Gastroenterology Flashcards
Gastrin
Secreted by G-cells (antrum), stimulates parietal cells in fundus
Cholecystokinin
Secreted by I-cells (duodenum), contracts gallbladder and plrolongs gastric emptying time
Secretin
Secreted by S cells (duodenum), inhibits acid secretion
Glucose-dependent Insulinotropic Peptide
Secreted by K cells (duodenum), stimulates insulin secretion
Gastrin, Histamine, Acetylcholine
Stimulate gastric acid secretion (synergistic effect)
Motilin
Stimulates motility during fasting
Mucus Neck Cells
Secretes mucus in the stomach
Parietal Cells
Secretes HCl and intrinsic factor in the stomach
Chief Cells
Secretes pepsinogen in the stomach
Enterochromaffin cells
Secretes serotonin in the stomach
Enterochromaffin-like cells
Secretes histamine in the stomach
Interstitial cells of Cajal
Pacemaker cells of the GI that generates slow waves
Liver Acinus Model (Zones 1-3)
Preferred functional unit of the liver
Ito Cells
Stores Vitamin A in the liver
Enterokinase
Intestinal enzyme that triggers conversion of pancreatic trypsinogen to trypsin
Enterohepatic circulation
Main mechanism for bile salt reabsorption
Triglyceride Absorption
Lumer -> intestinal cells as micelles –> lacteals as chylomicrons
Mouth (salivary amylase/ptyalin)
Initial digestion of carbohydrates
Stomach (lingual lipase)
Initial digestion of fats
Stomach (pepsin and HCl denaturation)
Initial digestion of proteins
Duodenum
For iron and vitamin C absorption
Jejunum
Main site for Carbohydrates, fats, proteins, water absorption
Ileum
Main site for vitamin B12, IF, bile salts and vitamins ADEK absorption
Rule of 2’s in Meckel’s diverticulum
2% of population, 2 years old, 2:1 male to female ratio, 2 tissue types involved, 2 inches long, 2 feet from Ileocecal valve
Diagnostic Criteria for Irritable Bowel Syndrome
Recurrent abdominal pain or discomfort for at least 3 days per month in the last 3 months associated with 2 or more of the following: improvement with defecations, onset associated with a change in frequency of stool, onset associated with a change in appearance of stool
Charcot’s Triad for Ascending Cholangitis
Fever, Abdominal Pain, Jaundice
Charcot’s Triad for Multiple Sclerosis
Scanning speech, intention tremor, nystagmus
Reynold’s Pentad
Charcot’s Cholangitis Triad + Shock and confusion
Triad of Hepatopulmonary Syndrome
Liver disease, Hypoxemia, Pulmonary arteriovenous shunting
Triad of Acute Cholecystitis
Sudden RUQ tenderness, fever, leukocytosis
Triad of Choledochal Cyst
Abdominal pain, jaundice, abdominal mass
Triad of Hemobilia
Biliary Pain, Obstructive Jaundice, Melena
Diagnosis of Acute Pancreatitis
Typical abdominal pain, 3x or grater elevation in serum amylase and/or lipase levels, Confirmatory findings on cross-sectional abdominal imaging
Pseudocyst
Increase in size of the mass, a localized bruit over the mass, sudden decrease in hemoglobin and hematocrit without external blood loss
Classic Symptoms of GERD
Water brash and substernal heart burn
Gastroesophageal reflux
Most common cause of esophageal chest pain
24-hour ambulatory pH monitoring
Most sensitive test for diagnosis of GERD
Globus hystericus
Perception of a lump or fullness in the throat that is felt irrespective of swallowing
Odynophagia
Characteristic symptom of infectious esophagitis
Schatzki ring in the lower esophagus
Common cause of steakhouse syndrome
Bird’s beak appearance
Radiographic sign in achalasia
Corkscrew or rosary bead esophagus
Seen radiographically in diffuse esophageal spasm or spastic achalasia
Esophageal manometry
Detects impaired LES relaxation and absent peristalsis in achalasia
Endoscopy or esophagogastroduodenoscopy
Best test for evaluation of proximal GIT
Crohn’s disease
Cobblestone appearance of esophagus
Endoscopic biopsy
Gold standard for confirmation of Barrett’s esophagus
Typical presentation of esophageal cancer
Progressive solid food dysphagia and weight loss
Squamous cell CA
Middle third of the esophagus, associated with smoking
Adenocarcinoma
Distal third of the esophagus, associated with GERD and Barrett’s esophagus (metaplasia from squamous to columnar epithelium)
Peptic ulcers
Most common cause of UGIB
Hemorrhoids
Most common cause of LGIB overall
Anal fissure
Most common cause of rectal bleeding during infancy
Meckel’s diverticulum
Most common cause of significant LGIB in children
BD and juvenile polyps
Most common colonic causes of significant GIB in children and adolescents
Hemorrhage from a colonic diverticulum
Most common cause of hematochezia in the elderly
Small intestinal sources of bleeding
