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Surgery Review 7

SR 7: GI tract (esophagus, stomach, small bowel, colorectal, anus)

QuestionAnswer
What are the effects of gastrin? Increase HCl, instrinsic factor, and pepsinogen secretion
What are the effects of cholecystokinin (CCK)? Stimulates gallbladder contraction and pancreatic enzyme secretion, and relaxes sphincter of Oddi
Where is cholecystokinin (CCK) produced? I cells of duodenum and jejunum
What are the effects of secretin? Stimulates flow and alkalinity of bile and pancreatic secretions while inhibiting gastric acid secretion and gastrin release
What is the primary stimulus of pancreatic bicarb secretion? Secretin
What effects the amount of bicarbonate in pancreatic secretions? Flow rate: high flow = high bicarb and low Cl. Slow flow allows more HCO3/Cl exchange
What are the effects of somatostatin? Universal “off” switch – inhibits release of GI and pancreatic hormones and gastric acid
Where is somatostatin produced in the GI tract? D cells in antrum
What stimulates somatostatin secretion? acid in duodenum
What are the effects of gastrin-releasing peptide (Bombesin)? Universal “on” switch – stimulates release of all GI hormones except secretin and increases GI motility
What is the effect of motilin? stimulates GI tract motility
What drug stimulates motilin receptors? Erythromycin
What are the effects of vasoactive intestinal peptide? potent vasodilator, stimulates pancreatic and intestinal secretion and motility, inhibits gastric acid secretion
What are the effects of gastric inhibitory peptide? inhibit gastric acid secretion and stimulate insulin release
What is the effect of peptide YY? Inhibits pancreatic and gastric secretion and gallbladder contraction, "ileal break"
Where is peptide YY secreted? terminal ileum
Where is gastric inhibitory peptide produced? K cells in duodenum
What is the effect of omeprazole? Blocks H/K ATPase of parietal cell (final pathway for H+ release)
What is the effect of pancreatic polypeptide? deceased pancreatic and gallbladder secretion
What is the order of bowel recovery after surgery? Small bowel 24 hours, stomach 48 hours, large bowel 3-5 days
What are the layers of the esophagus? Squamous epithelium, circular inner muscle layer, outer longitudinal muscle layer; no serosa. Upper esophagus – striated muscle; lower esophagus – smooth muscle
What is the blood supply to the esophagus? Cervical – inferior thyroid artery; thoracic – directly off aorta; abdominal – left gastric and inferior phrenic arteries
What is normal LES tone and length? 15-25 mm Hg, 4cm long, 40cm from incisors
What is primary, secondary, and tertiary peristalsis? Primary - CNS initiates swallow, occurs with food bolus; Secondary - occurs with esophageal distention (propagating waves); Tertiary - non-propagating/dysfunctional
What is the most common site of esophageal perforation? Cricopharyngeus muscle (usually after EGD)
What are the 3 anatomical areas of narrowing of the esophagus? Cricopharyngeus muscle, compression by left mainstem bronchus and aortic arch, and diaphragm
What is the surgical approach to the esophagus? Cervical – left; upper 2/3 thoracic – right (avoids aorta); lower 1/3 thoracic – left
What is Killian's triangle? A potentially weak spot where a pharyngoesophageal diverticulum (Zenker's) is more likely to occur. Posterior triangular area in the pharynx between the inferior constrictor and the cricopharyngeus muscle
What are the types of esophageal diverticula? Traction (true) and pulsion (false, Zenker’s, epiphrenic)
What is the treatment for a Zenker’s diverticulum? cricopharyngeal myotomy (removal of diverticula not necessary)
What is the cause of a traction diverticulum? granulomatous inflammation (TB or fungal disease) or tumor
What is an epiphrenic diverticulum? Treatment? Acquired pulsion diverticula in distal 10 cm of the esophagus usually associated with esophageal motor disorders (achalasia, DES); Tx: diverticulectomy and long esophageal myotomy on side opposite of diverticulectomy
What is the pathophysiology of achalasia? Decreased ganglion cells in Auerbach's plexus, absence of peristalsis and esophageal dilation. High LES pressures
What does manometry showing normal LES tone but strong unorganized contractions suggest? Diffuse esophageal spasm
What does manometry showing increased LES pressure, incomplete relaxation, and no peristalsis suggest? Achalasia
What is the treatment of diffuse esophageal spasm? calcium channel blockers, nitrates, Heller myotomy (transect circular layer of upper and lower esophagus). Surgery better at resolving dysphagia than pain
What is the treatment for achalasia? Calcium channel blockers, dilation effective in 60%. Heller myotomy with transection of circular layer of lower esophagus only and partial Nissen fundoplication if failed medical treatment)
