Surgery of the Anal and Perianal Regions Flashcards
What is the term to describe the junction between the rectum and anal canal?
Anorectal line
At the anus the mucocutaneous junction with the perianal skin is known as
Anocutaenuous line
What muscles is the anal canal surrounded by? (2)
Internal smooth muscles
Striated external anal sphincter muscle
The anal mucosa and the external anal sphincter muscle are supplied via (3)
The right and left caudal rectal arteries
Branches of the internal pudendal arteries
The cranial rectal artery in some individuals.
What are anal glands? Where do they sit?
circumanal glands that lie in the cutaneous tissue of the anus
What are anal sacs; where are they found?
These are spherical/conical sacs, found between the inner smooth muscle and outer straited muscle of the anus.
Where do anal sacs excrete in dogs?
level of the mucocutaneous junction at approximately 4 and 8 o’clock on the anus.
Where do anal sacs excrete in cats?
Lateral to the anus.
What is atresia ani?
Congenital abnormality; failure of the normal rectoanal canal and anal aperture to develop
Define Type I Atresia ani
stenosis of the anal canal
Define Type II Atresia ani
Persistence of an anal membrane with the rectum ending immediately proximal to this as a blind pouch
Define Type III Atresia ani
Closed anus with a more cranially positioned blind ending rectum
Define Type IV Atresia ani
Cranial rectum ends in a blind pouch within the pelvic canal.
Clinical signs of atresia ani type I.
Essentially normal until after weaning when constipation and/or tenesmus can develop.
Clinical signs of atresia ani type II-IV. (4)When does it develop?
A normal initially 2-4 weeks of life before developing abdominal enlargement,
Anorexia
Restlessness
Unable to defecate.
Some will have a perianal bulge indicating the anal membrane.
What can be used to assess the location and degree of anal stenosis? (2)
Physical exam
Abdominal radiographs
Treatment of type I atresia ani (2)
bougienage or balloon dilation of the stenosis/stricture, although repeated procedures may be necessary.
Treatment of type II/III atresia ani
small linear incision can be made over the location of the absent anal aperture, preserving the anal sphincter. The rectum can then be identified and brought caudally to then be opened and sutured to the surrounding subcutaneous tissues if necessary.
What tumour of the anal sacs accounts for 17% of all tumours in the perianal area?
Apocrine gland adenocarcinoma
The three most common non-neoplastic conditions that affect the anal sac are
impaction
sacculitis
abscessation
Why is it thought that cats are less likely to suffer anal sac issues?
secretion of the sebaceous glands within the anal sacs is more lipid based -a more fluid secretion which is less likely to occlude the duct
What is an impacted anal sac, and how do treat?
anal sacs become swollen/engorged but are typically not painful. Impacted anal sacs are easy to palpate but can be less easy to express.
Treatment by manual expression is common, although in some cases sedation and flushing of the duct is required.
True or false
Sacculitis can occur without impaction, in which case hypersecretion can occur.
True
Sacculitis
A) What is it like on palpation?
B) What other clinical findings might there be?
A) Painful
B) pyrexia
What can form with sacculitis which is similar on exam to an anal mass?
metaplastic ossification (formation of irregular foci of bone
What medication is appropriate with anal sacculitits?
ABx
anti-inflam
How to treat anal sac abscessation?
Abscessation of the anal gland can be treated with incision, drainage and lavage of the abscess cavity.
Antibiotics and or anti-inflammatory medication are appropriate.
Proposed theories leading to anal sac disease? (11)
Abnormal seborrheic glandular secretions in patients with generalised seborrhea
Activity level
Anatomic variation *
Anal/Perianal swelling
Diarrhoea
Diet
Inflammatory bowel disease
Obesity
Perianal fistulae
Prolonged retention of secretions
Pudendal nerve dysfunction.
Where are anal sac ducts located in GSD which pre-disposes them to dx?
More cranial
Which of these conditions is typically not painful?
Impaction
Sacullitis
Anal sac abscessation
Impaction
How to position/prepare a patient for anal sacculectomy?
- Ventral recumbency
- Elevated tail (secured dorsally)
- Evacuate rectum
How to minimise contamination with anal sacculectomy?
Purse string suture cranial to anal sac
Which method of identifying anal sacs in anal sacculectomy has been identufied as having a higher complication rate?
Wax/resin
How is the initial incision made in an anal sacculectomy?
A curved incision is made over the caudal and lateral aspect of the anal sac.
During the approach to an anal sacculectomy, what muscles are seperated from the anal sacs? (2)
Internal and external anal sphincter muscle
During the approach to an anal sacculectomy; care not to damage which artery which lies medial to the duct?
Caudal rectal a
During anal sacculectomy; wha stuture is placed around the anal sac duct at the level of the mucocutaneous junction?
A synthetic monofilament absorbable ligature (1.5 metric size is appropriate)
What do do before closure of anal sacculectomy?
Lavage
How to close anal sacculectomy site?
Routine subcutaneous and skin closure with synthetic monofilament absorbable suture material (1.5/2 metric)
Are more complications seen with open or closed anal sacculectomy?
Open
What is the approach to an open anal sacculectomy?
1 Scissors or a blade are placed into the anal sac duct.
2 Skin, subcutaneous tissue, internal and external anal sphincter muscle, duct and anal sac are incised. (a)
3 The duct and sac are then dissected out from the surrounding tissue
What is the rate of faecal incontinence with anal sacculectomy? Does this resolve?
