GI Flashcards
Foregut becomes
Esophagus to upper duodenum
Midgut becomes
Lower duodenum to prox 2/3 transverse colon
Hindgut becomes
Distal 1.3 of transverse colon to anal canal over pectinate line
Midgut herniates at…
6wks
Midgut returns to cavity and rotates around SMA at…
10 wks
Degree rotation of midgut
270
Rostral fold closure defect–>
Sternal defect (ectopic cordis)
Lateral fold closure defect–>
Omphalocele and gastroschisis
Caudal fold closure defect–>
Bladder extrophy
Gastroschisis
Abdomen contents extrude through abdominal folds (usually rt of umbilius) – no covering
Omphalocele
Persistent herniation of abdomen contents into umbility cord – SEALED by peritoneum
Congenital umbility hernia
Incomplete closure of umbilical ring - can close spontaneously
Most common tracheoesophageal abnormality
Esophageal atresia w/ distal TEF
Esophageal atresia w/ distal TEF symptoms
Polyhydramnios (can’t swallow), drool/choke/vomit at first feeding, air in stomach, cyanosis due to reflux mediated larygospasm, cannot pass nasogastric tube into stomach
Pure EA presentation
CXR – gasless abdomen
Intestinal atresia presentation
Billious vom and abdominal distension w/ first 1-2 days of life
Duodenal atresia
Didn’t recanalize! Double bubble (dilates stomach, prox duodenum), DS association
Jejunal and ileal atresia
Disruption of mesenteric vessels, ischemic necrosis, segmental resorption (bowel discontinuity/apple peel)
Most common gastric outlet obstrxn in infants
Hypertrophic pyloric stenosis – palpable olive shaped mass at epigastric region, visible peristaltic waves, nonbiliious projective vom at 2-6 wks
First born male assc, macrolide exposure
Results in hypokalemic hypochloremia metabolic alkalosis (2o to vom and volume contraction
Tx: incision pyloromyotomy
Pancreas derivation
Foregut
Ventral pancreatic buds –>
Uncinate process and main pancreatic ducts
Dorsal pancreatic bud–>
Body, tail, isthmus, accessory pan duct – both cont to pancreatic head
Annular pancreas
Ventral bud encircles 2nd part of duoedenum -> ring of pancreatic tissue can cause obstruction
Pancreas divisum
Ventral and dorsal dont fuse at 8 wks – common, usually asymptomatic but can cause chronic abdominal pain/pancreatitis
Spleen arises in…
Mesentery of stomach
Spleen derivation
Mesodermal
Spleen blood supply
Celiac truck –> splenic a.
Retroperitoneal stuctures defined
GI structures w/ no messentery and non GI structures
Injuries to retroperitoneal structures ->
Suprarenal glands (adrneal) Aorta and IVC Duodenum (2-4 parts) Pancreas (except tail) Ureters Colon (Descending and ascending) Kidneys Esophagus (thoracic) Rectum (partial)
SAD PUCKER
Falciform ligament
Connects liver –> ant abdominal wall, has ligamentum teres hepatis in it
Falciform ligament derivation
Ventral mesentery
Ligatmentum teres hepatis derivation
Fetal umbilical v
Hepatoduodenal ligament
Connects liver–>duodenum
In the hepatoduodenal ligament…
Portal triad – proper hep a, portal v., common bile duct
Pringle maneuver
Compress ligament between thumb/index finger in omental foramen to control bleeding
Gastrohepatic ligament
Connects liver to lesser curvature of stomach
Contents of gastrohepatic ligament
Gastric arteries
Separates greater/lesser sacs on the right
Gastrohepatic ligament
Lesser omentum ligamnets
Hepatoduodenal, gastrohepatic
Gastrocolic
Connects greater curvature and transverse colon
Within gastrocolic
Gastroepiploic aas.
Greater omentum ligatments
Gastrocolic, gastrosplenic
Gastroc splenic
Connects greater curvature and spleen
Contents of gastrosplenic
Short gastrics, left gastroepiploic vessels
Separates greater/lesser sac on the left
Gastrosplenic lig
Splenorenal ligament
Spleen to post ab wall
Splenorenal lig contents
Splenic a and v, tail of pancreas
Serosa
Intraperitoneal
Adventitia
Retroperitoneal
Ulcer
Extend into submucosa, muscle layers
Erosion
Mucosa only
Freq of stomach basal waves
3/min
Freq of duodenal basal waves
12/min
Freq of ileal basacl waves
8-9/min
Brunner glands
Secrete HCO3, in submucosa of duodenum
Crypts of Lieberkuhn
Have stem cells to replace enterocytes/goblet cells; in small intestine and colon
Paneth cells
Secrete defensins, lysozyme, TNF – duodenal
Plicae circulares
In distal duodenum, jejunum, ileum
Peyer patches
Lymphoid aggs in lamina propia, submucosa – ileum
Villi are in…
SI but not colon
Colon has many
Goblet cells
SMA syndrome
Intermittent intestinal obstruction sx (postprandial pain) when transverse (3rd portion duodenum) is compressed between SMA and aorta – usually in conditions w/ diminished mesenteric fat (e.g. low body wt, malnutrition)
Forgut artery
Celiac
Foregut PNS
Vagus
Foregut vertebral level
T12/L1
Foregut structures
Pharynx (vagus only), lower esophagus (celiac a only) to prox duodenum, liver, gallbladder, pancreas, spleen (mesoderm)
Midgut artery
SMA
Midgut PNS innervation
Vagus
Midgut vertebral level
L1
Midgut structures
Distal duodenum to prox 2/3 transverse colon
Hindgut artery
IMA
Hindgut PNS
Pelvic
Hindgut vertebral level
L3
Hindgut structures
Distal 1/3 transverse colon to upper portion of rectum
T12 arteries
inf Phrenic, Sup suprarenal, mid supraprenal, celiac
L1 aa’s
SMA, Inf suprarenal, half renal
