SAOP2- Anorectal

  1. What is the anatomical location of the rectum?
    • descending colon turns into rectum as it enters the pelvic canalĀ 
    • at the entry point of the cranial rectal artery
    • covered by mesorectum- attached to sacrum
  2. What nerves are by the rectum? (2)
    reflections of mesorectum contain the pelvic plexus- hypogastric n (sympathetic) and pelvic nn (parasympathetic)
  3. What muscles make up the pelvic diaphragm? (3)
    • levator ani m.
    • coccygeus m.
    • external anal sphincter m.
  4. What are the 3 zones of the anus?
    • columnar [proximal]
    • intermediate
    • cutaneous [distal]- contains anal sac openings, sebaceous, apocrine, and circumanal glands
  5. Where are the anal sacs?
    • sit along the columnar and intermediate zones b/c the internal and external anal sphincter mm.
    • opening are at the mucocutaneous junction (anus meets skin)
  6. Describe the anatomy of the anal sacs.
    • lined with squamous epithelium
    • apocrine and sebaceous glands
  7. What is the main control of fecal continence?
    • external anal sphincter
    • innervated by caudal rectal n.
  8. What is the innervation of the internal sphincter m.?
    hypogastric n (sympathetic) and pelvic n. (parasympathetic)
  9. What is the blood supple of the anus?
    internal pudendal a.
  10. Clinical signs of anorectal disease. (7)
    • discomfort (scooting, licking)
    • hematochezia/ dyschezia
    • diarrhea + mucus and blood
    • constipation
    • perianal swelling
    • draining tracts
    • fecal incontinence
  11. What can you feel with a rectal exam? (12)
    • masses
    • strictures
    • perianal thickening
    • anal sac enlargement
    • reduced sphincter tone
    • rectal sacculation
    • lymphadenopathy
    • prostate
    • pelvic diaphragm weakness
    • patency of pelvic canal
    • urethral palpation
    • texture of mucosa
  12. How is proctoscopy achieved?
    complete enema--> air insufflation--> scope

    permits biopsy but not complete resection
  13. Describe the use of perioperative antibiotics with anorectal surgery.
    • perioperative antibiotic use reduced morbidity and mortality associated with infection
    • flora is mixed population--> 2nd gen cephalosporins (Cefoxitin, cefmetazole) or combinations (IV amikcain or fluoro + ampicillin AND oral neomycin + metro)
    • start oral therapy 24 hours before sx
  14. What are your suture choices for anorectal surgery? What pattern is usually used?
    • monofilament, absorbable suture (3-0 or 4-0)
    • appositional pattern
  15. What are potential surgical complications with anorectal surgery? (5)
    • incontinence
    • infection
    • dehiscence
    • stricture
    • tumor recurrence
  16. What are indications for rectal resection? (4)
    • neoplasia
    • trauma
    • perforation
    • stricture
  17. Describe the ventral approach to the rectum and when this approach is appropriate.
    • appropriate for dz at colorectal junction
    • ventral midline abdominal approach combined with pubic osteotomy
  18. Describe the anal/ transanal approach to the rectum and when it is used.
    • appropriate for excision of small, partial thickness lesions that can be exteriorized through the anus
    • stay sutures at rectocutaneous junction and evert rectal mucosa until lesion can be excised
  19. Describe the rectal pull-through approach to the rectum and when it is used.
    • appropriate for mid-rectal lesions (intrapelvic) not amenable for ventral or transanal approaches
    • evert the whole rectal layer out the anus; aggressive approach, not recommended
  20. Describe the dorsal approach to the rectum and when it is used.
    • appropriate for extramurial/ extra luminal lesion
    • incision made from one tuber ishii to another
    • transect rectococcygeus m.
  21. Describe the lateral perineal approach to the rectum and when it is used.
    • used for diverticulae, laceration/ perforations/ perineal hernias, sacculectomy
    • unilateral exposure
  22. How much of the anal sphincter can you remove and maintain continence?
    up to half of the anal sphincter
  23. What are the techniques for anal sacculectomy? (2)
    • open- chronic abscessation, increased risk of infection/ incontinence
    • close- complete excision of all epithelial lining, reduced contamination
  24. What are potential complications of anal sacculectomy? (3)
    • fecal incontinence (damage to caudal rectal n)
    • draining tracts/ fistula
    • recurrent abscessation
  25. What are benign (4) and malignant (2) neoplasias of the rectum?
    • Benign: adenomatous polyp, leiomyoma, hemangioma, plasmacytoma
    • Malignant: mucoid adenocarcinoma, leiomyosarcoma
  26. Describe adenomatous polyps. (5)
    • grape-like
    • pedunculated or sessile
    • friable
    • 25% transform to malignancy
    • mucosal excision usually curative
  27. What underlying conditions predispose to rectal prolapse? (10)
    • enteritis
    • parasites
    • colitis
    • rectal neoplasia
    • foreign objects
    • UTI
    • prostatic dz
    • dystocia
    • perineal hernia
    • sphincter denervation
  28. How do you repair a first-incidence partial rectal prolapse?
    replace mucosa and purse string
  29. How do you treat a recurrent rectal prolapse?
    • resection of prolapsed tissue
    • colopexy (abdominal approach)
  30. What is a surgical emergency differential for rectal prolapse?
    • ileocecocolic intussusception
    • differentiate by placing a probe in and it goes a long way
  31. Describe perianal adenomas. (5)
    • most common perianal tumor
    • poster child: older intact male dog (hormone dependent!!! driven by testosterone)
    • 90% will regress after castration
    • raised, firm, well circumscribed, +/- ulceration/ large
    • Dx: hepatoid cells on cytology
  32. How can you dx perianal adenoma versus adenocarcinoma?
    • biopsy
    • will metastasize- wide surgical margins
Card Set
SAOP2- Anorectal
vetmed SAOP2