GI Flashcards
Gastroschisis
Extrusion of abdominal contents through abdominal folds (typically right of umbilicus); not covered by peritoneum or amnion
Omphalocele
Persistent herniation of abdominal contents into umbilical cord, covered by peritoneum
Esophageal atresia with distal tracheoesophageal fistula
Polyhydramnios in utero; neonates drool, choke, and vomit with 1st feeding
Duodenal atresia
Intestinal atresia
Bilious vomiting and abdominal distension within 1–2 days of life
“Double bubble”
Associated with Down syndrome
Jejunal and ileal atresia
Disruption of mesenteric vessels -> ischemic necrosis -> segmental resorption (bowel discontinuity or “apple peel”)
Hypertrophic pyloric stenosis
Palpable olive-shaped mass in epigastric region, visible peristaltic waves, and nonbilious projectile vomiting at ∼2–6 weeks
Falciform ligament
Connects Liver to anterior abdominal wall
Contains Ligamentum teres hepatis
Derivative of ventral mesentery
Hepatoduodenal ligament
Connects Liver to duodenum
Contains Portal triad: proper hepatic artery, portal vein, common bile duct
Gastrohepatic ligament
Connects Liver to lesser curvature of stomach
Contains gastric arteries
Separates greater and lesser sacs on the right
How do you treat portosystemic anastomoses cause by portal HTN
Transjugular intrahepatic portosystemic shunt (TIPS) between the portal vein and hepatic vein
Venous drainage above the pectinate line
Superior rectal vein -> inferior mesenteric vein -> splenic vein -> portal vein
What is the pectinate line?
Formed where endoderm (hindgut) meets ectoderm (divides the upper two thirds and lower third of the anal canal)
Pathology that occurs above the pectinate line?
internal hemorrhoids, adenocarcinoma
Blood supply above the pectinate line?
Superior rectal artery (branch of IMA)
Venous drainage below the pectinate line
Inferior rectal vein -> internal pudendal vein -> internal iliac vein -> common iliac vein -> IVC
Pathology that occurs below the pectinate line?
External hemorrhoids (painful d/t somatic innervation), anal fissures, squamous cell carcinoma
Blood supply below the pectinate line?
Inferior rectal artery (branch of internal pudendal artery)
Lymph drainage above the pectinate line?
To internal iliac lymph nodes
Lymph drainage below the pectinate line?
To super cial inguinal nodes
Kupffer cells
Specialized macrophages in the liver, form the lining of sinusoids
Hepatic stellate (Ito) cells
In space of Disse store vitamin A (when quiescent) and produce extracellular matrix (when activated)
What comprises the portal triad?
Bile ductule, Portal vein, Hepatic artery
Pathology that affects Zone I first
Viral hepatitis Ingested toxins (cocaine)
Pathology that affects Zone II first
Yellow fever
Pathology that affects Zone III first
Ischemia
Metabolic toxins
Alcoholic hepatitis
Courvoisier sign
Painless jaundice and enlarged gallbladder d/t adenocarcinoma of the head of the pancreas
What is contained in the femoral triangle?
Contains femoral nerve, artery, vein
What is contained in the femoral sheath?
Femoral vein, artery, and canal (deep inguinal lymph nodes)
Where does an indirect hernia protrude?
Through the deep (internal) inguinal ring, lateral to the epigastric vessels and into the scrotum
Where does a direct hernia protrude?
Protrudes through the inguinal (Hesselbach) triangle directly through parietal peritoneum medial to inferior epigastric vessels but lateral to rectus abdominis
Through the external (super cial) inguinal ring only
What is the most common diaphragmatic hernia?
Hiatal hernia: stomach herniates through the esophageal hiatus
Where does a femoral hernia protrude?
Below inguinal ligament through femoral canal below and lateral to pubic tubercle
Source, action and regulation of gastrin?
G cells in antrum and duodenum
Increases: acid secretion, gastric mucosa, gastric motility
Increased by stomach dissension, ↑ pH, AA, vagal stimulation
States that increase gastrin release?
Chronic PPI use
Chronic atrophic gastritis
Zollinger-Ellison
Source, action and regulation of Somatostatin?
D cells (pancreatic islets and GI mucosa)
Decreases: gastric acid, pepsinogen, pancreatic fluids, gallbladder contraction, insulin release
Increased by acid and decreased by vagal stimulation
What is octreotide an analogue of?
Somatostatin
Source, action and regulation of cholecystokinin?
I cells (duodenum, jejunum)
Increases: pancreatic secretion, gallbladder contraction and sphincter relaxation; decrease gastric emptying
Increased with FA and AA
Source, action and regulation of Secretin?