What is the key maneuver in a Nissen fundoplication? identification of left crura
What is the most common cause of dysphagia after a Nissen fundoplication? wrap is too tight
What are the types of hiatal hernia? Type I – sliding hernia from dilation of hiatus; II – paraesophageal, normal GE junction; III – combined I+II; IV – entire stomach plus another organ in chest
What is the treatment of a type II hiatal hernia? Repair of diaphragm and Nissen fundoplication (diaphragm repair can affect LES, also helps anchor stomach)
What is the indication for esophagectomy in Barrett’s esophagus? severe dysplasia or a diagnosis of adenocarcinoma
What is the effect of a Nissen fundoplication on Barrett’s esophagus? Surgery will decrease esophagitis and progression of metaplasia, but will not induce regression or prevent malignancy. Still need close follow-up for lifetime
What suggests unresectability of esophageal cancer? hoarseness (RLN), Horner’s syndrome, phrenic nerve involvement, malignant pleural effusion, malignant fistula, airway invasion, or vertebral invasion
What is main arterial supply to stomach when used to replace esophagus? right gastroepiploic artery
What is the standard chemotherapy regimen for esophageal cancer? 5-FU and cisplatin
What is the treatment of esophageal leiomyoma? If symptomatic or >5cm excise by enucleation via thoracotomy. Do not biopsy on EGD
What type of caustic esophageal injury causes deep liquefaction necrosis? alkali
What type of caustic esophageal injury causes coagulation necrosis? acid
What is the workup and treatment for caustic esophageal injuries? CXR for free air, then EGD if no perforation. Conservative treatment of NPO, IVF, spitting, ABx. NO nasogastric tube
What is the initial treatment of GI bleeding in Mallory-Weiss syndrome? Observation - most cases stop with nonoperative management
Describe the anatomy of the vagus innervation of the stomach Left vagus (anterior) gives hepatic branch, Right (posterior) gives celiac branch and "criminal nerve of Grassi"
Which cells produce pepsinogen? Chief cells
Which cells produce intrinsic factor? Parietal cells
What are the main stimuli for H+ production in the stomach? Gastrin, acetylcholine, and histamine
What are the 3 phases of gastric acid stimulation? Cephalic (30%) – anticipation of eating signaling through vagus; Gastric (50%) – stimulated by stomach distention and amino acids; Intestinal (10-20%) – small bowel distention and amino acids
What is the treatment for gastric volvulus? Reduction and Nissen
How does vagotomy affect gastic empyting? All forms increase liquid emptying – vagally mediated receptive relaxation is removed resulting in increased gastric pressure accelerating liquid emptying. Complete (truncal or selective) causes decreased emptying of solids
What is the most common symptom post-vagotomy? Diarrhea (30-50%) caused by sustained MMC forcing bile acids into colon
What are the risk factors for rebleeding of an UGIB at time of EGD? 1 – spurting blood vessel (60% chance of rebleed), 2 – visible blood vessel (40%), 3 – diffuse oozing (30%)
What is the treatment for an UGIB in a patient with liver failure? EGD with sclerotherapy or TIPS, not OR as patient is likely bleeding from esophageal varices
What are the types of gastric ulcers? I – lesser curvature, II – 2 ulcers (lesser curve and duodenal), III – prepyloric, IV – along cardia of stomach, V – NSAID use
What types of gastric ulcers are due to high acid secretion? What types are due to decreased mucosal protection? Types I and IV – decreased mucosal protection; types II and III – high acid secretion
What is the mechanism of ulcer formation with chronic NSAID use? Inhibits prostaglandin synthesis, causing decreased mucus and bicarb secretion and increased acid production
What blood types are associated with gastric ulcers? Type A blood – type I ulcers; type O blood – type II-IV ulcers
What is the most common benign gastric neoplasm? gastric leiomyoma (GIST tumor). Most are C-KIT positive
What is the cells of origin for GIST tumors? interstitial cells of Cajal
What is the treatment of a GIST? Resection with 1-cm margins, +/- chemotherapy -> Gleevec (tyrosine kinase inhibitor)
What is the treatment for gastric lymphoma? chemotherapy and XRT, surgery for complications
What is MALT a precursor to? gastric lymphoma - regresses with H. pylori treatment
What is the treatment for MALT (mucosa-associated lymphoproliferative tissue)? triple therapy antibiotics for H. pylori, as most are associated with H. pylori and regress after treatment. Chemotherapy (CHOP) if does not regress
What are some specific complications of roux-en-Y gastric bypass? marginal ulcers, leak, necrosis, B12 deficiency (losses acidic environment needed to bind B12), iron deficiency anemia (bypasses duodenum), gallstones
