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Colorectal Flashcards

(52 cards)

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1
Q

Diagnosis and tx

A

Sigmoid volvulus, tx: colonoscopy if patient is stable, likely will have to sigmoid resection in same hospital stay

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2
Q

Diagnosis and tx

A

Cecal volvulus

Tx: ex lap

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3
Q

What embryological layer is the primitive gut derived from?

A

Endoderm

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4
Q

Three segments of the primitive gut?

A

Foregut

Midgut

Hindgut

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5
Q

What embryological layer of primitive gut is colon derived from?

A

Hindgut

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6
Q

Three unique anatomic characteristics of colon?

A

Taenia coli

Haustra

Epiploic appendages

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7
Q

What are taenia?

A

Condensations of the outer longitudinal muscle layer of colon

There are three taenia

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8
Q

What is the course of taenia?

A

Originate at the appendix, run the course of the colon and then converge at the rectosigmoid junction

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9
Q

Average length of colon?

A

150 cm

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10
Q

5 layers of the colon

A
  1. Mucosa - columnar epithelium with crypts and goblet cells
  2. Submucosa - strength layer, contains Meissner’s plexus
  3. Inner circular muscle layer - contains Auerbach’s plexus
  4. Outer longitudinal muscle layer
  5. Serosa
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11
Q

MC position of the appendix in relation to the cecum

A

Appendix lies posterior to the cecum, lateral and inline with the terminal ileum (85% to 95% of people)

Retrocecal - towards the psoas muscle

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12
Q

What important structure is behind the hepatic flexure?

A

2nd portion of duodenum

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13
Q

Attachments of greater omentum?

A

Greater curve of the stomach to the transverse colon anterio-superior edge

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14
Q

How to mobilize the right colon?

A

Open the white line of Toldt (peritoneal attachment)

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15
Q

How to mobilize the transverse colon or enter the lesser sac?

A

Open the plane between greater omentum and transverse colon

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16
Q

What important structure should be identified when mobilizing the mesentery of the sigmoid?

A

Left ureter

Identify when performing high ligation of IMA or sigmoid colon is being mobilized

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17
Q

What important landmarks mark the upper/middle/lower third of the rectum?

A

Valves of Houston

  • Lower valve: 7-8 cm from anal verge
  • Middle valve: 9-11 cm from anal verge
  • Upper valve: 12-13 cm from anal verge
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18
Q

Where is the mesorectum most prominent?

A

Posterior to the rectum (although it invests the rectum circumeferentially)

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19
Q

What is the fascia propria of the rectum?

A

Investing fascia, includes the distal 2/3 of the posterior rectum and distal 1/3 of the anterior rectum

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20
Q

What is a total mesorectal excision entail?

A

Removal of the entire rectum without violating the fascia propria of the rectum

This involves mobilizing the rectum using plane between fascia propria of the rectum and the presacral fascia

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21
Q

What layer separates rectum from its anterior structures?

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A

Denonvilliers fascia (anterior the investing fascia propria)

22
Q

Waldeyer (rectosacral) fascia is where?

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A

Extension of presacral fascia from periosteum of sacrum to posterior wall of rectum

23
Q

Where does anal canal start?

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A

Anorectal ring or levator ani muscles and extends into the anal verge

24
Q

What is the dentate/pectinate line?

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A

Transition between the columnar epitherlium of the colon and the squamous epithelium of the anal canal

