Chapter 94 Rectum, Anus and Perineum Flashcards
1
Q
Name 4 proposed locations for transition from colon to rectum
A
- Pelvic inlet
- Pubic brim
- Where cranial rectal artery penetrates serosa
- L7
2
Q
What is the difference between intra-peritoneal and retroperitoneal part of rectum?
A
Retroperitoneal part doesnt have serosal layer
3
Q
Which artery provides the majority of the blood supply to terminal colon and rectum in the dog
A
Cranial rectal (branch of caudal mesenteric artery)
4
Q
Label the diagram
A
5
Q
How does blood supply to caudal colon and rectum differ between dogs and cats
A
Middle and caudal rectal arteries supply variable and relatively insignificant amounts in dogs, whereas in cats, intrapelvic rectum is adequately supplied by middle and cudal rectal arteries.
6
Q
Where is the anal canal?
A
- Between termination of rectum and anus
- 1-2cm long
- Surrounded by internal and external sphincter m
7
Q
Label the diagram.
A
- The columnar zone contains longitudinal or oblique ridges, known as anal columns, which extend caudally for approximately 7 mm.
- The intermediate zone is an irregular, sharp-edged fold, less than 1 mm wide, that unites with the anal columns. The fold is divided into four arches that give it a scalloped appearance and contain large pockets known as anal sinuses.
- The anocutaneous line is considered the boundary between the mucous membrane and the skin, but it cannot be differentiated from the intermediate zone.
- The cutaneous zone is divided into internal and external portions, and the plane separating the two is considered the anus.
8
Q
What is the difference in epithelium cranial vs caudal to anorectal line?
A
Anal canal lined by stratified squamous epithelium (because deveops from invagination of surface ectoderm)
Rectum has simple columnar epithelium
Anorectal line is demarcation of this transition
9
Q
Where do the anal sac canals open
A
Internal portion of cutaneous zone of anus.
10
Q
What is another word for anal sacs?
A
Para-anal sinus
11
Q
Where are teh anal sacs located?
A
Between internal and external sphincter muscles
12
Q
What kind of epithelium of in anal sacs?
A
Stratified squamous
13
Q
What is the perineal fascia
What is the perineal body?
A
Perineal fascia: Convergence of fascia from tail, pelvic region, thighs
Perineal body: Region where fascia unites on midline, bwteen anus and vulva/bub of penis
14
Q
What structures make up the pelvic diaphragm?
A
- Pelvic fascia
- Coccygeus
- Levator ani
15
Q
What glands sit around the anus and what glands are present in the anal sacs?
A
Glands sitting peri-anally:
- Circumanal glands: Superficial sebaceous part, deeper non-sebaceous. Regress in females
- Apocrine glands
- Sweat glands
- Anal glands = tubuloalveolar glands that produce fatty secretions
Glands within anal sacs:
- Paranal sac glands: Produce anal sac fluid
- Sebaceous glands
16
Q
What muscle form the internal anal sphincter?
A
Cicular smooth muscle of anal canal
17
Q
What other muscle do external anal sphinter fibres blend with ventrally in male vs female dog?
A
Male: Bulbospongiosus muscle
Female: Constrictor valvae
18
Q
What muscle sits dorsally over anus?
A
Rectococcygeus
19
Q
What nerve provides motor innervation to the external anal sphincter?
And sensory innervation?
Which nerve is it a branch of?
A
- Caudal rectal nerve supplies motor innervation
- Perineal branch of pudendal nerve provides sensory innervation
Branches of pudendal nerve (the motor nerve!)
(Pelvic = parasympathetic, hypogastric = sympathetic)
20
Q
Label the diagram
A
21
Q
Comment on mechanical pre-op bowel prep.
A
No benefit, potentially detrimental (increased leakage)
22
Q
What is estimated bacterial load of faeces in rectum?
What proportion are anaerobes?
A
109 bacteria/gram
90% anaerobes
23
Q
What antibiotic class is recommended for rectal surgery
A
Cephalosporins as good activity against both gram +ve and -ve and some anaerobes.
+ metronidazole for anerobic cover
24
Q
What are the 4 approaches to the rectum?
A
- Ventral
- Pelvic symphysiotomy
- Pubic + ischial osteotomy
- Pubic osteotomy
- Dorsal
- Lateral
- Caudal
- Transcutaneous rectal pull-through
- Transanal rectal pull-through
- Rectal eversion
- (Combined abdominal + transanal)
25
What muscles are elevated off pelvic symphysis for osteotomy?