What are the specific complications of jejunoileal bypass? increased liver cirrhosis and kidney (stones) problems, osteoporosis (decreased calcium)
What is the cause of early (15-30 min) dumping syndrome? Hyperosmotic load, fluid shift causes neuroendocrine response, peripheral and splanchnic vasodilation
What is the cause of late (2-3 hrs) dumping syndrome? Increased insulin with decreased glucose
What is the treatment of dumping syndrome? Dietary changes resolve 90% - small, low-fat, low-carbohydrate, high-protein meals with no liquid and no lying down after meals. Octreotide may be effective. Conversion of billroth I or II to roux-en-Y is rarely needed
What is the cause after gastrectomy of postprandial epigastric pain associated with N/V, but not relieved after vomiting? Treatment? alkaline reflux gastritis. Tx: H2 blockers, cholestyramine, metoclopramide, or possible conversion of billroth to roux-en-Y
What is the treatment of roux stasis? metoclopramide, prokinetics, possible shortening of roux limb to 40 cm
What causes blind-loop syndrome? bacterial (E. coli, GNR) overgrowth and stasis in afferent limb, therefore treat with antibiotics (tetracycline, flagyl)
What is the most common site of GI lymphoma? stomach
What margins are necessary for gastric cancer resection? 5-6cm due to intramural microscopic spread and extensive lymphatics around stomach
Describe the phases of the migratory motor complex Phase I - quiescence; Phase II - acceleration, gallbladder contraction; Phase III - peristalsis; Phase IV - subsiding electric activity; occurs in 90 min cycles
What is the key stimulatory hormone of the MMC? motilin
How are bile salts reabsorbed? 50% passive absorption (45% ileum, 5% colon), 50% active resorption in terminal ileum
What test can assist with the diagnosis of short gut syndrome? Schilling test – checks for B12 absorption (radiolabeled B12 in urine)
What are the causes of a non-healing fistula? FRIENDS – foreign body, radiation, IBD, epithelialization, neoplasm, distal obstruction, and sepsis
What is able to induce remission and fistula closure with small bowel Crohn’s disease? TPN
What is the pathology of Crohn’s disease? transmural involvement, cobblestoning, skip lesions (segmental disease), fistulas, perianal disease
What is the surgical treatment for a crohn's patient with multiple strictures? Do not resect (to avoid short gut), do stricturoplasties
What are the side effects of terminal ileum resection? bile salt diarrhea, cholelithiasis, megaloblastic anemia, nephrolithiasis
What are the cells of origin of gastrointestinal carcinoid tumors? Kulchitsky cells (enterochromaffin or argentaffin) at the base of the crypts of Lieberkuhn
What are the most common sites of carcinoid tumors? AIR – appendix, ileum, and rectum; 10% arise in bronchus or lung
What are the symptoms of carcinoid syndrome? flushing, diarrhea, asthma, R sided heart valve dz
What is the test for carcinoid syndrome? urinalysis for 5-HTP (secreted by foregut), 5-HIAA, and serotonin
What chemotherapy agents are used for carcinoid tumors? Steptozocin, doxorubicin, 5 FU
What % of patients with carcinoid tumors get carcinoid syndrome? 9% - mostly those with extensive mets to the liver
What is the most reliable tumor marker for carcinoid? serum chromagranin A
What is the most common second malignancy seen in a patient who has a midgut carcinoid? another midgut carcinoid (50% of the time)
What pressor is most useful in GIB? Vasopressin: reduces splanchnic blood floow, portal flow ~40%. Give with B-blocker to avoid angina
What agent is able to significantly decrease nausea and vomiting in a patient with malignant bowel obstruction? Octreotide
What is the treatment for diversion colitis of a Hartmann’s pouch? short-chain fatty acid enemas
What is the most common stomal infection? Candida
What is the treatment of mucocele of the appendix? appendectomy; right hemicolectomy if malignant. Avoid rupture – can result in pseudomyxoma peritonei
What is the preferred fuel of the colon? Short chain fatty acids - butyric acid
What electrolytes are actively secreted by the colon? K and HCO3
What is the treatment of lymphocytic colitis? sulfasalazine
What is the most common type of colon polyp? hyperplastic – no cancer risk
What is the most common type of intestinal neoplastic polyp? tubular adenoma
When is polypectomy adequate treatment for invasive carcinoma? >2mm margin, well differentiated, and no lymphovascular invasion
When is the next colonoscopy after removal of a polyp? If <1cm and single – 5 years, if >1cm or high risk – 3 years, if resection needed – 1 year
What infection is colon cancer associated with? Clostridium septicum
What is the most common presenting symptom of colorectal carcinoma in patients under 40? Rectal bleeding
What are the most common genetic mutations in colon cancer? p53 (85%), DCC (70%), ras (50%)
