USMLE (Fach) / Gastrointestinal (Lektion)
In dieser Lektion befinden sich 136 Karteikarten
USMLE First Aid
Diese Lektion wurde von estoffel erstellt.
- Gastroesophageal reflux disease Chronic condition in which retrograde flow of stomach contents causes irritation of the esophageal lining. Main mechanism is due to transient relaxations of the LES. Risk factors: - Increased intra-abdominal ...
- Autoimmune gastritis Autoimmune distruction of the parietal cells found predominantly in the upper glandular layer of the gastric body and fundus.→ Achlorhydria → hypergastrinemia→ Lack of intrinsic factor → ...
- Kernicterus - a small amount of unconjugated bilirubin is present as an albumin-free anion in plasma. This fraction may in increase in severe hemolytic disease of the newborn (erythroblastosis fetalis) and may diffuse ...
- Hereditary hyperbilirubinemias Hepatic conjugating enzyme UGT1A1 catalyzes the glucuronidation of bilirubin. Hereditary unconjugated hyperbilirubinemias:- Crigler-Najjar syndrome: complete UGT1A1 deficiency, fatal- Gilbert syndrome: ...
- Barrett esophagus Characterized by intestinal metaplasia – replacement of nonkeratinized stratified squamous epithelium with intestinal epithelium (nonciliated columnar with goblet cells) in distal esophagus. - Due ...
- Esophageal cancer Squamous cell carcinoma- Risk factors: Alcohol, smoking, diet low in fruits/vegetables, hot liquids, caustic strictures, achalasia- Upper 2/3 Adenocarcinoma- Risk factors: GERD, Barrett esophagus, obesity, ...
- Familial adenomatous polyposis (FAP) Autosomal dominant disorder in which patients develop thousands of polyps as teenagers.- Pancolonic, always involves rectum - Mutation of the adenomatous polyposis coli (APC) tumor suppressor gene on ...
- Hereditary Non-Polyposis Colorectal Cancer = Lynch syndromeAutosomal dominant mutation in mismatch repair genes (MHL1, MSH2, MSH6, PMS2) with subsequent microsatellite instability. ~80% progress to CRC - Proximal colon always involved (right ...
- Tracheoesophageal anomalities Esophageal atresia with distal tracheoesophageal fistula is the most common (85%).- Often presents as polyhydramnios in utero (due to inability of fetus to swallow amniotic fluid). - Drooling, choking, ...
- Hernias Protrusion of peritoneum through an opening, usually at a site of weakness. Contents may be at risk for incarceration (not reducible back into abdomen/pelvis) and strangulation (ischemia and necrosis). ...
- Achalasia Failure of LES to relax due to loss of myenteric (Auerbach) plexus due to loss of postganglionic inhibitory neurons (which contain NO and VIP). - 2° achalasia (pseudoachalasia) may arise from Chagas ...
- Ménétrier disease Gastritis featuring massive hyperplasia of gastric mucosa → hypertrophied rugae (look like brain gyri). - Causes excess mucus production with resultant protein loss and parietal cell atrophy with ↓ ...
- Irritable bowel syndrome Recurrent abdominal pain associated with >2 of the following- Related to defecation- Change in stool frequency- Change in form (consistency) of stool - No structural abnormalities.- Most common in middle-aged ...
- Appendicitis Acute inflammation of the appendix due to obstruction by fecalith (adults) or lymphoid hyperplasia (children). - Initial diffuse periumbilical pain migrates to McBurney point (1/3 the distance from right ...
- Diverticula of the GI tract Diverticulum: Blind pouch protruding from the alimentary tract that communicates with the lumen of the gut. Most diverticula (esophagus, stomach, duodenum, colon) are acquired and termed "false diverticula".- ...
- Hypertrophic pyloric stenosis Most common cause of gastric outlet obstruction in infants (1:600). - Palpable "olive" mass in epigastric region, visible peristaltic waves, and nonbilious projectile vomiting at ~2-6 weeks old.- "Hungry ...
