Surgery of the Rectum Flashcards
There is no specific anatomical point defining the junction of the colon and rectum, however, a number of landmarks have been suggested as markers (4)
The pelvic inlet;
The pelvic brim;
L7;
The level at which the cranial rectal artery enters the intestinal seromuscular layer.
2 portions of the rectum?
Intraperitoneal
Retroperitoneal
Where is the retroperitoneal portion of the rectum, and what lacks with this section?
Distal to 2nd coccygeal vertebrae. It lacks a serosal layer
Where is the external anal sphincter located?
Between rectum and anus
What secures the rectum to the sacrum?
Mesorectum
The mesorectum becomes progressively shorter distally to a point where it ends where?
The level of the 2nd or 3rd coccygeal vertebrae
When the mesorectum end, it is reflected onto the sides of the pelvis, and what is formed either side of the rectum?
Pararectal fossa
What muscles are dorsal to the rectum?
Ventral sacrocaudal muscles
What muscles are lateral to the rectum? (2)
Levator ani
Coccygeus
What is the main blood supply to the rectum?
What are the 2 less dominant blood supply?
MAIN: Cranial rectal a.
Middle rectal a. Caudal rectal a.
Middle rectal a. Caudal rectal a. to the rectum:
Are these more significant in dogs or cats?
Cats
Why should the cranial rectal artery be preserved during surgery unless the intrapelvic portion of the rectum is to be resected?
The distal portion of the rectum in dogs is particularly reliant on this
Which part of the rectum can be resected where the cranial rectal a. is not important?
Resection of the intrapelvic region
Rectal surgery ABx combination?
A combination of cefuroxime (20 mg/kg IV q90 minutes during surgery) and metronidazole (10 mg/kg IV q8-12 hours) can be considered in rectal surgery.
Some authors advocate post-operative courses of such medication for up to 10 days.
4 approaches to the rectum surgically?
Ventral
Dorsal
Lateral
Caudal
Where is the ventral approach to the rectum suitable? (2)
- Proximal part of rectum
- Colorectal junction
What can the ventral approach to rectum be made via?
Caudal abdominal celiotomy (extended to level of pubis)
- Pelvic symphysiotomy
- Pubic osteotomy
Which access via ventral approach is suitable for distal parts of rectum?
- Pubic osteotomy
Dorsal approach to the rectum: What does this allow access to? (2)
Mid and distal rectum
How is a patient positioned for dorsal approach to rectum?
The animal is positioned in sternal with the tail elevated
Dorsal approach to the rectum:
How is the incision made?
Curved incision between anus and the tail
Dorsal approach to the rectum:
Following incision of perineal fascia;
A) What muscles are transected?
B) How is rectum exposed?
A) Retrococcygeus muscles
B) Blunt dissection between the external anal sphincter and levator ani muscles
How can access be improved with the dorsal approach to rectum?
Transect levator ani muscle
Negative of the lateral approach to the rectum? When may it be used?
Uncommon to be used - access to one side only
Use in small focal lesions
Lateral approach to the rectum:
A) Where is the incision?
B) How is the surface of the rectum exposed?
A) Lateral to anus; curved incision
B) Dissect between the levator ani and external anal sphincter
What are the 3 ways a caudal approach can be made?
1 Anal approach.
2 Transanal rectal pull through.
3 Combined abdominal and transanal approach.
Another term for the “Anal approach”
Pull out technique
How is the anal approach performed?
- What are placed + where?
Stay sutures or Babcock forceps are placed just proximal to the anocutaneous junction and caudal traction is applied to evert the rectum. Further sutures or pairs of forceps are continually applied to evert and prolapse more of the rectum until the lesion is exposed.
Transanal Rectal Pull Through:
A) Initial circumferential incision is made where?
B) The above technique leaves a distal cuff of anus and rectum allowing what?
A) Cranial to anocutaneous junction
B) Anal sacs to be avoided