Congenital Megacolon (HiCongenital Megacolon (Hirschsprung’s disease)rschsprung’s disease)

소아과 소아과 R3R3안선영안선영

IncidenceIncidence

absence of ganglion cells in the bowel wall absence of ganglion cells in the bowel wall beginning in the internal anal sphincter and beginning in the internal anal sphincter and extending proximallyextending proximally

1/5000 live births1/5000 live births

M:F = 4:1 M:F = 4:1

Racial distribution similarRacial distribution similar

Embryology and EtiologyEmbryology and Etiology

Neuroenteric cells migrate from neural Neuroenteric cells migrate from neural crest to upper end of alimentary tract acrest to upper end of alimentary tract and proceed in distal directionnd proceed in distal direction

1212thth week : migration to distal colon – fi week : migration to distal colon – first into myenteric (Auerbach’s plexus) trst into myenteric (Auerbach’s plexus) then into submucosal plexushen into submucosal plexus

Embryologic defectEmbryologic defect

Failure of neural crest migrationFailure of neural crest migration

Immunologic mechanism: increased expressiImmunologic mechanism: increased expression of class II antigens in the mucosa and subon of class II antigens in the mucosa and submucosa-> causes fetus to mount an immunolmucosa-> causes fetus to mount an immunologic response against the neuroblastogic response against the neuroblast

Genetic factors: May affect more than one faGenetic factors: May affect more than one family member in 3-7% of casesmily member in 3-7% of cases

Deletion in the RET gene chromosome 10q11 Deletion in the RET gene chromosome 10q11 and EDNRB gene located on 13q22 and EDN and EDNRB gene located on 13q22 and EDN 3 gene (major role in the development of the 3 gene (major role in the development of the enteric nervous system)enteric nervous system)

PathologyPathology Neonatal period: intestine is normalNeonatal period: intestine is normal

Proximal ganglionic intestine hypertrophies and becoProximal ganglionic intestine hypertrophies and becomes thicker and longer than normalmes thicker and longer than normal

Taeniae disappear and longitudinal muscle layer comTaeniae disappear and longitudinal muscle layer completely surrounds colonpletely surrounds colon

Distal intestine: absence of ganglion cells in the subDistal intestine: absence of ganglion cells in the submucosal (Meissner’s) plexus and myenteric (Auerbacmucosal (Meissner’s) plexus and myenteric (Auerbach’s) plexush’s) plexus

Marked increase in nerve fibers which extend into the Marked increase in nerve fibers which extend into the submucosa (seen with acetylcholinesterase stain)submucosa (seen with acetylcholinesterase stain)

Aganglionosis extends to rectosigmoid region in 80% Aganglionosis extends to rectosigmoid region in 80% of casesof cases

Clinical SymptomsClinical Symptoms Should be considered in any child who has history of Should be considered in any child who has history of

constipation dating to newborn periodconstipation dating to newborn period

90% of cases diagnosed in newborn period90% of cases diagnosed in newborn period

Most common presentation in newborns: delayed stool passage Most common presentation in newborns: delayed stool passage within first 48 hrs of lifewithin first 48 hrs of life

Constipation, abdominal distension, poor feeding and vomitingConstipation, abdominal distension, poor feeding and vomiting

Constipation followed by explosive diarrhea, failure to thriveConstipation followed by explosive diarrhea, failure to thrive

in older children, large fecal mass palpable in left lower quadrant. in older children, large fecal mass palpable in left lower quadrant. rectum is emptyrectum is empty

stools: small pellets, ribbon-like, fluid consistency stools: small pellets, ribbon-like, fluid consistency

Rectal exam: normal anal tone followed by explosive Rectal exam: normal anal tone followed by explosive discharge of feces and gasdischarge of feces and gas

failure to pass stool leads to dilatation of proximal bfailure to pass stool leads to dilatation of proximal bowel -> increased intraluminal pressure, decreased bowel -> increased intraluminal pressure, decreased blood flow and deterioration of the mucosal barrierlood flow and deterioration of the mucosal barrier

stasis leads to bacterial proliferation and enterocolitistasis leads to bacterial proliferation and enterocolitis with sepsiss with sepsis

early diagnosis important in reducing mortalityearly diagnosis important in reducing mortality

Study of 123 patients with HDStudy of 123 patients with HD

60% were diagnosed in neonatal period60% were diagnosed in neonatal period

Delayed passage of meconium (65%), abdoDelayed passage of meconium (65%), abdominal distension and constipationminal distension and constipation

17% had associated anomalies17% had associated anomalies

86% had aganglionosis extending to rectos86% had aganglionosis extending to rectosigmoid regionigmoid region