S cells (duodenum)
Increases: pancreatic HCO3 and bile; decreases gastric acid
Increased by low pH, FA
Source, action and regulation of glucose dependent insulinotropic peptide (GIP)?
K cells (duodenum, jejunum) Exocrine function: decreases gastric H Endocrine function: increases insulin release Increased by FA, AA, oral glucose
Source, action and regulation of Motilin?
Small intestin
Produces migrating motor complexes
Increased when fasting
Source, action and regulation of vasoactive intetinal polypeptide?
PSNS ganglia in sphincter, gallbladder and small intestine
Increases: intestinal water secretion and smooth muscle relaxation
Increased by dissension and vagal stimulation
Decreased by adrenergic
What is a VIPoma?
non-α, non-β islet cell pancreatic tumor that secretes VIP
Watery Diarrhea, Hypokalemia, and Achlorhydria
Source, action and regulation of Ghrelin?
Stomach
Increases appetite
Increased when fasting
Source, action and regulation of IF?
Parietal cells
Bind B12 for uptake in ileum
Source, action and regulation of gastric acid?
Parietal cells
Decrease pH
Increased by histamine, ACh, gastrin
Decreased by somatostatin, GIP, prostaglandins and secretin
Source, action and regulation of Pepsin?
Chief cells
Aid protein digestin
Increased by X
α-amylase
Secreted by pancreas
Digests starch
Lipase
Secreted by pancreas
Digests fat
Protease
Secreted by pancreas
Digests protein
Trypsinogen
Secreted by pancreas
Converted to trypsin-> activates other enzymes
What is bilirubin conjugated with?
Glucuronate
Location of a salivary gland tumor
Parotid gland
Pleomorphic adenoma of salivary gland
Most common salivary gland tumor
Composed of chondromyxoid stroma and epithelium and recurs if incompletely excised or ruptured intraoperatively
Mucoepidermoid carcinoma of salivary gland
most common malignant tumor, has mucinous and squamous components
Warthin tumor (papillary cystadenoma lymphomatosum)
benign cystic tumor with germinal centers
Typically found in smokers
Achalasia
Failure of LES to relax d/t loss of myenteric (Auerbach) plexus
Will see bird’s beak
Progressive dysphagia to solids and liquids
achalasia
Boerhaave syndrome
Transmural, usually distal esophageal rupture with pneumomediastinum d/t vomiting
Eosinophilic esophagitis
Infiltration of eosinophils in the esophagus often in atopic patients
Esophageal rings and linear furrows often seen on endoscopy
Mallory-Weiss syndrome
Partial-thickness mucosal lacerations at GE junction due to severe vomiting
Plummer-Vinson syndrome
Dysphagia, Iron de ciency anemia, and Esophageal webs
Barrett esophagus
Replacement of nonkeratinized stratified squamous epithelium with intestinal epithelium (nonciliated columnar with goblet cells) in distal esophagus.
Squamous cell carcinoma of esophagus
Upper 2/3
Incr risk with EtOH, hot liquids, smoking
Most common worldwide
Esophageal adenocarcinoma
Lower 1/3
Incr risk w/ GERD, smoking
More common in America
Causes of acute gastritis
NSAIDS (↓ PGE2 -> ↓ mucosa)
Burns (Curling ulcer): mucosal ischemia
Brain injury (Cushing ulcer): ↑ CNX -> ↑ ACh -> ↑ H production
Area of autoimmune gastritis
Body/Fundus
Ménétrier disease
Hyperplasia of gastric mucosa -> hypertrophied rugae
Excess mucous, loss of protein, parental cell atrophy
Sister Mary Joseph nodule
subcutaneous periumbilical metastasis of gastric ca
Krukenberg tumor
Bilateral metastases of gastric ca to ovaries
Abundant mucin-secreting, signet ring cells
Intestinal gastric ca
Associated with H pylori, dietary nitrosamines (smoked foods), tobacco smoking, achlorhydria, chronic gastritis
Commonly on lesser curvature; looks like ulcer with raised margins
Diffuse gastric ca
Signet ring cells
Stomach wall grossly thickened and leathery (linitis plastica)
Abdominal pain that increases with meals
Gastric ulcer
Abdominal pain with decreases with meals
Duodenal ulcer
Complications with ruptured gastric ulcer on lesser curve
Bleeding from left gastric artery
Complications with ruptured ulcer on posterior wall of duodenum
Bleeding from gastroduodenal artery
Area affected in celiac
Distal duodenum and/or proximal jejunum
d-xylose test
Passively absorbed in proximal small intestine;
Decreased blood and urine levels with mucosa defects or bacterial overgrowth
normal in pancreatic insufciency
Pancreatic insufficiency will have
↓ duodenal pH (bicarb) and fecal elastase
Malabsorption of fat and fat-soluble vitamins and vitamin B12
Whipple disease
PAS + (foamy macrophages)
Cardiac symptoms, Arthralgias, and Neurologic symptoms
Most common in older men
Location of Crohn disease
Any portion of the GI tract, usually the terminal ileum and colon
Morphology of Crohn disease
Skip lesions
Cobblestones, creeping fat, string sign
Treatment for Crohn disease
Corticosteroids, azathioprine, antibiotics (cipro or metro), infliximab, adalimumab
Location of UC
Colon; always has rectal involvement
Continuous lesions
Morphology of UC
Mucosal and submucosal inflammation
Loss of haustra: “lead pipe”
Treatment for UC
5-aminosalicylic preparations (eg, mesalamine), 6-MC, infliximab, colectomy
Diverticulosis
Many false diverticula of the colon, commonly sigmoid.
