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Small Animal Surgery > Colorectal Surgery > Flashcards

Colorectal Surgery Flashcards

1
Q

In what 3 ways does the large intestine differ from the small intestine is regards to surgery?

A
  1. higher bacterial population
  2. slower wound healing due to collagenolysis
  3. more segmental blood supply

(+ collection of stool increases tension)

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2
Q

What are the 3 major blood supplies to the large intestine?

A
  1. ileocolic
  2. cranial mesenteric
  3. caudal mesenteric
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3
Q

What are the 3 indications for colotomies? How are they closed?

A
  1. foreign body removal (not common, if it made it to the rectum, it will likely pass)
  2. impacted feces
  3. biopsy**

longitudinal closure in a single layer of simple interrupted appositional pattern

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4
Q

What is a colopexy? What should be avoided?

A

creation of a permanent seromuscular adhesion between the colon and abdominal wall

creating an adhesion close to the ventral midline - easy to nick in future abdominal surgeries

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5
Q

What are the 3 most common complications associated with colopexies?

A
  1. infection
  2. dehiscence
  3. recurrence
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6
Q

What are the 2 major indications for colopexies?

A
  1. recurrent rectal prolapse
  2. perineal hernia
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7
Q

How are incisional colopexies performed?

A
  • apply cranial traction to the descending colon
  • create a longitudinal incision to the colon
  • create another longitudinal incision through the seromuscular layers of the transversus abdominus of the body wall
  • suture (fish mouth) them together

(can perform in more than one spot on the colon)

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8
Q

What is the purpose of colopexies?

A

prevent the caudal displacement of the colon and rectum

(especially with recurrent rectal prolapse)

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9
Q

What are the 4 indications for colonic R/A?

A
  1. megacolon
  2. perforation
  3. neoplasia
  4. irreducible/necrotic intussusception
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10
Q

What is the preferred technique for performing colonic R/A?

A

subtotal with colocolic anastamosis

  • preserving the ileocecal valve is ideal and doable because megacolon most commonly occurs in the transverse and descending colon
  • colon is 2x the diameter of the ileum and anastomosis is difficult
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11
Q

In what animals is megacolon most common? What are 3 causes?

A

older Manx cats

  1. mechanical or functional colonic obstruction
  2. neurologic
  3. idiopathic
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12
Q

What is the pathophysiology behind the development of megacolon?

A
  • feces concretions form, which are painful and too large to pass, causing the colon to stretch
  • prolonged distension leads to smooth muscle and nerve damage
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13
Q

What is the cause of congenital megacolon?

A

aganglionic distal colonic segment causes the absence of inhibitory neurons, essentially a functional obstruction

(rare, cats)

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14
Q

What are 5 causes of neurologic conditions that lead to megacolon?

A
  1. lumbosacral disease
  2. dysautonomia
  3. Key-Gaskell disease - feline progressive dysautonomia
  4. autonomic ganglioneuritis
  5. sacral spinal cord deformity
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15
Q

How does pelvic trauma cause megacolon? How is it treated?

A

callus formation from a healing pelvic fracture or SI luxation causes pelvic nerve injury

pelvic osteotomy (hemipelvectomy) to take out offending piece of bones

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16
Q

What is the most common cause of obstruction/entrapment of the colon that leads to megacolon? How is it treated?

A

adhesion formation from ovariohysterectomy - a delayed complication weeks to years post-op or an incidental finding on exploratories

surgical dissection and removal with potential for R/A

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17
Q

What is feline idiopathic megacolon? What is thought to cause a similar disorder in dogs?

A

acquired disorder characterized by colonic dilation and ineffective transport of feces, resulting in chronic constipation

perianal fistulas

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18
Q

What is postulated to be the etiology in feline idiopathic megacolon? What signalment is most common?

A

neural or smooth muscle defects (aganglionosis rare)

middle-aged males

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19
Q

What are the most common signs of feline idiopathic megacolon?

A
  • constipation
  • tenesmus
  • inappetence
  • depression
  • weight loss (commonly not seen due to pot-bellied appearance)
  • poor hair coat
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20
Q

How is feline idiopathic megacolon diagnosed?