Associated AnomaliesAssociated Anomalies

Present in 10-30% of HDPresent in 10-30% of HD

Urogenital tract (11%), cardiovascular sUrogenital tract (11%), cardiovascular system (6%), GI system (6%), other malfystem (6%), GI system (6%), other malformations, cataract, cleft palate (8%)ormations, cataract, cleft palate (8%)

3% Down SD3% Down SD

Diagnosis IDiagnosis I

Abdominal x-rays: air fluid levels in colon and distended loops oAbdominal x-rays: air fluid levels in colon and distended loops of intestinef intestine

Barium enema: narrow distal segment and dilated proximal intesBarium enema: narrow distal segment and dilated proximal intestine; presence of funnel-shaped transition zone between these 2 tine; presence of funnel-shaped transition zone between these 2 segments (diagnostic accuracy 80-90%)segments (diagnostic accuracy 80-90%)

Transition zone may not be present before 1-2 weeks of ageTransition zone may not be present before 1-2 weeks of age

significant barium remaining in colon in 24-hr delayed film significant barium remaining in colon in 24-hr delayed film

helpful in determining level of aganglionosishelpful in determining level of aganglionosis

Should not be done with clinical enterocolitis: may cause perforShould not be done with clinical enterocolitis: may cause perforationation

Diagnosis IIDiagnosis II

Anorectal manometry: absence of relaxation refleAnorectal manometry: absence of relaxation reflex after distension of balloon in rectumx after distension of balloon in rectum

Diagnostic Diagnostic accuracy 85%accuracy 85%

May be done at bedside or as outpatient procedurMay be done at bedside or as outpatient procedure : no complicationse : no complications

Test unreliable in cases where gestational age pluTest unreliable in cases where gestational age plus age after birth is less than 39 weeks and weight is age after birth is less than 39 weeks and weight is less than 2.7kgs less than 2.7kg

Diagnosis IIIDiagnosis III

Rectal biopsy: gold standardRectal biopsy: gold standard

Can be performed at bedside without general anesthCan be performed at bedside without general anesthesiaesia

Biopsy taken at 2 cm, 3 cm, 5 cm above dentate lineBiopsy taken at 2 cm, 3 cm, 5 cm above dentate line

Diagnostic accuracy: 99.7%Diagnostic accuracy: 99.7%

Most common problem is inadequate specimen (insuMost common problem is inadequate specimen (insufficient amount of submucosa) fficient amount of submucosa)

Differential diagnosisDifferential diagnosis

Meconium plug SD, small left colon SD, Meconium plug SD, small left colon SD, distal ileal atresia, low imperforate anusdistal ileal atresia, low imperforate anus

Neonatal sepsis, hypothyroidism, brain Neonatal sepsis, hypothyroidism, brain injury, prematurity may result in delayeinjury, prematurity may result in delayed passage of stoold passage of stool

TreatmentTreatment

Decompression: nasogastric tube, rectal tubeDecompression: nasogastric tube, rectal tubess

perform surgery after diagnosis established operform surgery after diagnosis established or perform temporary colostomy until infant is r perform temporary colostomy until infant is 6-12 mos old 6-12 mos old

3 basic surgical approaches: 3 basic surgical approaches:

1)1) Swenson: excise aganglioniSwenson: excise aganglionic segment and anastomose c segment and anastomose the normal proximal bowel tthe normal proximal bowel to the rectum 1-2 cm above to the rectum 1-2 cm above the dentate linehe dentate line

2)2) Duhamel: neorectum createDuhamel: neorectum created-> normally innervated bod-> normally innervated bowel brought down behind awel brought down behind aganglionic rectum: anterior ganglionic rectum: anterior aganglionic half with normaaganglionic half with normal sensation and posterior hal sensation and posterior half ganglionic with normal prlf ganglionic with normal propulsionopulsion

3)3) Soave: endorectal pull-thr Soave: endorectal pull-through procedure-> strip muough procedure-> strip mucosa from the aganglionic cosa from the aganglionic rectum and bring normally rectum and bring normally innervated colon through tinnervated colon through the residual muscular cuffhe residual muscular cuff

Ultrashort segmental HD: Ultrashort segmental HD: excision of strip of rectal excision of strip of rectal

musclemuscle

ComplicationsComplications

Early complications: anastomotic strictures Early complications: anastomotic strictures (15%), wound infections (11%), anastomotic l(15%), wound infections (11%), anastomotic leaks (7%)eaks (7%)

Late complications: chronic constipation, entLate complications: chronic constipation, enterocolitis, encoporesiserocolitis, encoporesis

Good prognosis: more than 90% of children aGood prognosis: more than 90% of children achieve normal bowel movementchieve normal bowel movement