chapter 36: colorectal Flashcards
Colon secretes ____ and reabsorbs _____
colon secretes K and reabsorbs Na and water (mostly in right colon and cecum)
4 layers of the colon
mucosa (columnar epithelium) -> submucosa -> muscularis propria -> serosa
colonic layer: small interwoven inner muscle layer just below mucosa but above basement membrane
muscularis mucosa
colonic layer: circular layer of muscle
muscularis propria
retroperitoneal portions of colon
ascending, descending and sigmoid colon are all retroperitoneal
- peritoneum covers anterior upper and middle 1/3 of the rectum
transverse bands that form haustra
plicae semiliunares
3 bands that run longitudinally along colon. at rectosigmoid junction, these become broad and completely encircle the bowel
taenia coli
cm: dentate line from anal verge
2cm
cm: anal transition zone from anal verge
4 cm
vasculature: ascending and 2/3 of transverse colon
SMA (ileocolic, right and middle colic arteries)
vasculature: 1/3 transverse, descending colon, sigmoid colon, and upper portion of the rectum
IMA (left colic, sigmoid branches, superior rectal artery)
vascular: runs along colon margin, connecting SMA to IMA (provides collateral flow)
marginal artery
artery: short direct connection between SMA and IMA
Arc of Riolan
how is vascular supply distributed in the colon?
80% of blood flow goes to mucosa and submucosa
venous drainage of colon?
follows arterial except IMV, which goes to the splenic vein
what forms the portal vein?
splenic vein joins the SMV to form the portal vein behind the pancreas
what does superior rectal artery branch off of?
superior rectal artery - branch of IMA
what is the middle rectal artery a branch of?
branch of internal iliac
what contains the middle rectal arteries during low anterior resection [LAR] or abdominoperineal resection [APR]?
the lateral stalks
what is the inferior rectal artery a branch of?
branch of internal pudendal (which is a branch of the internal iliac).
where do superior and middle rectal veins drain?
superior and middle rectal veins drain into the IMV and eventually the portal vein.
where do inferior rectal veins drain?
inferior rectal veins drain into the internal iliac veins and eventually the caval system
major blood supply of the colon
SMA and IMA
drain to IMA nodal lymphatics
superior and middle rectum
drains primarily to IMA nodes, also to internal iliac nodes
lower rectum
does the bowel wall contain lymphatics?
bowel wall contains mucosal and submucosal lymphatics.
what are the watershed areas in the colon?
- splenic flexure (Griffith’s point)
- rectum (Sudak’s point)
watershed area: SMA and IMA junction
splenic flexure (Griffith’s point)
watershed area: superior rectal and middle rectal junction
rectum (sudak’s point)
more sensitive to ischemia: colon vs small bowel
colon more sensitive to ischemia than small bowel secondary to decreased collaterals
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
- involuntary control
- is the continuation of the muscularis propria (smooth muscle)
- is normally contracted
internal sphincter
inner nerve plexus
meissner’s plexus
outer nerve plexus
auerbach’s plexus
parasympathetic to colon
pelvic splanchnic nerves
sympathetics to colon
lumbar and sacral plexus
from anal verge: anal canal
0 - 5 cm
from anal verge: rectum
5 - 15 cm
from anal verge: rectosigmoid junction
15 - 18 cm
marks the transition between anal canal and rectum
levator ani
mucus-secreting goblet cells
crypts of lieberkuhn
slow transit time; patients may need subtotal colectomy
colonic inertia
main nutrient of colonocytes
short-chain fatty acids
tx: stump pouchitis (diversion or disuse proctitis)
short-chain fatty acids
tx: infectious pouchitis
metronidazole (flagyl)
rectovesicular fascia in men; rectovaginal fascia in women
denonvilliers fascia (anterior)
rectosacral fascia
waldeyer’s fascia (posterior)
most common polyp; no cancer risk
hyperplastic polyps
most common (75%) intestinal neoplastic polyp (these are generally pedunculated)
tubular adenoma
polyp most likely to produce symptoms
- these are generally sessile and larger than tubular adenomas
villous adenoma
villous adenomas: percent that have cancer
50% of villous adenomas have cancer
polyps: characteristics of lesions with increased cancer risk
> 2cm
sessile
villous
polyps have ___ side predominance
polyps have left side predominance
what type of polyps can be removed endoscopically?
most pedunculated polyps can be removed endoscopically
management: if not able to get all of the polyp endoscopically (which usually occurs with sessile polyps)
need segmental resection
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.
polyps: basement membrane is intact (carcinoma in situ)
high-grade dysplasia
what is carcinoma in situ?
malignant cells are confined to the mucosa
polyps: into muscularis mucosa (CIS -> still has not gone thru the basement membrane)
intramucosal cancer
polyps: into submucosa (T1)
invasive cancer
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)
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
what can cause a false-positive guaiac?
beef, vitamin C, iron, cimetidine
when do you not want to do colonoscopy?
recent MI, splenomegaly, pregnancy (if fluoroscopy planned)
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
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.
