36 Colorectal Flashcards
anatomy and physiology: colon function
secretes K and reabsorbs Na and water (mostly in R colon and cecum)
anatomy and physiology: layers
4 … mucosa (columnar epithelium), submucosa, muscularis propria, serosa (in to out)
anatomy and physiology: describe muscularis mucosa vs muscularis propria
musc mucosa = small interwoven inner muscle layer just below mucosa but above basement membrane … musc propria = circular layer of muscle
anatomy and physiology: what part is retroperitoneal?
ascending, descending, and sigmoid colon … peritoneum covers anterior upper and middle 1/3 of the rectum
anatomy and physiology: plicae semilunares
transverse bands that form haustra
anatomy and physiology: taenia coli
3 bands that run longitudinally along the colon, at rectosigmoid junction the taeniae become broad and completely encircle the bowel
anatomy and physiology: anorectal anatomy with important landmarks
distance from anal verge … 2cm - dentate line …. 4cm - anorectal ring …. 8cm - end of lower 1/3 …. 12cm - end of middle 1/3 …. 16cm - end of upper 1/3
anatomy and physiology: vascular supply
ascending and 2/3 of transverse colon - SMA (ileocolic, R and middle colic arteries) …. 1/3 transverse, descending colon, sigmoid colon, upper portion of the rectum - IMA (L colic, sigmoid branches, superior rectal artery) …. marginal artery - runs along colon margin, connects SMA to IMA (provides collateral flow) …. arc of Riolan - short firect connection between SMA and IMA …. 80% of blood flow goes to mucosa and submucosa
anatomy and physiology: venous drainage
follows arterial except IMV, which goes to splenic vein … splenic vein joins the SMV to form the portal vein behind the pancreas
anatomy and physiology: superior rectal artery
branch of IMA
anatomy and physiology: middle rectal artery
branch of internal iliac - the lateral stalks during low anterior resection (LAR) or abdominoperineal resection (APR) contain the middle rectal arteries
anatomy and physiology: inferior rectal artery
branch of internal pudendal (which is a branch of internal iliac)
anatomy and physiology: rectal venous drainage
superior and middle rectal veins drain into the IMV and eventually the portal vein …. inferior rectal veins drain into the internal iliac veins and eventually into the caval system
anatomy and physiology: nodal drainage
superior and middle rectum - drain into IMA nodal lymphatics …. lower rectum - drains primarily to IMA nodes and also to internal iliac nodes …. bowel wall contains mucosal and submucosal lymphatics
anatomy and physiology: watershed areas
splenic flexure aka Giffith’s point - SMA and IMA junction …. rectum aka Sudak’s point - superior rectal and middle rectal junction …colon more sensitive to ischeia than small bowel 2/2 fewer collaterals
anatomy and physiology: part of bowel most sensitive to ischemia
colon is more sensitive to ischemia than small bowel 2/2 decreased collaterals
anatomy and physiology: external vs internal sphincter - muscle, innervation
external = puborectalis muscle, continuation of levator ani (striated) muscle, under CNS control via inferior rectal branch of internal pudendal nerve …. internal = continuation of muscularis (smooth) muscle, involuntary control, normally contracted
anatomy and physiology: inner and outer nerve plexi
inner = meissner’s plexus … outer = Auerbach’s plexus
anatomy and physiology: sympathetic vs parasympathetic
sympathetic = lumbar and sacral plexi …. parasympathetic = pelvic splanchnic nerves
anatomy and physiology: distance from anal verge - anal canal, rectum, rectosigmoid junction
anal canal 0-5cm …. rectum 5-15cm … rectosigmoid junction 15-18cm
anatomy and physiology: levator ani
marks the transition between anal canal and rectum
anatomy and physiology: crypts of lieberkuhn
mucus-secreting goblet cells
anatomy and physiology: colonic inertia
slow transit time, pts may need subtotal colectomy
anatomy and physiology: main nutrient of colonocytes
short-chain fatty acids
anatomy and physiology: tx of infectious pouchitis
flagyl
anatomy and physiology: denonvilliers fascia and waldeneyer’s fascia
denonvilliers = anterior, retrovesicular in M, rectovaginal in F ….. waldeneyer’s = posterior, rectosacral
polyps: list types
hyperplastic polyp, tubular adenoma, villous adenoma