Majority of obscure GIB
Boerhaave Syndrome
Full-thickness esophageal tear
Mallory-Weiss Tear
Partial-thickness esophageal tear
Classic history of Mallory-Weiss Tear
Vomiting, retching, coughing, hematemesis in an alcoholic/bulimic patient
NSAID, alcohol, stress
Most important causes of Hemorrhagic and erosive gastropathy
Heart rate and BP
Best way to initially assess a person with GIB
Upper endoscopy
Procedure of choice in UGIB
Colonoscopy after an oral lavage solution
Procedure of choice in LGIB
Angiography
Initial test for massive obscure GIB
Key enzyme in rate-limiting step of prostaglandin synthesis
Cyclooxygenase
Most common causes of gastric/duodenal ulcers
H. pylori and NSAU+Iss
Most common location of GU’s
1st portion of duodenum
Most discrimating symptom of Dus
Pain that awakens the patient from sleep
Most frequent finding in patients with GU/DU
Epigastric tenderness
PUD-related complications
GI bleeding > perforation > gastric outlet obstruction (in order of decreasing frequency)
Most potent acid inhibitory agents
Proton pump inhibitors
Most common toxicity with sucralfate
Constipation
Most common toxicity with prostaglandin analogs
Diarrhea
Most feared complication with amoxicillin, clindamycin
Pseudomembranous colitis
GU: failure to heal after 12 weeks of therapy, DU: failure to heal after 8 weeks of therapy
Refractory Peptic Ulcers
Most common cause of treatment failure in compliant patients
Antibiotic-resistant H. pylor strains
Test of choice for documenting eradication of H. pylori
Urea breath test
Most commonly performed operations for DU’s
Vagotomy and drainage, highly selective vagotomy, vagotomy with antrectomy
High ulcer recurrence rate but lowest complication rate
Highly selective vagotomy
Lowest ulcer recurrence rate but highest complication rate
Vagotomy with antrectomy
Surgery of choice for an antral ulcer
Antrectomy (including ulcer) with a Billroth I anastomosis
Cornerstone therapy for dumping syndrome
Dietary modification
Severe peptic ulcer diathesis secondary to gastric acid hypersecretion due to unregulated gastrin release from gastrinomas
Zollinger-Ellison Syndrome
Most common location of gastrinomas
Pancreas»_space; duodenum
Gastrinoma triangle (contains over 80% of these tumors)
Superior border: cystic and common bile duct; Inferior border: junction of the 2nd and 3rd portions of duodenum; Medial border: junction of the neck and body of the pancreas
Most common clinical manifestation of gastrinoma
Peptic ulcer followed by diarrhea
Most sensitive/specific Gastrin Provocative Test
Secretin study
Treatment of choice for Gastrinoma
PPIs
Most common presentation of Stress-Related Mucosal Injury
GI bleeding
Treatment of choice for stress prophylaxis
PPIs (preferably oral, if tolerated)
Most common cause of acute gastritis
Infectious
Important predisposing factor for gastric cancer
Intestinal metaplasia
Involves primarily the fundus and body with antal sparing. It is the less common type
Type A gastritis (Autoimmune: anti-parietal cell antibodies)
Antral predominant. The more common type
Type B gastritis (Bacteria: H. pylori-associated)
Large, tortuous gastric mucosal folds (not a form of gastritis)
Menetrier’s disease
Ulcerative Colitis
Mucosal disease that usually involves the rectum and extends proximally to involve all or part of the colon
Crohn’s disease
Can affect any part of the GIT from mouth to anus but rectum is often spared
Toxic megacolon
Transverse or right colon with diameter of >6cm and loss of haustrations in severe attacks of UC
pANCA Positivity (perinuclear anti-neutrophil Cytoplasmic antibodies)
UC»_space; CD
ASCA positivity (Anti-Saccharomyces cerevisiae antibodies)
CD»_space; UC
Fecal lactoferrin and calprotectin
Markers of intestinal inflammation
Appendectomy
Protective against UC, increased risk for CD
Aphthoid ulcerations and focal crypt abscesses
Earliest lesion in CD
Granulomas
Pathognomonic feature of CD
Terminal ileum
Most common site of inflammation in CD
Fine mucosal granularity
Earliest radiologic change of UC seen on barium enema
Perforation
Most dangerous local complication of UC
Conjunctivitis, anterior uveitis/iritis and episcleritis
Most common ocular complications of IBD
Calculi, ureteral obstruction and fistulas
Most common genitourinary complications of IBD
Sulfazaline and other 5-ASA afaents
Mainstay of therapy for mild to moderate UC and Crohn’s colitis
Glucocorticoids (no role as maintenance therapy)
Treatment of moderate to sever IBD
Infiximab (TNF-alpha antibody)
First biologic therapy approved for CD
Ileal Pouch Anal Anastomosis
