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
Transanal Rectal Pull Through:
How are lesions in mid to caudal rectum accessed?
Stay sutures are then used to bring the proximal rectal segment through
What is eversion limited by with transanal rectal pull through?
Traction required on rectal vasculature.
Transanal rectal pull through can be modified to transcutaneous rectal pull through.
A) How?
B) What is preserved where poss?
A) a circumferential incision around the anus
B) The external anal sphincter muscle
Step-by-step guide to a rectal pull through for cases of proximal or mid rectal lesions.
A) Patient position?
B) Where are stay sutures placed initially?
A) ventral recumbency with the pelvis/hindquarters elevated
B) t cranial to the mucocutaneous junction and apply caudal traction using these and/or Babcock forceps
Step-by-step guide to a rectal pull through for cases of proximal or mid rectal lesions.
A) Where is the incision?
B) Where are stay sutures then placed?
A) Leaving a 1-2 cm cuff of caudal rectal tissue attached to the anus where possible, make a 360° incision in the rectum
B) Place stay sutures in the cuff of caudal rectum
Step-by-step guide to a rectal pull through for cases of proximal or mid rectal lesions.
A) Following the approach, what is bluntly dissected to identify the lesion?
B) Transect the rectum and appose with what?
A) round the wall of the rectum, internal to the external anal sphincter muscle, evert/prolapse the rectum
B) The caudal rectal cuff using stay sutures to help move the segments
Step-by-step guide to a rectal pull through for cases of proximal or mid rectal lesions.
Closure:
- Pattern?
- Size?
- Material
- Layers?
- Simple interrupted sutures
- 1.5 or 2 metric
- synthetic monofilament (polydioxanone, polyglyconate or poliglecaprone)
- Some surgeons prefer to close the seromuscular layer and mucosal-submucosal layer separately
Combined Abdominal and Transanal Approach:
What is this also known as?
Swenson’s pull through
Swenson’s pull through, what is the approach?
caudal abdominal coeliotomy is combined with a rectal pull through
During Swensons pull through the distal rectum is dissected where compared to the lesion?
Proximal
During Swensons pull through, what happens to the distal segment?
Abdomen can then be closed
2nd person then uses forceps to grasp the distal stump and pull the rectum through, everting the tissue. The distal lesion containing segment can then be resected and anastomosis or closure performed with sutures or a stapling device.
Common post op complication of rectal pull through; how to reduce this?
Faecal incontinence
- reduce disruption to external sphincter
Which approach is most suitable to access the colorectal junction?
Ventral
Prolapse of the rectum through the anus can be the sequel to (9)
chronic diarrhoea
tenesmus
intestinal inflammation
gastrointestinal parasitism
neoplasia,
prostatomegaly
perineal hernia
urolithiasis
complication of parturition
To distinguish rectal prolapse from a bowel which has formed an intussusception,
a blunt lubricated probe should be applied between the prolapse and the anus. In a rectal prolapse, it will not be possible to pass the probe as it will press against the mucocutaneous junction of the anus. In a case in which the prolapsed bowel has an intussusception, the probe will pass easily (to a depth of at least 5-7 cm) as it slides between the rectal wall and the prolapsed bowel with the intussusception.
What is a partial rectal prolapse?
It is only mucosa that protrudes from the anus
What is a complete prolapse
a cylindrical elongated mass containing all the layers of the rectum protrudes.
In cases where the prolapsed rectum is not damaged and has been presented acutely, what should you do?
manual reduction should initially be attempted. Topical 50% dextrose or systemic furosemide have been suggested to help reduce oedema and aid reduction.
General and/or epidural anaesthesia is required, and prior to reduction the prolapsed tissue should be cleaned with a warm isotonic solution.
Once a rectal prolapse is replaced - what is done to prevent relapse? How long for?
purse string suture is then placed to narrow (not occlude)
The patient should be able to pass faeces through the narrowed anal orifice as the suture should remain in place for 3-5 days.
What medical treatment can be given to aid defecation?
Softners
What can be considered in recurrent or severe cases of rectal prolapse?
Colopexy
What may be necessary if the prolapsed tissue has been traumatised or become ischemic or necrotic?
Resection or a prolapsed rectum
What technique for resection and anastomosis?
Rectal pull through
What can be used to help with a rectal anastomosis?
Placement of a probe
How is a rectal anastomosis performed/ (material/pattern)
The anastomosis should be performed using simple interrupted 1.5 or 2 metric synthetic monofilament sutures (polydioxanone is a good choice).
What aged animals are rectal strictures more common in?
Older
Clinical signs of rectal strictures? (4)
Tenesmus
Dyschezia
Haematochezia
Faecal ribobning
Diagnostics for rectal stricture? (4)
- Rectal exam
- Contrast x ray
- CT
- Proctoscopy
Which type of structure does The necessity for a biopsy to differentiate neoplastic strictures commonly apply to?
Annular
Non-neoplastic mild strictures will often respond to..? (2)
Balloon dilation or bougienage
What medication has been documented as a concurrent medical therapy for rectal structure?
Triamcinolone
The surgical approach required is dependent on..?
location of the stricture (and can be decided as for other rectal lesion)
What can rectal perforation occur 2ry to? (2)
trauma (damage during surgery or examination, foreign bodies, secondary to fractures)
adverse effects of some drugs (such as following corticosteroid administration)
Rectal perforation can also lead to (2)
retroperitoneal infection
generalised peritonitis
Many retroperitoneal cases of rectal perforation ill heal via what treatment?
2ry intention (provided the retroperitoneal contamination is minimal and adequate drainage is provided)
Approach and treatment for rectal perforation? (4)
Drain placement
Broad-spectrum antibiotics
Debridement via a dorsal or lateral approach to the rectum.
It may be possible to temporarily protect the repaired area by introducing a covered stent (e.g. portion of an endotracheal tube) in the rectum.
Most common colorectal tumour?
Adenocarcinoma
In the rectum the most common neoplasm?
Benign adenomatous polyp
What are benign adenomatous polyps formed of?
Rectal lamina propria with an abnormal epithelial surface
Clinical signs of rectal polyp? (6)
Haematochezia
Dyschezia
Tenesmus
Abnormal faeces
D+
Polyp protruding
Those polyps that involve the lamina propria and submucosa (but not the basement membrane) are…?
carcinoma in situ
What is a carcinoma in situ?
A midstage between an adenomatous benign polyp and a malignant invasive carcinoma.
What diagnostic for a rectal polyp can be helpful?
Proctoscopic biopsy
Rectal tumour types? (7)
Adenocarcinoma
lymphosarcoma
hemangiosarcoma
plasmacytoma
mast cell tumour
melanoma
fibrosarcoma
