Chapter 17- The GI Tract Flashcards
What congenital anomalies are common in the GI tract?
Atresia
Fistula
Stenosis
Congenital duplication cysts
Diaphragmatic hernia
Omphalocele
Gastroschisis
Ectopia
Meckel diverticulum
Congenital hypertrophic pyloric stenosis
Hirschsprung disease
What is the most common form of intestinal atresia?
Imperforate anus
What is esophageal atresia associated with?
A fistula connecting the upper or lower esophageal pouches to a bronchus or the trachea
Esophageal atresia causes what form of obstruction?
Mechanical
What is the most common site of intestinal fistula?
Esophagus-trachea
Stenosis is an incomplete form of what?
Atresia
What causes stenosis?
Fibrous thickening of the wall
What areas of the GI tract does stenosis commonly affect?
Esophagus
Small intestine
What are congenital duplication cysts?
Masses with redundant smooth muscle layers
What is a diaphragmatic hernia?
An incomplete diaphragm allows the abdominal viscera to herniate into the thoracic cavity
What is the difference between an omphalocele and gastroschisis?
Omphalocele- abdominal musculature is incomplete, viscera herniates into the ventral membranous sac
Gastroschisis- involves all the abdominal wall layers, not just the musculature, not contained
What is the most common form of intestinal ectopia?
Gastric mucosa in the upper third of the esophagus (acid production)
What are the features of Meckel diverticulum?
Blind outpouching of the GI tract
Includes all three layers of the bowel wall
Occurs in the ileum (2ft of ileocecal valve)
Tip shows ectopia tissue
Pouch is antimesenteric
How does Meckel diverticulum occur?
Failed involuntary of the vitelline duct
How does Meckel diverticulum differ from acquired?
Acquired only lacks the muscularis layer (or show diminished muscularis propria)
What is congenital hypertrophic pyloric stenosis?
Hyperplasia of the pyloric muscularis propria, obstructs gastric outflow
What are the characteristics of congenital hypertrophic pyloric stenosis?
Onset at 3-6th week
Regurgitation, nonbilious vomiting after feeding
Firm ovoid mass
Left to right hyperperistalsis during feeding
What increases the risk of congenital hypertrophic pyloric stenosis?
Male
Monozygotic twins
Turner syndrome and trisomy 18
Exposure to erythromycin and azithromycin in first 2 weeks of life
What is Hirschsprung disease?
Aganglionic megacolon (loss of bowel innervation)
How does Hirschsprung disease occur?
Neural crest cell migration from the caecum to the rectum is arrested
Distal segment lacks Meissner submucosal and Auerbach mesenteric plexus
What are the characteristics of Hirschsprung disease?
Impaired peristalsis
Functional obstruction
Dilation proximal to affected segment
Mucosal inflammation or shallow ulcers
What disorders can cause esophageal obstruction?
Spasms
Diverticuli
Mucosal webs
Esophageal/Schatzki rings
Achalasia
What type of obstruction is caused by esophageal spasms?
Functional
What are the different types of esophageal diverticuli and where are they found?
Zenker- above upper esophageal sphincter
Traction- midpoint
Epiphrenic- above lower esophageal sphincter
How many walls do esophageal diverticuli involve?
One or more
What are mucosal webs?
Ledge-like protrusions of mucosa
What is Plummer-Vinson syndrome?
Constellation of mucosal webs, IDA, glossitis and Cheilosis
What is another name for Plummer-Vinson syndrome?
Paterson-Brown-Kelly syndrome
How do esophageal rings differ from mucosal webs?
Rings are thicker and circumferential
What are the two types of esophageal rings and what are their characteristics?
A- squamous epithelium above the gastroesophageal junction
B- gastric cardiac mucosa at the squamocolumnar junction
What is achalasia?
Triad of incomplete LES relaxation, increased LES tone and esophageal aperistalsis
What causes primary achalasia?
Failure of distal esophageal neurons to induce LES relaxation or degenerative changes in neuron innervation
What can cause secondary achalasia?
Chaga’s
Disorders of vagaries dorsal motor nuclei
Diabetic autonomic neuropathy
Infiltrative disorders
What are the chief symptoms of esophagitis?
Pain
Dysphagia
What can cause esophagitis?
Lacerations (Mallory Weiss tears)
Chemicals
Infections- HSV, CMV, candida
Reflux
How do the ulcers in esophagitis caused by HSV and CMV differ?
HSV- punched out
CMV- shallower
What is the most common cause of esophagitis?
Reflux
What causes reflux?
Decreased LES tone
Increased abdominal pressure
Hiatal hernia
What are the characteristics of esophagitis caused by reflux?