L2 aas
Half renal, gonadal
L3 aas
IMA
L4…
Bifurcation
L5 aas
Right/left common iliac, int iliac, median sacral
Celiac trunk branches
Common hepatic, splenic, lft gastric
Anastamoses at…
Left/right gastroepiploics, lft/right gastrics
Post duodenal ulcers–>
Pentrate gastroduocenal a –>hemorrhage
Ant duodenal ulcer–>
Pneumoperitoneum
Anastamoses sites
Esophagus, umbilicus, rectum
Esophageal portal/systemic
Lft gastric/azygos
Umbilical portal/system
Paraumbilical/small epigastric vvs of ant. abdominal wall
Rectal portal/systemic
Sup rectal/inf. and middle rectal
Tx of portal HTN and complication
TIPS hepatic v and portal v shunt but can cause hepatic encephalopathy
Pectinate line
Endoderm of hindgut meets ectoderm
Above pectinate line – a, v, l, what can go wrong
IMA branch – sup. rectal a
Drained by sup rectal v –> IMV –>splenic v–>portal v
Internal iliac lymphatic drainage
Internal hemorrhoids (not painful – visceral innervation, adenocarcinoma
Below pectinate line – a, v, l, what can go wrong
Inf rectal a. (branch of int. pudendal)
Inf rectal v –>int. pudendal v.–>int iliac v.–> common iliac v–>IVC
Superficial inguinal lymph nodes
Ext. hemorrhoids (painful if thrombose – innervated somatically by inf. rectal branch of int. pudendal n), anal fissures, squamous cell carcinoma
Anal fissue
Tear in anal mucosa below pectinate line –> pain while pooping, blood on TP – located posteriorly because poor perfusion
Assc. low-fiber diets and constipatioin
Stellate cells in liver
Store vit A when quiescent
Produce ECM when activated
Zone I
Periportal – affected 1st by viral hepatitis and ingested toxins (e.g. cocaine)
Zone II
Intermediate zone – yellow fever
Zone III
Pericentral vein/centrilobular – affected 1st by ischemia, contains P450 – most sensitive to metabolic toxins, alcoholic hepatitis
Site of gallstone lodging to cause double duct sign
Confluence of common bile and pancreatic ducts at the ampulla of Vater –> cholangitis and pancreatitis
Tumors in head of pancreas
Most often ductal adenocarcinoma –> obstruction of CBD –> large gallbladder, painless jaundice (Courvosier sign)
Femoral triangle
Femoral n, a, v
Femoral sheath
Femoral a, v and canacl (deep inguinal lymph nodes)
Indirect inguinal hernia –
Through internal (deep) inguinal ring, external and into scrotum
Enters inguinal ring LATERAL to inf epigastric vessels
Infants – no closure of processus vaginalis (can form hydrocele)
MALES
Covered by all 3 payers of spermatic fascia and follows descent of testes
Laters of fascia on spermatic cord
Internal spermatic fascia (transversalis fascia)
Creamasteric muscle/fascia (int. oblique)
External spermatic fascia (Ext. oblique)
ICE TIE
Direct inguinal hernia
Protrues through inguinal (Hesselbach) triangle – bulges directly through parietal peritoneum MEDIAL to inf epigastric vvs but lateral to rectus abdominis
Goes through external/superficial inguinal ring onlly
Covered by external spermatic fascia
Older men – acquired weakness in transversalis fascia
Femoral hernia
Protrudes below inquinal ligament though femoral canal below/lateral to pubic tubercle
FEMALES! (but overall inguinal most common)
More likely to have incarceration or strangulation
Hesselbach tirangle
Inf epigastric vessels
Lat border of rectus abdominus
Inguinal ligament
Gastrin source and location
G cells in antrum of stomach, duodenum
Actinon of gastrin
Increase gastric H secretion, growth of gastric mucosa, motility
Gastrin regulation
Increased by stomach distension/alkalinization, amino acids, peptides, vagal stim via GRP
Lowered by low pH (<1.5)
Gastrin is increased in which syndromes/drugs
PPI, chronic atrophic gastritis (H pylori), Z-E syndrome (gastrinoma)
Somatostatin source and location
D cells in pancreas and GI mucosa
Action of somatostatin
Lower gastric acid/pepsinogen secretion, pancreatic/small intestine fluid secretion, gallbladder contraction, insulin/glucagon release
Regulation of somatostatin
Increased by acid, decreased by vagal stim
Cholecystokinin source and location
I cells in duodenum and jejunum
CCK action
Increases pancreatic secretion (via neural muscarinic pathways), gallbladder contraction, sphincter of Oddie relaxation
Decreases gastric emptying
CCK regulation
Increased by fatty acids and amino acids
Secretin source and location
S cells in duodenum
Secretin action
INcreases pancreatic bicarb secretion (lowers pH so pancreatic enzymes fxn) and bile secretion
Decreases gastric acid secretion
Secretin regulation
Increased by acid, fatty acids in lumen of duodenum
Glucose dependent insulinotropic peptide source/location
K cells in duodenum and jejunum
Exocrine fxn of GIP
Lower gastric H secretion
Endocrine fxn of GIP
Increased insulin release
GIp regulation
Increased by fatty acids, amino acids, oral glucose
Motilin source
Small intestine
Motilin action
Produces migrating motor complexes
Motilin regulation
Increased in fastin state
Motilin receptor agonists
Erythromycin – can stimulate intestinal peristalsis
VIP source
Parasympathetic ganglia in sphincters, gallbladder, small intestine
VIP action
Increase intestinal water and electrolyte secretion, as well as relxation of intestinal smooth muscle/sphincters
