Good Morning!

1. Good Morning! Monday, August 6th, 2012

2. Neonates: First Stool • Healthy full term neonates: • 60% stool in first 8 hours • 91% by 16 hours • 98.5% by 24 hours • >99% by 48 hours • Premature neonates: • 95% stool by 48 hours

3. Illness Script • Predisposing Conditions • Age, gender, preceding events (trauma, viral illness, etc), medication use, past medical history (diagnoses, surgeries, etc) • Pathophysiological Insult • What is physically happening in the body, organisms involved, etc. • Clinical Manifestations • Signs and symptoms • Labs and imaging

5. Barium Enema

6. Barium Enema

9. Hirschsprung: Predisposing Conditions • Sporadic or familial (4 gene mutations identified) • Male predominance (3.8:1) • Slightly more common in African-American and Asian ethnicities • 70% are isolated birth defect • 30% associated with other disorders • Trisomy 21 • Waardenburg, Laurence-Moon-Biedl, Smith-Lemli-Opitz, MEN type IIa, congenital central hypoventilation syndrome (Haddad syndrome)

10. Hirschsprung: Pathophysiology • Congenital absence of ganglion cells in the myenteric and submucousal colonic plexuses • Failure of migration of ganglion cell precursors to migrate from the neural crest to GI tract (5-12 WGA) • Begins at the internal anal sphincter and extends proximally to a variable distance • The earlier the arrest in migration occurs, the longer the segment involved • Abnormal innervation disrupts the inhibitory paraympathetic nerves  results in sustained contraction of the aganglionic segment • Leads to colonic obstruction • 80% are short segment (S-HSD) • Distal to splenic flexure; often limited to rectosigmoid • 20% are long segment (L-HSD) • Rarely can affect entire colon and small intestine

11. Hirschsprung: Clinical Manifestations** • Failure to pass meconium in first 24hrs of life** • Abdominal distension • Bilious emesis • Diarrhea • Feeding intolerance • Short-segment HD: Presents later in childhood • Intractable constipation • Ribbon-like stools • Abdominal distension • FTT • Rectal exam: increased tone, empty rectal vault, explosive release of stool

13. Barium enema • Transition zone • Narrow-diameter rectosigmoid colonic segment • Dilated/hypertrophied proximal colon

14. Hirschsprung: Diagnosis • Barium enema: suggestive; but absence of transition zone does not rule out HD • Anorectalmanometry • Tests response to balloon inflation in the region of the internal and external sphincters • Normally, balloon inflation/dilation of rectum induces relaxation of internal sphincter • Absence of this relaxation indicates HD • Rectal biopsy (Gold standard)** • Suction rectal biopsy at 2 and 5cm from anal verge • Looking for absence of ganglion cells • Acetylcholinesterase staining shows hyperplastic axons due to absence of ganglion cells • If inconclusive, may need full thickness biopsy

15. Hirschsprung: Complications** • Enterocolitis** • Bacterial infection secondary to stasis/dilated colon • Watery, explosive foul-smelling stools, +/- bleeding • Abdominal distension • Fever • Hemodynamic instability • 20% mortality • Sepsis • Bowel Perforation • Stricture formation after surgery

16. Treatment • Surgery • Remove all or most of the aganglionic segment • Reanastomose normal proximal bowel to the distal rectum or anal canal • Goal: to establish regular defecation and maintain continence • Most have a good outcome, however 30% remain constipated or never develop fecal continence

17. Thank you!! • Noon conference: NICU Radiology (Dr. Congeni)