Chapter 36: Colorectal Flashcards
(250 cards)
1
Q
Colon secretes ____ and reabsorbs _____
A
colon secretes K and reabsorbs Na and water (mostly in right colon and cecum)
2
Q
colonic layer: small interwoven inner muscle layer just below mucosa but above basement membrane
A
muscularis mucosa
3
Q
retroperitoneal portions of colon
A
ascending, descending and sigmoid colon are all retroperitoneal
- peritoneum covers anterior upper and middle 1/3 of the rectum
4
Q
transverse bands that form haustra
A
plicae semiliunares
5
Q
3 bands that run longitudinally along colon. at rectosigmoid junction, these become broad and completely encircle the bowel
A
taenia coli
6
Q
cm: dentate line from anal verge
A
2cm
7
Q
cm: anal transition zone from anal verge
A
4 cm
8
Q
vasculature: ascending and 2/3 of transverse colon
A
SMA (ileocolic, right and middle colic arteries)
9
Q
vasculature: 1/3 transverse, descending colon, sigmoid colon, and upper portion of the rectum
A
IMA (left colic, sigmoid branches, superior rectal artery)
10
Q
vascular: runs along colon margin, connecting SMA to IMA (provides collateral flow)
A
marginal artery
11
Q
artery: short direct connection between SMA and IMA
A
Arc of Riolan
12
Q
how is vascular supply distributed in the colon?
A
80% of blood flow goes to mucosa and submucosa
13
Q
venous drainage of colon?
A
follows arterial except IMV, which goes to the splenic vein
14
Q
what forms the portal vein?
A
splenic vein joins the SMV to form the portal vein behind the pancreas
15
Q
what is the middle rectal artery a branch of?
A
branch of internal iliac
16
Q
what contains the middle rectal arteries during low anterior resection [LAR] or abdominoperineal resection [APR]?
A
the lateral stalks
17
Q
what is the inferior rectal artery a branch of?
A
branch of internal pudendal (which is a branch of the internal iliac).
18
Q
where do superior and middle rectal veins drain?
A
superior and middle rectal veins drain into the IMV and eventually the portal vein.
19
Q
where do inferior rectal veins drain?
A
inferior rectal veins drain into the internal iliac veins and eventually the caval system
20
Q
drain to IMA nodal lymphatics
A
superior and middle rectum
21
Q
drains primarily to IMA nodes, also to internal iliac nodes
A
lower rectum
22
Q
does the bowel wall contain lymphatics?
A
bowel wall contains mucosal and submucosal lymphatics.
23
Q
what are the watershed areas in the colon?
A
- splenic flexure (Griffith’s point)
- rectum (Sudak’s point)
24
Q
watershed area: SMA and IMA junction
A
splenic flexure (Griffith’s point)
25
watershed area: superior rectal and middle rectal junction
rectum (sudak's point)
26
sphincter: is the continuation of the levator ani muscle (striated muscle)
- nerve: inferior rectal branch of internal pudendal nerve
external sphincter (puborectalis muscle) - under CNS (voluntary) control
27
- involuntary control
- is the continuation of the muscularis propria (smooth muscle)
- is normally contracted
internal sphincter
28
inner nerve plexus
meissner's plexus
29
outer nerve plexus
auerbach's plexus
30
parasympathetic to colon
pelvic splanchnic nerves
31
sympathetics to colon
lumbar and sacral plexus
32
from anal verge: anal canal
0 - 5 cm
33
from anal verge: rectum
5 - 15 cm
34
from anal verge: rectosigmoid junction
15 - 18 cm
35
marks the transition between anal canal and rectum
levator ani
36
mucus-secreting goblet cells
crypts of lieberkuhn
37
slow transit time; patients may need subtotal colectomy
colonic inertia
38
main nutrient of colonocytes
short-chain fatty acids
39
tx: stump pouchitis (diversion or disuse proctitis)
short-chain fatty acids
40
tx: infectious pouchitis
metronidazole (flagyl)
41
rectovesicular fascia in men; rectovaginal fascia in women
denonvilliers fascia (anterior)
42
rectosacral fascia
waldeyer's fascia (posterior)
43
most common polyp; no cancer risk
hyperplastic polyps
44
most common (75%) intestinal neoplastic polyp (these are generally pedunculated)
tubular adenoma
45
polyp most likely to produce symptoms
| - these are generally sessile and larger than tubular adenomas
villous adenoma
46
villous adenomas: percent that have cancer
50% of villous adenomas have cancer
47
polyps: characteristics of lesions with increased cancer risk
> 2cm
sessile
villous
48
polyps have ___ side predominance
polyps have left side predominance
49
what type of polyps can be removed endoscopically?