Regulation of VIP
Increased by distension and vagal stim
Lowered by adrenergic input
VIPoma
non alpha or beta islet cell pancreatic tumor –> secretes VIP –> Watery Diarrhea, Hypokalemia, Achlorhydria syndrome
NO action
Relaxes smooth muscle, including lower esophageal sphincter
NO in achalasia
Lower NO secretion–> increased LES tone
Ghrelin source
Stomach
Ghrelin action
Increase appetite
Ghrelin regulation
Increased in fasting state
Decreased by food
Ghrelin is increased in
Prader Willi
Ghrelin is decreased in
Post-gastric bypass
Intrinsic factor source and location
Parietal cells in stomach
Action of IF
Binds B12 for uptake in terminal ileum
Pernicious anemia pathophys
Autoimmune destruction of parietal cells–>chronic gastritis and pernicious anemia from low B12
Gastric acid source/location
Parietal cells in stomach
Action of gastric acid
Lower stomach pH
Gastric acid is increased by
Histamine, ACh, gastrin
Gastric acid decreased by
Somatostatin, GIP, prostaglandin, secretin
Pepsin source and location
Chief cells in stomach
Pepsin action
Protein digestion
Pepsin regulation
INcreased by vagal stim and local acid
What activates pepsinogen
H+
Bicarb source and location
Mucosal cells in stomach/duodenum/salivary glands/pancreas
Brunner glands in duodenum
Bicarb action
Acid neutralization
Bicarb regulation
Increased by panctreatic/biliary secretion w/ secretin
Main method of gastrin mediated acid secretion
+ on ECL –> Histamine –> + on parietal cells –> H+ (indirect – also works direct but this is more of the primary effect)
WHen pancreas senses low flow
More Cl- secretion
When pancreas senses high flow
More HCO3 secretion
Alpha amylase
Starch digestion – secreted active by pancreas
Lipases
Secreted by pancreas for fat digestion
Proteases
Protein digestion enzymes trypsin, chymotripsin, elastase, carboxypeptidases secreted by pancreas as zymogens
Trypsinogen
First converted by brunch border enteropeptidase in duodenum and jejunal mucoase – cleaved to be activated and cleaves more enzymes and itself – secreted by pancreas
Carb absorption
Must be monosaccharides
SGLT1 (Na dependent – glucose and galactose)
GLUT5 (fructose – facilitated diffusion)
Blood transported via GLUT2
Fe absorbed
Fe2+ in duodenum
Folate absorption
Small bowel
B12 absorption
Terminal ileum w/ bile salts, req IF
Peyer patches – capsule?
Nope
Peyer patches found
Malmina propria and submucosa of ileum
Fxn of M cells
Sample/present ags to immune cells in peyer patches –> IgA plama cells which ultimately reside in LP
Bile composition
Bile salts (bile acids conjugate to glycine or taurine to be water soluble), pospholipids, cholesterol, bilirubin, water, ions
Rate limiting step of bile acid synthesis
Catalyzed by cholesterol 7a hydroxylase
Fxns of bile
Digest/absorb lipids and fat soluble vitamins, cholesterol excretion (primary method), antimibrobial (membrane disruption)
Heme–>biliverdin enzyme
Heme oxygenase
Biliverdin–>
bilirubin
Unconjugated bilirubin–>
removed from blood by liver–> conjugated w/ glucuronate –> excreted in bile
Direct bilirubin=
Conjugated –water soluble
Indirect bilirubin
Unconjugate –water insoluble
Conjugation of bilirubin enzyme
UDL glucouronosyl transferase
Suggestion of malignancy in salivary gland tumor
Smaller glands, facial pain or paralysis (involvedment of CN7)
Pleomorphic adenoma
Benign mixed tumor – most common; chondromyxoid stroma/epithelium and recurs if incompletely excised or ruptured intraoperatively
Mucoepidermoid carcinoma
Most common malignant tumor – mucinous and squamous components
Warthin tumor
Papillary cystadenoma lymphomatosum – benign cystic tumor w/ germinal centers typically in smokers, can be bilateral/malignant (10%)
Cause of achalasia
Lost of myenteric (Auerbach plexus)–> lost of post ganglionic inhibitory neurons w/ NO and VIP –> failure of LES to relax/uncoordinated/absent peristalsis–>progressive dysphagis to solids and liquirds
Achalasia imagin
Dilated esophagus and are aof distal stenosis – birds beak
Achalasia assocation
Increased risk of esophageal cancer, can arise 2o to Chagas diease or extra esophageal malignancies (mass effect or paraneoplastic)
Boerhaave syndrome
Transmural usually distal esophageal rupture w/ pneumomediastinum due to biolent retching – may detect subcutaneous emphysema due to dissecting air w/ crepitus in neck or chest wall – surgical emergency
Eosinophilic esophagitis
Infilitration of eos in the esophagus in atopic patients; food allergy–>dysphagia/food impaction; see esophageal rings and linear furrows on endoscopy and will be unresponsive to GERD therapy
Esophageal strictures assocatiation
Caustic ingestion and acid reflux
Esophageal varices
Dilated submucosa vvs in lower 1/3 of esophagus due to portal HTN – common in cirrhosis and may cause life threatening hematemesis
Esophagitis associations
Reflux, infxn in immunocompromised (candida, HSV, CMV), caustic ingestion or pill esophagitis (bisphosphonates, tetracycline, NSAIDs, iron, KCl)
Candida esophagitis
White pseudomembrane (immunocompromised)
HSV 1 esophagitis
Punched out ulcers (immunocompromised)
CMV esophagitis
Linear ulcers (immunocompromised)
GERD