Gracillis and adductor magnus et brevis (has two parts, other part is adductor longus, originates at pubic tubercle)
26
What degree of pulvic widening is tolerated without Si lux?
25% width of sacrum
| (unilateral lux with 50-75% widening)
27
What muscles are cut for dorsal approach to rectum
Rectococcygeus +- levator ani
28
What muscles are divided during lateral approach to rectum?
Dissect between external sphincter + levator ani
29
Whatadditional procedure has to performed with transcutaneous ractal pull through and why?
Bilateral anal sacculectomy as both ducts will be included in cutaneous inscision.
30
List 4 treatment options or rectal stricture
* Bugienage
* Balloon
* Surgical inscision of constricting band
* R + A
31
List potential complications after colorectal resection
* Tenesmus
* Haematochezia + dyschezia
* Stricture
* Dehiscence
* Increased frequency of defaecation/diarrhoea
* Faecal incontinence (usually transient 5-10d)
32
What 2surgical factors has been associated with increased risk of dehisence after colorectal excision?
And incontinence?
Dehisence:
* Removal of \>6cm
Incontinence:
* Removal of \>6cm
* Removal of distal 1.5cm of rectum (therefore transanal pull through preferred over transcutaneous where possible)
33
What two factors contribute to faecal continence
* External anal sphinter function
* Resevoir continence (a function of length and motility)
34
Name 3 congenital abnormalities of the rectum and anus
* Atresia ani
* Rectovaginal/rectourethral fitula
* Anogenital clefts
35
Describe the types of atresia ani
1. Type 1 congenital stenosis of anus
2. Type 2 persistence of anal membrane and rectum ends immediately canial to imperforate anus
3. Type 3 anus also closed, rectum ends more cranial
4. Type 4 anus and terminal rectum develop normally but cranial rectum ends as a blind pouch in pelvic canal
ie. in summary type 1 stenosis, type 2 and 3 have imperforate anus with varying distance between rectum and anus and type have normal terminal rectum + anus with abnormality more cranial
36
What are c/sof atresia ani
Abdo enlargement, unthrifty, anorexia, restlessness, not passing faeces.
Usually ok for first 2-4 weeks
37
How is each type of atresia ani treated?
_Type 1:_ Bougie or balloon
_Type 2 and 3:_ Vertical inscision (preserve external sphincter and anal sacs), dissect out rectum, mobilise caudally and appose to skin
_Type 4:_ Abdo approach
38
List 3 main concerns following atresia ani sx
Incontinence, stenosis, megacolon
39
What embryonic abdnormality leads to rectovaginal/urethrorectal fistula?
What condition are they associated with?
failure of urorectal septum
type 2 atresia ani
40
Comment on imaging
Contrast radiography of a rectovaginal fistula. A Foley catheter is inserted into the vaginal vault for infusion of contrast material. The arrows indicate the fistula location.
41
Comment on imaging
How is megacolon dx on rads
Type II atresia ani. On the lateral abdominal radiograph, the rectum is noted to end as a blind pouch immediately cranial to the closed anus.
Megacolon if diameter of colon \> 1.5xlength of L7
42
What is best method to dx urethrorectal fistula
Positive contrast retrograde urethrography
(Can also do vagino urethrography, fistulography, voiding cystourethrography)
43
List 3 techniques for management of rectovaginal fistula
1. The anal and vaginal defects are each closed with simple interrupted sutures, and the atresia ani is repaired as described previously.
2. Alternatively, the rectum is transected cranial to the fistulous opening; the affected segment of the rectum is removed, and the cranial segment is sutured to the anus as a rectal pull-through.
3. A third alternative is to transect the fistulous tract near its vaginal or vestibular attachment and use the distal rectal portion of the fistula to reconstruct the anal canal and anus
44
List reported complications of rectal fistula sx
* incontinence
* wound dehiscence
* tenesmus
* obstipation
* rectal prolapse
* anal stenosis
* perianal edema
45
what condition is shown
Anogenital cleft (ie common cloaca)
46
What is a *complete* rectal prolapse
All layers of rectum aroudn entire circumference protrude (vs just *anal* mucosa)
47
List 4 predisposing factors for rectal prolapse
1. Weakness of perirectal/perianal supporting tissues
2. Uncordinated peristaltic contractions
3. Excessive straining
4. Inflammation/oedema of rectal mucosa
e.g. with gastrointestinal parasitism; typhlitis; colitis; proctitis; colonic duplication; congenital defects; tumors of the colon, rectum, or anus; rectal foreign bodies; perineal hernia; anal laxity; cystitis; cystocele; prostatic disease; urolithiasis; and dystocia
48
DDX for rectal prolapse
prolapsed intussusception
insert somethign between anus and protrusion to distinguish
49
How is rectal prolapse managed initially?
