Gastroenterology Flashcards
Gastroesophageal reflux disease
Inappropriate transient relaxation of lower esophageal sphincter (most common) or low basal LES tone (scleroderma). Contributing factors such as delayed esophageal clearence, delayed gastric emptying, increased intra-abdominal pressure, hiatus hernia (worsens reflux). Acid hypersecretion by Zollinger-Ellison syndrome is a rare cause.
Features
- Typical: heartburn, acid regurgitation
- Atypical: chest pain, dysphagia, odynophagia
- Respiratory: chronic cough, wheezing, aspiration pneumonia
- Others: sore throat, hoarsness, dental erosions
Investigations
- Clinical diagnosis with symptom history and relief following trial of PPI (80% sensitive for reflux)
- Gastroscopy: rule out other differentials, distinguishes between esophagitis and non-esophagitis reflux, diagnoses Barrett’s esophagus
- Esophageal manometry: diagnose abnormal peristalsis/decreased LES tone
Management
- PPI most effective
- PRN: antacids
- weight loss, elevating head of bed for nocturnal symptoms
Complications
- esophageal stricture
- ulcer
- bleeding
- Barrett’s esophagus and esophageal adenocarcinoma
Barrett’s esophagus
Metaplasia of normal squamous epithelium to abnormal columnar epithelium, results in displacement of squamocolumnar junction at gastroesophageal junction.
More common in males, >50, Caucasians, smokers, overweight, long history of reflux symptoms.
Diagnosis
- endoscopy + biopsy: low-high grade dysplasia
- rate of malignant transformation is approx 0.4% per year for all BE patients prior to dysplasia
Managment
- high grade dysplasia: sureillence with intensive biopsy, endoscopic ablation/resection
- low grade dysplasia: surveillence gastroscopy with esophageal mucosal biopsy, one year after initial diagnosis then every 3 yrs
- PPI high dose in all patients
Dysphagia
Oropharyngeal (difficulty initiating swallow)
- Neurological: cortical, bulbar, peripheral
- Muscular: muscular dystrophy, polymyositis, myasthenis gravis, cricopharyngeal
- Structural: Zenker’s diverticulum, thyromegaly, cervical spur
Esophageal (inability to move food down esophagus)
Solid foods = Mechanical obstruction
- Progressive: carcinoma (age >50 + wt loss), peptic stricture (heartburn)
- Intermittent: Lower esophageal ring
Solid foods + liquids = Neuromuscular disorder
- Progressive: achalasia, scleroderma (relux symptoms)
- Intermittent: diffuse esophageal spasm
Achalasia
Failure of smooth muscle relaxation at LES, progressive loss of peristaltic function. Usually idiopathic but can be secondary to malignancy.
Pathophysiology
- inflammatory degeneration of Auerbach’s plexus, increase in LES pressure, incomplete relaxation of LES with swallowing.
Diagnosis
- CXR: no air in stomach, dilated esophageus
- Barium swallow: “bird’s beak” at LES
- Manometry: definitive diagnosis
Treatment
- dilation of LES with balloon + GERD prophylaxis, 50% good response
- botulinum injection into LES
- myomectomy
Scleroderma
Systemic disease characterised by vasculopathy and tissue fibrosis. Dysphagia caused by reflux and/or dysmotility, resulting in stricture.
Pathophysiology:
- Blood vessel damage, intramural neuronal dysfunction, distal esophageal muscle weakening, aperistalsis and loss of LES tone, reflus and stricture
Diagnosis:
- Clinical features of scleroderma
- manometry: decreased pressure in LES, decreased peristalsis in body of esophagus
Treatment
- medical: aggressive PPI therapy
- surgery: anti-reflux surgery
Diffuse esophageal spasm
Normal peristalsis interspersed with frequent, repetitive, spontaneous, high pressure, non-peristaltic waves. Idiopathic.
Diagnosis
- Barium swallow: “corkscrew”
- Manometry: >30% but <100%
Treatment
- reassurance
- medical: nitrates, CCB
- surgical: long esophageal myotomy if unresponsive to medical, balloon dilatation
Esophageal diverticula
Outpouching of one or more layers of GI tract.
Features:
- motility disorders
- dysphagia, regurgitation, retrosternal pain, intermittent vomiting
Classification
Pharyngoesophageal (Zenker’s) diverticulum
- most common
- posterior pharyngeal outpouching, left-sided above cricopharyngeal muscle
- dysphagia, regurgitation, halitosis
Mid-esophageal diverticulum
- secondary to mediastinal inflammation, motor disorders,
- usually asymptomatic, no treatment required
Proximal to LES
- usually associated with motor disorders
- no treatment required
Webs vs Rings
Web = partial occlusion (upper esophageal) Ring = circumferential narrowing (lower esophagus)
Features
- asymptomatic with lumen >12mm
- Plummer-Vinson syndrome: upper esophageal web with dysphagia, iron deficiency.