Heartburn, regurg, dysphagia, chronic cough, hoarseness (laryngopharyngeal reflux) due ot transient decrease in LES tone
GERD assocation
Asthma
Mallory Weiss syndrome
Partial thickness mucosal lacerations at GE jxn due to severe vomiting –> hematemesis – alcoholics and bulemics
Plummer Vinson
Dysphagia, Iron deficiency anemia, Esophageal webs – can be associated w/ glossitis; higher risk of esophageal SCC
“Plumbers DIE”
Sclerodermal esophageal dysmotility
Esophageal smooth muscle atrophy –> lower LES pressure and dysmotility –> acid reflux/dysphagia –> stricture, Barrett esophagus, aspiration
Part of CREST
Barrett Esophagus
Intestinal metaplasia in previously nonkeratinized strat squamous epithelium in esophagus due to chronic GERD –> increased risk of esophageal ADENOcarcinoma
Intestinal metaplasia
Nonciliated columnar w/ goblet cells
Presentation of esophageal cancer
Progressive dysphagia starting w/ solids, wt loss, poor prognosis
SCC of esophagus location
Upper 2/3 esophagus
SCC of esophagus risk factors
Alcohol, hot liquires, caustic strictures, smoking, achalasia
Adenocarcinoma of esophagus location
Lower 1/3
Adenocarcimona risk factors
GERD, Barrett esophagus, obesity, smoking, achalasia
Prevalence of esophageal cancers
SCC more worldwide but adeno more in America
Cause of erosions (acute gastritis)
NSAIDs –> less PGE2–>less gastric mucosa protection
Burns (curling ulcer) hypovolemia–>mucosal ischemia
Brain injury (Cushing ulcer) – more vagal stim–> more ACh–>more H prodxn
Chronis gstritis
Mucosal inflamation –> atrophy (hypochlorhydria–>hypergastrinemia) and intestinal G cell metaplasia (higher risk of gastric cancers)
H pylori
Most common chronic gastritis; increased risk of PUD, MALT lymphoma – antrom first and spreads to body
Autoimmune chronic gastritis
Autoabs to parietal cells and IF –> higher risk of pernicious anemia; affects body/fundus of stomach
Menetrier disease
Hyperplasia of gastric mucosa –> hypertrophied rugae (look like brain gyri), excess mucus and protein loss/parietal cell atrophy –> less acid production
Precancerous
Gastric cancer most common
Gastric adenocarinoma
Signs of gastric cancer
Usually present late – wt loss, early satiety, acanthosis nigricans or Leser Trelat
Instestinal gastric cancer associations
H pylori, dietary nitrosamines, tobacco smoking, achorhydria, chronic gastritis
Intestinal gastric cancer most commonly located
Lesser curvature (ulcer w/ raised margins)
Diffuse gastric cancer histology
Signet ring cells
Diffuse gastric cancer grossly
Stomach wall grossly thickend and leathery (linitus plastica)
Virchow node
Left suprclavicular spread from gastric metastatses
Krukenberg tumor
Bilateral ovarian metastatses in diffuse CA
Sister mary joseph nodule
Subcutaneous periumbilical metastatsis
Gastric ulcer pain
Made greater w/ meals –> wt loss
Gastric ulcer causes
H pylori, NSAIDs
Gastric ulcer cause
Less mucosal protection against gastric acid
Duodenal ulcer pain
Less w/ meals –> weight gain
Mechanism of duodenal ulcer
Less mucosal protection or increased gastric acid secretion
Causes of duodenal ulcer
H pylori or ZE syndrome
Seen in duodenal ulcer
Hypertrophy of Brunner glands
Complications of ulcers
Hemorrhage (gastric or duodenal (post>ant), obstruction (pyloric channel, duodenal) perforation (duodenal – ant>post)
Lesser curvature ulcer hemorrhage–>
Bleeding from lft gastric a
Duodenal post. hemorrhage–>
Bleeding form gastroduodenal a
Duodenal ulcer –>perforation –> sx
Free air under diaphragm w/ referred pain to shoulder via phrenic n irritation
In celiac disease, autoimmune mediated intolerance of…
Gliadin (gluten protein found in wheat)
HLA w/ celiac
HLA DQ2, DQ8
Seen in celiac disease
European descent, dermatitis herpetiformis, lower bone density, IgA TTG, antiendomysial and anti deamidated gliadin peptide abs
Histology: villous atrophy, crypt hyperplasia, intraepithelial lymphocytosis
Increased risk of T cell lymphoma
Mucosal malabsorption primary affects distal duodenum/proximal jejunum
D xylose test
Passively absorbed in prox SI – blood and urine levels decrease w mucosa defects or bacterial overgrowth, normal in pancreatic inufficiency
Lactose intolerance causes
Lactase deficiency – viral or acquired
Histology/labs in lactose intolerance
Normal appearing villi (except when 2o injury at tips due to viral enteritis –> osmotic diarrhea w/ low stool pH (colonic bacteria ferment); lactose hydrogen breath test (pos for lactos malabsorption if postlactose breath hydrogen rises > 20 ppm compared to baseline)
Pancreatic insufficiency causes
Chronic pancreatitis, CF< obstructive cancer
Pancreatic insufficiency results in
Malabsorption of fat/fat soluble vitamins (ADEK) and B12 – low duodenal pH (bicarb) and fecal elastase
Tropical sprue
Like celiac sprue but respons to Abx -
Whipple disease bug
Tropheryma whipplei – PAS +
Whipple disease histology
PAS foamy macrophages in lamina propia and mesenteric nodes
Signs of Whipple disease
Cardiac symptoms, Arthralgias, Neuro symptoms, later –> diarrhea/steatorrhea
Whpple disease demographic
Older men
Crjohn disease location
Any part of GI tract – usually terminal ileum and colon w/ skip lesion and rectal sparing
Grossly Crohn disease