Diverticulitis
Inflammation of diverticula
LLQ pain, fever, leukocytosis
Zenker diverticulum
Pharyngoesophageal false diverticulum between the thyropharyngeal and cricopharyngeal parts of the inferior pharyngeal constrictor
Meckel diverticulum
True diverticulum. Persistence of the vitelline duct.
Hirschsprung disease cause
Congenital megacolon characterized by lack of ganglion cells/enteric nervous plexuses
Due to failure of NCC migration; RET mutation
Presentation of Hirschsprung disease
Bilious emesis, abdominal distention, and failure to pass meconium within 48h
Malrotation
Anomaly of midgut rotation during fetal development -> formation of fibrous bands (Ladd bands)
Volvulus
Twisting of portion of bowel around its mesentery
Midgut volvulus more common in infants and children
Sigmoid volvulus (coffee bean sign on XR) more common in elderly.
Intussusception
Commonly at ileocecal junction
“Currant jelly” stools
Acute mesenteric ischemia
Often embolic occlusion of SMA-> small bowel necrosis
“Currant jelly” stools
Chronic mesenteric ischemia
“Intestinal angina”: atherosclerosis of celiac artery, SMA, or IMA
Postprandial epigastric pain
Colonic ischemia
Crampy abdominal pain followed by hematochezia
Thumbprint sign on imaging due to mucosal edema/hemorrhage
Angiodysplasia
Tortuous dilation of vessels -> hematochezia
Most often found in the right-sided colon
Necrotizing enterocolitis
Seen in premature, formula-fed infants with immature immune system
Systemic Mastocytosis
Mast cell proliferation d/t KIT mutation
Release histamine: flushing, hypotension, itching and increased gastric aid secretion
Colonic polyps
Flat, sessile, or pedunculated (on a stalk) on the basis of protrusion into colonic lumen
Hamartomatous polyps
Generally non-neoplastic
Solitary lesions do not transform.
Growths of normal colonic tissue with distorted architecture.
Associated with Peutz-Jeghers syndrome and juvenile polyposis.
Mucosal polyps
Generally non-neoplastic
Small, usually < 5 mm.
Look similar to normal mucosa.
Clinically insignicant.
Submucosal polyps
Generally non-neoplastic
May include lesions such as lipomas, leiomyomas, fibromas, and others.
Hyperplastic polyps
Generally non-neoplastic
Generally smaller and predominantly located in the rectosigmoid region.
May occasionally evolve into serrated polyps and more advanced lesions.
Adenomatous polyps
Malignant potential
Neoplastic, via mutations in APC and KRAS
Tubular has less malignant potential than villous
Serrated polyps
Malignant potential
Premalignant, via CpG hypermethylationy with microsatellite instability and mutations in BRAF
“Saw-tooth” pattern of crypts
Familial adenomatous polyposis
Autosomal dominant mutation of APC tumor suppressor
Pancolonic; always involves rectum.
Prophylactic colectomy or else 100% progress to CRC.
Gardner syndrome
FAP + osseous and soft tissue tumors, congenital hypertrophy of retinal pigment epithelium, impacted/supernumerary teeth
Turcot syndrome
FAP/Lynch syndrome + malignant CNS tumor (eg, medulloblastoma, glioma)
Peutz-Jeghers syndrome
Autosomal dominant syndrome featuring numerous hamartomas throughout GI tract, along with hyperpigmented mouth, lips, hands, genitalia
↑ risk of breast and GI Ca
Juvenile polyposis syndrome
Autosomal dominant syndrome in children (typically < 5 years old) featuring numerous hamartomatous polyps in the colon, stomach, small bowel.