A
  • palpation of feces-filled colon
  • survey radiology to r/o narrowing of bony pelvic canal
  • US, barium enema, proctoscopy to r/o stricture or pelvic mass
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21
Q

How does diagnosis of feline idiopathic megacolon compare in barium enemas and proctoscopy?

A

BARIUM ENEMA - colon must be empty, uses mushroom-tip or Pezzer catheter

PROCTOSCOPY - evacuate distal colon, easier and faster

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22
Q

How can feline idiopathic megacolon be medically managed?

A
  • warm water enemas
  • lubrication and/or digital breakdown of feces
  • general anesthesia and manual evacuation

(provides only short-term relief!!)

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23
Q

What are the 2 main surgical managements of feline idiopathic megacolon? What is not recommended?

A
  1. TOTAL COLECTOMY - removal of colon, ileocolic valve, and cecum with ileorectal end-to-end anastromosis (electrolyte imbalance, diarrhea)
  2. SUBTOTAL COLECTOMY - partial removal of colon with preservation of the ileocolic valve and colorectal anastomosis

colotomy —> bowel is compromised and unlikely to decrease in size

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24
Q

What presurgical considerations are used for colectomies?

A
  • prophylactic antibiotics: high aerobe and anaerobe contents
  • extent of proximal resection is determined by the extent of dilation

(preoperative enemas are unnecessary and ineffective)

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25
Q

How are colectomies performed?

A
  • carefully pack off the colon
  • place a clamp at the distal resection at the junction of the colon and rectum approximately 2-3 cm cranial to the pubis
  • place a clamp at the proximal resection site
  • ligate colonic, mesenteric, and jejunal vessels
  • correct any lumen disparity and perform an end-to-end anastomosis with 3-0 or 4-0 monofilament suture (single or double layer) or EEA staples (double layer inversion)
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26
Q

What is the goal of subtotal colectomies?

A

remove as much colon as possible

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27
Q

How do colocolostomies and ileocolostomies compare?

A

COLOCOLOSTOMY - tension-free apposition more difficult due to the immovable nature of the colon

ILEOCOLOSTOMY - increased incidence of severe diarrhea

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28
Q

What medical treatment can help in cats with idiopathic megacolon?

A
  • Cisapride - gastroprokinetic agent
  • stool softeners
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29
Q

What is associated with removal of the ileocolic valve during colectomies?

A

reflux of colonic contents results in small intestine bacterial overgrowth (SIBO) and loose stool

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30
Q

What commonly occurs in patients following colectomies?

A
  • tarry feces: normal bleeding into the GIT for 2-3 days
  • tenesmus for 5-7 days, but may never become completely normal
  • anorexia: nasogastric or PEG tube placement
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31
Q

What is not commonly affected by colectomies? What diets are used post-op?

A

clinical changes in fluid, electrolyte, or vitamin absorption —> remaining bowel increases absorption

low residue - improve fecal consistency and decreases fecal volume

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32
Q

What is the most common post-op complication following colectomies?

A

surigcal site infections (SSI) - most common following intra-abdominal surgery due to handling of the colon

  • flushing of the abdomen and changing of gloves, equipment, and gown is recommended before closing the abdomen
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33
Q

What are some common complications following intestinal surgery?

A
  • ileus
  • adhesions
  • obstruction from intussusception, entrapment, or stenosis
  • dehiscence
  • peritonitis
  • short bowel syndrome
34
Q

What are 4 major risk factors for dehiscence after intestinal surgery?

A
  1. foreign bodies and trauma
  2. pre-op albumin <2.5 g/dL results in delayed healing
  3. post-op rise in band neutrophils indicates and active infection
  4. pre-operative peritonitis
35
Q

What increases mortality in patients undergoing intestinal surgery?

A

leakage or dehiscence

36
Q

What is cecal inversion? In what animals is it most common? What are some clinical signs?

A

cecal intussusception causes an obstruction of the ileocolic junction

young dogs < 4 years

NONSPECIFIC - diarrhea, hematochezia, tenesmus, weight loss

37
Q

How is cecal inversion diagnosed? Treated?

A
  • plain radiographs: small fluid-dense intraluminal mass in proximal colon
  • contrast radiographs: inverted cecum surrounded by contrast material in proximal colon
  • endoscopy

typhlectomy, manual reduction, colotomy

38
Q

What are 4 indications for typhlectomies?