most pedunculated polyps can be removed endoscopically
50
management: if not able to get all of the polyp endoscopically (which usually occurs with sessile polyps)
need segmental resection
51
when is polypectomy adequate treatment for invasive carcinoma?
only if the margin is sufficient (2mm), the carcinoma is not poorly differentiated, and no evidence of venous or lymphatic invasion is found.
52
polyps: basement membrane is intact (carcinoma in situ)
high-grade dysplasia
53
polyps: into muscularis mucosa (CIS -> still has not gone thru the basement membrane)
intramucosal cancer
54
polyps: into submucosa (T1)
invasive cancer
55
colon cancer screening recommendations
at 50 for normal risk, at 40 (or 10 years before youngest case) for intermediate risk (e.g. family history of colon CA)
56
colon cancer screening options
1) colonoscopy q 10 years - or -
2) high-sensitivity FOBT q3 AND flex sig q5yrs - or -
3) high-sensitivity FOBT annually
Possible option: double contrast barium enema or CT colonography
57
what can cause a false-positive guaiac?
beef, vitamin C, iron, cimetidine
58
when do you not want to do colonoscopy?
recent MI, splenomegaly, pregnancy (if fluoroscopy planned)
59
management: polypectomy shows T1 lesion
polypectomy is adequate if margins are clear (2mm), is well differentiated, and has no vascular / lymphatic invasion; otherwise, need formal colon resection
60
tx: 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.
```
61
management: pathology shows T1 lesion after transanal excision of rectal polyp
transanal excision is adequate if margins are clear (2mm), it is well differentiated, and it has no vascular / lymphatic invasion
62
tx: pathology shows T2 lesion after transanal excision of rectal polyp
patient needs APR or LAR
63
2nd leading cause of CA death
colorectal cancer
64
what infection is associated with colorectal cancer?
clostridium septicum
| strep bovis
65
main gene mutations in colorectal cancer
APC -> Kras -> DCC -> p53
66
most common site of primary colorectal cancer
sigmoid colon
67
most important prognostic factor for colorectal cancer
nodal status
| - spreads to nodes first
68
primary sites of metastases in colorectal cancer
```
#1 liver
#2 lung
```
69
how does colorectal cancer metastasize to lung?
iliac vein
70
5 year survival rate for colorectal cancer with liver metastases
if resectable and leaves adequate liver function, patients have 35% 5-year survival (5-YS) rate
71
5 year survival rate for colorectal cancer with lung metastases
25% 5-YS rate in selected patients after resection
72
management: isolated liver or lung metastases in colorectal cancer
isolated liver or lung mets should be resected
73
rate of patients with drop metastases to ovaries in colorectal cancer
5%
74
why can rectal CA metastasize to spine directly?
via Batson's plexus (venous)
75
does colon CA go to bone?
