Colorectal Flashcards
What is the Arc of Riolan?
a smaller arcade between the SMA and IMA that provides collateralization to the colon
What defines the proximal anal canal?
the puborectalis sling
What are the medical treatments for anal fissures?
- fiber and other bulking agents
- sitz baths
- topical anesthetics/nitrates/CCB
What are the procedural treatment options for anal fissures?
- botox injection
- lateral internal sphincterotomy
- an-cutaneous flap
What are the contraindications for lateral internal sphincterotomy for anal fissure?
- incontinence with botox injection
- women of childbearing age or with prior obstetrical injuries
- inflammatory bowel disease
What is the rule for the course that an anorectal fistula takes?
- anteriorly they take linear tracts unless > 3cm from the anus
- posterior they take curvilinear tracts
Which perirectal abscesses should be drained trans-anally?
deeper intersphincteric and supralevator
What is the proper procedure for draining a horseshoe abscess?
posterior mildline trans-anal incision with bilateral counter incisions
Which patients with peri-rectal abscesses should be treated with antibiotics?
those with cellulitis, systemic signs of infection, or with underlying immunosuppression
How does a seton work?
it induces fibrosis of the tract
When can you perform a fistulotomy?
if there is < 25% involvement of the sphincter
What is the physiologic function of hemorrhoids?
they provide volume to assist with continence
What procedure is the preferred intervention for acute symptomatic external hemorrhoids?
excision (not I&D)
Which hemorrhoids can be banded?
only internal since they have no somatic innervation
When should perc drain placement be pursued for those with diverticular abscess?
when the abscess is accessible and > 3cm
When should colonoscopy be performed after diverticulitis? Why?
- typically 6 weeks after resolution of the episode
- rule out ischemia, IBD, and neoplasm
What is the natural history of diverticulitis?
the first episode tends to be the worst
What class of bacteria is C. diff?
an anaerobic, gram-negative rod
For C. diff, how are the following treated:
- non-severe disease
- severe disease
- fulminant
- recurrent (1st)
- recurrent (2nd)
- PO vanco or flagyl
- PO vanco or PO fidaxomicin
- PO vanco and IV flagyl
- PO fidaxomicin
- longer course of vanco or fixaxomicin
What is the operative procedure of choice for C. diff colitis?
subtotal colectomy with ileostomy
What is the next step for a patient with suspected sigmoid volvulus on KUB?
CT scan to confirm diagnosis and assess colonic viability
When should you consider sigmoid colectomy for volvulus?
- on presentation if there is ischemic bowel
- otherwise during index admission given high risk for recurrence
What is the important difference between management of sigmoid v cecal volvulus?
there is no role for endoscopic management of cecal volvulus
What are risk factors for perforation in Ogilvie’s?
cecum > 12cm, fever, leukocytosis, abdominal tenderness
What medication can be given to decompress the colon in someone with Ogilvie’s? How does it work?
neostigmine, an acetylcholinesterease inhibitor
What is the most common side effect of neostigmine?
bradycardia
If someone with a dilated colon does not respond to neostigmine, what is the next step?
endoscopic decompression
What lifestyle modification can be used to help manage rectal prolapse?
a high fiber diet, but surgery remains the mainstay of treatment
What is the first line therapy for a relatively healthy patient with rectal prolapse?
- rectopexy is the key component
- LAR or sigmoid colectomy is added if the patient has constipation
What is the key difference between a Delorme and an Altemeier procedure?
- both are perineal approaches for rectal prolapse
- Delorme is a partial thickness resection while an Altemeier is full thickness
Which study has the highest sensitivity for bleeding?
a tagged RBC scan > CT angio > angio
What are the classic pathology findings for UC and Crohn’s?
- UC: pseudopolyps and crypt abscesses
- Crohn’s: creeping fat and transmural inflammation
How is UC medically managed?
- mesalamine enemas for maintenance
- infliximab added if resistant
- steroids for flares
What is the recommended surveillance for those with UC?
- endoscopy every 1-2 years, beginning 8 years after diagnosis
- make sure to take 4 quadrant random biopsies every 10cm
What is the best next step for a patient with high-grade dysplasia on a random biopsy?
total proctocolectomy with or without IPAA
What is the preferred emergency operation for those with UC?
- total or subtotal colectomy with end ileostomy
- can perform completion proctectomy later
Which UC patients are a candidate for TAC with ileorectal anastomosis? What surveillance do they still need?
- can perform if they have an uninvolved rectum (rare)
- should have annual endoscopic surveillance of rectal cuff
What are the three kinds of stricturoplasties?
