
Prognosis
Excellent
Percentage and type of defractory problems following surgical treatment
10-20%
Enterocolitis
Incontinence
Persistent constipation