colon CA typically does not go to bone
76
surgery: colorectal CA growing into adjacent organs
can be resected en bloc with a portion of the adjacent organ (i.e., partial bladder resection)
77
colorectal ca prognosis: lymphocytic penetration
patients have an improved prognosis
78
colorectal ca prognosis: mucoepidermoid
worst prognosis
79
colorectal ca: good at assessing depth of invasion (sphincter involvement), recurrence, and presence of enlarged nodes
rectal ultrasound
80
mandatory in diagnosis of colorectal ca
need total colonoscopy to rule out synchronous lesions in patients with colorectal CA
81
colorectal ca: goals of resection
en bloc resection, adequate lymphadenectomy
82
management of most right-sided colon CAs
can be treated with primary anastomosis without ostomy
83
management of rectal pain with rectal ca
patient needs APR
84
margins for colorectal cancer surgery
generally need 2-cm margins
85
colorectal ca: best method of picking up intrahepatic metastases
intraoperative ultrasound (U/S)
86
resolution: abdominal CT
5-10mm
87
resolution: abdominal MRI
5-10mm (better resolution than CT)
88
resolution: intraoperative U/S
3-5mm
89
permanent colostomy; anal canal is excised along with the rectum
abdominoperineal resection (APR)
90
potential complications of abdominoperineal resection (APR)
can have impotence and bladder dysfunction (injured pudendal nerves)
91
margins for abdominoperineal resection (APR)
need at least a 2-cm margin (2cm from levator ani muscles) for LAR, otherwise will need APR
92
risk of local recurrence: rectal CA vs colon CA
risk of local recurrence higher with rectal CA than with colon CA in general
93
produces complete response in some patients with rectal CA; preserves sphincter function in some
preoperative chemo-XRT
94
T1?
into submucosa
95
T2?
into muscularis propria
96
T3?
into serosa or thru muscularis propria if no serosa is present
97
T4?
through serosa into free peritoneal cavity or into adjacent organs / structures if no serosa is present
98
N1?
1-3 nodes positive
99
N2?
>= 4 nodes positive
100
N3?
central nodes positive
101
tx: low rectal T2 or higher
APR or LAR
102
chemotherapy: stage 3 and 4 colon ca (nodes positive or distant metastases)
postop chemo, no XRT
103
chemotherapy: stage 2 and 3 rectal ca
pre-op chemo-XRT
104
chemotherapy: stage 4 and rectal CA
chemo and XRT +/ surgery (possibly just colostomy, may want to avoid APR in patients with metastatic disease)
105
colorectal CA: chemo regimen
5FU, leucovorin, and oxaliplatin (FOLFOX)
106
colorectal CA: benefits XRT
decreases local recurrence and increases survival when combined with chemotherapy
107
colorectal CA: XRT damage
rectum most common site of injury -> vasculitis, thrombosis, ulcers, strictures
108
colorectal CA: pre-op chemo XRT
may help shrink rectal tumors, allowing down-staging of the tumor and possibly allowing LAR versus APR
109
colorectal CA: rate of recurrence
20% have a recurrence (usually occurs within 1 year)
| - 5% get another primary -> main reason for surveillance colonoscopy
110
why does colorectal ca require surveillance?
5% get another primary -> main reason for surveillance colonoscopy. follow up colonoscopy at 1 year -> mainly to check for new primary colon CA (metachronous)
111
familial adenomatous polyposis (FAP) - inheritance pattern
autosomal dominant; all have cancer by age 40
112
gene involved in FAP
APC gene - chromosome 5
113
how many FAP syndromes are spontaneous?
20% of FAP syndromes are spontaneous
114
when do FAP syndromes present?
polyps not present at birth; are present in puberty
115
do you need colonoscopy surveillance in FAP?