polyps: MC type overall vs neoplastic vs sx
hyperplastic MC overall (NO cancer risk) … tubular adenoma is MC intestinal neoplastic polyp (75%) …. villous adenoma is most likely to be symptomatic
polyps: pedunculated vs sessile
tubular adenoma is most often pedunculated … villous adenoma is usually sessile and larger than tubular
polyps: rate of cancer in villous adenoma
50%
polyps: inc cancer risk in which polyps
> 2cm, sessile, villous
polyps: more common on which side
L
polyps: which are removed endoscopically
pedunculated
polyps: mgmt when you cannot remove entire polyp
segmental resection (usually occurs w sessile)
polyps: carcinoma in situ vs invasive carcinoma - difference and mgmt
in situ - malignant cells confined to mucosa, tx w polypectomy ….. carcinoma - malignant cells past mucosa, can tx w polypectomy ONLY IF >2mm margin, NOT poorly differentiated, NO evidence of venous or lymphatic invasion is found
polyps: high grade dysplasia vs intramucosal cancer vs invasive cancer
high grade dysplasia = basement membrane is intact (i.e. carcinoma in situ) …. intramucosal cancer = into muscularis mucosa (carcinoma in situ, still has not gone through basement membrane) …. invasive cancer = into submucosa (T1)
screening
at 50 for normal risk, at 40 (or 10yrs before youngest case) for intermediate risk (i.e. family hx of cancer)
screening options
(1) colonoscopy every 10 years …OR … (2) high-sensitivity FOBT every 3 years AND flex sig every 5 years …. OR … (3) high-sens FOBT annually … OR … (4) double contrast barium enema or CT colonography every 5 years
falsa positive guaiac
beef, vit C, Fe, cimetidine
NO colonoscopy with what?
recent MI, splenomegaly, pregnancy (if fluoroscopy planned)
mgmt if polypectomy shows T1 lesion
polypectomy is adequate if margins are clear (2mm), well differentiated, and has no vascular/lymphatic invasion …. o/w need formal colon resection
mgmt of extensive low rectal villous adenomas with atypia
transanal excision (can try mucosectomy) as much of the polyp as possible … NO APR unless cancer is present
mgmt if pathology shows T1 lesion after transanal excision of rectal polyp
transanal excision is adequate if margins clear (2mm), well differentiated, no vascular/lymphatic invasion
mgmt if pathology shows T2 lesions after transanal excision of rectal polyp
pt needs APR and LAR
rate of cancer death
colorectal cancer is 2nd MC cause of cancer death
colorectal cancer: sx
anemia, constipation, bleeding
colorectal cancer: diet risk
red meat and fat … O2 radicals are thought to play a role
colorectal cancer: assoc with which infections
assoc w clostridium septicum infection
colorectal cancer: gene mutations
APC, DCC, p53, k-ras
colorectal cancer: MC primary site
sigmoid colon
colorectal cancer: disease spread - 1st spread
nodes
colorectal cancer: disease spread - most important prognostic factor
nodal status
colorectal cancer: disease spread - MC sites of mets and route of spread
1 = liver via portal vein … #2 = lung via iliac vein
colorectal cancer: disease spread - prognosis of liver mets vs lung mets
if resectable and leaves adequate liver function - 35% 5yr survival ….. after resection lung mets - 25% 5yr survival
colorectal cancer: disease spread - mgmt of isolated liver or lung mets
resect
colorectal cancer: disease spread - rate of mets to ovaries
5% with drop mets to ovaries
colorectal cancer: disease spread - bone mets in rectal CA and colon CA mets
rectal CA - can met to spine directly via Batson’s plexus (venous) … colon CA - usually does NOT go to bone
colorectal cancer: disease spread - mgmt of colon CA spread into adjacent organs
can be resected en bloc with a portion of the adjacent organ (i.e. partial bladder resection)
colorectal cancer: disease spread - worst vs better prognosis
mucoepidermoid is worst prognosis … lymphocytic penetration has improved prognosis
colorectal cancer: disease spread - use of rectal U/S
good at assessing depth of invasion (sphincter involvement), recurrence, and presence of enlarged nodes
colorectal cancer: workup
need total colonoscopy to r/o synchronous lesions
colorectal cancer: goals of resection
en bloc resection, adequate margins, regional adenectomy …. most R sided colon CAs can be treated with primary anastomosis without ostomy …. rectal pain w rectal CA requires APR …. generally need 2cm margins