Transmural inflamm –> fistula, cobblestone mucosa, creeping fat, bowel wall thickening (string sign on barium swallow), linear ulcers, fissure
Microscopic Crohns
Moncaseating granulomas and lymphoid aggregates – Th1 mediated
Complications of Crohn
Malabsorption/malnutrition, colorectal cancer, fistulas (enterovesicular –> recurrent UTI, pneumaturia), phlemon/abcess, strictures (–>obstruction), perianal disease
Crohn disease diarrhea
Bloody or nah
Extraintestinal manifestations common to both IBDs
Rash (pyoderma gangrenosum, erythema nodosum), eye inflammation (episcleritis, uveitis), oral ulcers (apthous stomatitis), arhtritis (peripheral, spondylitis)
Crohn specific extraintestinal manifestations
Kidney stones (Ca oxalate), gallstones, may have positive anti Saccharomyces cervisiae abs (ASCA)
Tx of Crohns
Corticosteroids, AZA, abx (cipro, metro), infliximab, adalimumab
Ulcerative colitis location
Continuous from rectum up (not past end of colon)
Grossly ulcerative colitis
Mucosal and submucosal inflam only – firable mucosa w/ superficial/deep ulcerations, loss of haustra (lead pipe appearance on imaging)
Histology of UC
Crypt abcesses and ulcers, bleeding, no granulomas, Th2 mediated
Complications of UC
Malabsorption/malnutrition, colorectal CA 9increased risk w pancolitis), fulminant colitis, toxic megacolon, perf
Diarrhea in UC
Always bloody
UC specific extraintestinal manifestations
1o sclerosing cholangitis (pANCA)
Tx of UC
5ASA preps (mesalamine), 6MP, infliximab, colectomy
IBS
Recurrent abdominal pain w/ 2+: - Related to defecation -Change in stool freq -Chain in form (consistency) of stool w/ no structural abnormalities Can be diarrhea predom, constipation predom, or mix
IBS demographic
Middle aged women
Appedicitis most common cause
Kids: lymphoid hyperplasia
Adults: fecalith
Complication of appendicits
Perf–>peritonitis
Buzzwords for appendicits
McBurney’s point pain, posas, obturator, Rovsing signs
True diverticulum
All 3 gut wall layers outpouch (meckl)
False diverticulum
Only mucosa and submucosa outpouch (esp where vasa recta perforate muscularis externa)
Diverticulosis
Many false diverticula of colon, commonly in sigmoid
Diverticulosis cause
Increased intraluminal pressure and focal weakness in colonic wall, low fiber diets
Complications of diverticulosis
Diverticular bleeding (painless hematochezia) or diverticulitis
Diverticulitis
Inflammation fo diverticula – LLQ pain, fever, leukocytosis (tx w/ abx)
Diverticulitis complications
Abscess, fistula (colovesical–>pneumaturia), obstruction (inflammatory stenosis), perf –>peritonitis
Zenker diverticulum
Pharyngoesophageal false diverticulum – esophageal dysmotility –> herniation of mucosa at Killian triangle vtween thyropharyngeal and cricopharygeal parts of inf pharyngeal contricture –> dysphagia, obstruction, gurgling, aspiration, foul breath, neck mass (usually elderly males)
Meckle diverticulum
True diverticulum – persistence of vitellin duct, may contain ectopic acid secreting gastric mucosa +/- pancreatic tissue; most common congenital anomaly of GI tract –> hematochezia/melena, RLQ pain, intussusception, volvulus, obstruction near terminal ileum
Omphalomestnteric cycst
Cystic dilation of vitelline duct
Diagnose meckel diverticulum
Pertechnetate study for uptake by ectopic gastric mucosa
Rule of 2s in Meckle’s
2x more likely in males, 2 inches long, 2 feet from ileocecal vavle, 2% of population, presents in first 2 years of life, 2 types of epithelia
Hirschprung disease
Congenital megacolon due to lack of ganglion cells/enteric nervous plexuses (Auerbach, Meissner) in distal colon due to failure of neural crest migration
Hirschprung genetics
RET mutations, higher in DS
Presentation of Hirschprung
Bilious emesis, abdominal distention/failure to pass meconium w/in 48 hrs –> chronic constipation; explosive expulsion of feces (squirt sign) –> empty rectum on digital exam
Hirschsprung diagnosis
Rectal suctino biopsy
Malrotation
Anomaly of midgut rotation during fetal development –> improper position of bowel, formation of fibrous bands (Ladd bands)
Malrotation complications
Volvulus, duodenal obstruction
Volvulus
Twisting of part of bowel around its mesentary –> obstruction or infactrion
Common volvulus in kids
Midgut
Elderly volvulus
Sigmoid (coffee bean)
Intussusception
Telescoping of prox bowel into distal – usually at ileocecal jxn –> compromised blood supply –> abdominal pain w/ currant jelly stools
Cause of intussusception in adults
Intraluminal mass or tumor
Most common lead point in intussuception
Meckel diverticulum (usually kids)
Associations w/ intussusception
Recent viral infxn (adenovirus –> Peyer patch hypertrophy –> lead point; rotavirus vax
Acute mesenteric ischemia
Critical blockage of intestinal blood flow (often embolic occlusion of SMA) –> SI necrosis –> abdominal pain out of proportion to physical findings, may see current jelly stools
Chronic mesenteric ischemia
Intestinal angina – atherosclerosis of celiac a, SMA, IMA –> intestinal hypoperfusion –> posprandial epigastric pain –> food aversion/wt loss
Colonic ischemia
Reduction in intestinal blood flow –> ischemia –> crampy abdominal pain followed by hematochexia