do not need colonoscopy for surveillance in patients with suspected FAP -> just need flexible sigmoidoscopy to check for polyps
116
management of FAP
all need total colectomy prophylactically at age 20
117
UGI surveillance for FAP
UGI every 2 years for duodenal polyps
118
surgical intervention for FAP
proctocolectomy, rectal mucosectomy, and ileoanal pouch (J-puch)
- need lifetime surveillance of residual rectal mucosa
- total proctoceolectomy with end ileostomy is also an option
119
MCC death in FAP patients following colectomy
periambpullary tumors of the duodenum
120
Gardner's syndrome
patients get colon CA (associated with APC gene) and desmoid tumors / osteomas
121
Turcot's syndrome
patients get colon CA (associated with APC gene) and brain tumors
122
Lynch syndromes (HNPCC)
5% of the population, autosomal dominant
- associated with DNA mismatch repair gene
- predilection for right-sided and multiple cancers
123
Lynch 1 - type of cancer
just colon CA risk
124
Lynch 2 - type of cancer
patients also have increased risk of ovarian, endometrial, bladder, and stomach cancer
125
Amsterdam criteria for Lynch syndrome
"3,2,1" -> at least 3 first degree relatives, over 2 generations, 1 with cancer before age 50
126
surveillance for Lynch syndrome
need surveillance colonoscopy starting at age 20-25 or 10 years before primary relative got cancer (also need surveillance program for the other CA types in the family)
127
rate of metachronous lesions in Lynch syndrome
50% get metachronous lesions within 10 years; often have multiple primaries
128
surgical intervention for Lynch syndrome
need total proctocolectomy with first cancer operation
129
sigmoid volvulus (demographic and symptoms)
- more common with high-fiber diets (Iran, Iraq)
- occurs in debilitated psychiatric patients, neurologic dysfunction, laxative abuse
- symptoms: pain, distention, and obstipation
130
what type of obstruction is sigmoid volvulus?
causes closed-loop obstruction -> sigmoid colon twists on itself
131
abdominal Xr: sigmoid volvulus
bent inner tube sign; gastrograffin enema may show bird's beak sing (tapered colon)
132
management of gangrenous bowel in sigmoid volvulus
do not attempt decompression with gangrenous bowel or peritoneal signs -> go to OR for sigmoidectomy
133
tx: sigmoid volvulus
decompress with colonoscopy (80% reduce, 50% will recur), give bowel prep, and perform sigmoid colectomy during same admission
134
cecal volvulus (demographic)
less common than sigmoid volvulus; occurs in 20s-30s
| - can appear as SBO with dilated cecum in the RLQ
135
role of colonoscopy in cecal volvulus
can try to decompress with colonoscopy but unlikely to succeed (only 20%)
136
OR treatment for cecal volvulus
Right hemicolectomy probably best treatment; can try cecoplexy if colon is viable and patient is frail
137
bloody diarrhea, abdominal pain, fever and weight loss
- involves the mucosa and submucosa
- strictures and fistulae unusual
ulcerative colitis
138
IBD: spares anus
```
ulcerative colitis (unlike crohn's)
- usually starts distally in rectum and is contiguous (no skip areas like crohn's)
```
139
universal bleeding and mucosal friability with pseudo polyps and collar button ulcers
ulcerative colitis
140
what do you need to rule out in ulcerative colitis?
always need to rule out infectious etiology
141
ulcerative colitis: when can backwash ileitis occur?
backwash ileitis can occur with proximal disease
142
characteristics of barium enema in chronic ulcerative colitis
loss of haustra, narrow caliber, short colon, and loss of redundancy
143
medical treatment: ulcerative colitis
sulfasalazine (or 5-ASA) and loperamide for maintenance therapy
- steroids for acute flares
144
ulcerative colitis: medical treatment that can maintain remission
5-ASA and sulfasalazine
145
ulcerative colitis: medical treatment for steroid-resistant disease
consider cyclosporine or infliximab
146
ulcerative colitis: > 6 bloody stools/d, fever, increased HR, drop in hemoglobin, leukocytosis
toxic colitis
147
ulcerative colitis: > 6 blood stools/d, fever, increased heart rate, drop in hemoglobin, leukocytosis, distention, abdominal pain and tenderness
toxic megacolon
148
toxic colitis and toxic megacolon: initial treatment
NGT, fluids, steroids, bowel rest, and antibiotics (ciprofloxacin and Flagyl) will treat 50% adequately; other 50% require surgery
- follow clinical response and abdominal radiography
149
what do you want to avoid in toxic colitis and toxic megacolon?
