Colon and Rectum Flashcards
what supplies the right colon and hepatic flexure?
SMA
What supplies the left colon?
IMA
Layers of the colon
inner circular outer longitudinal (tinea coli- 3)
what does the colon have that the small intestine doesn’t?
haustral markings
Functions of the colon
absorption
storage
propulsion
some digestion
are adhesions common in the large bowel?
No, rare to cause an obstruction
most common cause of large bowel obstruction
carcinoma
2 other common causes of large bowel obstruction
diverticulitis (20%)
volvulus (5%)
what area of the large bowel is most likely perforate?
cecum (thinnest part) perf at 10-12 cm
symptoms of large bowel obstruction
constipation or obstipation
abdominal pain and distention
blood per rectum
when does N/V occur w/ LBO?
if ileocecal valve is incompetent
vomitus looks and smells like stool
how do you differ SBO from LBO
plain films show distented LB w/ normal SB (can be dilated if IC valve incompetent)
if gangrene or perf is suspectted what type contrast should you use?
water solubule
should you do a colonoscopy if a perf is supected
No, can make it worse
what is the primary goal w/ a LBO?
decompression
removal of obstruction is secondary
a twisting of the large bowel on its mesentery of at least 180 degrees
volvulus
what type obstruction is there w/ a volvulus?
closed loop obstruction and progressive stangulation of teh bowel
most common sites of a volvulus
sigmoid
cecal
transverse colon
what are most patients w/ a sigmoid volvulus like?
mostly >65 in a nursing home
abdominal pain and distention
obstipation
where do you see a sigmoid volvulus
right quadrant
look likes a coffee bean, with inside of bean pointing toward RQ
sigmoid has flipped onto itself
bird’s beak appearance
tx w/ sigmoid volvulus w/ potentially strangulated bowel
emergent resection w/ colostomy
Tx w/ sigmoid volvulus w/ no signs of strangulation
endoscopic reduction- if successful do a
rectal tube
bowel prep
semi-elective resection (after 50% decompression)
how can you tell if a sigmoid volvulus is strangulated
abdomen becomes tender
If a sigmoid volvulus can’t be reduced what needs to be done?
emergent operation (sigmoid resection)
what do patients w/ a cecal volvulus tend to present?
younger and female
similar to SBO
How does a cecal volvulus point?
Coffee bean point to left quadrant
tx for cecal volvulus
surgery
what is a sign of diverticulitis
thickened bowel wall
fat stranding, inflammation in pericolonic fat
Massive colonic distention without a mechanical obstruction often in
Bed ridden patients with comorbid diseases
COLONIC PSUEDO-OBSTUCTION – OGILVIE’S SYNDROME
how do you diagnose colonic pseudo-obstruction- ogilive syndrome
contrast enema and sigmoidoscopy
surgery for diverticulitis if they aren’t getting better (immediate/ emergent/ urgent)
sigmoidectomy with end colostomy with Hartman’s pouch
who can have elective sx for diverticulitis
recurrent diverticulitis
complicated diverticulitis that was tx w/ abx
age less than 50
what is tx of uncomplication diverticuli?
high fiber diet
with delayed or elective surgery for sigmoid diverticulitis what do they get?
sigmoidectomy w/ colorectal anastamosis (no colostomy)
Caused by a ruptured diverticulum
90% occur in patients older than 50
Diverticulitis
95% of diverticulitis have involvement where?
sigmoid colon
is it common to have bleeding diverticitulitis?
No, usually have bleeding diverticuli or diverticulitis
Presentation of diverticulitis
Grandual onset LLQ pain Fever, anorexia, nausea or vomiting constipation UTI symptoms Pneumaturia (fistula)
what is an indication for surgery w/ diverticular bleeding?
