Colorectal Flashcards
How long is the rectum?
15cm
How long is the colon?
5-6 feet
What is considered an abnormal diameter of the cecum?
greater than 9 cm
What is the blood supply to the colon?
- SMA gives off the ileocolic, right colic, and middle colic arteries
- IMA gives off the left colic, sigmoid branches, and superior rectal arteries
- the marginal and arc of Riolan are collaterals
What are the marginal artery and the Arc of Riolan?
- the marginal artery is found along the colon wall and connects the SMA and IMA
- the Arc of Riolan is the meandering mesenteric artery and provide a smaller connection between the SMA and IMA via the middle colic and left colic
What are the watershed areas of the colon?
- the splenic flexure (Griffith’s point) between the SMA and IMA
- the rectosigmoid junction (Sudeck’s point) between the superior and middle rectal arteries
What is the arterial blood supply to the rectum?
- the superior rectal off the IMA
- the middle rectal off the internal iliac
- the inferior rectal off the internal pudendal
What is the venous drainage of the rectum?
- the superior rectal to the IMV and the portal venous system
- the middle and inferior rectals to the internal iliac vein and systemic venous system
What defines the anal canal?
- it begins at the puborectalis sling
- it ends at the anal verge where squamous mucosa blends into perianal skin
What is the appropriate resection for the following tumor sites:
- hepatic flexure
- splenic flexure
- transverse colon
- cecum
- left colon
- sigmoid
- hepatic flexure: extended right
- splenic flexure: extended left
- transverse colon: transverse
- cecum: right
- left colon: left
- sigmoid: sigmoid
Where are most anal fissures found?
90% are in the posterior midline
What is the non-operative treatment of anal fissures?
- psyllium fiber or other bulking agents
- sitz baths
- topical anesthetics
- topical nitrates
- topical calcium channel blockers (as effective as nitrates without the headaches)
- botulinum toxin
What are the surgical options for anal fissures? How do they compare?
- lateral internal sphincterotomy
- anocutaneous flap (inferior healing rates but lower incidence of incontinence, can be done in additional to LIS)
For a patient with anal fissures, what would be contraindications to lateral internal sphincterotomy?
- incontinence with botox injection
- women of childbearing age
- prior obstetric injuries
- IBD
- history of sphincter dysfunction/incontinence
Describe the management of anal fissures.
- start with non-operative treatments including bulking agents (fiber), sitz baths, topical anesthetics, and calcium channel blockers
- nitrates are an alternative to CCBs but typically equal success and more side effects
- next step up would be botox injections
- if patient’s fail these medical therapies, then lateral internal sphincterotomy or anocutaneous flap are possible surgical options
- LIS has a higher healing rate but greater risk of incontinence and is contraindicated for women of childbearing age or that have a history of sphincter dysfunction/incontinence
Where are the following anorectal abscess found?
- intersphincteric
- ischiorectal
- perirectal
- supralevator
- submucosal
- deep post-anal space
- intersphincteric: between the internal and external sphincter muscles
- ischiorectal: lateral to the rectal wall in the space next to the ischial tubercle
- perirectal: around the anus
- supralevator: above the elevator muscle
- submucosal: under the mucosa of the anal canal
- deep post-anal space: bilaterally ends in the ischiorectal fossa between the anococcygeal ligament and the levator muscle
How are anorectal abscess managed?
- primary treatment is drainage
- perianal and ischiorectal can be drained via an external incision while deeper intersphincteric and supralevator are done via internal transanal drainage
- those who are immunosuppressed, have cellulitis, or have systemic signs of infection require antibiotics after drainage
Which patients with anorectal abscess require antibiotics after drainage?
- immunocompromised
- systemic signs of infection
- accompanying cellulitis
What is the rate of fistula formation in patients with an anal abscess?
33%
What is Goodsall’s rule?
- helps track anal fistulas
- anterior external openings less than 3 cm from the anal verge take a direct line to the anal canal
- posterior external openings and those more than 3cm from the anal verge take a curvilinear rout to the posterior midline
What is the most common type of anal fistula?
intersphincteric
What is the difference between a high and a low trans-sphincteric anal fistula?
- high involve more than ⅓ of the muscle complex
- low involve less than ⅓ of the muscle complex
What is the difference between a suprasphincteric and an extrasphincteric anal fistula?
- suprasphincteric are lower, they run between the muscles and up and over the external sphincter
- extrasphincteric are higher and run over and above the whole sphincter complex
What is the goal of seton placement for fistula-in-ano?
generate fibrosis of the tract and convert a high fistula to a low fistula, preparing the tract for later procedures
Which anal fistulas can be treated with fistulotomy?
those that involve less than 25% of the sphincter complex
What are management options for fistula-in-ano?
- fistulotomy for those involving < 25% of the sphincter complex
- seton placement followed by subsequent LIFT or anorectal advancement flap
What separates internal and external hemorrhoids?
whether they are above or below the dentate line
How are internal hemorrhoids classified
by extend of protrusion
- I: internal only
- II: spontaneously reduce
- III: require manual reduction
- IV: non-reducible
What are the options for conservative management of hemorrhoids?
- reduce time sitting on the toilet
- high fiber intake (25-35g/day)
- high fluid intake/hydration
When can thrombosed external hemorrhoids be treated surgically?
within 72hrs of symptom onset
What defines complicated diverticulitis?
perforation, abscess formation, fistula formation, stricture, or obstruction
Which patients with diverticulitis require admission?
- those that can’t tolerate oral hydration
- those that are unreliable
- those with complicated disease (perforation, abscess formation, fistula formation, stenosis, obstruction)
- hemodynamic instability or diffuse peritonitis
What are the surgical options for sigmoid diverticulitis?
- resection with primary anastomosis
- resection with Hartmann’s
- resection with DLI
What size abscess is usually amenable to percutaneous drainage?
those greater than 3cm in diameter
What is the proper management of a patient with diverticulitis complicated by a large abscess that is not accessible by IR and not resolving with antibiotics?
can consider laparoscopic washout and drain placement
What is the typical course for patients with recurrent diverticulitis?
the first episode is often the worst and multiple uncomplicated episodes does not necessarily increase the risk of needing an emergent colectomy
Which patients should be offered elective sigmoidectomy for diverticulitis?
- those who recover from an episode of complicated disease
- those for whom recurrent disease has a significant impact on their lifestyle
What kind of bacteria is C. difficile?
an anaerobic, gram positive bacilus
What is the medical management of C. diff?
- first line is oral vancomycin followed by fidaxomicin
- can also add vancomycin enemas
When should you operate for C. diff?
- obvious signs like perforation or peritonitis
- but high mortality when you’ve gotten to sepsis or perf
- consider early operative intervention for patients requiring pressors or with signs of impending sepsis