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ABSITE Flashcards > Colorectal > Flashcards

Colorectal Flashcards

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?

A

Denonvilliers fascia (anterior the investing fascia propria)

22
Q

Waldeyer (rectosacral) fascia is where?

A

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

23
Q

Where does anal canal start?

A

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

24
Q

What is the dentate/pectinate line?

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
Q

What is the anal transitional zone?

A

Transition between columnar to squamous epithelium in the anus

26
Q

What are columns of Morgagni?

A

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
Q

Muscles that make up the pelvic floor/levator ani muscles?

A
  1. iliococcygeus
  2. pubococcygeus
  3. puborectalis (U-shaped sling)
28
Q

SMA branches and supplies what?

A

ileocolic: cecum

right colic: right colon

middle colic: proximal 2/3 transverse colon

29
Q

IMA branches and supplies what?

A

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
Q

SMA/IMA collateralization through?

A

marginal artery of Drummond

arc of Riolan (medial near trunk of IMA)

31
Q

Venous drainage of the colon

A
32
Q

Lymphatic drainage of lesions above and below the dentate line?

A

Above the dentate line: inferior mesenteric lymph nodes

Below the dentate line: internal iliac lymph nodes

33
Q

Key zones of sympathetic nerve damage during colon surgery?

A

During ligation of IMA and druing initial posterior rectal mobilization adjacent to the hypogastric nerves

34
Q

Where is salt (and thus water) absorption the greatest in the colon?

A

Right colon

35
Q

Colon flora consists of?

A

Anaerobes: mostly Baceroides (B. fragilis)

MC aerobe: E. coli

36
Q

Role of colonic flora?

A
  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
Q

After abdominal surgery how long does it take each part to recover from post-op ileus:

  • stomach
  • small bowel
  • colon
A

stomach: 1-2 days

small bowel: 1 day

colon: 3-5 days

38
Q

Massive dilation of the colon without an actual mechanical obstruction?

A

Colonic pseudo-obstruction (Ogilvie syndrome)

39
Q

Treatment options for colonic pseudo-obstruction?

A
  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
Q

Treatment options for anal incontinence?

A
  • bulking agents/constipating agents
  • Biofeedback (PT that retrains muscles)
  • Sacral nerve stimulator (1st line surgical option)
  • Overlapping sphincteroplasty
  • Injectable agents
  • Colostomy (last resort)
41
Q

Lynch syndrome

A

Autosomal dominant

Mutation in DNA mismatch repair system resulting in microsatellite instability

Patients typically present in their 40s

42
Q

FAP (familial adenomatous polyposis)

A

Germline mutation in APC gene

Autosomal dominant

Develope hundres of polyps in the colon

A/w thyroid cancers, desmoid tumors, hepatoblastomas

43
Q

Treatment of choice for anal fistula that does not involve external anal sphincter?

A

Fistulotomy

44
Q

After endoscopic polypectomy, which T1 rectal lesions can undergo transanal local excision (TAE)?

A
  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
Q

Post-hemmorhoidectomy bleeding (BRBR) causes

A

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
Q

Contraindications for strictureplasty

A

Excessive tension

Perforation

Fistula/abscess

Hemorrhagic stricture

Multiple strictures within a short segment

Malnutrition

Malignancy

47
Q

Solitary rectal ulcer syndrome

A

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
Q

Which type of repair has the lowest recurrence rate for a parastomal hernia?

A

Repair with synthetic mesh

Sugarbaker approach shows improved outcomes over keyhole technique

49
Q

Intractable anal pruritus with associated ezcetamous lesion

A

Paget’s disease of the anus - should undergo occult carcinoma work up

50
Q

Tx of recurrent anal squamous cell cancer

A

APR in those who can tolerate surgery

51
Q

Tx of noninvasive Pagets disease of the anus

A

mapping biopsies followed by WLE with 1 cm microscopic margins

52
Q

Leading cause of death in patients with FAP who have had prophylactic colectomy

A

Duodenal cancer

Desmoid tumors

ABSITE Flashcards (19 decks)

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