Surgery of the large intestine, rectum, and anus Flashcards
What is a cecal inversion? What are the typical signs?
- Cecal inversion = cecal intussusception
- Signs
- Diarrhea
- Hematochezia
- Weight loss
- Tenesmus
What is the treatment for cecal inversion?
- Manual reduction
- Colotomy if necessary
- Typhylectomy
How do you perform a typhylectomy?
- Ligate arterial supply
- Dissect ileocolic fold
- Milk out contents
- Transect and suture
How is blood supply and healing of the large intestine different from the small intestine?
- Higher bacteria count
- Increased collaginase 1-3 days after sx
- Segmental blood supply
- Ileocolic, cranial mesenteric, caudal mesenteric
- Major: ileocolic, cranial mesenteric
- If you ligate the segmental blood supply you must remove that section–will get necrosis
- Ileocolic, cranial mesenteric, caudal mesenteric
What are the most common cecal tumors?
Leiomyoma and leiomyosarcoma
What are the causes of megacolon?
- Usually idiopathic (62%)
- Pelvic obstruction (23%)
- Neurologic (6%)
- Endocrine
What are the treatment options for megacolon? What are the specifics for medical management?
- Medical management
- Correct dehydration
- Deopstipate
- Inc. fiber diet
- Stool softeners
- Osmotic laxatives (lactulose)
- Prokinetic agents (cisapride)
- Subtotal colectomy
What are the goals of subtotal colectomy in the treatment of megacolon?
Goal is to remove as much colon as possible
What are the advantages/disadvantages of ileocolostomy and colocolostomy when performing a subtotal colectomy?
- Colocolostomy
- Remove entire colon and reattach it, leaving ileocolic valve intact
- Preferable
- Tension free apposition more difficult (impossible in some patients)
- Remove entire colon and reattach it, leaving ileocolic valve intact
- Ileocolostomy
- Tension-free closure
- Exposes patient to bacteria
- Increased incidence of severe diarrhea
- Tend to do worse than colocolostomy patients
What is the typical post-operative course after subtotal colectomy? Prognosis?
- Fluids 1-3days
- Analgesics
- Continue antibiotics if gross contamination
- Feed w/in 24hrs
- Diarrhea should improve in 2-8wks
- Good prognosis
- Dogs–fair to guarded
What is the incidence of dehiscence after intestinal surgery? What is the prognosis?
Occurs at about the same rate as with the SI, but can be much worse due to high amounts of bacteria
What is atresia ani (tell me all the things)?
- Stenosis or persistent membrane of the anus or rectum
- Most commonly reported anomaly
- Increased incidence in toy poodles and Boston terriers
- Signs occur at a few wks of age
- Clinical signs
- Straining
- Anal dimple
- Perineal swelling
Tell me everything about rectovaginal fistulas
- Often associted w/ atresia ani
- Vulvar irritation, cystitis
- Passage of urine through rectum or feces through vula
- Diagnose with positive contrast
- Treat by transecting and closing defect
- Treat underlying UTI
3 facts of anogenital clefts?
- Common opening for anus and genital tract-cloaca
- Leads to ascending UTI
- Treat with plasty procedure
Differentiate between anal and rectal prolapse
- Anal prolapse
- Incomplete prolapse
- Anal mucosa protrudes from orifice
- Determine underlying cause and treat
- Manually reduce and place purse string
- Rectal prolapse
- Complete–all layers of rectum protrude through anal orifice
What are the predisposing factors for rectal prolapse?
- Parasites
- Colitis
- Urogenital disease
- Younger patients
- Tumors
How do you differentiate between rectal prolapse and prolapsed intussusception?
If actual prolapse, blunt probe/finger cannot be inserted
How do you treat a rectal prolapse if the tissue is still viable?
- Manually reduce
- Facilitate reduction with saline, lubricants, or mannitol
- Place purse string to keep reduced but allow soft feces
- Leave for several days
How do you treat a rectal prolapse with non-viable tissue?
- Surgically prep area
- Place 4 full-thickness stay sutures
- Use test tube to minimize contamination
- Resect 1-2cm from anus
- Simple interrupted
- Reduce prolapse
What are the treatment options for a recurrent rectal prolapse?
Incisional colopexy
Non-incisional colopexy
Describe the procedure of a non-incisional colopexy for treatment of recurrent rectal prolapse
- Ventral celiotomy
- Cranial traction on colon
- Reduce prolapse
- Engage submucosa
- Antimesenteric border
- Left abdominal wall
- 2 rows of 5-6 non-absorbable sutures
Describe the procedure for an incisional colopexy
- Similar to gastropexy
- > 3cm incision through serosa and muscular layers
- Incision through transverse abdominus muscle
- Can perform in more than one area
What is the most common malignant rectal tumor in dogs? What is the signalment?
- Most common: adenocarcinoma
- German shepherds and poodles predisposed
- Older dogs
- Increased incidence in males
- Not quite as aggressive as SI
What is the most common tumor in the rectum? What is the signalment?
Adenomatous polyp
- Most commonly found in distal rectum
- Collies predisposed
- Can undergo malignant transformation
- Single or multiple lesions (higher incidence of transformation in multiple lesions)
What are the clinical signs of rectal tumors?