colorectal cancer: best method of detecting intrahepatic mets
intraop U/S
colorectal cancer: resolution of different imaging techniques
conventional U/S 10mm …. abd CT 5-10mm …. abd MRI 5-10mm (better resolution than CT) … intraop U/S 3-5mm
colorectal cancer: APR - describe
permanent colostomy, anal cancal is excised along with the rectum
colorectal cancer: APR - complications
impotence and bladder dysfunction 2/2 injured pudendal nerves
colorectal cancer: APR - indications
malignant lesions only (NOT benign tumors) that are not amenable to LAR
colorectal cancer: APR - margins
need at least 2cm margin (2cm from levator ani muscles) for LAR, o/w will need APR
colorectal cancer: APR - risk of local recurrence
higher risk with rectal CA then colon CA
colorectal cancer: preop chemo-XRT
produced complete response in some pts w rectal CA, reserves sphincter function in some
colorectal cancer: TNM staging
T1 = into submucosa, T2 = into muscularis propria, T3 = into serosa or through muscularis propria, T4 = through serosa and into free peritoneal cavity or into adjacent organs/structures if no serosa is present ….. N0 = nodes negative, N1 = 1-3 nodes positive, N2 = >=4 nodes positive, N3 = central nodes positive …. M1 = distant mets
colorectal cancer: stages
0 = Tis, N0, M0 … 1 = T1-2, N0, M0 … 2a = T3, N0, M0 … 2b = T4, N0, M0 …. 3a = T1-2, N1, M0 … 3b = T3-4, N1, M0 … 3c = ant T, N2, M0 …. 4 = any T, any N, M1
colorectal cancer: low rectal T1
limited to submucosa, can be excised transanally if <4cm, has negative margins (need 1cm), is well differentiated, and there is no neurologic or vascular invasion, otherwise pt needs and APR or LAR
colorectal cancer: low rectal T2 or higher
LAR or APR
colorectal cancer: chemotherapy
stage 3 and 4 colon CA - node positive or distant mets —> postop chemo, NO XRT ….. stage 2 and 3 rectal CA —> preop chemo-XRT …. stage 4 rectal CA —> chemo and XRT +/- surgery (possibly just colostomy, may want to avoid APR in pts w metastatic disease) …. chemo = 5FU, leucovorin, and oxalplatin (FOLFOX)
colorectal cancer: XRT - role, damage, indications
decreased local recurrence and increased survival when combined with chemo …. XRT damage - rectum most common site of injury 2/2 vasculitis, thrombosis, ulcers, strictures …. pre-op chemo-XRT may help shrink rectal tumors, allows for down-staging of the tumor and possible allowing for LAR or APR
colorectal cancer: recurrence rate
20%, usually within 1 year, 5% get another primary (main reason for surveillance colonoscopy)
colorectal cancer: follow-up colonoscopy - timing and reason
1 year, main purpose is to check for new primary colon CA (metachronous lesion)
familial adenomatous polyposis (FAP): inheritence
autosomal dominant, APC gene, chromosome 5 …. 20% are spontaneous
familial adenomatous polyposis (FAP): cancer rate
all have cancer by age 40
familial adenomatous polyposis (FAP): polyp presentation
NOT present at birth, present at puberty
familial adenomatous polyposis (FAP): surveillance
do NOT need colonoscopy for surveillance in pts w suspected FAP …. just need flex sig
familial adenomatous polyposis (FAP): mgmt
ppx total colectomy at age 20
familial adenomatous polyposis (FAP): other sites of polyps
duodenal polyps –> check duo w endoscopy every 2 years
familial adenomatous polyposis (FAP): surgical mgmt
proctocolectomy, rectal mucosectomy, ileoanal pouch (J pouch) …. need lifetime surveillance of residual rectal mucosa …. another option is total proctocolectomy with end ileostomy
familial adenomatous polyposis (FAP): MC cause of death after colectomy
periampullary duodenal tumors
familial adenomatous polyposis (FAP): Gardner’s and Turcot’s syndromes
Gardner’s = pts get colon CA (assoc w APC gene) and desmoid tumors/osteomas …. Turcot’s = pts get colon CA (assoc w APC gene) and brain tumors
lynch syndrome: aka
HNPCC = hereditary nonpolyposis colon cancer
lynch syndrome / HNPCC: rate
5% of population
lynch syndrome / HNPCC: inheritance
autosomal dominant
lynch syndrome / HNPCC: genetics
DNA mismatch repair gene
lynch syndrome / HNPCC: which side
MC on R side, MC multiple
lynch syndrome / HNPCC: type 1 and 2
1 = just colon CA risk …. 2 = patients also have inc risk of ovarian, endometrial, bladder, stomach cancer
lynch syndrome / HNPCC: amsterdam criteria