What is the treatment for a low T2 rectal carcinoma? APR or LAR (need 2cm margin from levator muscles for LAR)
What is the extent of a T2 colorectal cancer? Into muscularis propria
What is the main purpose of colonoscopy after colectomy for cancer? Detect new colon cancers (metachronous) – 5%
When is XRT indicated for rectal CA? T3 tumors (into serosa) or positive nodes
What gene is FAP associated with? APC gene on chromosome 5 (but 20% of FAP are spontaneous)
What is the most common cause of death following colectomy in patients with FAP? periampullary tumors of duodenum
Amsterdam criteria ”3, 2, 1” - 3 first degree relatives, over 2 generations, 1 diagnosed before age 50
What is Lynch syndrome associated with? DNA mismatch repair gene; Lynch 1 – just colon CA; Lynch II – colon, ovarian, endometrial, bladder, and stomach CA
Gardner's syndrome colon CA and desmoid tumors
Turcot's syndrome colon CA and brain tumors
Peutz Jeghers polyposis and mucocutaneous pigmentation; increased risk of GI, gonadal, breast cancers
What is the treatment of sigmoid volvulus? Colonoscopic decompression (80% reduce, 50% will recur), bowel prep, then sigmoid colectomy during admission
What is the pathology of ulcerative coloitis? Rectal involvement in 90%, but spares anus, contiguous involvement, involves mucosa and submucosa, rectal bleeding
What is the most common site of perforation in Crohn’s disease? UC? Crohn’s – terminal ileum, UC – transverse colon
What gene is associated with sacroiliitis in IBD? HLA B27
What is the most common extraintestinal manisfestation requiring total colectomy in UC? failure to thrive in children
Which extraintestinal manisfestations of UC do not improve after colectomy? Primary sclerosing cholangitis and ankylosing spondylitis
What is pyoderma gangrenosum? What is the treatment? Painful raised pustules on skin with necrotic center which progress to spreading ulceration - a/w IBD; Rx - local wound care, steroids, dapsone
What is the treatment of low rectal carcinoid tumors? <2cm – wide local excision with negative margins; >2cm or invasion of muscularis propria – APR
What is the law of LaPlace? tension = pressure x radius
What are the indications for surgery in diverticulitis? emergent complications, recurrent disease, or inability to exclude cancer
What demonstrates cyanotic edematous mucosa covered with exudates on colonoscopy? Ischemic colitis
What is a key finding in pseudomembranous colitis? PMN inflammation of mucosa and submucosa
What marks the transition between the anal canal and the rectum? Levator ani
What marks the anatomic transition between the anal canal and the anal verge? Anal canal is above dentate line, anal verge is below it
Describe the blood supply of the rectum Superior rectal artery off IMA Middle off internal iliac Inferior off internal pudendal (off internal iliac)
What is the arterial supply to the anus? inferior rectal artery
What are the two types of fascia surrounding the rectum? Denonvilliers (anterior – rectovesicular/rectovaginal fascia) and Waldeyer’s (posterior – rectosacral fascia)
What is the grading of internal hemorrhoids? 1 – slides below dentate with strain, 2 – prolapse that reduces spontaneously, 3 – prolapse with manual reduction, 4 – unable to reduce
What are the surgical indications for hemorrhoids? recurrent disease (bleeding), thrombosis, large external component
What is the cause of rectal prolapse? pudendal neuropathy and laxity of anal sphincters
What is the treatment for rectal prolapse? High fiber initially; LAR is definitive surgery, but may perform rectosigmoid resection (Altmier) if older and frail or simply rectopexy in the absence of large redundant colon or constipation symptoms
Where are most anal fissures located? posterior midline, 10% are anterior in women
What are the causes of anal fissures which are lateral or recurrent? IBD, TB, or syphilis
What is Goodsall’s rule? anterior fitulas contact with rectum in a straight line, whereas posterior fistulas go toward midline internal opening in rectum
What are the most common types of anal canal tumors? Squamous cell (AKA epidermal, basaloid, cloacogenic, transitional), Adenocarcinoma, and melanoma
What is APR indicated in squamous cell CA of the anal canal? Only with persistent or recurrent cancer (after treatment with Nigro protocol)
What is Nigro protocol? 5FU, mitomycin, and XRT
What is the treatment for adenocarcinoma of the anal canal? APR; WLE if <3cm, <1/3 circumference, T1, well differentiated, and no lymphovascular invasion
What is intraepidermal apocrine gland CA of the anal margin that stains PAS positive? Treatment? Paget’s disease, tx – WLE, groin dissection for positive nodes
What is intraepidermal squamous cell CA of the anal margin (squamous cell carcinoma in situ)? Treatment? Bowen’s disease, tx – WLE, check for other malignancies
Created by: jclanton82