> 4 units pRBC in 24 hours
tx for mild diverticulitis
clear liquid diet (must be able to tolerate this)
oral abx for 7-10 days (broad spectrum)
follow up in 58-72 hours
must have active arterial bleeding at time of study (0.5 – 1 mL/min)
angiography
if there is a perf diverticulitits what needs to happen?
surgery- laporotomy
what needs to happen after someone has healed from diverticulitis?
colonscopy to r/o cancer
complications of diverticulitis
Abscess/ Phelgmon
perforation w/ peritonitis
fistula (may need sx)
what is the second leading cause of cancer death?
colorectal cancer
Need for immediate surgery w/ diverticulitis
free perf
lack of improvement w/ conservative therapy
obstruction
with delayed or elective surgery for sigmoid diverticulitis what do they get?
sigmoidectomy w/ colorectal anastamosis (no colostomy)
Most common cause of LGI bleed
Diverticular bleeding
How does someone w/ diverticular bleed present?
BRBPR
hemodynamic instability- need iV fluids
for localized diverticular bleeding what procedure is done?
segmental colectomy
for non-localized diverticular bleeding what is needed?
total colectomy
what rule out rectal source of bleeding
rigid protoscope
can dectect at slower rate of bleeding than angiography (0.1 mL/min)
bleeding scan
what s a premalignant lesion, type of colon polyps
adenomas
most colorectal cancers arise from what?
adenomas
a colon polyp bigger than what has malignant potential?
> 1cm
should all colon polyps be removed?
yes
what is the second leading cause of cancer death?
colorectal cancer
what drug may be protective for colorectal cancer?
NSAIDs
Colon cancer develops in nearly all untreated patients by age 40
Genetic testing in at risk patients
Colectomy
Familial adenomatous polyposis (FAP)
what type polyps is FAP associated with?
Associated with duodenal/periampullary adenomatous polyps
earlier average age of onset of cancer
need to look for cancer at multiple spots
Hereditary nonpolyposis colorectal cancer (aka Lynch syndrome)
screening for colorectal cancer
Flexible Sigmoidoscopy every 5 years
Colonoscopy every 10 years
when should someone w/ a family hx of colon cancer be tested?
age 40 or ten years prior to youngest person in family presentation
presentation of colorectal cancer?
asymptomatic - found on screening
how many stool cultures do you get for C Diff?
3
tx for C Diff
D/C abx
metronidazole (better PO)
oral vancomycin is 2nd line
what is the only chance for cure of early colorectal cancer?
surgical resection
also remove a lot of messentery (lymph nodes)
Inflammation in GI tract is confined to colon and rectum
ulcerative colitis
age distribution w/ UC
20 - 29 years
60 - 70 years
where is UC always found?
Rectum, then works its way proximal
diagnosis for UC?
sigmoidoscopy for active dz
colonoscopy
biopsy
do people with Crohn’s or UC bleeding more?
UC
what will UC look like on a barium enema?
lead pipe appearance
people w/ UC are at high risk of what type cancer?
carcinoma of the colon or rectum
tx for UC
antidiarrheal and bulking meds
mesalazine
corticosteroids (acute attacks)
drug for maintenance w/ UC
Oral aminosalicylates
surgical therapy for UC (fulminant colitis)
total abdominal colectomy w/ ileostomy
what is resection of the rectum?
proctectomy
Antibiotic associated colitis Occurs during or after antibiotic treatment Diarrhea Abdominal cramping Vomiting Fever Leukocytosis
Clostridium difficile colitis
tx for C Diff
D/C abx
metronidazole (better PO)
oral vancomycin is 2nd line
complications of severe C Diff
Toxic Megacolon
Perforation
Septic shock
what may C Diff colitis require?
subtotal colectomy
Caused by mesenteric vascular occlusion or nonocclusive mechanisms
Often occurs in patients with multiple comorbidities and/or the elderly
may be due to thrombosis, emboli, low flow state, venous occlusion
ischemic colitis
what do you get for dx for ischemic colitis
Luekocytosis
CT scan- thickened large bowel
sigmoidoscopy/ colonoscopy
tx of ischemic colitis
volume resuscitation
borad spectrum ABX
NPO
surgery if med management fails
