Colorectal Flashcards
What are the two major collaterals between the SMA and IMA?
- the marginal artery
- the arc of Riolan
What are the watershed areas of the colon?
the splenic flexure and the transition zone between superior and middle rectum
What is the blood supply to the rectum?
- superior rectal artery off the IMA
- middle off the internal iliac
- inferior off the pudendal
What is the venous drainage of the rectum?
- superior to the IMA and portal circulation
- middle and inferior to the internal iliac and systemic circulation
What defines the anal canal?
- proximal: puborectalis sling
- distal: anal verge
What defines the anal margin?
within 5cm of the anal verge
How are anal fissures treated?
- start with fiber, sit baths, and topical anesthetics
- can advance to topical nitrates and CCBs
- consider botox, LIS, or anocutaneous flap
What are contraindications to lateral internal sphincterotomy for anal fissure?
- fecal incontinence
- women of childbearing age
- prior obstetrical injuries
- IBD
Describe the course of most anorectal fistulas.
- anteriorly they tend to be linear unless > 3cm from the anal verge
- posteriorly then tend to be curvelinear
When are antibiotics indicated for those with anorectal abscesses?
when there is cellulitis, systemic signs of infection, or they are immunocompromised
What proportion of patients with anorectal abscesses develop fistulas?
about one third
What is the difference between a high and low trans-sphincteric anorectal fistula?
- high involve > 33% of the sphincter complex
- low involve less
What is the goal of a fistula?
to convert a high fistula to a low one, thereby preparing the tract for later intervention
How are internal hemorrhoids classified?
- I: internal only
- II: spontaneously reduce
- III: manually reduce
- IV: don’t reduce
How should thrombosed hemorrhoids be managed?
- can do a thrombectomy if < 72hrs after onset
- otherwise manage expectantly with symptomatic control
When should patients with diverticulitis have a colonoscopy?
6 weeks after resolution of their episode
Describe the natural course of diverticulitis.
the first episode tends to be the worst
Who should have a sigmoidectomy for diverticulitis?
- anyone with complicated disease needs an operation at some point
- those with uncomplicated disease get a more customized approach with shared decision making since the first episode tends to be the worst
What is the surgery of choice for someone with complicated C. diff?
subtotal colectomy with ileostomy
Sigmoid volvulus is discovered on AXR, what are the next steps?
- CT scan to evaluate colonic viability
- endoscopic decompression
- sigmoidectomy during index admission
What are the risk factors for colonic perforation?
- cecum > 12 cm
- duration of Ogilvie’s > 6 days
What medication is used to treat Ogilvie’s and what is the predominant side effect to know?
- can use neostigmine (anti-acetylcholinesterase)
- causes bradycardia
What is the key component to a trans-abdominal rectal prolapse repair?
rectopexy, can add LAR or sigmoidectomy if patient has constipation
What is the difference between a Delorme and Altemeier procedure?
- Delorme: mucousectomy via perineal approach with muscle plication
- Altemeier: full thickness rectosigmoidectomy via perineal approach with coloanal anastomosis
