Surgery Of The Colon Flashcards
3 divisions of the colon?
Ascending
Transverse
Descending
Which side of the abdo is the ascending colon found?
RHS
What does the ascending colon run cranial to?
Right colic flexure
Which direction does the transverse colon run?
R –> L
Where does the transverse colon run to on the LHS?
Left colic flexure
What is the arterial supply of the colon?
Cranial abdominal branches of the aorta
What branch supplies the ascending colon?
ileocolic
What branch supplies the transverse colon?
Right colic
What branch supplies the proximal descending colon?
Middle colic
What do the colon supply arteries then divide and branch into?
Short irregular vasa recta
Which border do the arteries enter?
Mesenteric
The distal portion of the descending colon is supplied initially by the A) branch of the caudal abdominal branches of the aorta and then more distally by the B) artery which run similarly along the mesenteric border.
A) left colic
B) cranial rectal
Due to the particular longitudinal course of the blood simply to the colon, when considering a segmental resection of the colon - where should this be done?
Level of the vasa recta
What is the ascending colon attached to? (2)
- Mesocolon
- Mesoduodenum
Why is the ascending colon difficult to visualise/exteriorise in surgery?
Attachments are short - 2-3cm
What is revealed in the colonic manoeuvre?
L sublumbar fossa
What is lifts in the colonic manoeurve?
Descending colon
What are reabsorbed in the colon? (4)
- Water
- Sodium
- Chloride
- Short chain fatty acid
What is secreted in the colon? (2)
Bicarbonate
Mucous
What are the reasons for increased complications for colon surgery? (5)
- High bacterial load
- Short mesenteric attachments
- Damage to mesenteric blood supply
- Infect
- Surgeon familiarity
Peri-operative natibacterial prophylaxis for colon surgery?
Cefuroxime (20 mg/kg q90m from induction to abdominal closure) and metronidazole (10 mg/kg q8h) are often used in combination.
Use of post op antibiotics in colon surgery?
However, following uncomplicated colonic surgery there is no indication for postoperative use of antibiotics and with an increasing risk of bacterial resistance, veterinary surgeons have responsibilities to limit the use of antibacterial medication.
What is the term for caecal resection?
Thyhlectomy
When is a typhlectomy indicated? (6)
- Perforation
- Caecal inversion
- Impaction
- Inversion
- Severe thyphlitits
- Neoplasia
What should try to be preserved in a thyplectomy?
Ileo-colic junction
Prior to resection, what needs to be done with the caecal when inverted?
Evert it!
What suturing is done for a typhlectomy? Include material?
Following resection between two sets of clamps, a Parker-Kerr suture pattern can be used to oversew the remaining clamp, inverting the edges of the incision. An inverting Lembert pattern can then be used to reinforce the incision. 1.5-2 metric synthetic monofilament absorbable suture material is appropriate
If using a stapler, what stapler height should be used for typhlectomy?
2mm
What is done during a typhlectomy?
Following dissection of the ileocaecal fold, atraumatic clamps such as Doyen bowl forceps are placed across the base of the caecum
What type of biopsy if preferred for colon?
Excisional
Colotomy:
How to SURGICALLY prepare the area? (2)
- Isolate with lap swabs or sponges
- The contents of the identified section should be moved proximally and distally to further minimise risk of contamination
Where is the colotomy incision made?
Antimesenteric border
How to facilitate minimal handling with colotomy?
A full thickness monofilament stay suture can be placed through the colon at the proposed site of biopsy with an elliptical incision then made around this stay suture.
How to suture colotomy site:
- Prep/
- Material
- Pattern
- cleaned before being sutured
- monofilament absorbable material (polydioxanone or polyglyconate are good choices)
-simple continuous or simple interrupted pattern. It is possible to add an inverting layer (Lembert suture).
Following colon suture; what is done before abdo closure? (2)
- Clean colon site
- Abdo flush
(can omentalise - not not needed)
Indications for colectomy (5)
Neoplasia
Megacolon
Perforation
Trauma
Chronic Intussusception.
Most common condition + species for colon surgery?
megacolon - cat
What is a subtotal colectomy?
Colon resection WITHOUT the removal of ileocaecal valvce
What is a total colectomy?
Removal of colon AND ileocecal valve
Which part of the colon remains with a total colectomy?
Distal - unless pelvic approach made
Where is the colectomy started with subtotal colectomy?
1-2cm distal to ileocolic junction
Where is total colectomy started?
1-2cm proximal to ileocolic junction
How to approach colectomy?
The appropriate area of colon is identified and isolated from the abdomen using moistened laparotomy swabs or sponges. The contents are milked proximally and distally before Doyen bowel clamps are placed across the colon about 3 cm away from each of the proposed incision sites.
What forceps can be placed across the portion of colon to be resected and the transection incision made adjacent to these before the portion of resected colon is removed?
Rochester-Carmalt
What is ligated with colectomy?
INDIVIDUAL vasa recta
When is segmental colectomy performed?
