Large Intestine SA Surgery Flashcards
What defines the colon and rectum?
Section of LI in the abdomen (colon) and pelvis (rectum)
Give 3 surgical approaches to the colon
Ventral Midline Laparotomy
Pelvic Split
Transanal
What tool is used for a pelvic split? Where is the cut made?
Osteotome (small/young animals)
Saw
> cut pubic symphisis
When is colonotomy indicated? How is this carried out?
Rarely!
- If full thickness biopsy required
> principles same as enterotomy
Does a FB trapped in the colon require surgery?
No, milk FB out of anus
What can removal of the colon cause? How much can be removed before complications arise?
- Decreased colon length -> loss of reservoire and absoprtion capacity, so feaces ^ frequency and ^ wateryness
- <6cm in a labrador sized dog can be removed without faecal incontinence
What should always be preserved in a colon resection?
Ileoceacal junction - preserves ileal function to prevent retrograde flow of colonic bacteria -> SI (could -> bacterial overgrowth and chronic D+)
What is the name of the nerve bundle sitting on the wall of the rectum?
Pelvic plexus
What closure materials can be used for a LI anastomosis? What are the pros and cons of each?
> Sutures (single layer, simple, interrupted, appositional, PDS 2 monofilament) - optimise would healing, faster gain in tensile strength, minimise v in lumen diameter to v risk of stricture formation, fewer complications.
Staples - rapid and reliable, insert via rectum or incision in ceacum, provide inverted anastomosis, cause post-opbleeding (heals by itself), higher bursting pressures on d7 but no overall difference in healing
Give 7 post-op complications of colorectal surgery
- Would dehiscence and septic peritonitis
- Wound infection
- Abscess
- Faecal incontinence
- Stricture and tenesmus
- Rectal prolapse
- Haematochezia
How are ABs usually used? How does this differ in colorectal surgery?
Therapeutically (culture and sensitivity)
- In colorectal surgery used prophylactically to prevent contamination progressing to a full on infection
What is the most common cause of megacolon? What should first be ruled out?
1* idiopathic megacolon most common 2* causes should be ruled out first (usually problems resulting in constipation for >5m) - Pelvic Fx - Intrapelvic space occupying lesion (neoplasia, lymphadenopathy, abscess) - Colorectal neoplasia - Colorectal abscess - Perineal hernia (pelvic floor mm) - Innapropriate diet
Outline the clinical signs of megacolon
- chronic constipation
- tenesmus
- V+ if v long term
- anorexia
- weight loss
- large colon containing faecal material
- dehydration
- poor body condition
What should be the first option for megacolon Tx? What are the 2 main Tx options?
> Treat underlying 2* disease
- Medical management (evacuation of colon, laxatives, prokinetics, frequent walks, ^ fibre v residue diet)
- Surgery (subtotal coloctomy)
What are the post-op complications associated with subtotal colectomy? What is the prognosis?
- recurrent constipation
- ^ defeacation freqency
- soft watery feaces
- tenesmus
- rectal prolapse
> prognosis good
What % of colorectal neoplasia is malignant? Give examples of benign and malignant tumours.
50%
- Benign: Adenomatous polyps [~50% show malignant transformation], leiomyomas
- Malignant: Adenocarcinomas, leimyosarcoma, lymphoma, haemangiosarcoma (endothelial cells of BVs) plasmacytoma
Which artery should NOT be ligated when performing colorectal resection?
Caudal mesenteric - may appear small in the cat! Will remove entire blood supply to rectum. Always ligate close to rectum.
What signalment is over-represented for colorectal neoplasia?
- older dogs 6-9yo
- adenocarcinomas in GSD, Great Dane, Boxer, Doberman
What are the clinical signs of colorectal neoplasia?
- tenesmus
- haematochezia
- ^ defaeatory frequency
- Ribbon-like feaces
- Rectal prolapse
- weight loss
Where are 60-80% colorectal adenocarcinomas? What would be felt on rectal exam?
- Mid-caudal rectum, palpable on rectal exam
- Polypoid mass, irregular mucosal surface, annular stricture
What diagnostics may be used to diagnose colorectal neoplasia?
Radiography (abdo and thorax)
Ultrasound guiding FNA
Colonoscopy and grab biopsy
What are the 2 types of surgical treatments of colorectal neoplasia? Are these curative?