Location of colonic ischemia
Watershed areas (splenic flexure, distal colon)
Colonic ischemia demographics
Elderly
Clonoic ischemia imaging
Thumbprint sign due to mucosal edema/hemorrhage
Angiodysplasia
Tortuous dilation of vessels –>hematochezia; confirmed by angiography
Angiodysplasia location
Rt colon
Angiodysplasia demographics
Elderly
Adhesion
Fibrous band of scar tissue, commonly after surgery –> most common cause of SI obstruction, can have well demarkated necrotic zones
Ileus
Intestinal mypomotility w/o obstruction –> constipation and less flatus
Presentation of ileus
Constipation, less flatus, distended/tympanic abdomen w/ less bowel sounds
Associations w/ ileus
Abdominal surgeries, opiates, hypokaemia, sepsis,
Tx of ileus
Bowel rest, electrolyte correction, cholinergic drugs (stim intestinal motility)
Meconium ileus
In CF – meconium plub obstructs intesting preventing stool passage at birth
Necrotizing enterocolitis
Premature forumla fed infants w/ immature immune system – necrosis of intestinal mucosa (esp colonic) w/ possible perfs –> pneumatosis intestinalis, free air in abdomen, portal venous gas
Hamartmoatous polyps
Generally non neoplastic and solitary – growths of normal colonic tissue w/ distorteed architecture
Associated with hamartomatous polyps
Peutz-Jeghers, juvenile polyposis
Mucosal polyps
Small, less than 5 mm, look similar to normal, clinically insignificant (non neoplastic)
Inflammatory pseudopolyps
Result of mucosal erosion in inflam bowel disease (non neoplastic)
Submucosal polyps
Lipomas, leimyomas, fibromas, etc (non neoplastic)
Hyperplastic polyps
Smaller and mostly in rectosigmoid region – only rarely evolve into serrated and more advanced lesions
Adenomatous polyps
Neoplastic via chromosomal instability pathway with mutation in APC and KRAS – tubular worse than villous, tubulovillous in the middle; usually asymptomatic but may present w/ occult bleeding
Serrated polyps
Premalignant via CpG hypermethylation phenotype w/ microsatillite instability and BRAF mutations; saw tooth crypts – up to 20% of sporadic CRC
FAP genetics
AD mutation of APC tumor suppressor (2 hit) on chr 5q21
FAP sx
Thousands of polyps after puberty – pancolonic and always involves rectum
FAP tx
Prophylactic colectomy – 100% progression
Gardner syndrome
FAP+osseous and soft tissue tumors, congenital hypertrophy of RPE, impacted/supernumerary teeth
Turcot syndrome
FAP/Lynch syndrome and malignant CNS tumor (medulloblastoma, glioma)
Peutz Jeghers syndrome genetics
AD
Peutz Jeghers sx
Numerous hamartomas through GI tract, hyperpigmented mouth, lips, hands, genitalia
Peutz Jeghers assoc
Higher risk of breast and Gi cancers (colorectal, stomach, SI, pancreatic
Juvenile polyposis syndrome genetics
AD
JPS demographics
Children under 5
JPS sx
Numerous hamartomatous polyps in colon, stomach, SI
JPS assoc
Higher risk of CRC
Lynch syndrome aka
HNPCC
Lynch syndrome genetics
AD mutation of DNA mismatch repair gene –> microsatillite instability
Lynch prognosis
80% progression to CRC
Lynch syndrome assoc
Endometrial, ovarian, skin CA and CRC
CRC demographics
most >50, 25% family hx
CRC risk factors
Adenomatous/serrated polyps, familiar CA syndromes, IBD, tobacco use, diet of processed meat w/ low fiber
CRC sx
Rectosigmoid>
ascending – exophytic, IDA, wt loss>
descending – infiltrating, partial obstruction, colicky pain, hematochezia
Assoc w/ CRC
S bovis bacteremia
IDA in males >50 and postmenopausal females
Screening for CRC
Starts at 50 w/ colonoscopy (40 or 10 yrs prior to family member if family hx in 1st degree relative)
Tumor marker for CRC
CEA – mointors recurrence/tx, not screening
Molecular pathogenesis of CRC chromosomal instability
APC mutation –> less adhesion and more proliferation (at risk) –> KRAS mut –> unregulated incracell signalling –> adenoma –> loss of tumor suppressor gene (e.g. p53) –>increased tumorienesis –> carcinoma
Molecular pathogenesis of CRC microsatilite instability
Mutations or methylation of mismatch repair genes (e.g. MLH1)
May cause or prevent CRC
Overexpression of COX2 linked to CRC – NSAIDs chemoprotective
Cells most involved in cirrhosis
Stellate
Causes of portal HTN
Cirrhosis (most), vascular obstruction (e.g. portal vein thrombosis, Budd chiari), schistosomiasis
Metabolic changes in portal HTN
Hyponatremia, hyperbilirubinemia
Spontaneous bacterial peritonitis aka
Primary bacterial peritonitis
Predisposes to spontaneous bacterial peritonitis
Cirrhosis/ascites
Sx of spontaneous bacterial peritonitis
Often asymptomatic, but can cause fevers, chiils, abdominal pain, ileus, worsening encephalopathy
Causes spontanoeous bact peritonitis
Aerobic gram neg organism – esp E coli
Diagnose spont. bact peritonitis
Paracentesis w/ ascitic fluid abs. neutrophil count >250cells/mm3
Most liver disease liver enzymes and exception to rule
ALT>AST
Exception alcohol (AST>ALT)
If AST>ALT in non alcoholic liver disease – probably progression to advanced fibrosis of cirrhosis
Alk phos
Increased in cholestasis, infiltrative disorders, and bone disease
GGT
Increased in liver and billiary disease (like alk phos) but not in bone disease; assc w/ alcohol use
Why are plts low in liver disease?