3, 2, 1 = at least 3 first degree relatives, over 2 generations, 1 with cancer before age 50
lynch syndrome / HNPCC: surveillance
need surveillance colonoscopy starting at age 25 or 10 years before primary relative got cancer (also need surveillance program for the other CA types in the family)
lynch syndrome / HNPCC: cancer rate
50% with metachronous lesions within 10 years, often with multiple primaries
lynch syndrome / HNPCC: surgical mgmt
need total proctocolectomy with first cancer operation
which type of volvulus is most common
cecal less common than sigmoid
sigmoid volvulus: most common with which diets
high-fiber (Iran, Iraq)
sigmoid volvulus: MC pts
debilitated psych pts, neurologic dysfunction, laxative abuse
sigmoid volvulus: sx
pain, distention, obstipation
sigmoid volvulus: pathophys
sigmoid colon twists on itself —> closed loop obstruction
sigmoid volvulus: abd xray findings
bent inner tube sign
sigmoid volvulus: gastrograffin enema
bird’s beak sign, tapered colon
sigmoid volvulus: mgmt
decompress with colonoscopy - 80% reduce, 50% will recur, give bowel prep and perform sigmoid colectomy during same admission …. gangrenous bowel or peritoneal signs: do NOT attempt decompression —> go to OR for sigmoidectomy
cecal volvulus: MC age
20s-30s
cecal volvulus: px
can appear as SBO with dilated cecum in the RLQ
cecal volvulus: decompression
can try to decompress with colonoscopy but only 20% success rate
cecal volvulus: tx
OR for R hemicolectomy is usually best, can try cecopexy if colon is viable and pt is frail
UC: sx
bloody diarrhea, abd pain, fever, weight loss
UC: involves which parts
mucosa or submucosa
UC: strictures and fistulae
unusual in UC
UC: location of disease
spares anus (unlike Crohn’s), usually starts in distal rectum and is contiguous (no skip lesions like Crohn’s)
UC: bleeding
universal, has mucosal friability with pseudopolyps and collar button ulcers
UC: workup
always need to r/o infectious etiology
UC: backwash ileitis
can occur w proximal disease
UC: barium enema
with chronic disease you see many haustra, narrow caliber, short colon, loss of redundancy
UC: medical tx
sulfasalazine (or 5-ASA) and loperamide for maintenance …. steroid for acute flares …. 5-ASA and sulfasalazine can maintain remission in UC … consider cyclosporine or infliximab for steroid-resistant disease
UC: toxic colitis and toxic megacolon - describe
toxic colitis = >6 bloody stools/day, fever, inc HR, drop in Hb, leukocytosis … toxic megacolon = above plus distention, abd pain, tenderness
UC: toxic colitis and toxic megacolon - initial tx
NGT, fluids, steroids, bowel rest, abx (cipro and flagyl) will treat 50% adequately, 50% need surgery
UC: toxic colitis and toxic megacolon - monitor response to tx
clinical response, abdominal radiographs
UC: toxic colitis and toxic megacolon - avoid what
barium enemas, narcotics, anti-diarrheal agents, anti-cholinergics
UC: toxic colitis and toxic megacolon - indications for surgery
absolute = pneumoperitoneum, diffuse peritonitis, localized peritonitis with increasing abd pain and/or colonic distention >10cm, uncontrolled sepsis, major hemorrhage …. relative = inability to promptly control sepsis, increasing megacolon, failure to improve within 24-48 hours, increasing toxicity or other signs of clinical deterioration, continued transfusion requirements
UC: surgical indications
massive hemorrhage, refractory toxic megacolon, acute fulminant UC (occurs in 15%), obstruction, ANY dysplasia, cancer, intractability, systemic complications, failure to thrive, long-standing disease (>10yrs) as ppx against colon cancer (some controversy)
MC site of perforation - Crohn’s vs UC
distal ileum vs transverse colon
UC: emergent/urgent resections
total proctocolectomy and drink up ileostomy, perform definitive hook up later
UC: elective resections
ileoanal anastomosis or APR with ileostomy
UC: elective resections - ileoanal anastomosis - describe, benefits, surveillance, resection
rectal mucosectomy, J pouch, and ileoanal (low rectal) anastomosis (NOT used with Crohn’s disease) … can protect bladder and sexual function … need lifetime surveillance of residual rectal area …. many ileoanal anastomoses need resection 2/2 cancer, dysplastic changes, refractory pouchitis, pouch failure (incontinence) …. need temporary diverting ileostomy 6-8 weeks while pouch heals .