Ulceration, hematemesis, melena, stricture, Barrett esophagus
Nasal zone hyperplasia
Elongation of lamina propria papillae
What are the characteristics of eosinophilic esophagitis?
Dysphagia and feeding intolerance (GERD-like symptoms)
Large number of superficial intraepithelial eosinophils
Mostly atopic
What are esophageal varices?
Congested subepithelial and submucosal venous plexi
Tortuous, dilated veins within the submucosal of the distal esophagus and proximal stomach
What types of patients are esophageal varicies seen in?
Cirrhotic patients (hypertension)
Alcoholic liver disease
Schistomiasis infections
Barrett esophagus is a complication of what?
Chronic GERD
What is Barrett esophagus?
Intestinal metaplasia within the esophageal mucosa (glandular tissue replaces squamous)
What is Barrett esophagus a precursor lesion to?
Esophageal adenocarcinoma
What is required for the diagnosis of Barrett esophagus?
Endoscopic evidence of metaplastic columnar mucosa above the gastroesophageal junction
What is the gross morphology of Barrett esophagus?
Tongues of velvety red mucosa extending upwards from the gastroesophageal junction
The majority of esophageal tumours are what kinds?
Adenocarcinoma
Squamous cell carcinoma
What is the most common form of benign esophageal tumours?
Leiomyomas
Adenocarcinoma in the esophagus normally evolves from what?
Barrett esophagus
Where is SCC often found in the esophagus?
Middle third
What is the pathology of acute gastritis?
Neutrophils present
Mechanisms that protect the mucosa are overwhelmed/defective
What are causative agents of acute gastritis?
NSAIDS
Alcohol
Bile
Stress-induced injury
What are the types of ulcers associated with acute gastritis and when do they occur?
- Stress- shock, sepsis, severe trauma
- Curling- in the proximal duodenum after severe burns or trauma
- Cushing- in the esophagus, duodenum and stomach of patients with intracranial disease
How do NSAIDS cause ulcers?
Inhibit COX-dependent synthesis of PGE2 and I2 (stimulate defence mechs)
What is the morphology of stress-related ulcers?
Small, diffuse
Stained brown/black
How does intracranial injury cause ulcers?
Stimulates vagal nuclei (hypersecretion of gastric acid)
What is the most common cause of chronic gastritis?
H. pylori
Where does H. pylori most often cause chronic gastritis?
Antrum (increased acid production)
What is the gross morphology associated with gastritis caused by H. pylori?
Erythmatous, coarse, nodular mucosa
Chronic gastritis due to H. pylori can progress to what?
Multifocal atrophic gastritis
Intestinal metaplasia
Chronic gastritis not caused by H. pylori is the result of?
Autoimmune disorder or peptic ulcer disease
Autoimmune gastritis normally spares what area of the stomach?
The antrum
What is autoimmune gastritis associated with?
Hypergastrinemia
What is the gross morphology of autoimmune gastritis?
Rugal folds lost
Diffuse mucosal damage in body and fundus
Inflammatory infiltrate
What is PUD?
Chronic mucosal ulceration
What is the morphology of PUD?
Solitary ulcers with punched out defects and a clean base
What is the cause and morphology of hypertrophic gastropathies?
Epithelial hyperplasia linked to excessive GF production
Giant enlargement of rugal folds
What are two forms of hypertrophic gastropathies?
- Menetrier disease
2. Zollinger-Ellison syndrome
What is the pathology of Menetrier disease?
Folveolar cell hyperplasia in body and fundus
Protein losing enteropathy (hypoproteinemia)
What is the pathology of Zollinger-Ellison syndrome?
Gastronomes in the small bowel or pancreas increase gastric release
Increased number of gastric parietal cells and HCl production
Ulcers and/or diarrhea
What are the different types of benign gastric polyps and what are their characteristics?
Inflammatory and hyperplastic- less than 1cm, multiple lesions, can have surface ulceration
Fundic gland- single or multiple smooth, well circumscribed lesions
Gastric adenoma- usually solitary and greater than 2cm
What percentage of gastric adenomas harbour carcinoma?
30%
What is the most common form of gastric malignancies?
Adenocarcinoma
What is important for the oncogenesis of adenocarcinoma?
Loss of intracellular adhesion (E-cad)
Adenocarcinoma affects what areas of the stomach most?
Antrum > lesser curve > greater curve
Gastric adenocarcinoma is associated with what?
H. pylori
N-nitro compounds
Benzo-alpha-pyrene
What are the two forms of gastric adenocarcinoma and their characteristics?
- Intestinal- bulky, exophytic masses with glandular structures and flat dysplasia
- Diffuse- signet ring cells, no glands with flat desmoplastic response (thickened wall/linitus plastic)
What does the prognosis of gastric adenocarcinoma depend on?
Depth of invasion
Node involvement