Pediatric GI Disease

Question 1

Anatomic features/pathogenesis of tracheo-esophageal fistula

Answer 1

• = 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

Question 2

Anatomic features/pathogenesis of infantile hypertrophic pyloric stenosis

Answer 2

• 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

Question 3

Developmental basis of tracheo-esophageal fistula

Answer 3

• 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

Question 4

Anatomic features/pathogenesis of Meckel Diverticulum

Answer 4

• 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

Question 5

Presentation of Meckel diverticulum

Answer 5

• often asymptomatic
• obstruction
• bleeding
• inflammation

Question 6

Anatomy/pathogenesis of omphalocele

Answer 6

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

Question 7

Omphalocele vs. Gastroschisis

Answer 7

• 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

Question 8

Anatomy/pathogenesis of malrotation of intestines

Answer 8

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

Question 9

Anatomy/pathogenesis of GI duplications/cysts

Answer 9

• 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

Question 10

Anatomy/pathogenesis of intestinal atresia

Answer 10

• 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)

Question 11

Anatomy/pathogenesis of imperforate anus/rectal agenesis

Answer 11

• 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

Question 12

Developmental abnormality of hirschprung disease

Answer 12

• 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

Question 13

Predisposing factors/pathogenesis of neonatal necrotizing enterocolits

Answer 13

• 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

Question 14

Characteristics of reflux esophagitis

Answer 14

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

Question 15

Characteristics of allergic esophagitis

Answer 15

•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