avoid barium enemas, narcotics, anti-diarrheal agents, and anti-cholinergics
150
absolute indications for surgery with toxic colitis and toxic megacolon
pneumoperitoneum, diffuse peritonitis, localized peritonitis with increasing abdominal pain and/or colonic distention > 10 cm, uncontrolled sepsis, major hemorrhage
151
relative indications for surgery with toxic colitis and toxic megacolon
inability to promptly control sepsis, increasing megacolon, failure to improve within 24-48 hr, increasing toxicity or other signs of clinical deterioration, continued transfusion requirements
152
more common location of perforation with ulcerative colitis
transverse colon more common
153
more common location of perforation with crohn's disease
distal ileum most common
154
surgical indications for ulcerative colitis
massive hemorrhage, refractory toxic megacolon, acute fulminant ulcerative colitis (occurs in 15%), obstruction, any dysplasia, cancer, intractability, systemic complications, FTT, and long stranding disease (> 10 years) as prophylaxis against colon CA (Some controversy here)
155
ulcerative colitis: emergent/urgent resection
total proctocolectomy and bring up ileostomy
| - perform definitive hook-up later
156
elective resection: ulcerative colitis
ileoanal anastomosis - rectal mucosectomy, J-pouch and ileoanal (low rectal) anastomosis; not used with crohn's disease
157
what does illeoanal anastomosis protect in ulcerative colitis?
can protect bladder and sexual function
158
ulcerative colitis: why do many illeoanal anastomoses need resection?
secondary to cancer, dysplastic changes, refractory pouchitis, or pouch failure (incontinence)
- need temporary diverting ileostomy (6-8 weeks) while pouch heals
159
two options with elective resections in ulcerative colitis
ileoanal anastomosis and APR with ileostomy
160
cancer risk in ulcerative colitis
1% per year starting 10 years after initial diagnosis for patients with pancolitis
- cancer more evenly distributed throughout colon
- need yearly colonoscopy starting 8 years after diagnosis, q1-2 years
161
most common extra intestinal manifestation of ulcerative colitis requiring total colectomy
failure to thrive in children
162
ulcerative colitis: do not get better with colectomy
primary sclerosing cholangitis, ankylosing spondylitis
163
ulcerative colitis: get better with colectomy
most ocular problems, arthritis, and anemia
164
ulcerative colitis: 50% get better
pyoderma gangrenosum
165
HLA b27
marker in sacroilitis, ankylosing spondylitis, ulcerative colitis
166
is thromboembolic disease a risk in ulcerative colitis?
yes
167
tx: pyoderma gangrenosum in ulcerative colitis
steroids
168
represents 15% of all carcinoids; infrequent cause of carcinoid syndrome
- metastases related to size of tumor
- 2/3 have either local or systemic spread
carcinoid of the colon and rectum
169
treatment: low rectal carcinoids
wide local excision with negative margins
170
treatment: low rectal carcinoids > 2cm or invasion of muscularis propria
APR
171
tx: colon or high rectal carcinoids
formal resection with adenectomy
172
location: colon perforation with obstruction
most likely to occur in cecum
173
law of laplace
tension = pressure x diameter
174
colonic obstruction: can be worrisome; can have rapid progression and perforation with minimal distention
closed loop-obstruction
175
what can lead to closed-loop obstruction in colonic obstruction?
competent ileocecal valve
176
primary causes of colonic obstruction
```
#1 cancer
#2 diverticulitis
```
177
air in the bowel wall, associated with ischemia and dissection of air through areas of bowel wall
pneumatosis intestinalis
178
usually indicates significant infection or necrosis of the large or small bowel; often an ominous sign
air in the portal system
179
pseudo obstruction of colon
- associated with opiate use; bedridden or older patients; recent surgery, infection or trauma
- get a massively dilated colon, which can perforate
ogilvie's syndrome
180
tx: ogilvie's syndrome
check and replace electrolytes (especially K); discontinue drugs that slow the gut (e.g. morphine); NGT
181
high risk of perforation in ogilvie's syndrome
if colon > 10 cm (high risk of perforation) -> decompression with colonoscopy and neostigmine; cecostomy if that fails
182
- from contaminated food and water with feces that contain cysts
- risk factors: travel to Mexico, ETOH; fecal-oral transmission
amoebic colitis: entamoeba histolytica
183
symptoms: similar to ulcerative colitis (dysentery); chronic more common form (3-4 bowel movements/day, cramping, and fever)
amoebic colitis - entamoeba histolytica
184
primary and secondary infection of amoebic colitis
- primary infection - occurs in colon
| - secondary infection - occurs in liver
185
dx: amoebic colitis
endoscopy -> ulceration, trophozoites; 90% have anti-amebic antibodies
186
tx: amoebic olitis
flagyl, diiodohydroxyquin
187
can present as a mass, abscess, fistula, or induration; suppurative and granulomatous
actinomyces
188
most common location of actinomyces
cecum most common location; can be confused with CA
189
pathology: actinomyces
yellow-white sulfur granules
190
tx: actinomyces
penicillin or tetracycline, drainage of any abscess
191
herniation of mucosa though the colon wall at sites where arteries enter the muscular wall
diverticula
192
how is adjacent colon affected by diverticula?