And if unsuccessful
* GA or epidural
* 50% dextrose or live yeast or systemic frusemide
* CSL
* Pursestring 3-5d
* Low residue diet + laxative
Colopexy
50
What are 3 most common canine perianal tumours/
Perianalgland adenoma, adenocarcinoma, apocrine gland anal saca adenocarcinoma (AGASAC)
51
Where do perianal gland tumours originate from
Circumanal modified sebaceous glands (called hepatoid as look a bit like hepatocytes on histo)
(reported around tail base, prepuce etc - wide area basically!)
52
What size of LN size means liekly mets (from perianal/rectal tumour)
\> 1cm
53
What drives perianal adenoma growth
What condition has it been associated with
Androgens i.e.usually seen in ME dogs (or neutered females - oestrogen --\> regression. or hyper A --\> androgenic stimulation)
Interstitial cell ("Leydig cell" = testosterone secreting) testicular tumour therefore always submit for histo
54
What IHC can be used on perianal adenoma/adenocarcinoma to differentiate between benign and malignant (5 points)
* pcna
* ki67 or AgNOR
* markers for apoptosis
* expresion of claudins 1, 4, 5, 7
* monoclonal antibody labelling
55
What breeds are predisposed to adenocarcinoma or perianal glands
GSD and artic circle breeds
and \>35kg dogs
56
What is the only prognostic factor for perianal gland adenocarcinoma
Clinical stage
57
Describe staging of peianal gland adenocarcinoma
_T1:_ tumor \< 2 cm, superficial or proliferative
_T2:_ tumor of 2 to 5 cm or with minimal invasion independent of size
_T3:_ tumor \> 5 cm or invasive tumors independent of size
_T4:_ (invasive tumor) have a median survival of 6 to 12.5 months.
The median survival time with confirmed metastasis is 7 months.
How is stage 4 different from invasive stage 3.... maybe mets with stage 4 but dont know
58
List 3 adjunctive treatments for analgland adenocarcinoma
Radiotherpay
Chemo
Electrochemotherapy
59
When does a rectal polyp become carcinom in situ?
Carcinoma in situ = polyps that invade the intestinal lamina propria and submucosa but not the basement membrane
(transition stage between adenomatous polyp and invasive carcinoma with some histologic features of malignancy that may progress to true malignancy in 17% to 50% of cases).
60
How does recurrence rate compare between rectal polyps and carcinoma in situ/
Rectal polyp recurrence 17%
Carcinoma in situ 55%
61
HOw does rectal adenocarcinoma compare with SI adenocarcinoma
Rectal less invasive and lower rate of mets
62
What are the three 'presentations' of rectal adenocarcinoma?
* Pedunculated (distal rectum)
* Cobblestone (middle rectum)
* Infiltrative (middle rectum)
63
List 5 rectal neoplasms
* Adencocarcinoma
* Leiomyoma
* Leiomyoosarcoma
* Lymphoma
* Fibrosarcoma
* HSA
* MCT
* Extramedullary plasmacytoma
* GIST
64
What is IHC marker for GIST?
CD117
65
what is mst of rectal lymphoma
1600d
66
List paraneoplastic syndromes that have been reported with anorectal tumours
* Leucocytosis (adenomatous polyps)
* Peripheral eosinophilia
* Neutrophilia
* Hypercholesterolaemia
* Hypoalbuminaemia
* Hypoglycaemia (leiomyosarcoma)
* Monoclonal gammopathy (plasmacytoma)
67
Name a way to evaluate rectal mass, aside form the usual
Contrast radiography i.e. barium enema
68
What % of endoscopic biopsies of rectal masses were incorrect?
30%
(endoscopic sample usually underestimated severity)
69
Name a non-neoplastic mass of feline GI
FGESF
Feline Gastrointestinal Eosinophilic Sclerosing Fibroplasia
70
What method is reported to reduce recurrence of rectalpolyp after removal fromthe base/
Cryosurgery applied to base
71
In patients with malignant tumours of distal rectum, how did outcome differ with local excision, cryosurgery or electrocoagulation
Local excision prolonged survival by 7 months
Cryosurgery by 24 months
Higher morbidity of cryisurgery inc stricture, rectal prolapse, pernieal hernia (due to tenesmus)
NB nitinol stent for palliation reported
72
Non-surgical tx of rectal polyps?