UC: elective resections - ileoanal anastomosis - MC morbidity
leak is the MC major morbidity, can lead to sepsis, tx w drainage and abx
UC: tx of infectious pouchitis
flagyl
UC: cancer risk
1% per year startin 10 years after initial dx for pts w pancolitis …. cancer more evenly spread throughout the colon …. need yearly colonoscopy every 8-10 years after dx
UC: extraintestinal manifestations - MC requiring total colectomy in kids
failure to thrive
UC: extraintestinal manifestations - list those that do NOT get better with colectomy
primary sclerosing cholangitis, ankylosing spondylitis
UC: extraintestinal manifestations - list those that DO get better with colectomy
most ocular problems, arthritis, anemia
UC: extraintestinal manifestations - pyoderma gangrenosum cure rate and tx
50%, steroids
UC: extraintestinal manifestations - complications
can get thromboembolic diseases
HLA B27 assoc with that
sacroiliitis, ankylosing spondylitis, UC
UC vs Crohn’s: transmural inflammation
seldom, common
UC vs Crohn’s: granulomas
seldom, >50%
UC vs Crohn’s: fissuring
rare, common
UC vs Crohn’s: fibrosis
rare, common
UC vs Crohn’s: submucosal inflammation
rare, common
UC vs Crohn’s: crypt abscesses
common, uncommon
UC vs Crohn’s: small bowel involvement
rare (backwash ileitis), common
UC vs Crohn’s: anatomic location
continuous, skip
UC vs Crohn’s: rectal involvement
common, may be spared
UC vs Crohn’s: bleeding
common, absent
UC vs Crohn’s: fistulas
rare, common
UC vs Crohn’s: perianal disease
rare, common
UC vs Crohn’s: ulcers
rare, common
UC vs Crohn’s: surrounding mucosa
pseudopolyps, relatively normal
UC vs Crohn’s: cobblestoning of mucosa
none, long-standing disease
UC vs Crohn’s: mucosal friability
common, uncommon
UC vs Crohn’s: vascular pattern
absent, normal
UC vs Crohn’s: fat wrapping
rare, common
carcinoid of colon and rectum: rate
15% of all carcinoids, infrequent cause of carcinoid syndrome
carcinoid of colon and rectum: mets related to what
size of tumor
carcinoid of colon and rectum: amnt w spread
2/3 w local or systemic spread
carcinoid of colon and rectum: mgmt of low rectal carcinoids vs colon or high rectal
<2cm low rectal = wide local excision with negative margins …. >2cm low rectal or invasion of musc propria = APR …. colon or high recal = formal resection with adenectomy
colonic obstruction: colon perf with obstruction
most likely to occur in cecum … law of LaPlace: tension = pressure x diameter
colonic obstruction: closed loop obstruction
can be worrisome, can have rapid progression and perforation with minimal distention …. competent ileocecal valve can lead to closed loop obstruction
colonic obstruction: causes
1 cancer, #2 diverticulitis
colonic obstruction: pneumatosis intestinalis
air in bowel wall, assoc w ischemia and dissection of air through areas of bowel wall
colonic obstruction: air in portal system
usually indicates significant infection or necrosis of large or small bowel, usually an ominous sign
Ogilvie’s syndrome: describe
pseudoobstruction of colon
Ogilvie’s syndrome: assoc with what
opiate use, bedridden or older patients, recent surgery, infection, trauma
Ogilvie’s syndrome: complications
massive dilated colon which can perforate
Ogilvie’s syndrome: tx
check and replete electrolytes (esp K), discontinue drugs that slow the gut (i.e. morphine), NGT … if colon >10cm - high risk of perforation —> decompression with colonoscopy and neostigmine … cecostomy if that fails
amoebic colitis: organism, source
entamoeba histolytica … from contaminated food and water with feces that contain cysts
amoebic colitis: primary vs secondary infection
primary - in colon … secondary - in liver
amoebic colitis: risk factors
travel to mexico, etoh, fecal-oral transmission
amoebic colitis: sx