Operation of choice for UC
Pouchitis
Most frequent late complication of IPAA
Abdominal pain or discomfort
Key symptom/prerequisite clinical feature for the diagnosis of IBS
Altered bowel habits (most commonly constipation alternating with diarrhea)
Most consistent clinical feature in IBS
Evidence of anemia, elevated sedimentation rate, presence of leukocytes or blood in stool, stool volume > 200-300 mL/day
Laboratory features that argue against IBS
Antispasmodics 30 minutes before meals
Best management for postprandial pain
Peripherally-acting opiate-based agents
Initial theapy of choice for IBS-D (diarrhea predominant)
Rifaximin
Only antibiotic for IBS with sustained benefit beyoin therapy cessation
True diverticulum
Saclike herniation of the entire bowel wall
False diverticulum
Only a protrusion of the mucosa through the muscularis propria of the colon (where the vasa recti penetrates)
Diverticulitis
Inflammation of the diverticulum
Giant diverticulum of the sigmoid colon
Air-fluid level in the LLQ on plain abdominal film
Hinchey Classification System
Staging system for predicting outcomes after surgery for perforated diverticulitis
Sigmoid diverticula, thickened colonic wall > 4 mm, Inflammation within the pericolic fat with or without collection of contrast material or fluid
Diagnosis of diverticulitis is best made with these findings
6 weeks after an attack of diverticular disease (should not be performed in acute setting due to higher risk of infection)
Safety window for barium enema or colonoscopy
Angiography with or without coiling (if patient unstable or has had a 6-unit bleed within 24 hours, emergent surgery should be performed)
Best management for massive diverticular bleeding in a stable patient
Diet alterations
best management for asymptomatic diverticular disease
Antibiotics and bowel rest
Initial treatment for symptomatic uncomplicated diverticular disease
Procidentia
Circumferential, full-thickness protrusion of the rectal wall through the anal orifice
Fecal incontinence
Involuntary passage of fecal material > 10 mL for at least 1 month
Anismus
The result of attempting to defecate against a closed pelvic floor (aka non relaxing puborectalis)
Mucosal vs. Full Thickness rectal prolapse
Radial vs. circumferential grooves around anus
Surgical correction
Mainstay of Therapy for rectal prolapse
Left lateral, right anterior, right posterior
3 hemorrhoidal complexes in the anal canal
Bleeding and/or protrusion
Most common presentation of hemorrhoids
Perianal pain and fever
Hallmarks of anorectal abscess
Perianal, followed by ischiorectal
Most common location of anorectal abscess
Posterior position, followed by anterior (lateral fissure is worrisome and systemic disorders should be ruled out)
Most common location of anal fissures
Dentate line
Most common location of Internal Opening of Fistula in Ano (FIA)
Intersphincteric, followed by transsphincteric
Most common type of FIA
Goodsall’s Rule for FIA
Anterior fistula: straight tract to nearest crypt, Posterior fistula: curved tract to enter anal canal at posterior midline. Exception: fistulas exiting a >3cm from the anal verge may not obey Goodsall’s rule
Seton (vessel loop or silk tie placed through the tract)
Best management for newly-diagnosed FIA
Strangulated small bowel obstruction followed by ischemic colitis
Most common form of acute intestinal ischemia
Ischemic colitis
Most prevalent gastrointestinal disease complicating cardiovascular surgery
Griffith’s point: splenic flexure and Sudeck’s point: descending sigmoid colon
Most common locations for Colonic Ischemia
Laparotomy
Gold standard for diagnosis and management of Acute Arterial Occlusive Disease
Mesenteric angiography
Gold standard for confirmation of mesenteric arterial occlusion in chronic intestinal ischemia
Fluid resuscitation
Intervention of choice to maintain hemodynamics in nonocclusive/vasospastic mesenteric ischemia
Resection of ischemic bowel and formation of proximal stoma
Optimal treatment for ischemic colitis
Timeliness of diagnosis and treatment
Most significant indicator of survival in mesenteric ischemia
Mesenteric venous insufficiency
Best prognosis of all acute intestinal ischemic disorders
Area of immunofluorescence > 5 mm in diameter under UV illumination with Woods lamp
Marker of intestinal nonviability
Adynamic ileus, primary intestinal pseudo-obstruction
Main differentials for acute intestinal obstruction
Adhesions
Most common cause of small-intestinal obstruction
Colon cancer
Most common cause of intestinal obstruction