↑ risk of CRC
Lynch syndrome
Autosomal dominant mutation of DNA mismatch repair genes with subsequent microsatellite instability.
∼80% progress to CRC. Proximal colon always involved.
Associated with endometrial, ovarian, and skin cancers
Location of colorectal Ca
Rectosigmoid > ascending > descending
Presentation of colorectal Ca
Ascending—exophytic mass, iron deficiency anemia, weight loss
Descending—infiltrating mass, partial obstruction, colicky pain, hematochezia
(Right side bleeds; left side obstructs)
Dx of colorectal Ca
Iron de ciency anemia in males (especially > 50 years old) and postmenopausal females
Colonoscopy
“Apple core” lesion seen on barium enema x-ray
CEA tumor marker: good for monitoring recurrence
Pathogenesis of colorectal Ca
Mutation in APC cause FAP and sporadic CRC via A-C sequence (APC gene, KRAS mutation, loss of p53)
Cirrhosis
Diffuse bridging fibrosis (via stellate cells) and regenerative nodules
Elevated alkaline phosphatase
↑ in cholestasis (eg, biliary obstruction), infiltrative disorders, bone disease
Elevated γ-glutamyl transpeptidase
Various liver and biliary diseases (just as ALP can), but not in bone disease; associated with alcohol use
Albumin as a liver marker
↓ in advanced liver disease
Reye syndrome
Often fatal childhood hepatic encephalopathy
Alcoholic hepatitis
Swollen and necrotic hepatocytes with neutrophilic infiltration
Mallory bodies
Cause of Hepatic encephalopathy
Cirrhosis -> portosystemic shunts -> ↓ NH3 metabolism -> neuropsychiatric dysfunction
Treatment of hepatic enceophalopathy
Lactulose ( NH4+ generation) and rifaximin or neomycin (NH3 producing gut bacteria)
Cavernous hemangioma
Common, benign liver tumor
Hepatic adenoma
Rare, benign liver tumor, often related to oral contraceptive or anabolic steroid use
Budd-Chiari syndrome
Thrombosis or compression of hepatic veins with centrilobular congestion and necrosis -> congestive liver disease
α1-antitrypsin deficiency
Misfolded gene product protein aggregates in hepatocellular -> ER cirrhosis with PAS ⊕ globules
Gilbert syndrome
Mildly ↓ UDP-glucuronosyltransferase conjugation and impaired bilirubin uptake.
Asymptomatic or mild jaundice usually with stress, illness, or fasting
Crigler-Najjar syndrome, type I
Absent UDP-glucuronosyltransferase. Presents early in life; patients die within a few years
Dubin-Johnson syndrome
Conjugated hyperbilirubinemia due to defective liver excretion. Grossly black liver. Benign
Rotor syndrome
Looks like Dubin Jonson but liver is not dark; Due to impaired hepatic uptake and excretion
Cause of Hemochromatosis
Recessive mutations in HFE gene: abnormal iron sensing and ↑ intestinal absorption
Primary sclerosing cholangitis
Concentric “onion skin” bile duct fibrosis : alternating strictures and dilation with “beading” of intra- and extrahepatic bile ducts
Assoc w/UC, pANCA
Primary biliary cholangitis
Autoimmune reaction -> lymphocytic infiltrate;
+granulomas destruction of intralobular bile ducts
+AMA, Incr IgM
Secondary biliary cholangitis
Extrahepatic biliary obstruction -> incr pressure in intrahepatic ducts injury/ fibrosis and bile stasis
Ascending cholangitis
Charcot triad of cholangitis: Jaundice, Fever, RUQ pain
Dx acute pancreatitis
2 of 3:
- acute epigastric pain radiating to back
- serum amylase or lipase up to 3× upper limit of normal
- Characteristic imaging findings
Pancreatic adenocarcinoma
CA 19-9 tumor marker
Migratory thrombophlebitis—redness and tenderness on palpation of extremities (Trousseau syndrome)
Misoprostol
A PGE1 analog: ↑ production and secretion of gastric mucous barrier, ↓ acid production
Sulfasalazine
A combination of sulfapyridine (antibacterial) and 5-aminosalicylic acid (anti-inflammatory)
Activated by colonic bacteria.
For UC and Crohn
Loperamide
Agonist at μ-opioid receptors; slows gut motility
Orlistat
Inhibits gastric and pancreatic lipase; use for weight loss
Aprepitant
Substance P antagonist
Blocks NK1 receptors in brain