Low TPO, liver sequestration
Why are plts low in portal HTN?
Splenomealy, spenic sequestration
Reye syndrome
Oft fatal hepatic encephalopathy in kids; sx: mitochondrial abnormalities, fatty liver (microvesicular fatty change), hypoglycemia, vomiting, hepatomegaly, coma
Cause of Reyes syndrome
Viral infxn (esp VZV and influenza B) tx w/ aspirin
Reye syndrome mechanism
Aspirin metabolites decrease B-oxidation by reversible inhib of mitochondrial enzymes
Hepatic steatosis
MACROvesicular fatty change – may be reversible w/ alcohol cessation
Alcoholic hepatitis
Req sustained long-term consumption – swollen/necrotic hepatocytes w/ neutrophilic infiltration, Mallory bodies (intracytoplasmic eosinophilic inclusions of damaged keratin filaments)
Alcoholic cirrhosis
Final and irreversible form of liver damage – regnerative nodules surrounded by fibrous bands in response to chronic liver injury –> portal HTN and end stage liver disease; sclerosis around central vein in early disease
Nonalcoholic fatty liver disease
Metabolic syndrome (insulin resistance, obesity) –> fatty infiltratin of hepatocytes –> cellular ballooning and eventual necrosis –> can –>cirrhosis and HCC
Hepatic encephalopathy
Cirrhosis –>portosystemic shunts –> less HN3 metabolism –> neuropsych dysfxn (from disorientation/asterixis to difficult arousal or coma)
Triggers of hepatic encephalopathy
Increase NH3 prodxn and absorption (due to dietary protein, GI bleed, constipation, infxn)
or
Less NH3 removal (due to renal failure, diuretics, TIPS)
Tx of hepatic encephalopathy
Lactulose (increased NH4 prodxn) and refaximen or neomycin (less NH3 producing gut bacteria)
HCC assoc
HBV (w/ or w/o cirrhosis), HCV, alcoholic and nonalcoholic fatty liver disease, autoimmune disease, hemochromatosis, alpha1 AT def, aflatoxin
Findings in HCC
Jaundice, TENDER hepatomegaly, ascites, polycythemia, anorexia
Spread of HCC
Hematogenously
What can HCC progress to cause?
Budd chiari
Diagnosis of HCC
AFP, ultrasound or contrast CT/MRI, biopsy
Cavernous hemangioma
Common benign liver tumor occuring 30-50 yrs
DO NOT BIOPSY – risk of hemorrhage
Hepatic adenoma
Rare benign liver tumo r– related to OCP or anabolic steroids – can regress spontaneously or rupture (abdominal pain/shock)
Angiosarcoma
Malignant tumor of endothelium – assoc w/ exposure to arsenic, vinyl chloride
Metastases
Most common liver tumor altogether – usually multiple; most commonly GI, breast, and lung cancer
Budd chiari
Thrombosis/compression of hepatic vvs w/ centrilobular congestion/necrosis –>congestive liver disease (hepatomegaly, ascities, varices, abdominal pain, liver failure) – can cause nutmeg liver
No JVD
Budd chiari assoc
Hypercoagulable states, polycythemia vera, postpartum, HCC
a1 AT deficiency
Misfolded gene product protein aggregates in hepatocellular ER –> cirrhosis w/ PAS + globules in liver
a1 AT genetics
codominant
Presentation of a1AT def
young pt w/ liver damage and dyspnea and no hx of smoking
Common causes of jaundice (increased bili)
HOT Liver Hemolysis Obstruction Tumor Liver disease
Unconjugated hyperbilirubinemia
Hemolytic, physiologic in newborns, Crigler-Najjar, Gilbert
Conjugated hyperbilirubinemia
Biliary tract obstruction – gallstones, cholangiocarcinoma, pancreatic/liver cancer, liver fluke
Biliary tract disease: 1o sclerosis cholangitis or 1o biliary cholangitis
Excretion defect: duin-Johnson, Rotor syndrome
Cuase of neonatal jaundice and danger
Immature UDP glucuronosyltransferase – can cause kernicterus esp in basal ganglia
Usually w/in 24 hours of life and resolves in 1-2 wks
Tx: phototerapy
Gilber syndrome v Crigler Najjar
Mildly low UDPGTase vs. absent UDPGTase Relatively asymptomatic (sx on fasting/stress) vs early in life presentation and death w/in a few years
Type I vs Type II C-N
Type II is less severe and responds to phenobarb (increases liver enzyme synth)
Dubin johnson
Defective liver secretion – grossly black liver (Rotor – same, no black liver)
Wilson disease genetics
AR mutation in hepatocyte copper transporting ATPase – ATP7B gene on Chr 13
Wilson disease mechanism
Less Cu exretion into bile and incorporation into apoceruloplasmin –> less serum ceruloplasmi –> Cu accumulation, esp in liver, brain, cornea, kidneys; higher urine Cu
Wilson disease presentation
Before age 40 – liver disease (hepatitis, acute liver failure, cirrhosis), neurologic disease (e.g. dysarthria, dystonia, treamor, parkinsonism), psych disease, K-F rings (deposits in Descemet membrane of cornea), hemolytic anemia, renal disease (Fanconi syndrome)
Tx of Wilson disease
Chelation w/ penicillamine or trientine, oral Zn
Hemochromatosis genetics
AR mutation in HFE gene (C282Y>H63D) chr 6, assc w/ HLA A3
Hemochromatosis mechanism
Abnormal Fe sensing and increased int absorption (high ferritin, high iron, low TIBC –> high transferrin sat), OR 2o to chronic blood transfusion –> Iron accumulation in liver, pancreas, skin, heart, pituitary, joints
Hemochromatosis findings
Hemosiderin identified on liver MRI or biopsy w/ Prussian blue stain
Demographics of hemochromatosis
Pts older than 40 when total body iron >20 g – iron loss through menstruation slows progression in women
Presentation of hemochromatosis
Cirrhosis, DM, skin pigmentation (bronze), restrictive cardiomyopathy or dilated (reversible), hypogonadism, arthropathy (Ca pyrophosphate deposition – esp in MCP jnts), can lead to HCC
Tx of hemochromatosis
Repeated phlebotomy, chelation w/ desfersirox, deferoxamine, oral deferiprone
Presentation of biliary tract disease
Pruritis, jaundice, dark urine, light colored stool, hepatosplenomegaly –> cholestatic pattern of LFT (high conj bilirubin, high chol, high alk phos)
PSC pathology
Something causes concentric onion skin bile duct fibrosis –> alternating strictures and dilation w/ beading of intra/extrahepatic bile ducts on ERCP or MRCP
Epidemiology of PSC
Middle aged men w/ IBD
Associations of PSC
Assc w/ UC, pANCA+, can lead to 2o biliary cholangitis, higher risk of cholangiocarcinoma and gallbladder CA
PBC pathology
Autoimmune rxn –> lymphocytic infilitrate and granulomas –> destruction of intralobular bile ducts
Epidemilogy of PBC
Middle aged women
Assoc w/ PBC
Anti mitochondrial ab +, high igM; assc w/ other autoimmune conditions (Sjogrens, Hashimotos, CREST< RA, celiac)
2o biliary cholangitis pathology
Extrahepatic biliary obstruction –> higher pressure in intrahepatic ducts –> injury/fibrosis and bile statsis
2o BCitis assc.