Autonomic innervation before dentate/somatic innervation after dentate line

25
What is the anal transitional zone?
Transition between columnar to squamous epithelium in the anus
26
What are columns of Morgagni?
6-14 longitudinal folds located at the dentate line Small pockets between these columns are called anal crypts (contain anal glands -\> become blocked and can be infected)
27
Muscles that make up the pelvic floor/levator ani muscles?
1. iliococcygeus 2. pubococcygeus 3. puborectalis (U-shaped sling)
28
SMA branches and supplies what?
ileocolic: cecum right colic: right colon middle colic: proximal 2/3 transverse colon
29
IMA branches and supplies what?
left colic: distal 1/3 transverse colon, descending colon sigmoid: sigmoid superior rectal: proximal rectum (collateralizes with middle/inferior rectal arteries from internal pudendal arteries - hypogastrics)
30
SMA/IMA collateralization through?
marginal artery of Drummond arc of Riolan (medial near trunk of IMA)
31
Venous drainage of the colon
32
Lymphatic drainage of lesions above and below the dentate line?
Above the dentate line: inferior mesenteric lymph nodes Below the dentate line: internal iliac lymph nodes
33
Key zones of sympathetic nerve damage during colon surgery?
During ligation of IMA and druing initial posterior rectal mobilization adjacent to the hypogastric nerves
34
Where is salt (and thus water) absorption the greatest in the colon?
Right colon
35
Colon flora consists of?
Anaerobes: mostly Baceroides (B. fragilis) MC aerobe: E. coli
36
Role of colonic flora?
1. Produce vital vitamins that host absorbs: K and B12 2. Fermentation of carbohydrates generates short-chain fatty acid - primary nutrient source for colonic mucosa 3. Mucosal immunity (prevents growth of pathogenic bacteria) 4. Bilirubin degradation
37
After abdominal surgery how long does it take each part to recover from post-op ileus: - stomach - small bowel - colon
stomach: 1-2 days small bowel: 1 day colon: 3-5 days
38
Massive dilation of the colon without an actual mechanical obstruction?
Colonic pseudo-obstruction (Ogilvie syndrome)
39
Treatment options for colonic pseudo-obstruction?
1. NG decompression, NPO, correct electrolyte imbalance, avoid narcotic/anticholinergics; consider CT scan to r/o mechanical obstruction 2. No signs of peritonitis but not responding to conservative therapy - 2.5 mg neostigmine IV (stimulates intestinal parasympathetic receptors to promote colon motility) 3. If neostigmine fails, attempt decompressive colonoscopy 4. If peritonitic at any point --\> surgical resection
40
Treatment options for anal incontinence?
* bulking agents/constipating agents * Biofeedback (PT that retrains muscles) * Sacral nerve stimulator (1st line surgical option) * Overlapping sphincteroplasty * Injectable agents * Colostomy (last resort)
41
Lynch syndrome
Autosomal dominant Mutation in DNA mismatch repair system resulting in microsatellite instability Patients typically present in their 40s
42
FAP (familial adenomatous polyposis)
Germline mutation in APC gene Autosomal dominant Develope hundres of polyps in the colon A/w thyroid cancers, desmoid tumors, hepatoblastomas
43
Treatment of choice for anal fistula that does not involve external anal sphincter?
Fistulotomy
44
After endoscopic polypectomy, which T1 rectal lesions can undergo transanal local excision (TAE)?
1. 3 mm margins 2. within 8 cm of the anal verge 3. well to moderately differentiated 4. no lymphovascular invasion 5. non-fragmented polyp (no removed in piecemeal fashion)
45
Post-hemmorhoidectomy bleeding (BRBR) causes
within first 24hrs post-op: likely secondary to technical error, needs to be re-explored to stop bleeding POD#5: likely secondary to sloughing of eschar and should resolve
46
Contraindications for strictureplasty
Excessive tension Perforation Fistula/abscess Hemorrhagic stricture Multiple strictures within a short segment Malnutrition Malignancy
47
Solitary rectal ulcer syndrome
Rectal bleeding, copious mucous discharge, anorectal pain, difficulty passing stool Initial management: conservative therapy Symptoms of prolapse: consider perineal procedures, mucosal or perineal proctectomy and abdominal procedures
48
Which type of repair has the lowest recurrence rate for a parastomal hernia?
Repair with synthetic mesh Sugarbaker approach shows improved outcomes over keyhole technique
49
Intractable anal pruritus with associated ezcetamous lesion
Paget's disease of the anus - should undergo occult carcinoma work up
50
Tx of recurrent anal squamous cell cancer
APR in those who can tolerate surgery
51
Tx of noninvasive Pagets disease of the anus
mapping biopsies followed by WLE with 1 cm microscopic margins
52
Leading cause of death in patients with FAP who have had prophylactic colectomy
Duodenal cancer Desmoid tumors

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