circular muscle thickens adjacent to diverticulum with luminal narrowing
193
what causes diverticula?
caused by straining (increased intraluminal pressure)
194
where do most diverticula occur?
most diverticula occur on left side (80%) in the sigmoid colon
195
symptoms: right-sided diveritucula
bleeding is more likely with right-sided diverticula (50% of bleeds occur on right)
196
diverticula: more likely to present on the left side
diverticulitis
197
rate of diverticula in the populations
presents in 35% of the population
198
lower GIB: how long does stool guaic stay positive
for up to 3 weeksn
199
bleeding anywhere near pharynx to ligament of Treitz
hematemsis
200
passage of tarry stools; need as little as 50 cc
melena
201
management of lower gastrointestinal hemorrhage
- rule out UGI: NGT
| - r/o rectal source: proctoscopy
202
what causes azotemia after GIB?
caused by production of urea from bacterial action on intraluminal blood (increased BUN; also get elevated total bilirubin)
203
bleeding rate to see arteriography
bleeding must be >/ 0.5 cc/min
204
bleeding rate for tagged RBC scan
bleeding must be >/ 0.1 cc/min
205
denotes infection and inflammation of the colonic wall as well as surrounding tissue
- LLQ pain, tenderness, fever, leukocytosis
diverticulitis
206
what causes diverticulitis
result of mucosal perforations in the diverticulum with adjacent fecal contamination
207
dx: diverticulitis
CT scan is needed only if worried about complications of disease
208
follow-up after episode of diverticulitis
need follow-up colonoscopy after an episode of diverticulitis to rule out colorectal cancer
209
most common complication of diverticulitis
abscess formation; can usually percutaneously drain
210
signs of complications of diverticulitis
obstruction symptoms, fluctuant mass, peritoneal signs, temperature > 39 and WBCs > 20
211
tx: uncomplicated diverticulitis
levofloxacin and Flagyl; bowel rest for 3-4 days (mild cases can be treated as an outpatient)
212
indications for surgery in diverticulitis
for significant complications (total obstruction not resolved with medical therapy, perforation, or abscess formation not amenable to percutaneous drainage) or inability to exclude cancer
213
surgery: diverticulitis
need to resect all of the sigmoid colon down to the superior rectum (distal margin should be normal rectum)
214
80% discovered at time of incision for appendectomy
right-sided diverticulitis
| - tx: right hemicolectomy
215
fecaluria, pneumouria
| - occurs in men; women are more likely to get colovaginal fistula
colovesicular fistula
216
best diagnostic test for colovesicular fistula
cystoscopy is the best diagnostic test
217
tx: colovesicular fistula
close bladder opening, resect involved segment of colon, and perform reanastomosis, diverting ileostomy; interpose momentum between the bladder and colon
218
MCC of lower GIB
diverticulosis (usually causes significant bleeding)
219
diverticulosis bleeding: ___stops spontaneously; recurs in ___
75% stops spontaneously; recurs in 25%
220
what causes diverticulosis bleeding?