Intra or extra luminal mass present
Suture material for colectomy?
Monofilament (PDS or polyglyconate) 1.5-2m
If an approach to the pelvic colon is needed; what needs to be performed?
pelvic flap
How to suture colectomy?
- Simple interrupted sutures
= initially laced 180° apart at mesenteric and antimesenteric borders
Side: sutured using either a simple continuous or simple interrupted appositional suture pattern.
What layer has to be included in colectomy closure?
Submucosa
After leak testing colectomy; what needs to be applied?
Omental patch - interrupted sutures
How can staples be used for colectomy? (2)
Transrectal
Transcaecal
What is used in colopexy?
Descending colon to left abdo wall
When might colopexy be used? (2)
Rectal prolapse
Perineal hernia
What is the only acceptable technique of colopexy?
Appositional technique
How is an appositional colopexy performed?
Interrupted or simple continuous monofilament sutures (polypropylene, polydioxanone and polyglyconate are suitable materials) are placed through the wall of the descending colon (including the submucosa) and then through the left lateral abdominal wall musculature.
Why is incisional colopexy not used?
RISK - colonic perforation
What should be given post op from a colopexy?
Stool softener - reduce straining/risk of breakdown
What is megacolon? (2)
- Hypomotility
- Increase colon diameter
What are the 4 underlying types of megacolon?
Idiopathic
Mechanical
Neuropathic
Endocrine
What does congenital megacolon occur as a result of?
Failure or abnormality in the development of the neural plexuses that supply the distal colon
How common is congenital megacolon?
Very rare
What is a common identified prequel to megacolon in cats?
Stenosis of the pelvic canal, secondary to pelvic fracture malunion
With Stenosis of the pelvic canal, secondary to pelvic fracture malunion. When is surgery advised?
Narrowing <45%
What surgery has been shown to cause acquired megacolon?
OVH
What can cause mechanical obstruction causing acquired megacolon? (4)
- Neoplasia
- Stenosis of pelvic canal
- Prostatomegaly
- Stricture
What can cause functional obstruction causing acquired megacolon? (4)
HypoT4
HypoK
Dysautonomia
Ileus Sacral spinal cord defmormities
Define obstipation
Inability to pass faeces
What % of megacolon is cats are idiopathic?
60
Signs of megacolon? (7)
- Constipation
- Obstipation
- anorexia
- V+
- weight loss
- dehydration
- Urinary obstruct (2ry to space occupying)
Diagnosis of megacolon is made how (3)
- CE
- Rectal exam
- Lateral x ray
What is an enlagred colon on lateral xray?
If the colonic diameter exceeds 1.5 times the length of the seventh lumbar vertebra, megacolon is confirmed.
When can megacolon be treated medically? What can be used? (3)
Early cases
- Soften/laxative, dietary fibre, prokinetic e.g. cisapride
What is the issue of using partial colectomy for megacolon?(3)
Leaves damaged, atonic, albeit narrowed colon in situ
What % of intestinal tumours in dogs are colonic?
60
Most common tumour of colon in dogs?
Addenocarcinoma
Most common neoplasia of colon in cats? (2)
Lymphoma
Adenocarcinoma
colonic tumours in dogs? (8)
Adenocarcinoma
Lymphosarcoma
GI stromal tumour
Leiomyocarcoma
Plasmacytoma
MCT
Neuroendocrine tumour
Lymphoma
Clinical sings of colon neoplasia? (5)
- D+
- V+
- An/hyporexia
- Constipation + haematochezia
- Tenesmus
Surgical resection margins for colon tumour?
5-8cm
Which tumour cannot be surgically removed?
Lymphoma
The mean survival time for dogs following resection of a colorectal adenocarcinoma is reported to be between?
6-22mo
In cats, the mean survival time is between 9 and 20 weeks with colon tumours. But how many were found to be metastatic at surgery?
75%+
How common are colon torsions?
Rare
Breeds for colon torsion?
Medium - large breed
T or F
Most cases of colon torsion include the ileocecocolic junction
True
Following volvulus, the what artery is occluded or restricted leading to a reduction in perfusion and potential ischemia of the small intestines, caecum and colon.
cranial mesenteric
Colon Torsion & Colonic/Caecocolic Volvulus
Clinical signs? (6)
Dehydration
Abdo distension
Tenesmuc
Poor peripheral pulse
Tachycardia
Low temp
What is seen on xray with Colon Torsion & Colonic/Caecocolic Volvulus?
Large gas filled distended bowel loops (esp in caudal abdo)
Treatment of Colon Torsion & Colonic/Caecocolic Volvulus?
- Ex lap (Stabilise first!)
It is sometimes necessary to deflate the distended section of colon with a torsion; how is this done? (2)
This can be done using a 16- or 18-gauge needle and suction.
What does prognosis of colonic torsion depend on?
Ischaemic damage
Mortality with colonic torsion?
50%
What is done during ex alp with colonic torsion? (2)
Colectomy
Colopexy