- Schatzki’s ring: mucosal ring at squamo-columnar junction above a hiatus hernia, causes intermittent dysphagia with solids.
Infectious esophagitis
Mucosal inflammation and ulceration secondary to viral or fungal infection.
Risk factors:
- diabetes
- malignancy
- immunocompromised states
Features
- odynophagia, dysphagia
Treatment
- Candida: nystatin swish and swallow, fluconazole
- Herpes: self-limiting, aciclovir
- CMV: IV gancyclovir
Gastric secretion
Parietal cells
- gastric acid, intrinsic factor
- stimulated by histamine, ACh, gastrin
Chief cells
- pepsinogen
- stimulated by vagal input and local acid
G-cells
- gastrin
- stimulates H+ production from parietal cells
Superficial epithelial cells
- mucus, HCO3-
- protect gastric mucosa
Neuroendocrine cells
- somatostatin
- involved in neural, hormonal and paracrine pathways
Gastritis
Inflammation of the stomach mucosa.
Acute gastritis
- Hemorrhagic/erosive: alcohol, NSAID/aspirin, shock, physiological stress
- Helicobacter gastritis: H. pylori
Chronic gastritis
- Non-atrophic: H. pylori
- Atrophic: H. pylori, dietary, environmental, autoimmune
- Chemical: NSAID, bile
- Radiation: radiation injury
- Lymphocytic: celiac, drug
- Eosinophilic: food allergies
- Non-infectious granulomatous: Crohn’s, sarcoidosis
Features
- bleeding if erosive, non-erosive are asymptomatic
Management:
- H. pylori eradication
- NSAID avoidance
- Restrict food irritants: alcohol, spices
Peptic ulcer disease
Penetrates the muscularis mucosa and can result in scarring. Associated with cirrhosis, COPD, CRF.
Etiology
- H. pylori: 90% of duodenal, 60% of gastric
- NSAIDs: 35% of gastric, 7% of duodenal
- Physiologic stress-induced: <5% of gastric, <3% of duodenal
- Zollinger-Ellison: rare
- Idiopathic: 15% of duodenal, 10% of gastric
- Others: CMV, ischemic
Features:
- Gastric: atypical symptoms
- Duodenal: epigastric pain, burning, develops 1-3h after eating, relieved by eating or antacids, interrupts sleep, periodicity
- Complication: bleeding, perforation, gastric outlet obstruction, penetration into pancreas
Investigations
- endoscopy
- H. pylori tests
- fasting serum gastrin for Zollinger-Ellison syndrome
Management
- Stop NSAIDs
- Start PPI
- H.pylori eradication
- Smoking cessation
- Avoid alcohol, caffine and spices
Management of bleeding peptic ulcers
- NG tube + aspiration to confirm upper GI bleed
- IV pantoprazole 80mg starting dose + 8mg/h continuous infusion
- Erythromycin 250mg 30 prior to endoscopy
- Endoscopy to explore upper GI tract
- Establish risk of rebleeding/continuous bleed: increased age, bleeding diathesis, previous hx of PUD, comorbid disease, hemodynamically unstable
- Consider ICU admission if high risk
H. pylori-induced ulceration
Gram-negative glagellated rod, resides on gastric mucosa within the mucus layer. Can cause gastritis and decrease protection by mucus.
Clinical outcomes
- Non-erosive gastritis: 100% of patients but asymptomatic
- Peptic ulcer: 15%
- Gastric malignancy
Investigations
- Urea breath test (affected by PPI)
- Serology (can remain positive after treatment)
- Stool antigen
- Histology (gold standard, affected by PPI)
- Rapid urease test on biopsy
Treatment
- Triple therapy for 7-14d: omeprazole BID + amoxicillin 1g BID + clarithromycin 500mg BID
- Quadruple therapy
- Sequential therapy
NSAID-induced ulceration
Cause gastric mucosal petechiae in all users, erosions in most users and ulcers in some users. Also inhibits mucosal COX, decreased prostaglandin synthesis, decrease mucus protection.
Risk factors:
- previous peptic ulcer/UGIB
- age
- high dose of NSAIDs
- concomitant steroid use
- concomitant cardiovascular disease
Management
- prophylactic PPI recommended with above risk factors
- lower NSAIDs, or switch to paracetamol
Stress-induced ulceration
Ulceration or erosion in upper GI tract of ill patients, usually in ICU, most common in fundus.