Hydrochloric acid, colonic contents, pancreatic enzymes
Most irritating substances to the peritoneum
Abdominal distention (more prominent in more distal sites of obstruction)
Hallmark of all forms of intestinal obstruction
Fluid and gas-filled loops of small intestine, stepladder pattern with air-fluid levels, absence of paucity of colonic gas
Pathognomonic signs for small bowel obstruction on plain abdominal film
Abdominal CT (can differentiate between adynamic ileus, partial obstruction and complete obstruction)
Most commonly used modality to evaluate postoperative patients for intestinal obstruction
> 10 cm on plain abdominal film
Cecal diameter that increases likelihood of perforation
Closed loop: lumen is occluded at two points by a single mechanism (such as fascial hernia or adhesive band) also often with occlusion of blood supply, leading to high pressures and gangrene
Most feared complication of acute intestinal obstruction
Appendicitis
Most common abdominal surgical emergency
Fecalith
Most common cause of appendiceal luminal obstruction leading to acute appendicitis (AA)
Sequence of abdominal discomfort and anorexia
Pathognomonic in AA
Urinalysis
Most useful test in excluding genitourinary conditions that may mimic AA
Appendicitis
Most common extrauterine condition requiring abdominal operation during pregnancy
Second trimester
Most common period of occurrence of AA during pregnancy
Ultrasound
Best diagnostic exam for AA during pregnancy
Acute abdominal pain and tenderness, usually with fever
Cardinal manifestations of peritonitis
Uncomplicated appendicitis and diverticulitis
Most common causes of localized peritonitis
Hepatocellular pattern of liver disease
Liver injury, inflammation and necrosis predominate
Cholestatic pattern of liver disease
Inhibition of bile flow predominates
Grading of liver disease
Histologic assessment of necroinflammatory activity: acute or chronic; active or inactive; mild, moderate or severe
Staging of liver disease
Level of progression of the disease, based on the degree of hepatic fibrosis: early or advanced, precirrhotic or cirrhotic
Criterion standard in evaluation of liver disease and most accurate means of assessing grade and stage
Liver biopsy
Prognostication for cirrhosis and provides standard criteria for listing for liver transplantation (Class B and C); utilizes serum bilirubin, serum albumin, PT-INR and severity of ascites and hepatic encephalopathy
Child-Pugh Score
More objective means of assessing disease severity; utilizes serum bilirubin, serum creatinine and PT-INR
Model for End-Stage Liver Disease Score
Indicates cirrhosis with Child-Pugh score of greater than or equal to 7 (Class B or C)
Liver decompensation
Occurrence of signs or symptoms of hepatic encephalopathy in a person with sever acute or chronic liver disease
Hepatic failure
Hepatic inflammation and necrosis that continue for at least 6 months
Chronic hepatitis
Most common and most characteristic symptom of liver disease
Fatigue
Hallmark of liver disease and most reliable marker of severity
Jaundice
Most reliable physical finding in examining the liver
Hepatic tenderness
Best physical exam maneuver to appreciate ascites
Shifting dullness on percussion
Major criterion for diagnosis of fulminant hepatitis
Hepatic encephalopathy during acute hepatitis (indicates poos prognosis)
Screening test for hepatopulmonar syndrome
Oxygen saturation by pulse oximetry
Most commonly used liver function test
Serum bilirubin, serum albumin, prothrombin time (PT)
Rate-limiting step in bilirubin metabolism
Transport of conjugated bilirubin into the bile canaliculi (not conjugation itself)
Any bilirubin found in the urine is in the form of
Conjugated/Direct Bilirubin
Exclusive sites for the synthesis of serum albumin
Hepatocytes
Only clotting factor not produced in the liver
Factor VIII
Single best acute measure of hepatic synthetic function
Protime (PT) (PT prolongation of > 5 secs not corrected by parenteral vitamin K administration is poor prognostic sign in acute viral hepatitis)
Most helpful in recognizing Acute Hepatocellular Disease
Elevated aminotransferases/transaminases
Differentials for striking elevations in aminotransferases (>1000 U/L)
Viral hepatitis, Ischemic liver injury, Toxin- or drug-induced liver injury, acute phase of biliary obstruction caused by passage of gallstone in the CBD
AST>ALT
Alcoholic liver disease
ALT>AST
Viral hepatitis
Key events in hepatic fibrogenesis
Stellate cell activation and collagen production
First indication of worsening hepatic fibrosis
Mild thrombocytopenia