Yes. Pred + cyclosporine
73
What is most common location for rectal perforation ?
Caudal 4cm (extraperitoneal)
74
What are the two types of faecal incontinence. List 3 potential causes of each
**Resevoir incontinence** = failure of the colon and rectum to adapt to and contain their contents. Affected animals sense the urge to defecate but lose voluntary inhibition of the act, with subsequent passage of soft, unformed, or liquefied feces.
* Colorectal disease; colitis, proctitis, neoplasia, surgical excision fo part of colon/rectum
**Sphincter incontinence** = failure of the anal sphincter mechanism to resist the propulsive forces in the rectum, and feces are passed involuntarily, with a lack of awareness by the animal.
* Neurogenic; Nerve damage S1-S3, pudendal nerve/caudal rectal, pelvic nerve, CNS disease, peripheral neuropahty
* Non-neurogenic; Perianal disease, rectal prolapse, trauma, fistula, hernia
75
List 4 factors in rectal surgery --\> more likely to cause incontinence
* Removal of \>4cm rectum
* Removal of terminal 1.5cm
* Damage to perineal nerves
* Damage to \>50% extrenal sphincter
76
List 3 factors in medical mamangement in faecal incontinence
* Low residue diet
* Slow Gi transit time with opioids
* Induce defaecation by enema or rectal stimulation
77
List 2 surgical options for management of feacal incontinence
* Semitendinous muscle transposition beneath anus and up along affected side to simulate extrenal sphinter
* 225º rotation of terminal rectum in cat to create a spiral diaphragm
78
What are the three most common anal sac disease?
Impaction, sacculitis, abscessation
79
What is predominant cytology of normal cat anal sacs
Yeasts and cocci (rods also identified)
80
What breed is predisposed fo AGASAC
Cocker
81
IN what % af AGASAC is Cox-2 expressed
100%
82
What % of AGASAC are bilateral
10.5%
83
How is hypercalcaemia (paraneoplastic) treated?
0.9% NaCl --\> calciuresis
Frusemide 2 mg/kg iv bid once rehydrated if hyeprcalcaemia is severe
84
What chemo type has been shown to be beneficial in AGASAC
Platinum based
Carboplatin/cisplatiin
85
What was MST of AGASAC treated with radiotherapy alone
And radiotherpaty + mitoxantrone
650d
950d
86
List 4 tx options for AGASAC
* Surgery
* Chemo
* Radiotherapy
* Electrochemotherapy
87
What protocol for AGASAC reported the best MST and what was it?
Surgery, curative intent radiotherapy to perineal and sublumbar regions, mitoxanrone chemo
MST 31 months
88
What is most common complication after AGASAC
Recurrence (local and sublumbar LN)
29 - 45%
89
List some early and some late complications of radiotherapy for AGASAC
Early:
* Moist desquamation
* Colitis
* Perineal discomfort
Late:
* Rectal stricture
* Perforation
90
List negative prognostic indicators for AGASAC (8 points)
* Larger tumour size
* Presence of LN mets
* Presence of distant mets
* Advanced clinical stage
* E-cadherin expression
* Not performing surgery
* Treatment with chemo alone
* No treatment
* (Variably reported as negative progostic indicator, presence of hypercalcaemia)
91
Describe staging system for APASAC and MST for each stage
_Stage 1:_ MST 40 months
* Primary tumour \<2.5cm
* No mets
_Stage 2:_ MST 24 months
* Primary tumour \>2.5cm
* No mets
_Stage 3a:_ MST 15-16 months
* LN \<4.5cm
_Stage 3b:_ MST 10-11 months
* LN \>4.5cm
_Stage 4:_ MST \<3 months
* Distant mets
92
What was MSt of cats with AS neoplasia (tx w biopsy or exisicion)
3 months
(only 15% mets but \>55% progression/recurence - suggests local aggressive disease is the problem moe so than mets)
93
What factors are associated with increased complications after anal sacculectomy (3 points)?
* Open technique
* Dogs \<15kg
* Anal sac filled with gel
94
What is the preferred term for anal furunculosis?
Perianal fistula (although fistula implies tract fromskin to rectum so could argue perianal sinus better)
95
List 4 factors in GSDs thought to predispose them to perianal fistula
* Deeper seated AGs
* Higher density of perianal apocrine sweat glands in cutaneous zone of anal canal
* Certain major histocompatibility complex class 2 haplotypes
* Certain TNF-alpha haplotype
96
In dogs with perianal fistula, how is the inflammatory process characterised?