Risk factors
- mechanical ventilation
- anticoagulation
- multiorgan failure
- septicemia
- severe surgery/trauma
- CNS injury
- burns >35% body surface
Management
- PPI/H2-blockers decreases risk of upper GI bleed but may increase risk of pneumonia
Acute diarrhea
Inflammatory - disruption of intestinal mucosa - bloody, small volume, high frequency, often lower abdominal cramping with urgency +/- tenesmus - fecal WBC and RBC positive Causes - Bacterial: Shigella, Salmonella, Campylobacter, Yersinia, E. coli (0157:H7), C. difficile - Protozoal: E. histolytica - Others: NSAIDs, IBD, ischemic
Non-inflammatory
- intestinal mucosa intact
- watery, large volume, upper/periumbilical pain
- fecal WBC negative
Causes
- Bacterial: s. aureus, C. perfringens, E. coli, Salmonella enteritidis, Vibrio cholera
- Protozoal: Giardia lamblia
- Viral: rotavirus, norwalk, CMV
- Drugs: antibiotics, colchicine, laxatives, antacids/magnesium
Chronic diarrhea
> 14d of loose bowel motions.
Inflammatory
- IBD
- Infectious: C. difficile, TB, CMV, HSV
- Ischemic bowel
- Radiation colitis
- Neoplasia
Secretory
- Stimulant laxatives
- Post-ileal resection/cholecystectomy (bile salts)
- Bacterial toxins
- Vasculitis
- Neoplasia: colon ca, carcinoid, VIPoma
- Addison’s disease
- Congenital syndromes
Steatorrhea
- Giardia lamblia
- Celiac sprue
- Chronic pancreatitis
- Diabetes mellitus
Osmotic
- Osmotic laxatives
- Lactose intolerance
- Chewing gum (sorbitol, mannitol)
Functional
- IBS
- Constipation with overflow
- Anal sphincter dysfunction
Maldigestion and malabsorption
Maldigestion: inability to break down large molecules
- post-gastrectomy
- pancreatic insufficiency
- bile salt deficiency
Malabsorption
- inadequate absorption area: Whipple’s disease, giardiasis, celiac, radiation
- drug induced: cholestyramine, ethanol, antibiotics
- diabetes
Sites of absorption:
- Duodenum: iron, calcium, carbohydrates
- Jejunum: iron, calcium, folic acid, carbohydrates, protein
- Ileum: IF-B12 complex
Celiac disease
Autoimmune reaction of gliadin. HLA-DQ2 found in 80-90% of patients. 15% of first degree relatives, peak presentation at infancy.
Features
- diarrhea, weight loss, anemia, symptoms of vitamin/mineral deficiency, failure to thrive, bloating, gas iron deficiency
- disease is usually most severe in proximal bowel, iron, calcium, folic acid deficiency more common than B12 deficiency
- dermatitis hepertiformis, epilepsy, myopathy, depression, paranoia, infertility, bone fractures/metabolic bone disease
Investigations
- anti-tTG antibody
- Mucosal biopsy: villous atrophy, crypt hyperplasia, increased plasma cells and lymphocytes
- low ferritin, Ca, albumin, cholesterol, carotene, B12 absorption
Management
- Dietary couselling: avoid wheat, barley, rye, (oats)
Prognosis
- increased risk of lymphoma, carcinoma
- risk of malignancy lowered by dietary gluten restriction
Crohn’s disease
Chronic transmural inflammatory disorder affecting from mouth to perianal region.
Features:
- Location: small bowel + colon in 50%
- Symptoms: post-prandial/colicky pain, fever, RLQ mass
- Endoscopic: ulcers, patchy lesions, pseudopolyps, cobblestoning
- Histologic: transmural distribution with skip lesions, focal inflammation, non-caseating granulomas, deep fissuring, apthous ulcerations, strictures
- AXR: cobblestone mucosa, frequent strictures and fistulas
- Complications: strictures, fistulas, perianal disease
- Increased risk of colon cancer
Extraintestinal manifestations
- Dermatologic: perianal skin tags, oral mucosal lesions, erythema nodusum, pyoderma gangrenosum
- Rheumatologic: peripheral arthritis and ankylosin spondylitis more common in Crohn’s, sacroiliitis
- Ocular: uveitis, episcleritis
- Hepatobiliary: cholelithiasis, primary sclerosing cholangitis
- Urologic: calculi, fistulae
Investigations
- Colonoscopy
- CT enterography (small bowel)
- elevated CRP
Management - Lifestyle: smoking cessation - Avoid anti-diarrheal agents during flareups - 5-ASA: sulfasalazine, mesalamine - Corticosteroids: prednisone - Immunosuppression: 6-mercaptopurineazathioprine, methotrexate - Immunomodulators: TNF-antagonist Surgery: reserved for complications
Prognosis
- highly variable course
- increased mortality with more proximal disease