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
tx: pathology shows T2 lesion after transanal excision of rectal polyp
patient needs APR or LAR
2nd leading cause of CA death
colorectal cancer
symptoms of colorectal cancer
anemia, constipation, and bleeding
why are red meat and fat associated with colorectal cancer?
O2 radicals are thought to have a role
what infection is associated with colorectal cancer?
clostridium septicum infection
main gene mutations in colorectal cancer
APC, DCC, p53, and k-ras
most common site of primary colorectal cancer
sigmoid colon
most important prognostic factor for colorectal cancer
nodal status
- spreads to nodes first
primary sites of metastases in colorectal cancer
#1 liver #2 lung
how does colorectal cancer metastasize to liver?
portal vein
how does colorectal cancer metastasize to lung?
iliac vein
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
5 year survival rate for colorectal cancer with lung metastases
25% 5-YS rate in selected patients after resection
management: isolated liver or lung metastases in colorectal cancer
isolated liver or lung mets should be resected
rate of patients with drop metastases to ovaries in colorectal cancer
5%
why can rectal CA metastasize to spine directly?
via Batson’s plexus (venous)
does colon CA go to bone?
colon CA typically does not go to bone
surgery: colorectal CA growing into adjacent organs
can be resected en bloc with a portion of the adjacent organ (i.e., partial bladder resection)
colorectal ca prognosis: lymphocytic penetration
patients have an improved pronosis
colorectal ca prognosis: mucoepidermoid
worst prognosis
colorectal ca: good at assessing depth of invasion (sphincter involvement), recurrence, and presence of enlarged nodes
rectal ultrasound
mandatory in diagnosis of colorectal ca
need total colonoscopy to rule out synchronous lesions in patients with colorectal CA
colorectal ca: goals of resection
en bloc resection, adequate adenectomy
management of most right-sided colon CAs
can be treated with primary anastomosis without ostomy
management of rectal pain with rectal ca
patient needs APR
margins for colorectal cancer surgery
generally need 2-cm margins
colorectal ca: best method of picking up intrahepatic metastases
intraoperative ultrasound (U/S)
intraoperative ultraound
- resolution: conventional U/S
10 mm
intraoperative ultraound
- resolution: abdominal CT
5-10mm
intraoperative ultraound
- resolution: abdominal MRI
5-10mm (better resolution than CT)
intraoperative ultraound
- resolution: intraoperative U/S
3-5mm
permanent colostomy; anal canal is excised along with the rectum
abdominoperineal resection (APR)
potential complications of abdominoperineal resection (APR)
can have impotence and bladder dysfunction (injured pudendal nerves)
when is abdominoperineal resection indicated?
indicated for malignant lesions only (not benign tumors) that are not amenable to LAR
margins for abdominoperineal resection (APR)
need at least a 2-cm margin (2cm from levator ani muscles) for LAR, otherwise will need APR
risk of local recurrence: rectal CA vs colon CA
risk of local recurrence higher with rectal CA than with colon CA in general
produces complete response in some patients with rectal CA; preserves sphincter function in some
preoperative chemo-XRT
T? - into submucosa
T1
T? - into muscularis propria
T2
T? - into serosa or thru muscularis propria if no serosa is present
T3
T? - through serosa into free peritoneal cavity or into adjacent organs / structures if no serosa is present
T4
N? - nodes negative
N0
N? - 1-3 nodes positive
N1
N? - >/ 4 nodes positive
N2
N? - central nodes positive
N3
M? - distant metastases
M1
tx: low rectal T1 (limited to submucosa)
can be excised transanally if
tx: low rectal T2 or higher
APR or LAR
chemotherapy: stage 3 and 4 colon ca (nodes positive or distant metastases)
postop chemo, no XRT
chemotherapy: stage 2 and 3 rectal ca
pre-op chemo-XRT
chemotherapy: stage 4 and rectal CA
chemo and XRT +/ surgery (possibly just colostomy, may want to avoid APR in patients with metastatic disease)
colorectal CA: chemo regimen
5FU, leucovorin, and oxaliplatin (FOLFOX)
colorectal CA: benefits XRT
decreases local recurrence and increases survival when combined with chemotherapy
colorectal CA: XRT damage
rectum most common site of injury -> vasculitis, thrombosis, ulcers, strictures
colorectal CA: pre-op chemo XRT
may help shrink rectal tumors, allowing down-staging of the tumor and possibly allowing LAR versus APR
colorectal CA: rate of recurrence
20% have a recurrence (usually occurs within 1 year)
- 5% get another primary -> main reason for surveillance colonoscopy
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)
autosomal dominant; all have cancer by age 40
familial adenomatous polyposis (FAP)
gene involved in FAP
APC gene - chromosome 5
how many FAP syndromes are spontaneous?