A
  1. cecal impaction
  2. cecal inversion
  3. perforation
  4. neoplasia
39
Q

How are typhlectomies performed?

A
  • ligate arterial supply
  • dissect ileocolic fold
  • milk out contents
  • transect and suture/staple
40
Q

What are the 3 most common cecal neoplasias? How are they treated? What is MST like?

A
  1. leiomyoma
  2. leiomyosarcoma
  3. gastrointestinal stromal tumor (GIST), a subclassification of leiomyosarcoma

surgical excision with wide borders in malignancies

7-12 months

41
Q

What are the 3 most common congenital diseases of the anus? Rectum?

A
  1. atresia ani
  2. rectovaginal fistula
  3. anogenital clefts
  • prolapse
  • neoplasia
  • strictures
42
Q

What is atresia ani?

A

stenosis or persistent membrane of the anus

43
Q

What are rectovaginal fistulas associated with? How are they diagnosed?

A

UTIs

contrast

44
Q

What are anogenital clefts? What do they lead to?

A

common opening for anus and genital tract

UTI

45
Q

What are anal prolapses? How are the treated?

A

anal mucosa protruding from orifice

  • determine underlying cause and treat
  • manually reduce and place a purse string before it becomes necrotic
46
Q

What is a complete rectal prolapse? What are 4 predisposing factors? What is the most common signalment?

A

all layers of the rectum protrude through the anal orifice

  1. parasites
  2. colitis
  3. urogenital disease
  4. tumors - vaginal leiomyoma causes constant straining

younger patients

47
Q

What is the primary differential of rectal prolapse?

A

prolapsed intussusception —> blunt probe/finger cannot be inserted

48
Q

How is a rectal prolapse with viable tissue treated?

A
  • manually reduce with cool saline, lubricants, or mannitol
  • place a purse string to keep reduced, but allow soft feces through
  • leave for several days
49
Q

How is a rectal prolapse with non-viable tissue treated?

A
  • surgically prep the area
  • place 4 full-thickness stay sutures
  • insert a lubricated test tube to minimize contamination and resect 1-2 cm from the anus around 180 degrees around
  • place simple interrupted sutures
  • repeat for the other 180 degrees
  • reduce prolapse
50
Q

What are the 4 most common complications following rectal prolapse amputation?

A
  1. infection
  2. dehiscence
  3. stricture
  4. recurrence, if underlying cause is not corrected
51
Q

How is a recurrent rectal prolapse treated/prevented?

A

incisional colopexy

  • > 3 cm incision through serosa and transversus layers
  • fish-mouth colon and muscle wall
    (can perform in more than one area)
52
Q

What are the most common rectal tumors? In what animals are they most common?

A

adenomatous polyps —> benign, malignant transformation

Collies

53
Q

What is the most common malignant rectal tumor? In what animals are they most common?

A

adenocarcinoma —> not as aggressive as in the small intestine

older GSDs

54
Q

What clinical signs are associated with rectal tumors?

A
  • tenesmus
  • dyschezia
  • rectal prolapse
  • protrusion of polyp
55
Q

How are rectal tumors diagnosed?

A
  • direct observation/rectal palpation
  • colonoscopy: determine extent
  • biopsy: determines stage and surgery, submission
  • thoracic radiographs
  • abdominal ultrasound
56
Q

What pre-operative measures should be done before rectal surgery?

A
  • withhold food 24-48 hours prior
  • multiple warm water enemas up to 12 hours prior
  • prophylactic antibiotics
57
Q

When are enemas contraindicated before rectal surgery?

A

with obstructive lesions

58
Q

What surgical approach to the rectum is rarely used?

A

lateral —> limited exposure

59
Q

When is the transanal approach to rectal surgery most commonly performed?

A

excision of small, non-invasive, pedunculated polyps in the caudal 4-6 cm of the rectum

60
Q

How is the dorsal approach to rectal surgery began? When is it used?

A

inverted U incision above the anus

excision of tumors of the caudal to mid rectum

61
Q

How are rectal pull-throughs performed? When are they most common?