- Meckel diverticulum Persistence of the vitelline (omphalomesenteric) duct (connects lumen to yolk sac). True diverticulum. "Rule of 2s":- Approximately 2% of the population- Within 2 feet (60 cm) of the ileocecal valve- ...
- Zenker diverticulum Pharyngoesophageal false diverticulum. - Esophageal dysmotility causes herniation of mucosal tissue at Killian triangle between the thyropharyngeal and cricopharyngeal parts of the inferior pharyngeal ...
- Hirschsprung disease Congenital megacolon characterized by lack of ganglion cells/enteric nervous plexus (Auerbach's and Meissner's plexuses) in distal segment of colon. Due to failure of neural crest cell migration. Associated ...
- Alcoholic liver disease Etiology: Alcohol consumption (♂ >210 g per week; ♀ >140 g per week) Hepatic steatosis: Macrovesicular fatty change that may be reversible with alcohol cessation. Alcoholic hepatitis: Requires sustained, ...
- Budd-Chiari syndrome Thrombosis or compression of hepatic veins with centrilobular congestion and necrosis → congestive liver disease (hepatomegaly, ascites, abdominal pain, varices, abdominal pain, liver failure). Etiology:- ...
- Wilson disease Autosomal recessive mutations in hepatocyte copper-transporting ATPase (ATP7B gene; chromosome 13) → ↓ copper incorporation into apoceruloplasmin and excretion into bile → ↓ serum ceruloplasmin. ...
- Hemochromatosis - Autosomal recessive with incomplete penetrance.- C282Y > H63D mutation on HFE gene, located on chromosome 6; associated with HLA-A3. - Defective binding of transferrin to its receptor → liver stops ...
- Malrotation Anomaly of the midgut rotation during fetal development → improper positioning of bowel (small bowel clumped on the right side), formation of fibrous bands (Ladd bands). - Can lead to volvulus, duodenal ...
- Physiologic neonatal jaundice At birth, immature UDP-glucuronosyltransferase → unconjugated hyperbilirubinemia → jaundice/kernicterus (deposition of unconjugated, lipid-soluble bilirubin in brain, particularly basal ganglia). ...
- Gilbert syndrome Mildly ↓ UDP-glucuronosyltransferase conjugation and impaired bilirubin uptake.- Most commonly inherited hyperbilirubinemia.- Prevalence 3-7% in the US. - Asymptomatic or mild jaundice usually with ...
- Crigler-Najjar syndrome Absent UDP-glucuronosyltransferase.- Presents early in life, patients die within a few years. Findings: - Excessive, persistent neonatal jaundice- Neurological symptoms caused by kernicterus (bilirubin ...
- Dubin-Johnson syndrome Defective MRP2 receptor → Impaired excretion of conjugated bilirubin into the bile canaliculi.- Benign. - Onset occurs during adolescence.- Mild-to-moderate jaundice.- May worsen because of medications ...
- Megacolon - Differential - Hirschsprung's disease - Chagas disease - obstruction (neoplasm, inflammatory stricture) - toxic - visceral myopathy
- Cushing ulcer - brain trauma --> elevated intracranial pressure --> increased vagal stimulation --> ulcers in esophagus, stomach, duodenum
- Curling ulcer - complication of severe burns/trauma - reduced plasma volume leads to ischemia of the gastric mucosa/duodenal ulcer
- Mallory-Weiss syndrome Acute upper gastrointestinal bleeding caused by partial-thickness mucosal lacerations at gastroesophageal junction due to severe vomiting. Etiology:- Severe vomiting- Usually found in alcoholics and bulimics ...
- Peutz-Jeghers syndrome Autosomal dominant syndrome featuring numerous hamartomas throughout GI tract, along with mucocutaneous hyperpigmentions (eg, mouth, lips, hands, genitalia). - Associated with ↑ risk of breast and ...
