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Flashcards in Pediatric GI Disease Deck (15):
1

Anatomic features/pathogenesis of tracheo-esophageal fistula

  • = connection of distal esophagus and trachea in the setting of esophageal atresia
    • proximal esophagus ==> blind pouch 
    • distal esophagus connected to trachia
  • commonly present w/other congenital anomalies
  • presentation:
    • @ intrauterine life
      • polyhydramnios
      • lack of stomach air on US
    • post-natal:
      • chocking w/feeds
      • inability to swallow

2

Anatomic features/pathogenesis of infantile hypertrophic pyloric stenosis

  • Presentation:
    • non-bilious, projectile vomiting (70%)
    • upper abdominal mass (60-80%)
    • usually presents around 3 wks of life
  • Anatomy
    • hypertrophy + hyperplasia of smooth muscle at gastric wall @ level of pylorus ==> narrow antrum ==> obstruction
    • secondary dilation of proximal stomach
       

3

Developmental basis of tracheo-esophageal fistula

  • TEF due to abnormal separation of foregut tube into esophagus and trachea.
  • Successive stages:
    • (A) The laryngotracheal diverticulum forms as a ventral outpouching from the caudal part of the primitive pharynx.
    • (B) Longitudinal tracheoesophageal folds begin to fuse toward the midline to eventually form the tracheoesophageal septum.
    • (C) If the tracheoesophageal septum deviates posteriorly, esophageal atresia with a tracheoesophageal fistula develops 

4

Anatomic features/pathogenesis of Meckel Diverticulum

  • most common malformation of small intestine
  • anatomy
    • partial persistence of vitelline (omphalomesenteric) duct or yolk stalk
    • ==> blind pouch fro terminal ileum (2-3 cm in length/width)
    • sometimes also a sinus tract/fibrous band from umblicus ==> small bowel obstruction
  • histology
    • hetertropic gastric/pancreatic tissue

5

Presentation of Meckel diverticulum

  • often asymptomatic
  • obstruction
  • bleeding
  • inflammation

6

Anatomy/pathogenesis of omphalocele

  • anatomy/embryology
    • failure of intestes to return to abdomen follwing physiologic herniation @ wks 6-10
    • peritoneal and amniotic covering

7

Omphalocele vs. Gastroschisis

  • gastroscchisis = bowel protrusion from abdomen, but by a different mechanism
    • due to defect in abdominal wall
    • ==> NO amniotic covering
  • omphalocele
    • both peritoneal and amniotic covering

8

Anatomy/pathogenesis of malrotation of intestines

  • intestine malformation ==> cannot assume normal position in abdomen
    • abnormal rotation/fixation of intestinal tract
  • most asymptomatic; typical presentation = midgut volvulus & obstruction (bilious vomiting)

9

Anatomy/pathogenesis of GI duplications/cysts

  • Anatomy/embryology
    • Saccular (cystic) or tubular structures containing all layers of normal bowel wall and gastrointestinal lining, which may or may not communicate with bowel
  • Common sites
    • small bowel
    • large bowel
    • gastric
       

10

Anatomy/pathogenesis of intestinal atresia

  • anatomy
    • stenosis = congenital narrowing
    • atresia = complete failure of development ==> blind ending
    • Duodenal atresia most common; up to 40% have Down Syndrome
  • Pathobiology: presumed vascular (ischemic) etiology
  • Presentation: polyhydramnios, obstructive symptoms (bilious vomiting)

11

Anatomy/pathogenesis of imperforate anus/rectal agenesis

  • Varying degrees of severity:
    • mild: membrane of tissue covering anus 
    • severe: complete agenesis of rectum
  • frequently associated with fistula formation (perineum, bladder/urethra, vagina)
  • up to 50% associated with other anomalies
     

12

Developmental abnormality of hirschprung disease

  • mutations @ RET receptor or ligand genes that control development of the nervous plexi of the colon
  • Endothelin 3 and endothelin receptor genes are also important regions of mutation
  •  mutations ==> failure of the bowel nerve plexi (both Auerbach and Meissner) to form in a segment of the bowel wall with a resulting absence of ganglion cells
    • ==> constricted segment at abnormality + upstream bowel = dilated

13

Predisposing factors/pathogenesis of neonatal necrotizing enterocolits

  • complication of prematurity during first week ==> 10 days of life
  • associated w/hypoxemia 
    • ==> blood diversion from intestine
    • ==> ischemic damage ==> invasion + gas gangrene
    • ==> perforation/peritonitis
  • pathogenesis
    • Enteric feeds; bacterial flora; immune immaturity; bowel hypoperfusion/ischemia 

14

Characteristics of reflux esophagitis

•Etiology: incompetent GE sphincter/ hiatal hernia
•pH probe: positive
•Histology
–Mild intraepithelial eosinophilic infiltrate
–Reactive epithelial changes
–Predominantly distal esophageal involvement
•Treatment
–Acid blockade
 

15

Characteristics of allergic esophagitis

•Etiology: immunologic reaction to dietary allergen; incompletely understood
•pH probe: negative
•Histology
–Marked intraepithelial eosinophilic infiltrate
–Reactive epithelial changes
–Frequent submucosal inflammation with fibrosis
–Distal and proximal esophageal involvement
•Treatment
–Dietary modification
–Steroids