Chapter 17: The GI Tract - Congenital Abnormalities and Esophagus Flashcards
What is the most common form of esophageal atresia?
- Blind upper segment of esophagus
- Fistula b/w lower segment and trachea, most commonly at or near tracheal bifurcation
*Figure B is most common
What is the most common form of congenital intestinal atresia
A result of what embryologically?
- Imperforate anus
- Failure of cloacal diaphragm to involute
Developmental abnormalities of the the esophagus are associated with what other defects?
- Congenital heart defects
- Genitourinary malformation
- Neurologic disease
What is the most frequent site of ectopic gastric mucosa and what is it referred to here?
May result in what problems?
- Upper 1/3 of esophagus = Inlet patch
- Dysphagia, esophagitis, Barrett esophagus, or rarely, adenocarcinoma
What are examples of ectopia seen within the GI tract?
- Inlet patch: ectopic gastric mucosa in upper 1/3 of esophagus
- Ectopic pancreatic tissue: in stomach or esophagus
- Gastric heterotropia: patches of ectopic gastric mucosa in the small bowel or colon
Gastric heterotropia may present with what signs/symptoms?
Occult blood loss due to peptic ulceration of adjancent mucosa
Differentiate Omphalocele from Gastroschisis.
- Omphalocele = incomplete closure of abdominal ms. and abdominal viscera herniate INTO a ventral membranous sac
- Gastroschisis = similar to omphalocele, BUT involves ALL layers of abdominal wall from peritoneum to the skin - organs are exposed!
What is the most common true diverticulum and where does it occur?
- Meckel diverticulum
- Ileum
Cause of Meckel Diverticulum?
Failed involution of vitelline duct
What is the rule of 2’s in regards to Meckel Diverticulum?
- 2% of population
- Present within 2 feet of ileocecal valve
- 2 in. long
- 2x more common in males
- Symptomatic by age 2 (only 4% are ever symptomatic!)
What may be present in a Meckel Diverticulum that causes symptoms and what are these symptoms?
- Ectopic pancreatic or gastric tissue
- Peptic ulceration of adjancent SI tissue –> occult blood or abdominal pain resembling appendicitis or obstruction
Which sex is most commonly affected by congenital hypertrophic pyloric stenosis?
3-5x more likely in males
Which genetic disorders are associated with an increased risk of Pyloric Stenosis?
- Turner syndrome
- Trisomy 18
Which enviornmental factors have been linked to an increased risk of developing pyloric stenosis?
Erythromycin or azithromycin exposure, orally or via mother’s milk in first 2 weeks of life
When and how does congenital hypertrophic pyloric stenosis typically present?
- Between 3rd and 6th weeks of life
- New onset regurgitation w/ projectile, NON-bilious vomiting after feeding w/ frequent demands of re-feeding
What is palpated on PE with a congenital hypertrophic pyrloric stenosis?
What is tx?
- Firm, ovoid, 1-2 cm abdominal mass
- Tx = myotomy = curative
Which genetic disorder predisposes a child to Hirschsprung disease?
Down syndrome
What is the pathogenesis of Hirschsprung Disease (congenital megacolon)?
Produces a distal intestinal segment lacking what?
- Normal migration of NCC from cecum to rectum is arrested prematurely
- OR when ganglion cells undergo premature death
- Lacking both the Meissner submucosal and Auerbach myenteric plexus, dilation proximal to affected segment
Which genetic abnormality can account for the majority of familial cases of Hirschsprung disease?
Loss-of-function mutation in RET (receptor tyrosine kinase)
How does Hirschsprung disease typically present?
- Failure to pass meconium
- Obstruction or constipation
- Abdominal distention —> bilious vomiting
What are the major threats to life in regards to Hirschsprung disease?
- Enterocolitis
- Fluid/electrolye imbalance
- Perforation
- Peritonitis
Diagnosis of Hirschsprung disease requires what?
Which stain can be used?
- Documenting absence of ganglion cells within affected segment
- Immunohistochemical stains for acetylcholinesterase for ganglion cells
Which part of the colon is ALWAYS affected in Hirschsprung Disease?
Rectum
What are some causes of acquired megacolon?
Which is associated with loss of ganglion cells and which aren’t?
- Chagas disease —> Trypanosoma cruzi(Reduviid bug) = loss of ganglion cells
- Obstruction by neoplasm, inflammatory stricture, or Ulcerative Colitis = NOT associated w/ loss of ganglion cells
How does achalasia differ from hypertensive LES abnormalities?
Achalasia also has reduced esophageal peristaltic contractions
Larger Zenker Diverticulum may produce what signs and symptoms?
A mass and symptoms including regurgitation and halitosis (bad breath)
Idiopathic ledge-like protrusions of mucosa that may cause obstruction in the esophagus are known as?
Esophageal mucosal webs
Esophageal mucosal webs most often occur in whom?
Associated with what other diseases?
- Woman >40 yo
- GERD, chronic GVHD, or blistering skin diseases
What are the characteristic findings in Plummer-Vinson syndrome?
- Esophageal mucosal webs of the upper esophagus
- Iron-deficiency anemia
- Glossitis (beefy red tongue)
- Cheilosis (cracking of corners of mouth)
What is the main symptom of esophageal webs?
Non-progressive dysphagia associated w/ incompletely chewed food
How do Schatzki rings differ from esophageal webs?
Are circumferential, thicker, and include mucosa AND submucosa w/ occasional hypertrophic muscularis propria
What is the triad of Achalasia?
1) Incomplete LES relaxation
2) Increased LES tone
3) Aperistalsis of esophagus
Primary achalasia is the result of what?
What nerve/nucleus may be affected?
- Degeneration of the distal esophageal inhibitory neuronal (ganglion cells)
- Extraesophageal vagus n. and dorsal motor nucleus may also undergo degenerative changes
Secondary achalasia may arise in relation to infection by what bug?
What are the characteristics of this type of achalasia?
- Chagas disease (Trypanosoma cruzi)
- Destruction of myenteric plexus
- Failure of peristalsis
- Esophageal dilation