20% of FAP syndromes are spontaneous
when do FAP syndromes present?
polyps not present at birth; are present in puberty
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
management of FAP
all need total colectomy prophylactically at age 20
why do you need to check the duodenum every 2 years in FAP?
also get duodenal polyps
FAP surgery
proctocolectomy, rectal mucosectomy, and ileoanal pouch (J-puch)
- need lifetime surveillance of residual rectal mucosa
- total proctoceolectomy with end ileostomy is also an option
MCC death in FAP patients following colectomy
periambpullary tumors of the duodenum
patients get colon CA (associated with APC gene) and desmoid tumors / osteomas
Gardner’s syndrome
patients get colon CA (associated with APC gene) and brain tumors
Turcot’s syndrome
5% of the population, autosomal dominant
- associated with DNA mismatch repair gene
- predilection for right-sided and multiple cancers
Lynch syndromes (hereditary nonpolyposis colon cancer)
Lynch syndrome: just colon CA risk
Lynch 1
Lynch syndrome: patients also have increased risk of ovarian, endometrial, bladder, and stomach cancer
Lynch 2
Amsterdam criteria for Lynch syndrome
“3,2,1” -> at least 3 first degree relatives, over 2 generations, 1 with cancer before age 50
surveillance for lynch syndrome
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)
rate of metachronous lesions in lynch syndrome
50% get metachronous lesions within 10 years; often have multiple primaries
surgery for lynch syndrome
need total proctocolectomy with first cancer operation
- more common with high-fiber diets (Iran, Iraq)
- occurs in debilitated psychiatric patients, neurologic dysfunction, laxative abuse
- symptoms: pain, distention, and obstipation
sigmoid volvulus
what type of obstruction is sigmoid volvulus?
causes closed-loop obstruction -> sigmoid colon twists on itself
abdominal Xr: sigmoid volvulus
bent inner tube sign; gastrograffin enema may show bird’s beak sing (tapered colon)
management of gangrenous bowel in sigmoid volvulus
do not attempt decompression with gangrenous bowel or peritoneal signs -> go to OR for sigmoidectomy
tx: sigmoid volvulus
decompress with colonoscopy (80% reduce, 50% will recur), give bowel prep, and perform sigmoid colectomy during same admission
less common than sigmoid volvulus; occurs in 20s-30s
- can appear as SBO with dilated cecum in the RLQ
cecal volvulus
role of colonoscopy in cecal volvulus
can try to decompress with colonoscopy but unlikely to succeed (only 20%)
OR treatment for cecal volvulus
Right hemicolectomy probably best treatment; can try cecoplexy if colon is viable and patient is frail
bloody diarrhea, abdominal pain, fever and weight loss
- involves the mucosa and submucosa
- strictures and fistulae unusual
ulcerative colitis
IBD: spares anus
ulcerative colitis (unlike crown's) - usually starts distally in rectum and is contiguous (no skip areas like crohn's)
IBD: universal bleeding and mucosal friability with pseudo polyps and collar button ulcers
ulcerative colitis
what do you need to rule out in ulcerative colitis?
always need to rule out infectious etiology
ulcerative colitis: when can backwash ileitis occur?
backwash ileitis can occur with proximal disease
characteristics of barium enema in chronic ulcerative colitis
loss of haustra, narrow caliber, short colon, and loss of redundancy
medical treatment: ulcerative colitis
sulfasalazine (or 5-ASA) and loperamide for maintenance therapy
- steroids for acute flares
ulcerative colitis: medical treatment that can maintain remission
5-ASA and sulfasalazine
ulcerative colitis: medical treatment for steroid-resistant disease
consider cyclosporine or infliximab
ulcerative colitis: > 6 bloody stools/d, fever, increased HR, drop in hemoglobin, leukocytosis
toxic colitis
ulcerative colitis: > 6 blood stools/d, fever, increased heart rate, drop in hemoglobin, leukocytosis, distention, abdominal pain and tenderness
toxic megacolon
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
what do you want to avoid in toxic colitis and toxic megacolon?