- Submucosal resection
- Wide surgical excision [3cm] with intestinal resection and anastomosis
> treatment but not cure
How can relaxation of the anus for transanal surgery be acheived?
Epidural
When is rectal pull-through for surgery advocated?
Lesion in caudal 1/3 to 1/2 of rectum
What is the prognosis for adenomatous polyps?
- surgical resection can -> cure
- 17% dogs recurrence at ~12months
- 25% dogs malignany transformation at 9-17months
- median survival >2years [GOOD!]
What is the prognosis for adenocarcinomas?
- cure possible with complete resection (low rate of distal metastasis)
- complete resection often difficult due to location
- median survival 22 months
What is the median survival time for treatment of colorectal tumours with fecal softeners alone?
15 moths
What is the 1st choice for treatment of colorectal tumours?
Submucosal section alone - Mean disease free interval: 36.8months
Complications all resolved within 1 week
Give 3 main causes of rectal prolapse. What age group are most commonly seen?
- GI parasites
- Rectal neoplasia
- Perineal hernias
> young animals
Give 4 conservative treatments of rectal prolapse
- Anthelmintics
- Feacal softeners
- Low residue diet
- Sedatives
Give 2 surgical treatments of rectal prolapse
- Purse string suture around anus (leave 1-2.5mm gap) cut and stitch simultaneously so free end of rectum not lost. Remove ~ 1 week
- if repeat prolapse suture colon wall to transversus abdominis (submucosa so almost full thickness)
What are anal sacs formed from?
Invaginations of skin
What clinical signs are associated with anal sac impaction, inflammation and infection?
- perineal irritation (scooting, licking, discomfort on defaecation)
- enlarged, potentially painful anal sacs
- abnormal secretions (should be watery brown, may become thick and pasty white/yellow/green)
- reddened inflamed skin or draining tract suggestive of infection or ruptured abscess
What is the treatment for anal sac impaction?
Manual expression
What is the treatment for anal sacculitis/abscess?
- sedate/anaesthesia
- catheterise duct opening (lacrimal cannulae) lavage sacs with 0.9% saline
- Collect sample for culture and cytology
- Instill dexamethasone and ABs
- Systemic ABs if evidence of abscess or systemic disease
- Topical treatment of yeast overgrowth if indicated on cytoloty
What are the 2 types of anal sac surgery? What should be done prior to this?
- Anal sacculotomy - open or closed
> treat inflammation/infection before surgery
What are the complications associated with anal sacculotomy? Are these common?
> uncommon
- fecal incontinence (if dissection was traumatic/aggressive)
- usually temporary unless BOTH caudal rectal nerves cut (if only one the other can compensate)
- persistent infection with draining tracts if failure to remove all anal sac tissue
Give a highly malignant anal sac tumour. What differential diagnoses should be considered?
Apocrine gland adenocarcinoma (50% metastasis at diagnosis)
DDx
- perianal adenoma (circumanal, hepatoid) - benign, common, testosterone driven, intact males and spayed females. -> Castration (±surgery)
- Perianal adenocarcinoma - malignant, rare -> treat as sac adenocarcinoma
How may anal sac apocrine gland adenocarcinoma be diagnosed?
- Paraneoplastic syndrome -> Hypercalcaemia, PUPD
- PE
- Haemotology, biochem, urinalysis
- FNA/incisional biopsy
- Radiography/ultrasound of thorax and abdo
What is the treatment for anal sac apocrine gland adenocarcinoma? What is the prognosis?
> Surgery, radiation, chemo
Prognosis
- Treatment including surgery 548d
- All 3 treatments 956d
Which breeds are predisposed to anal furunculosis?
GSDs
What is anal furunculosis?
Immune mediated fistulas and draining tracts from abscesses
What diagnostics should be performed for anal furunculosis?
- Biopsy (culture, histopath, bacteria)
- Check anal glands are intact
What is the usual treatment for anal furunculosis?
Immunomodulatory - Cyclosporine high dose until lesion clears then taper
- ketoconazole - prolongs cyclosporine action but side effects so not always used
How much does a standard dose regime of cyclosporine cost to treat one GSD?
£1000/month for ~4 months until lesions clear