Pts w/ gallstones, biliary strictures, pancreatic carcinoma (can be complicated by ascending cholangitis)
Cholesterol stones –
Radioluscent (most common_ assc w/ obesity, Crohn disease, advanced age, estrogen therapy, multiparity, rapid wt loss, Native American origin
Pigment stone –
Radiopaque, bilirubinate, hemolysis (black) or radiolucent from infxn (brown)
Assc w/ Crohn disease, chronic hemolysis, alcoholic cirrhosis, advanced age, biliary infxns, TPN
Most common complication of cholelithiasis
Cholecystitis (can also cause acute pancreatitis, ascending cholangitis, fistula btween gallbladder and GI tract –>air in biliary tree (pneumobilia) –> passage of gallstones into intestine –>obstruction of ileocecal valve (gallstone ileus))
Risk factors for cholelithiasis
Female Fat Fertile (preggers) Forty (4Fs)
Biliary colic
Cholelithiasis complicatio. Assc w/ NV, dull RUQ; neurohormonal activation by CCK after fatty meal –> contraction of gallbladder –> stone into cystic duct; normal labs (see stone on US)
Choledocholithiasis
Gallstone in common bile duct –> elevated ALP, GGT, direct bili, AST/ALT
Cholecytisis
Acute or chronic inflam of gallbladder from cholelithiasis (stone at neck of gallbladder) w/ gall bladder wall thickening
Calculous cholecystitis
Most common – gallstone impaction in cystic duct –> inflammation (can produce 2o infxn)
Acalculous cholecystitis
Due to gallbladder stasis, hypoperfusion, infxn (CMV) in critically ill pts
Cholecystitis test
Murphy sign (inspiratory arrest on RUQ palpation due to pain), increased ALp if bile duct involved (ascending cholangitis)< diagnosed w/ US or HIDA (can’t visulaize gallbladder on HIDA – obstruction)
Porcelain gallblader
Calcified gallbladder due to chronic cholecystitis – usually inceidental finding
Tx of porcelain gallbladder
Prophylactic cholecystectromy – high rates of gallbadder adenocarcinoma
Ascending cholangitis
Infxn of biliary tree usually due to obstruction –> stasis/bacterial overgrowth
Charcot triad of cholangitis
Jaundice, fever, RUQ pain; reynolds pentad adds alteed mental status and shock (hypotension)
Acute pancreatitis
Autodigestion of pancreas by pancreatic enzymes
Causes of acute pancreatitis
Idiopathic, Gallstones, EtOH, Trauma, Steroids, Mumps< Autoimmune, Scorpion sting, Hypercalcemia/hypertriglyceridemia (>1000 mg/dL), ERCP, Drugs (e.g. sulfa, NRTIs, protease inhibs)
I GET SMASHED
Diagnosis of acute pancreatitis
2 of 3: acute epigastric pain radiating to back, high serum amylase or lipase (more specific) to 3x ULN, characteristic imaging
Complications of acute pancreatitis
Pseudocyst (lined by granulation tissue – not epithelium), necrosis, hemorrhage, infxn, organ failures (ARDS, shock, renal failure), hypocalcemia (precipiation of Ca soaps)
Chronic pancreatitis major causes
EtOH abuse, idiopathic
Sx of chronic pancreattitis
Pancreatic insufficiency – statorrhea, fat soluble vit def, DM
+/- on lipase/amylase changes
Panctic adenocarcinoma
Arises from pancreatic ducts (disorganized gladular sturctionw/ cellular infiltration) — most common in pancreatic head –> obstructive jaundice
Tumor marker for pancreatic adenocarcinoma
CA199
Risk factors for pancreatic adenocarcinoma
Tobacco use, chronic pancreatitis (esp > 20 yrs), DM, age >50 yrs, Jewish and AfAm males
Presentation of pancreatic adenocarcinoma
Abdominal pain radiating to neck, wt loss (malabsorption, anorexia), migratory thrombophleibitis (redness and tenderness on palpation of extremeties – Troussea syndrome), obstructive jaundice w/ palpable nontender gallbladder (Courvosier sign)