3-14%
Often resolves in 10-14 days
Breeds pre disposed to Apocrine Gland Adenocarcinoma of the Anal Sacs (AGASACA)? (3)
Springer
Cocker
CKCS
Neutering status increasing chance of Apocrine Gland Adenocarcinoma of the Anal Sacs (AGASACA)?
If neutered
How is it thought Apocrine Gland Adenocarcinoma of the Anal Sacs (AGASACA) causes hypercalcaemia?
Due to secretion of a substance by the AGASACA which has an activity similar to parathyroid hormone causing a pseudohyperparathyroidism.
How to diagnose AGASACA?
FNA
With an AGASACA how many have metastasised at time of diagnosis? Where do they go to? (5)
96%
Sublumbar (medial iliac) lymph nodes are the most common sites but lungs, liver, spleen and bones (including the spinal cord)
Hypercalcaemia with adeocarcinomas; what needs to be done pre op and why?
IV crystalloid fluid therapy +/- furosemide) is necessary prior to surgery to protect against acute renal failure
Median survival time after surgical excision of adenocarcinoma?
18mo
Remove metasatic LN with anal gland adeocarcinoma?
Uncertain beneift
Which of these statements are true?
Select all that apply.
Sacculitis can occur without impaction
The rate of complication following anal sacculectomy is higher with the open technique
Entire dogs are at a slightly increased risk of developing AGASACA
Sacculitis can occur without impaction
The rate of complication following anal sacculectomy is higher with the open technique
What is an anogenital cleft?
A rare condition where faeces and urine enter a common cavity (a cloaca)
Females with anogenital cleft:
A) What aspect of anus is absnet/incomplete?
B) Common signs? (3)
C) Treatment?
A) Ventral aspect
B) Incontinence, faecal soiling, ascending UTI
C) Reconstruct ventral aspect of the anus and reconstruction of the tissues between the anus and the vulva.
Males with anogenital cleft:
A) What is present?
B) With is incomplete?
C) Continent?
D) Treatment?
A) Hypospadia; with
B) Incomplete urethra. Failure of ventral anus to develop and a continuous anal/utrethral mucosa
C) Good
D) Urethostomy
Perianal hepatoid adenomas:
Commonly seen with which sex/neutering status?
Older male entire
OR
Can be seen in female older entire (lack of oestrogen inhibition)
Perianal adenocarcinoma
A) Size/growth rate?
B) Almost half have previously had what removed?
C) Mets site? (6)
A) Large + fast
B) Perianal adenoma
C) Sublumbar LN, lungs, liver, spleen, kidney, bone
Prognosis for perianal adenocarcinoma:
Stage T1 and T2 ?
(tumour less than 5 cm and minimal invasion) have a 2-year disease free interval in 60-75% of cases
Prognosis for perianal adenocarcinoma:
Stage T3 and T4?
(tumour over 5 cm and/or invasive) have median survival times of 6-12 months.
Treatment of perianal adenocarcinoma? (inlcude margins)
Surgical en bloc excision, combined with extirpation of lymph nodes affected by metastasis (typically sublumbar), can be performed with 1-3 cm margins. Concurrent castration is often performed, although the benefit of this in cases of perianal adenocarcinoma is much less clear than in adenomas.
Possible chemo agents for perianal adenocarcinomas? (3)
doxorubicin +/- cyclophosphamide, cisplatin
Remission of perianal adenocarcinoma with radio or chemo?
Unlikely/temp
T or F
Adenomas are often larger and firmer than perianal adenocarcinoma.
False
Breed predisposition to perianal fistula?(5)
GSD (80%)
Labrador
Setter
Sheepdog
Collie
Histologically, the lesions seen in perianal fistulas are similar to those seen in people with..?
Crohns
What is perianal fistula often responsive to? How does this drug work?
Cyclosporin (inhibits T cell activtation)
How to diagnose perianal fistula?
Physical exam which will often reveal multiple discharging fistulas and a painful perianal region.
Perianal fistula and ciclosporin:
Provides lesion resolution in 70-100% of cases used alone. In a mean duration of..?
9 weeks
Perianal fistula and ciclosporin + ketoconazole:
how does it work?
What is a potential risk?
- Inhibiting/blocking cytochrome P450 pathways in liver
- Potenital for ketoconazole toxicitiy
How to use glucocorticoids in perianal fistulas? Resolution rate
Tapering prednisolone for 6-8 weeks lead to resolution of perianal fistula in a third of patients, improvement in a third and no change in a third.
How is tacrolimus applied with perianal fistula? Resolution rate?
Tacrolimus (immunosupressant) is applied topically and can also be combined with metronidazole, cyclosporin and ketoconazole.
A small study reported topical application of tacrolimus only with lesions resolving in 4-13 weeks.
Azathioprin + metronidazole:
A) Issues of this?
B) Resolution?
A) General immunosupressant; more side effects.
B) Rare for resolution; improves lesions
How can surgery be used with perianal fistulas?
Surgery can be used to attempt removal of sinuses and fistulous tracts whilst preserving as much of the regional anatomy as possible. Anal sacs are often involved (62% of cases have ruptured anal sacs) and bilateral anal sacculectomy can be required.
In very severe cases of perianal fistulas, what can be performed and what are the risk of this?
A complete or partial anal resection and anoplasty can be performed but with more extensive the resection of the anus, incontinence becomes likely, and owners should be counselled about this and the impact on quality of life (patient and owner) that can result.
Complication rate of perianal fistula surgery?
High! - wound dehisence, faecal inctont, recur