- Gardner syndrome - FAP + osseous and soft tissue tumors (eg, osteomas, desmoid tumors, sebaceous cysts, lipomas, fibromas) - Congenital hypertrophy of retinal pigment epithelium - Impacted/supernumerary teeth
- Turcot syndrome FAP/Lynch syndrome + malignant CNS tumor (eg, medulloblastoma, glioma)
- Juvenile polyposis syndrome Autosomal dominant syndrome in children (typically < 5 years) with incomplete penetrance. - Numerous hamartomatous polyps in the colon, stomach, small bowel. - Associated with ↑ risk of CRC
- Primary sclerosing cholangitis Progressive chronic inflammation of the intra- and extrahepatic bile ducts.- Classically in middle-aged men with IBD. Features:- Signs of cholestasis: jaundice, pruritus, fatigue, acute cholangitis- ...
- Primary biliary cholangitis Chronic progressive liver disease of autoimmune origin → lymphocytic infiltrate + granulomas → destruction of intralobular bile ducts. - Classically in middle-aged women.- Most common cause of ...
- Ileus Intestinal hypomobility without obstruction → constipation and ↓ flatus. - Distended/tympanic abdomen with ↓ bowel sounds. Associated with:- abdominal surgeries- opiates- hypokalemia- sepsis ...
- Acute mesenteric ischemia - Mainly occurs in adults >60 years- Young people with atrial fibrillation, vasculitis, or hypercoagulable states Etiology:- Embolic occlusion of SMA (~50%): generally resulting from atrial fibrillation, ...
- Chronic mesenteric ischemia "Intestinal angina": atherosclerosis of celiac artery, SMA, or IMA → intestinal hypoperfusion → postprandial epigastric pain → food aversion and weight loss. - Abdominal bruit caused by stenosis ...
- Peptic ulcer disease Gastric ulcer- Pain increases with meals → weight loss- 70% H pylori infection- Mechanism: ↓ mucosal protection, NSAIDs- ↑ risk of carcinoma- Biopsy margins to rule out malignancy (especially ...
- Salivary gland tumors Most commonly benign and in parotid gland. Tumors in smaller glands more likely malignant. - Typically present as painless mass/swelling. Facial pain or paralysis suggests malignant involvement of CN ...
- Eosinophilic esophagitis Infiltration of eosinophils in the esophagus often in atopic patients (eg, asthma, allergic rhinitis). - Food allergens → dysphagia, food impaction. - Esophageal rings and linear furrows often seen ...
- Plummer-Vinson syndrome Triad of dysphagia, iron deficiency anemia, and esophageal webs. - May be associated with glossitis. - Increased risk of esophageal squamous cell carcinoma.
- Boerhaave syndrome Transmural esophageal rupture with pneumomediastinum.- In >90% of cases, the rupture occurs in the distal third of the esophagus on the left dorsolateral wall surface. Etiology: Excessive intake of ...
- Gastritis Acute gastritisErosions can be caused by:- NSAIDs – ↓ PGE2 → ↓ gastric mucosa protection- Burns (Curling ulcer) – hypovolemia → mucosal ischemia- Brain injury (Cushing ulcer) – ↑ vagal ...
- Gastric cancer Most commonly gastric adenocarcinoma; lymphoma, GI stromal tumor, carcinoid. - Early aggressive local spread with node/liver metastases. - Often presents late, with weight loss, abdominal pain, early ...
- Ulcer complications Hemorrhage: - Gastric, duodenal (posterior > anterior).- Most common complication.- Ruptured gastric ulcer on the lesser curvature of stomach → bleeding from left gastric artery.- An ulcer on the posterior ...
- Lactose intolerance Lactase deficiency resulting in incomplete hydrolysis of lactose into glucose and galactose. The fermentation of undigested lactose by gut bacterial leads to increased production of short-chain fatty ...