A
  • evert rectal wall
  • place stay sutures
  • dissect the rectum from the external anal sphincter
  • mobilize rectum caudally and resect

excision of distal colonic or caudal to mid rectal tumors

62
Q

When is the ventral approach to rectal surgery performed?

A

lesions at the colorectal junction or more extensive lesions

63
Q

What approaches are recommended for rectal polyp and annular/more cranial tumors?

A

transanal submucosal resection per anus, since most are within 2 cm of the anus

dorsal, rectal-pull through, ventral

64
Q

What is the prognosis of colorectal tumors?

A

large/sessile tumors are more likely to recur due to a limited approach causing an inability to get proper margins (+ tension at the colon)

  • euthanasia is most commonly recommended due to failure to control dyschezia or hematochezia
65
Q

What are the most common benign and malignant colorectal tumors?

A

BENIGN - adenomatous polyps, leiomyoma, fibroma

MALIGNANT - adenocarcinoma, leiomyosarcoma, lymphosarcoma

66
Q

What are the most common clinical signs of rectal adenomas? How do they present?

A
  • hematochezia
  • tenesmus/dyschezia
  • visible (intermittent) mass

most occur in the distal rectum and are polypoid, sessile, or multiple

67
Q

How are colorectal tumors treated?

A

surgical excision - transanal, dorsal, mucosal resection

68
Q

Why is cryosurgery not commonly recommended for colorectal tumor treatment?

A
  • can’t evaluate margins
  • can’t confirm diagnosis
69
Q

Where are colorectal adenocarcinomas most commonly found? What lesion is a poor prognostic indicator? How do they act?

A

50% are abdominal

annular “napkin ring”

metastasis to regional lymph nodes and liver common

70
Q

What are the 3 most common surgical approaches colorectal tumor resection?

A
  1. anal - caudal rectum or anal canal
  2. dorsal - caudal or middle rectum, NOT anal canal
  3. rectal pull-through - distal colonal or midrectal lesions not approachable through the abdomen
71
Q

What is a Swenson’s pull-through?

A

combines anal and ventral approach to reach lesions that extend beyond peritoneal reflection into the abdominal cavity

72
Q

What are the 4 most common complications following rectal surgery?

A
  1. dehiscence
  2. infection
  3. stricture
  4. sphincteric/sensory incontinence
73
Q

What are the most common anal sac diseases? In what animals is this most common?

A

anal sac impaction, leading to anal sacculitis or abscesses

small dogs —> Poodle, Chihuahua

74
Q

How are anal sacculectomies pre-treated? Where are the anal sacs found?

A

manage infection or abscesses medically until inflammation involves and the anal sacs can be removed

within external anal sphincter

75
Q

How is an open anal sacculectomy performed?

A
  • insert one blade of scissors into the sac
  • apply upward pressure to tips to minimize tissue cut or insert the groove director or probe through duct into anal sac
  • incise over instrument with caudal tension to minimize damage to sphincter
  • dissect anal sac away from sphincter

SPHINCTER TO SAC

76
Q

How is a closed anal sacculectomy performed?

A

excise over anal sac and dissect away from sphincter

SAC TO SPHINCTER

77
Q

What are the 3 most common complications associated with anal sacculectomies?

A
  1. infection
  2. draining tracts due to incomplete removal of anal sac
  3. fecal incontinence
78
Q

What are the most common perianal gland tumors? In what animals are they most common?

A

adenomas/adenocarcinomas

intact males (benign) —> castration and resection with good prognosis

79
Q

What anal sac tumors are most common? What are 3 common signs?

A

apocrine gland adenocarcinomas

  1. paraneoplastic hypercalcemia
  2. PU/PD
  3. renal failure
80
Q

In what animals are perianal fistulas most common? What is thought to be its etiology? What is the most common clinical sign?

A

GSDs

immune-mediated

painful, perianal draining with fistulous tracts

81
Q

What are 3 common options for medical management of perianal fistulas? When is surgical intervention recommended?

A
  1. specialized diet - IBD may predispose/potentiate signs
  2. Cyclosporine*, Azithioprine, Tacrolimus - commonly recurs when discontinued, $$$
  3. Ketoconazole, glucocorticoids, Metronidazole

nonresponsiveness to medical management

Small Animal Surgery (34 decks)

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