Lower GI Disorders Flashcards
What is the most common tumor that metastasizes to the intestine?
melanoma
Metabolic acidosis with no other obvious cause warrants suspicion of __________-. What are next steps?
ischemic or necrotic bowel. Next steps are urgent exploration or mesenteric arteriography, depending on the patient’s overall status/radiographic findings
In an unplanned enterotomy (accidentally enter bowel lumen while lysing dense adhesions), when is primary repair acceptable?
If the hole is small! If holes are large, multiple, or involve densely adherent bowel, the segment may require resection
What is the greatest risk of an enterotomy?
post-op leak and development of small bowel fistula
Give an example of a low flow nonocclusive state causing mesenteric ischemia. What is the treatment?
IN CHF, low flow states can compromise circulation. Treatment involves direct mesenteric infusion of a vasodilator (like papaverine) and efforts to improve cardiac output
Ischemia of the intestines with multiple small punctate areas of necrosis throughout the jejunum and ileum in ap atient with a pulse in the SMA:
this is either multiple small emboli or a low flow state. Only necrotic areas warrant resection; angiography to see if low flow state.
Deep ulceration is a feature of (Crohn’s/UC)
Crohn’s (cobblestoning)
The “string sign” is seen on radiologic studies of (Crohn’s/UC). WHat is it due to?
Crohn’s: narrowing of terinal ileum from edema
What is the terminal ileum responsible for absorbing?
B12, bile acids (resection can lead to B12 deficiency and diarrhea, malabsorption, and oxalate stones)
What medication is useful for the management of perianal disease in Crohn’s?
metronidazole
Patient iwth proctocolectomy with ileoanal J pouch returns 6 months after surgery with fever, blood-tinged diarrhea, and pain on defecation. Most likely diagnosis? Treatment?
Pouchitis (inflammation of the reservoir from an unknown cause). Endscopy shows hemorrhagic mucosa with edema and small ulcerations. Treatment is metronidazole.
What is the initial management of toxic megacolon?
NG tube, NPO feeding, TPN, IV fluids, broad spectrum abx, IV STEROIDS. IF patient fails to improve over 3 days, surgery (leave Hartman pouch and rectum to be removed once patient recovers)
What is the name given to the incision in an open appendectomy?
McBurney
T/F: McBurney’s point is 1/3 the distance from the umbilicus to the ASIS.
FALSE!!!!!!!
It is 1/3 the distance from the ASIS to the UMBILICUS (or 2/3 the distance from the umbilicus to the ASIS)
Why are you looking for clear signs of dysuria and a urine white count of >10,000 hpf to make you think more UTI than appendicitis? What about mild dysuria nad urine WBC of 8-10 hpf?
The latter could be resulting from local inflammation of the appendix irritating the bladder and not really due to a UTI
Man with ruptured appendix recovers from surgery and is discharged, but presents one week later with fever, chills, anorexia, and malaise. What could it be?
wound infection or pelvic abscess (use CT or ultrasound to diagnose)
Individuals with a first degree relative with CRC or an adenomatous polyp should undergo colonoscopies starting at age
40 (not 50)
Once polyps are discovered on the yearly flexible sigmoidscopy of a person with FAP, what is the next step?
colectomy
Patients with HNPCC should undergo colonscopy starting when?
25 or 10 years before first degree relative got CRC
If an adenomatous polyp is found in a patient’s colonoscopy, when is the next one?
3 months (to make sure it was adequately resected) then 3 years after the initial exam. NOTE: if the polyp showed CIS, then 1 year after the initial exam.
A person with resected colon cancer should have CEA levels checked and physical exams every ___ months for the next 2 years.
3 months (CEA), 6 months (colonoscopy)
If a patient presents with external or internal hemorrhoids, in addition to treating the hemorrhoids, what should be performed?
a colonoscopy or sigmoidoscopy to rule out cancer
While pedunculated polyps are removed surgically if they are over 5 cm, sessile polyps must be removed surgically if they are over __ cm.
2
What is the treatment of carcinoma in a sessile lesion?
Bowel resection with repeat colonoscopy in 1 year
A rising CEA in the year following colon resection for CRC should prompt
CTA to identify metastases or recurrence
Progression from polyp to invasive cancer takes approximately __ years
10
Gardner syndrome involves a mutation of which gene?
The APC gene (like FAP)
Gardner syndrome may involve which extracolonic cancers?
desmoid (of fibroblasts), osteomas of the skull, thyroid cancer, epidermoid cysts, fibromas
What is the Amsterdam criteria for Lynch syndrome?
HNPCC
1) At least 3 relatives with histologically confirmed colorectal cancer, 1 of whom is a first degree relative of the other 2; familial adenomatous polyposis should be excluded;
2) At least 2 successive generations involved;
3) At least 1 of the cancers diagnosed before age 50.
Lynch syndrome can involve extracolonic cancers where?
endometrium (secondary most common up to 50%), ovary, stomach, small intestine, hepatobiliary tract, upper urinary tract, brain, and skin
An abscess post hemicolectomy is likely to be where in teh abdomen?
right paracolic gutter or pelvis (diagnosis by CT)
Rectal adenocarcinoma spread by distal extension and lymphatics to which nodal locations?
parallels the superior hemorrhoidal vessels and includes the internal iliac nodes, sacral nodes, and inferior mesenteric nodes.
Lesions <5 cm from the nal verge can also spread locally and to the inguinal nodes
What is the most common complications following APR?
impotence (50%) because the sympathetic plexus of nerves is located aroudn the rectum
Low anterior resections can be used for rectal cancers that lie more than __ cm proximal to the anal verge, otherwise abdominoperineal resection is necessary to avoid injuring the anal sphincter mechanism.