similar to UC (dysentery), chronic more common form (3-4 bowel movements per day, cramping, fever)
amoebic colitis: dx
endoscopy —> ulceration, trophozoites … 90% w anti-amebic Ab
amoebic colitis: tx
flagyl, diiodohydroxyquin
actinomyces: px
can present as mass, abscess, fistula, induration
actinomyces: types
suppurative, granulomatous
actinomyces: MC site
cecum (can be confused w cecal CA)
actinomyces: pathology
shows yellow-white sulfur granules
actinomyces: tx
penicillin or tetrocycline, drainage of any abscess
diverticula: describe / pathophys
herniation of mucosa through colon wall sites where arteries enter the muscular wall … circular muscle thickens adjacent to diverticulum with luminal narrowing …. caused by straining which increases intraluminal pressure
diverticula: more likely to present on which side? bleeding occurs on which side?
L side (80%) in the sigmoid colon …. R sided, 50% of bleeds occur on R (but L is more common overall)
diverticula: %
35% of population
lower GI bleeding: +stool guaiac
can be positive for 3 weeks after bleed
lower GI bleeding: hematemesis
bleeding anywhere from pharynx to ligament of Trietz
lower GI bleeding: melena
passage of tarry stools, need as little as 50cc
lower GI bleeding: azotemia after GI bleed
caused by production of urea from bacterial action on intraluminal blood (inc BUN and t bili)
lower GI bleeding: sensitivity w arteriography vs RBC scan
bleeding must be >= 0.5cc/min vs >= 0.1cc/min
lower GI bleeding: workup
NGT to r/o UGI source, proctoscopy to r/o recal source –> see continued massive hemorrhage vs low rate of intermittent hemorrhage
massive —> angiography —> either diagnostic or nondiagnostic
low rate or intermittent hemorrhage —> colonoscopy —> diagnostic vs if non diagnostic then get RBC scan, enterolysis, RBC scan
diverticulitis: pathophys
mucosal perforation in diverticulum with adjacent fecal contamination … denotes infection and inflammation of the colonic wall as well as surrounding tissue
diverticulitis: px
LLQ pain, tenderness, fever, inc WBCs
diverticulitis: dx
CT scan is needed only if worried about complications of disease
diverticulitis: follow up
need follow up colonoscopy after an episode of diverticulitis to r/o colorectal cancer
diverticulitis: most significant complication
abscess formation, can usually perc drain
diverticulitis: signs of complication
obstruction, sx, fluctuant mass, peritoneal signs, temp >39, WBCs >20
diverticulitis: tx of uncomplicated diverticulitis
levofloxacin and flagyl, bowel rest x3-4 days, mild cases an be treated as outpatient
diverticulitis: surgical indications
significant complications (i.e. total obstruction not resolved with medical therapy, perforation, or abscess formation not amenable to perc drainage)
diverticulitis: surgical approach
need to resect all of the sigmoid colon down to the superior rectum (distal margin should be normal rectum)
diverticulitis: R sided diverticulitis dx and mgmt
80% discovered at the time of incision for appendectomy …. tx w R hemicolectomy
diverticulitis: colovesicular fistula - px
fecaluria, pneumouria
diverticulitis: colovesicular fistula - MC pts
occurs in M, F are more likely to get colovaginal fistula
diverticulitis: colovesicular fistula - best diagnostic test
cystoscopy
diverticulitis: colovesicular fistula - tx
close bladder opening, resect involved segment of colon, perform re-anastomosis, diverting ileostomy, interpose omentum between the bladder and colon
MC cause of lower GI bleed
diverticulosis
diverticulosis bleeding: amnt
usually significant
diverticulosis bleeding: % stop spontaneously vs recurrence
75% stop spontaneously vs 25% recurs
diverticulosis bleeding: caused by which vessels
disrupted vasa rectum, creates arterial bleeding
diverticulosis bleeding: dx
