Alimentary Tract - Large Intestine Flashcards
The malignant potential of a colon polyp is determined by what?
histological type - requires biopsy
malignant potential: adenoma
neoplastic, precursor for many colorectal cancers
malignant potential: hamartoma polyp
nondysplastic, benign growth; non-neoplastic unless associated w/ Peutz-Jeghers, Cowden syndrome, juvenile polyposis syndrome
malignant potential: hyperplastic polyp
metaplastic, non-neoplastic, low risk if small (<1 cm) and distal
malignant potential: inflammatory pseudopolyp
not true polyp; associated w/ IBD, infectious colitis, ischemic colitis
What is the workup of a patient who presents with blood in his/her stool?
ABCs, H&P including frequency/character/timing, rectal exam, CBC, FOBT, colonoscopy
In a patient with polyps, what are some potentially modifiable risk factors to prevent CRC?
weight loss, fiber, decreased alcohol intake
What is the next step in a patient who was found to have an adenoma that wasn’t completely resected endoscopically? Why?
partial colectomy - incompletely resected adenomas harbor a 30% risk of cancer already being present, thus the benefits of cancer prevention outweigh surgical risks
During a colonoscopy, how would you remove a pedunculated polyp?
with a snare
During a colonoscopy, how would you remove a sessile polyp?
consider removing piecemeal, facilitated by a saline lift
During a colonoscopy, you encounter an ulcerated, friable, indurated polyp. How do you proceed?
biopsy and tattoo in 4 quadrants of the distal margin
What can be considered if a tattooed polyp cannot be found intraoperatively?
colonoscopy
What if a pedunculated polyp is positive for malignancy into the stalk?
polypectomy is adequate if the margins are negative
What parameters need to be met for pedunculated polyps with submucosal invasion (also sessile polyps) to be considered adequately treated with polypectomy?
if they are removed in a single piece with 2mm negative margins
High-risk lesions with invasion into the lower 1/3 of the submucosa, a resection margin <2 mm, lymphovascular invasion, piecemeal polypectomy, and/or poor differentiation should be treated how?
oncologic surgical resection
Follow up if no polyps found on colonoscopy and average risk?
10 yr colonoscopy
Follow up for 3–10 adenomas or 1 adenoma >1 cm or an adenoma with villous features or high-grade dysplasia on colonoscopy?
3 yr colonoscopy
Follow up for >10 adenomas found on colonoscopy? What should be considered at this point?
<3 year colonoscopy, consider adenomatous polyposis syndrome (FAP, AFAP, MAP)
Follow up for adenoma(s) removed piecemeal during colonoscopy?
2 to 6 month colonoscopy to ensure complete excision
Endoscopic follow up for Stage I-III colorectal CA surgically treated?
1 year colonoscopy, then every 3-5 years depending on findings
Endoscopic follow up for all patients with curative resection and anastomosis and LAR?
proctosigmoidoscopy +/- endorectal u/s every 6-12 months for 3-5 years; every 6 months for 3-5 years if higher risk of local recurrence
Endoscopic follow up for all patients s/p transanal local excision of rectal CA?
proctosigmoidoscopy +/- endorectal u/s every 6 months for 3-5 years
In regards to polyps, what are the Amsterdam criteria?
Criteria for HNPCC: 3-2-1 rule: 3 affected family members, 2 generations, 1 under age 50. 3 or more relatives with histologically verified Lynch-associated cancers (CRC, endometrial, small bowel, transitional carcinoma of the ureter or renal pelvis). One must be a first-degree relative of the other two. FAP must be excluded. 2 generations are affected by Lynch-associated cancers. 1 or more cancers diagnosed by age 50
What is the appropriate operation for an endoscopically unresectable polyp?
Segmental colectomy with high ligation of the vascular pedicle in order to sample the draining lymph node basin.
In a patient with a malignant polyp, when can you consider transanal full-thickness biopsy or transanal endoscopic microsurgery (TEM)?
low- or mid-rectal malignant polyps with no evidence on imaging of nodal disease
How does your surgical approach differ for a 24-year-old patient with familial adenomatous polyposis (FAP) versus a 43-year-old with three tubulovillous adenomas in the right colon who has a family history of colorectal and endometrial cancer?