- Tenesmus
- Dyschezia
- Painful defecation
- Rectal prolapse
- Protrusion of polyp
How do you diagnose rectal tumors?
- Direct observation
- Digital rectal palpation
- Colonoscopy/proctoscopy
- May help determine extent
- Biopsy
- Helps determine type, stage, and sx indication
- Always submit excised mass
- Thoracic and abdominal rads
What is the pre-operative treatment for rectal tumors?
- Withhold food 24-48hrs prior
- Consider multiple warm water enemas up to 12hrs prior
- If given w/in 12hrs of sx, fluid can be retained –> can lead to more difficult sx or contamination
- Enemas contraindicated with obstructive lesions
- Consider prophylactic antibiotics
- Aerobic and anaerobic activity
What are the indications for the trans-anal approach when removing rectal tumors?
- Excision of small, non-invasive pedunculated polyps
- Lesions in the caudal 4-6cm of rectum
What are the indications/procedure for using the dorsal approach when removing rectal tumors?
- Used for tumors in the mid-rectum
- Place purse string
- Make inverted U incision between tail and anus and tubur ischium laterally
- Transect rectococcygeus muscles
- Bluntly dissect between levator ani and external anal sphincter muscles
- Place stay sutures proximally and distally
What is the modified rectal pull through approach for removing rectal tumors used for? Describe the procedure
- Used for approach to the mid/caudal rectum
- Evert rectal wall through the anus
- Place multiple stay sutures
- Make incision proximal to anocutaneous junction leaving a 1.5cm cuff of rectum
- Bluntly dissect rectum from external anal sphincter
- Mobilize rectum caudally and resect
What is the Swanson’s rectal pull through approach for rectal tumor removal? When is it used?
- Combines trans and anal abdominal approach
- Used for more extensive lesions of the rectum
Describe the lateral approach to rectal tumor removal
- Limits approach to one side of rectum
- Used for rectal diverticulum or laceration
- Approach from base of tail to ischium 1-3cm lateral to anus
- Separate tissue between levator ani and ext anal sphincter to expose lateral rectum
- Preserve caudal rectal nerve
- Procedure rarely used
Describe the ventral approach for rectal tumor removal
- Lesions at colorectal junction
- Pubic osteotomy 1, 2
- Pubic symphysiotomy 1, 3
What is the medical management of anal saculitis?
- Express gland
- Cannulate and irrigate
- Infuse abx/steroids
- +/- systemic abx
- Drain/flush abscess
- Treat underlying problem
- Diarrhea
- Allergies
What is the surgical management for anal saculitis?
When is it indicated?
- Anal sacculectomy
- Indicated when medical management fails or neoplasia is suspected
Surgical management for anal saculitis should be performed after _______.
inflammation is controlled
Describe a closed anal sacculectomy
- Often performed in ferrets and for neoplasia
- Blunt probe/instrument
- Paraffin injection
- Catheter
Describe the technique for an open anal sacculectomy
- Exposes secretory lining
- Insert 1 blade of scissors into sac
- Apply upward pressure to tips to minimize tissue cut or insert groove director or probe through duct into anal sac
- Incise over instrument with caudal tension on instrument to minimize damage to sphincter
- Dissect anal sac from anal sphincter
What are the potential complications of anal sac surgery?
- Infection
- Draining tracts
- Incomplete removal of anal sac
- Must excise to resolve
- Fecal incontinence
- Trauma to caudal rectal nerve or external anal sphincter
- Give 3-4mo for reinnervation
What is the most common malignant tumor of the anal sac?
Apocrine gland adenocarcinoma
What are the characteristics/signalment of apocrine gland adenocarcinomas?
- Highly malignant
- Regional LN metastasis
- Older spayed female dogs???
- Perianal swelling or incidental finding
- 25-90% have paraneoplastic syndrome
What is paraneoplastic syndrome?
- Hypercalcemia and hypophosphatemia
- PU/PD
- Muscle weakness
- Vomiting
What is the prognosis of apocrine gland adenocarcinoma?
- Poor
- 50% have mets on presentation
- MST < 1yr with metastasis
- MST 16-18mo with no mets
- Monitor Ca levels pre- and post-op
What is the management of perianal adenomas?
- Regress with castration
- Castration/surgical excision
What are perianal fistulas?
Chronic suppurative ulcerative tracts
What are the potential etiologies of perianal fistulas?
- Broad base low carried tail
- Abscessed anal glands
- Hair follicle infection
- Immune-mediated
What is the signalment of perianal fistulas? Signs/diagnosis?
- Middle-aged German shepherds
- Diagnosis/signs
- Presence of fistulous tract
- Tenesmus
- Dischezia
- Licking
- Malodorous perianal discharge
- Pain
What is the medical management for perianal fistulas?
- Perianal cleansing
- Antibiotics
- Immunosuppressive therapy
- Prednisolone
- Cyclosporine
- Azathioprine
What are the surgical managements available for perianal fistulas?
- Surgical excision
- Concurrent anal sacculectomy
- Cryosurgery
- Fulguration
- Tail amputation
- Laser excision
- Anoplasty