caused by disrupted vasa rectum; creates arterial bleeding
221
dx: diverticulosis bleeding
NG tube to rule out upper GI source
- colonoscopy as a first step -> can be therapeutic (demo-clips best) and can localize bleeding should surgery be required
222
dx: massive bleeding in diverticulosis
angio 1st if massive bleed (hypotension, tachycardia) -> want to localize area for surgery; may be able to treat at angio with highly selective coil embolization
223
dx: diverticulosis bleeding if hypotensive and not responding to resuscitation
go to operative room if hypotensive and not responding to resuscitation -> colectomy at site of bleeding if identity or subtotal colectomy if bleeding source has not been localized
224
dx: diverticulosis bleeding for intermittent bleeds that are hard to localized
tagged RBC scan
225
tx: diverticulosis bleeding
colonoscopy can ligate bleeder
- with arteriography, can use vasopressin (to temporize) or highly selective coil embolization; also demonstrates with the bleed is should surgery be required
226
tx: diverticulosis bleeding that is not localized and not controlled with colonoscopy
may need segmental colectomy or possible subtotal colectomy
227
management of patients with recurrent diverticular bleeds
should have resection of that area
228
- increased on right side of colon
- bleeds are usually less severe than diverticular bleeds but are more likely to recur (80%)
- causes venous bleeding
angiodysplasia bleeding
229
soft signs of angiodysplasia on angiogram
tufts, slow emptying
230
coexisting comorbidity in angiodysplasia
20% of patients with angiodysplasia have aortic stenosis (usually gets better after valve replacement)
231
symptoms: abdominal pain, bright red bleeding
ischemic colitis
232
what can cause ischemic colitis?
can be caused by low-flow state (e.g. recent MI, CHF), ligation of the IMA at surgery (e.g. AAA repair), embolus or thrombosis of the IMA, sepsis
233
most vulnerable colonic sites to low-flow states
splenic flexure and upper rectum
234
point: SMA and IMA junction
Griffith's point (splenic flexure)
235
superior rectal and middle rectal artery junction
sudeck's point
236
dx: ischemic colitis
CT scan or endoscopy -> cyanotic edematous mucosa covered with exudates
237
why is the lower 2/3 of the rectum spared in ischemic colitis?
supplied by the middle and inferior rectal arteries (off internal iliac)
238
ischemic colitis: management of suspected gangrenous colitis (peritonitis)
no colonoscopy and go to OR -> sigmoid resection or let hemicolectomy usual
239
symptoms: watery, green, mucoid diarrhea; pain and cramping
- can occur up to 3 weeks after antibiotics; increased in post op, elderly, and ICU patients
- carrier state not eradicated; 15% recurrence
pseudomembranous colitis (C difficle colitis)
240
key finding: pseudomembranous colitis
PMN inflammation of mucosa and submucosa (pseudomembranes, plaques, and ringlike lesions)
241
most common location of pseudomembranous colitis (C diff)
most common in the distal colon
242
dx: c diff (pseudomembranous colitis)
c diff toxin
243
tx: pseudomembranous colitis (c diff)
oral - vancomycin or flagyl
IV: flagyl
- lactobacillus can also help; stop other antibiotics or change them
244
- follows chemotherapy when WBC are low (nadir)
- can mimic surgical disease
- can often see pneumatosis intestinalis (not a surgical indication)
neutropenic typhlitis (enterocolitis)
245
tx: neutropenic typhlitis (enterocolitis)
antibiotics; patients will improve when WBCs increase ; surgery only for free perforation
246
other causes of colitis
salmonella, shigella, campylobacter, cmv, yersinia (can mimic appendicitis in children), other viral infections, giardia
247
can mimic appendicitis; comes from contained food (Feces/urine)
-tx?
yersinia
| - tx: tetracycline or bactrim
248
propensity for volvulus; enlargement is proximal to non-peristalsing bowel
megacolon
249
megacolon - rectosigmoid most common
| - dx: rectal biopsy
hirschsprung's disease
250
megacolon: most common acquired cause, secondary to destruction of nerves
trypanosoma cruzi