The patient with FAP should be offered total proctocolectomy with ileal pouch-anal anastomosis or end ileostomy. Total abdominal colectomy with rectal surveillance can be considered if there is a low polyp burden in the rectum.
The <50 yr pt w/ right-sided adenomas should raise suspicion of HNPCC/Lynch. Lots of screening - colorectal, endometrial, ovarian, skin, neuro gastric.
You are asked to see an 86-year-old woman with a 2-cm sessile tubular adenoma in the right colon that was discovered after she had a positive test for occult blood during a routine physician appointment. A colonoscopic biopsy showed no dysplasia. The patient lives in a nursing home and has hypertension and mild congestive heart failure as well as early dementia. How will you counsel this patient and her family?
There is approximately a 5% chance of occult malignancy in a tubular polyp. An attempt should be made at endoscopic resection. The operative risk for partial colectomy with this patient’s comorbidities needs to be weighed against the advantages.
Describe how a 3-cm benign polyp may be different in terms of endoscopic management in the cecum versus the sigmoid.
Endoscopic management is the same in a 3-cm benign polyp in the cecum versus the sigmoid; however, an important consideration is that the cecum is thinner and there is a higher risk of perforation. Consider LIFT polypectomy by injecting the submucosa with an epinephrine solution.
A gastroenterologist refers a morbidly obese patient to you for management of a 4-cm sessile tubulovillous adenoma in the ascending colon that is not amenable to endoscopic resection. Describe your preoperative decision making.
It is important to localize the polyp endoscopically by tattooing it with India ink, particularly if a laparoscopic resection is planned. A right colectomy will be indicated; an oncologic resection should be performed for any endoscopically unresectable polyp. This morbidly obese patient may benefit from a laparoscopic approach which will minimize postoperative wound complications, pain, and narcotic use.
What types of polyps can occur in the large intestine, and which have malignant potential?
- Neoplastic (adenomatous) – highest malignant risk
- Hamartomatous (juvenile) – very low malignant risk
- Inflammatory (pseudopolyps) – seen with inflammatory bowel disease (IBD)
- Hyperplastic – almost no malignant potential
What are the hamartomatous polyposis syndromes?
- Peutz-Jeghers
- Cowden
- juvenile polyposis syndrome
CRCs in Lynch syndrome differ from sporadic CRCs in that they are predominantly where in location?
Right-sided
Lynch/HNPCC mutation
AD mutation in MMR causing microsatellite instability
Approach to screening for patient with known HNPCC
Sorted by age when starting screening
- 20-25: Q1y colonoscopy or 2-5 yrs prior to fam CRC
- 25-30: Q1yr PE w/ skin and neuro exam
- 30-35: Q1yr pelvic exam, endometrial bx, transvaginal U/S or 3-5 yrs prior to fam endometrial/ovarian cancer
- Q1yr UA beginning at
- Q2-3 yrs EGD w/ bx of gastric antrum if increased risk of gastric cancer
What do you recommend for a patient with HNPCC/Lynch and an endoscopically unresectable adenoma?
Unlike a regular risk patient, this patient should be offered TAC + IRA w/ annual endoscopy eval.
In a female undergoing colon resection for HNPCC/Lynch, what else should be offered?
Ppx TAH w/ BSOO
Diverticulum risk increases with what types of diet
high in fat, high in red meat, low fiber
What is complicated diverticulitis?
associated with complication - abscess, obstruction, perforation, fistula
Describe the presentations for uncomplicated and complicated acute diverticulitis.
- uncomplicated - acute increasing LLQ pain, nausea, vomiting, low-grade temp, point tenderness
- complicated - above + hypotension, peritonitis, palpable mass on abdominal/rectal exam, no improvement w/ pain/fever w/in 72 hrs of abx
Abdominal pain w/ profuse watery diarrhea, hematochezia, or bloody diarrhea should do what to diverticulitis on ddx?
These sx do not rule out diverticulitis, but other pathological processes should be worked up first, ie infectious colitis, IBD