5cm
For distal resection of rectal carcinomas, the recommended margins are __ cm for well-differentiated lesions and __ cm for poorly differentiated, anaplastic, or Signet.
Which are more likely to require abdominoperineal resection?
well-differentiated: 2 cm
poorly differentiated, anaplastic, SIgnet: 5 cm (these tumors are more likely to result in APR
What is the post op adjuvant chemo for rectal and colon cancer?
5FU, levamisole
In women, what is the anterior margin of the APR?
the posterior wall of the vagina (must be removed)
Epidermoid carcinoma of the anus (SCC) metastasizes to which LN?
inguinal, superior rectal
Why is meperidene, not morphine, used for pain associated with diverticulitis?
Meperidine decreases the intraluminal pressure, but morphine increases intracolonic pressure
The majority of patients with diverticulitis (will/will not) experience a recurrence.
will not
After a recurrence of diverticulitis, elective resection ischeduled ___ weeks after inflammation has resolved.
4-6
Although most diverticula in the colon are (left/right) sided, those on the (left/right) side are more likely to bleed.
most: left
most likely to bleed: right
AVMs in the colon occur between which vessels?
intestinal submucosal veins and overlying mucosal capillaries
Angiography is sued to isolate a bleeding lesion at a rate of
Technetium-labeled RBC scanning is used for bleeding at a rate of ____
angiography: 1-2 mL/min
RBC scanning: 0.1-0.5 mL/min
Many surgeons explore patients with lower GI bleeds once they have required ___ units of blood.
4-6. OR if patient unstable or with hard to determine blood types or who don’t want transfusions. RIght or left hemicolectomy to remove the bleeding source.
WHy can a primary anastamosis be peformed if a hemicolectomy is required to stop a GI bleed?
THe cathartic effect of blood in the colon; sufficiently clean colon to allow primary anastomosis (except if patient is unstable or severely malnourished)
What occurs most commonly in debilitated patients from nursing homes, often as a result of chronic laxative use, chronic illness, or dementia? Constiptation, recent deterioration in mental status, and abdominal distention.
Treatment?
sigmoid volvulus (closed loop obstruction)! Use rigid proctosigmoidoscopy and placement of rectal tube to “detorse” the sigmoid colon. If unsuccessful, laparotomy with sigmoid colectomy (either with diverting colostomy or primary anastamosis, depending on preop condition of patient)
In Ogilivie’s syndrome, if cecal diamter is >10cm, what is done next?
endoscopic decompression, neostigmine (<– if fails, then surgical decompression or right colectomy)
What is the treatment of a deep and chronic anal fistula?
lateral sphincterotomy
T/F: THe primary treatment of a perianal abscess is antibiotics.
FALSE. Drainage, not antibiotics.
Surgery for small bowel obstruction reveals paracaval lymph nodes revealing small round and homogenous lymphocytes and a “starry sky” appearance. Tumor cells stain positive for CD19, CD20, and Ki67.
What is it?
Burkitt lymphoma (treatment = rituximab = ab against CD20)
Watery diarrhea, stool with lower pH/elevated D-lactic acid levels, macrocytic anemia…
bacterial overgrowth in colon. Breath test can reveal early rise in hydrogen following ingestion of 14C glycocholic acid. Use tetracycline to rebalance natural flora
What are the “worrying signs” that make you consider something besides IBS?
age >50, weight loss, gross blood in stool, signs of infection, family history of bowel disease
“Spiral” or “corkscrew” appearance of bowel on barium study with abnormal position of superior mesenteric vessels…
volvulus; due to congenital malrotation of the gut, often
Name the layers of the gut starting at mucosa outwards!
Mucosa, muscularis mucosa, submucosa, circular muscular layer, (Auerbach’s/myenteric plexus), longitudinal muscular layer, serosa
Peutz Jegher’s features a mutation in what gene
STK11/LKB1
Native bacteria is a protective mechanism against invading bacterial growth in the (small/large) intestine
Large
What is the principle eptihelial cell of the small intestine?
Paneth cell: secretes defensins, lysozyme, phospholipae, and other molecules involved in host defense
What are the host defenses in the small intestine?
Mucin production, tight junctions, Paneth cells (main epithelial cell), and Gut-associated lymphoid tissue
Antiendomysial antibodies are characteristic of
celiac disease
T/F: Patients with Celiac disease are at higher risk of gut lymphomas.
True! Also miscarriage and infertility
The fecal occult blood test has high (sensitivity/specificity).
Neither!!!
Its positive predictive value is just 20%, too
Submucosal colonic wall degeneration occurs in the cecum and ascending colon of patients with
colonic angiodysplasia
T/F: In both diverticular bleeding and bleeding due to colonic angiodysplasia, bleeding is brisk, sudden, and self-limiting.
True
How do you treat diverticular phlegmon?
IV abx, bowel rest, IVF.
Phlegmons, unlike abscesses, cannot be drained
What are principles of surgical repair of fistula en ano?
unroofing of the tract, removal of primary opening, drainage, and exploration with a tract guide
In a patient with recurrent anal fistulas, what diagnosis must be ruled out?
anorectal carcinoma (low rectal or anal cancers may present as fistulas). Perform anoscopy.
In which direction do pilonidal sinus tracts run?
Cephalad in more than 90% of cases
Bronchospasm, valvular lesions of hte right side of the heart, flushing, and diarrhea are typical symptoms of
carcinoid syndrome
What produces the cobblestone appearance in Crohn’s?
Submucosal edema with elevation of the surviving mucosa