avoid barium enemas, narcotics, anti-diarrheal agents, and anti-cholinergics
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
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
more common location of perforation with ulcerative colitis
transverse colon more common
more common location of perforation with crohn’s disease
distal ileum most common
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)
ulcerative colitis: emergent/urgent resection
total proctocolectomy and bring up ileostomy
- perform definitive hook-up later
elective resection: ulcerative colitis
ileoanal anastomosis - rectal mucosectomy, J-pouch and ileoanal (low rectal) anastomosis; not used with crohn’s disease
what does illeoanal anastomosis protect in ulcerative colitis?
can protect bladder and sexual function
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
mc major morbidity in illeoanal anastomosis in ulcerative colitis
can lead to sepsis (Tx: drainage, antibiotics)
ulcerative colitis: tx - infectious pouchitis
flagyl
two options with elective resections in ulcerative colitis
ileoanal anastomosis and APR with ileostomy
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 8-10 years after diagnosis
most common extra intestinal manifestation of ulcerative colitis requiring total colectomy
failure to thrive in children
ulcerative colitis: do not get better with colectomy
primary sclerosing cholangitis, ankylosing spondylitis
ulcerative colitis: get better with colectomy
most ocular problems, arthritis, and anemia
ulcerative colitis: 50% get better
pyoderma gangrenosum
ulcerative colitis: HLA b27
sacroilitis, ankylosing spondylitis, ulcerative colitis
is thromboembolic disease a risk in ulcerative colitis?
yes
tx: pyoderma gangrenosum in ulcerative colitis
steroids
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
treatment: low rectal carcinoids
wide local excision with negative margins
treatment: low rectal carcinoids > 2cm or invasion of muscularis propria
APR
tx: colon or high rectal carcinoids
formal resection with adenectomy
location: colon perforation with obstruction
most likely to occur in cecum
law of laplace
tension = pressure x diameter
colonic obstruction: can be worrisome; can have rapid progression and perforation with minimal distention
closed loop-obstruction
what can lead to closed-loop obstruction in colonic obstruction?
competent ileocecal valve
primary causes of colonic obstruction
#1 cancer #2 diverticulitis
air in the bowel wall, associated with ischemia and dissection of air through areas of bowel wall
pneumatosis intestinalis
usually indicates significant infection or necrosis of the large or small bowel; often an ominous sign
air in the portal system
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
tx: ogilvie’s syndrome
check and replace electrolytes (especially K); discontinue drugs that slow the gut (e.g. morphine); NGT
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
- from contaminated food and water with feces that contain cysts
- risk factors: travel to Mexico, ETOH; fecal-oral transmission
amoebic colitis: entamoeba histolytica
symptoms: similar to ulcerative colitis (dysentery); chronic more common form (3-4 bowel movements/day, cramping, and fever)
amoebic colitis - entamoeba histolytica
primary and secondary infection of amoebic colitis
- primary infection - occurs in colon
- secondary infection - occurs in liver
dx: amoebic colitis
endoscopy -> ulceration, trophozoites; 90% have anti-amebic antibodies
tx: amoebic olitis
flagyl, diiodohydroxyquin
can present as a mass, abscess, fistula, or induration; suppurative and granulomatous
actinomyces
most common location of actinomyces
cecum most common location; can be confused with CA
pathology: actinomyces
yellow-white sulfur granules
tx: actinomyces
penicillin or tetracycline, drainage of any abscess
herniation of mucosa though the colon wall at sites where arteries enter the muscular wall
diverticula
how is adjacent colon affected by diverticula?
circular muscle thickens adjacent to diverticulum with luminal narrowing
what causes diverticula?
caused by straining (increased intraluminal pressure)
where do most diverticula occur?
most diverticula occur on left side (80%) in the sigmoid colon
symptoms: right-sided diveritucula
bleeding is more likely with right-sided diverticula (50% of bleeds occur on right)
diverticula: more likely to present on the left side
diverticulitis
rate of diverticula in the populations
presents in 35% of the population
lower GIB: how long does stool guaic stay positive
for up to 3 weeksn
bleeding anywhere near pharynx to ligament of Treitz
hematemsis
passage of tarry stools; need as little as 50 cc
melena
management of lower gastrointestinal hemorrhage
- rule out UGI: NGT
- r/o rectal source: proctoscopy
what causes azotemia after GIB?