- Heineke-Mikulicz: longitudinal incision with transverse closure
- Finney: fold structured segment on itself and make a common channel
- Michelassi: side-to-side isoperistaltic anastamosis
What is the most common complication after stricturoplasty?
bleeding
What is the standard recommendation for colon cancer screening?
- colonoscopies every 10 years starting at 45 years old
- alternative is sigmoidoscopy with FOBT every 5 years
What is the screening recommendation for those with FAP? For hereditary non-polyposis CRC?
- FAP: colonoscopy every 1-2 years for those age 10-12
- HNPCC: colonoscopy every 1-2 years for those age 20-25
What is the screening recommendation for those with the following:
- 1st degree relative with CRC or adenomas
- 2nd degree relative with CRC
- 1st: age 40 or 10 years before the youngest relative’s diagnosis, every 5 years
- 2nd: age 45 and every 10 years
What is the surveillance interval for the following colonoscopy findings:
- 1-2 tubular adenomas < 10mm
- 3-4 tubular adenomas < 10mm
- > 10 tubular adenomas
- adenoma > 10mm
- adenoma with HGD
- piecemeal resection
- hyperplastic polyps < 10mm
- hyperplastic polyps > 10mm
- 7-10 years
- 3-5 years
- 1 year
- 3 years
- 3 years
- 6 months
- 10 years
- 3-5 years
Which malignant colon polyps can be managed endoscopically?
those that meet these criteria:
- able to remove in 1 piece
- margins free of dysplasia/cancer
- well or moderately differentiated
- without angiolymphatic invasion
- limited submucosal invasion less than 2mm past the muscularis mucosa
Describe the TNM staging for colorectal cancer.
T1: invades submucosa
T2: invades muscularis propria
T3: invades into pericolonic tissue
T4a: penetrates serosa
T4b: invades surrounding structures
N1: 1-3 nodes
N2a: 4-6 nodes
N2b: 7+ nodes
stage 1: T1-T2
stage 2: T3-T4
stage 3: any N
stage 4: any M
What is the standard margin for colon cancer resection? How many nodes are required?
5-7cm proximally and distally to ensure adequate lymphadenectomy (12 nodes)
How should you manage colon cancer with isolated, resectable, hepatic metastases?
- 3 months neoadjuvant therapy (FOLFOX)
- surgery
- 3 months adjuvant therapy (FOLFOX)
Which patients are eligible for adjuvant chemotherapy for colon cancer? What regimen is used?
those with stage III disease (FOLFOX for 6 months; folinic acid, 5-FU, oxaliplatin)
What is tumor circumferential margin in those with rectal cancer?
the total distance between the tumor and mesorectal fascia
Which patients with rectal cancer should receive neoadjuvant chemotherapy? What is the typical regimen?
- locally advanced tumors of the mid-distal rectum (T3 or any N)
- give 5000Gy radiotherapy concurrently with 5-FU over 5-6 weeks
- surgery follows another 8-12 weeks after
When is local excision an option for rectal cancer?
must meet the following criteria:
- T1 lesions without high risk features
- well-to-moderately differentiated
- no lymph vascular or perineural invasion
- < ⅓ circumference of the bowel lumen
big consideration is that you can’t assess lymph nodes and has up to 20% recurrence
What is the adjuvant therapy for rectal cancer? Who is it recommended for?
- FOLFOX is the regimen
- should give to stage II that received neoadjuvant therapy (assume they were downstage) or stage III disease (upstaged at time of excision)
Name four histologic variants of anal SCC.
- cloacogenic
- basaloid
- epidermoid
- mucoepidermoid
What HPV serotypes are associated with anal SCC?
16 and 18
What is anal intra-epithelial neoplasm?
a precursor lesion to SCC
What is the primary treatment for SCC of the anal canal?
nigro protocol chemoradiotherapy (5-FU, mitomycin C, and 3000 cGy XRT)
What is the appropriate management of residual SCC of the anal canal after nigro protocol?
APR
How do you manage SCC of the anal margin?
like a skin cancer with WLE
How do you manage anal melanoma?
with APR
What is the appropriate management of an AIN lesion?
local treatment (photodynamic, imiquimod, topical 5-FU) with surveillance every 4-6 months
What is the main nutrient of colonocytes? Enterocytes?
- short chain fatty acids, particularly butyrate
- glutamine
What should you do with rectal cancer that had a complete clinical response to neoadjuvant therapy?
proceed with resection
Chronic pouchitis in a patient with UC should prompt a suspicion for what?
Crohns
What is the treatment of pouchitis?
- antibiotics
- supportive care
- budesonide enemas
During laparoscopy of appendicitis, the appendix looks normal with inflamed TI. What do you do next?
- lap appy if cecum is uninvolved
- otherwise, close and workup for Crohns