NGT to r/o UGI bleed …. colonoscopy usually 1st step –> can be therapeutic (place hemo-clips) and can localize bleed if surgery needed …. angio 1st if massive bleeding (hypotension, tachy) - want to localize area for surgery, may be able to treat at angio with highly selective coil embolization … OR if hypotensive and not responding to resuscitation —> colectomy at site of bleeding if identified or subtotal colectomy if no source identified … tagged RBC scan for intermittent bleeds that are hard to localize
diverticulosis bleeding: tx
colonoscopy can ligate bleeding …. arteriography - can use vasopressin (to temporize) or highly selective coil embolization, also demonstrates where the bleed is should surgery be required …. may need segmental colectomy or possible subtotal colectomy if bleeding is not localized and controlled
diverticulosis bleeding: mgmt of recurrent diverticular bleed
resection of that area
angiodysplasia bleeding: location
more common on R side
angiodysplasia bleeding: bleeding compared to diverticular
angiodysplasia is less severe but more likely to recur (80%)
angiodysplasia bleeding: causes what type of bleeding
venous
angiodysplasia bleeding: soft signs on angiogram
tufts, slow emptying
angiodysplasia bleeding: % with aortic stenosis
20%, usually gets better after valve replacement
ischemic colitis: sx
abdominal pain, bright red bleeding
ischemic colitis: causes
low-flow state (i.e. recent MI, CHF), ligation of the IMA intra-op (i.e. AAA repair), embolus or thrombosis of IMA, sepsis
ischemic colitis: locations most vulnerable
most vulnerable until low-flow state …. splenic flexure and upper rectum …. splenic flexure = Griffith’s point = SMA and IMA junction …. Sudeck’s point = superior rectal and middle rectal artery junction
ischemic colitis: dx
CT scan or endoscopy —> cyanotic edematous mucosa covered with exudates ….. lower 2/3 of the rectum is spared —> supplied by the middle and inferior rectal arteries (off internal iliacs) …. if gangrenous colitis is suspected (peritonitis), NO colonoscopy, instead go straight to OR for sigmoid resection or L hemicolectomy
pseudomembranous colitis: organisms
C difficile
pseudomembranous colitis: sx
watery, green, mucoid diarrhea, pain and cramping
pseudomembranous colitis: when does it occur?
up to 3 weeks after abx, increased in postop, elderly, and ICU patients
pseudomembranous colitis: carrier state
not eradicated, 15% recurrence
pseudomembranous colitis: key findings
PMN inflammation of mucosa and submucosa … pseudomembranes, plaques, and ringlike lesions
pseudomembranous colitis: MC site
distal colon
pseudomembranous colitis: dx
C diff toxin
pseudomembranous colitis: tx
oral - vanc or flagyl … IV - flagyl … lactobacillus can also help, stop other abx or change them
neutropenic typhlitis: aka
enterocolitis
neutropenic typhlitis: presentation and tx
follows chemo when WBCs are low (nadir), can mimic surgical disease, can often see pneumatosis intestinalis (NOT surgical indication in this case) … tx = abx, pts will improve when WBCs increase, surgery ONLY for free perforation
infectious causes of colitis
salmonella, shigella, campylobacter, CMV, Yersinia (can mimic appendicitis inkids), other viral infections, Giardia
Yersinia: px, source, tx
can mimic appendicitis, comes from contaminated food (feces, urine), tx w bactrim or tetracycline
megacolon: inc risk for what?
volvulus, enlargement is proximal to non-peristalsing bowel
megacolon: causes
hirschsprung’s, trypanosoma cruzi
Hirschsprung’s disease: MC area, dx
megacolon, rectosigmoid is most common, dx is rectal bx
Trypanosoma cruzi
MC acquired cause of megacolon, 2/2 destruction of nerves
Mut Y Homolog associated polyposis
AR: Right sided colonic polyps, MYH gene mutation. less polyps than FAP