caused by production of urea from bacterial action on intraluminal blood (increased BUN; also get elevated total bilirubin)
bleeding rate to see arteriography
bleeding must be >/ 0.5 cc/min
bleeding rate for tagged RBC scan
bleeding must be >/ 0.1 cc/min
denotes infection and inflammation of the colonic wall as well as surrounding tissue
- LLQ pain, tenderness, fever, leukocytosis
diverticulitis
what causes diverticulitis
result of mucosal perforations in the diverticulum with adjacent fecal contamination
dx: diverticulitis
CT scan is needed only if worried about complications of disease
follow-up after episode of diverticulitis
need follow-up colonoscopy after an episode of diverticulitis to rule out colorectal cancer
most common complication of diverticulitis
abscess formation; can usually percutaneously drain
signs of complications of diverticulitis
obstruction symptoms, fluctuant mass, peritoneal signs, temperature > 39 and WBCs > 20
tx: uncomplicated diverticulitis
levofloxacin and Flagyl; bowel rest for 3-4 days (mild cases can be treated as an outpatient)
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
surgery: diverticulitis
need to resect all of the sigmoid colon down to the superior rectum (distal margin should be normal rectum)
80% discovered at time of incision for appendectomy
right-sided diverticulitis
- tx: right hemicolectomy
fecaluria, pneumouria
- occurs in men; women are more likely to get colovaginal fistula
colovesicular fistula
best diagnostic test for colovesicular fistula
cystoscopy is the best diagnostic test
tx: colovesicular fistula
close bladder opening, resect involved segment of colon, and perform reanastomosis, diverting ileostomy; interpose momentum between the bladder and colon
MCC of lower GIB
diverticulosis (usually causes significant bleeding)
diverticulosis bleeding: ___stops spontaneously; recurs in ___
75% stops spontaneously; recurs in 25%
what causes diverticulosis bleeding?
caused by disrupted vasa rectum; creates arterial bleeding
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
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
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
dx: diverticulosis bleeding for intermittent bleeds that are hard to localized
tagged RBC scan
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
tx: diverticulosis bleeding that is not localized and not controlled with colonoscopy
may need segmental colectomy or possible subtotal colectomy
management of patients with recurrent diverticular bleeds
should have resection of that area
- 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
soft signs of angiodysplasia on angiogram
tufts, slow emptying
coexisting comorbidity in angiodysplasia
20% of patients with angiodysplasia have aortic stenosis (usually gets better after valve replacement)
symptoms: abdominal pain, bright red bleeding
ischemic colitis
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
most vulnerable colonic sites to low-flow states
splenic flexure and upper rectum
point: SMA and IMA junction
Griffith’s point (splenic flexure)
superior rectal and middle rectal artery junction
sudeck’s point
dx: ischemic colitis
CT scan or endoscopy -> cyanotic edematous mucosa covered with exudates
why is the lower 2/3 of the rectum spared in ischemic colitis?
supplied by the middle and inferior rectal arteries (off internal iliac)
ischemic colitis: management of suspected gangrenous colitis (peritonitis)
no colonoscopy and go to OR -> sigmoid resection or let hemicolectomy usual
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)
key finding: pseudomembranous colitis
PMN inflammation of mucosa and submucosa (pseudomembranes, plaques, and ringlike lesions)
most common location of pseudomembranous colitis (C diff)
most common in the distal colon
dx: c diff (pseudomembranous colitis)
c diff toxin
tx: pseudomembranous colitis (c diff)
oral - vancomycin or flagyl
IV: flagyl
- lactobacillus can also help; stop other antibiotics or change them
- follows chemotherapy when WBC are low (nadir)
- can mimic surgical disease
- can often see pneumatosis intestinalis (not a surgical indication)
neutropenic typhlitis (enterocolitis)
tx: neutropenic typhlitis (enterocolitis)
antibiotics; patients will improve when WBCs increase ; surgery only for free perforation
other causes of colitis
salmonella, shigella, campylobacter, cmv, yersinia (can mimic appendicitis in children), other viral infections, giardia
can mimic appendicitis; comes from contained food (Feces/urine)
-tx?
yersinia
- tx: tetracycline or bactrim
propensity for volvulus; enlargement is proximal to non-peristalsing bowel
megacolon
megacolon - rectosigmoid most common
- dx: rectal biopsy
hirschsprung’s disease
megacolon: most common acquired cause, secondary to destruction of nerves
trypanosoma cruzi