Infiltration of:
* CD3+ T lymphocytes
* IgA and IgG secreting B lyphocytes
* Macrophages
* Plasma cells
* Eosiniphils
i.e. consistent with immunologic activation
In summary, in perianal fistulas:
**Increased levels of WBCs, cytokines and MMPs**
97
What should be checked during perianal fistula PE
Rectal
- check for rectal/anal stenosis, anal sac abnormalities, presence/absence of anal tone
98
List 5 drugs that can be used in the medical management of perianal fistulas
* Cyclosporine
* (+- ketoconazole)
* Glucocorticoids
* Tacrolimus
* Azathioprine
* Metronidazole
99
What of dogs with perianal fistula respond to tx with cyclosporine alone
How long do they need to be treated for before resolution can be expected?
70 - 100%
8 weeks
100
What dose would you start cyclosporine at for perianal fistula
5 mg/kg bid for 4 weeks
then 5 mg/kg sid for 4 weeks
then 2.5 mg/kg sid for 4 weeks
the 1.25 mg/kg sid for 4 weeks
If lesions dont resolve --\> anal sacculectoym + tract resection
101
HOw does ketoconazole affect cyclosporine metabolism
What dose?
Ketoconazole inhibits hepatic and intestinal chyochrome p-450 oxidase
2.5-10 mg/kg
Ketoconazole --\> 75% dose reduction of cyclosporine
102
What was cure rate for perianal fistula treated with pred alone?
1/3rd
(i.e. much worse than 70-100% cure with cyclosporine)
103
What is tacrolimu does for perianal fistula
TOPICAL 0.1% tacrolimus solution bid
104
Aside from cyclosporine, name another combo medical therapy that had good rate of cure (79%)
* Novel protein diet
* Pred
* Metronidazole
* Topical 0.1% tacrolimus
105
What was cure rate for dogs with perianal fistula treated with azathioprine-metronidazole
57%
106
What was cure rate for perianal fistula witht he followig treatements:
Cyclosporine
Glucocorticoids
Tacroliums/pred/metronidazole/novel protein diet
Azathioprine/metronidazole
* Glucocorticoids 33%
* Azathioprine/metronidazole 57%
* Tacroliums/pred/metronidazole/novel protein diet 79%
* Cyclosporine 70-100%
107
What surgery is performed for perianal fistulas that have not resolved with medical management?
* Excision of all draining tracts
* Bilateral anal sacculectomy
* Cryptectomy (= resection of columnar zone of anal canl up to anorectal line)
108
What is main complication after surgery for perianal fistula
what is main complication w cryosurgery?
Recurrence up to 50%, wound dehisence up to 50%
Anal stricture (50%! vs 14% w regular surgery)
109
What are the 4 types of perineal hernia?
* Caudal (most common)
* Between levator ani, internal obturator and external sphincter
* Dorsolateral
* Between levator ani and coccygeus
* Ventral
* Between ischiourethralis, ischiocavernosus and bulbourethralis
* Sciatic
* Between coccygeus and sacrotuberous ligement
110
What is teh originand insetrion of these lot:
Levator ani
Coccygeus
Internal obturator
Sacrotuberous ligament
Levator ani (two parts; iliocaudalis and pubocaudalis)
* Origin: 7th caudal vetrebra
* Insertion: Perineal body (and fascial attachment to external anal sphincter)
Coccygeus
* Origin: Spine of ischium
* Insertion: Transverse processes of 2nd-5th caudal vertebrae
Internal obturator
* Origin: Intrapelvic border of obrurator foramen
* Insertion: Trochanteric fossa of femur
Sacrotuberous ligament (absent in cats)
* Origin: Caudal aspect of sacrum and transverse process of Cd1
* Insertion: Ischiatic tuberosity
111
What 4 muscles attach to the sacrotuberous ligament?
* Biceps femoris
* Abductor cruris caudalis
* Piriformis
* Superficial gluteal
112
What is the sole innervation to the external anal sphincter
Caudal rectal n (branch of pudendal)
113
What neurovascualar bundle courses over inetrnal obturator in pararectal fossa?
Internal pudendal artery, vein and nerve (--\> caudal rectal nerve which is sole innervation of extrenal anal sphincter)
114
Label the diagram
N.B. INternal iliac branches into internal pudendal and caudal gluteal.
Internal iliac a.
--\> Internal pudendal a.
* Caudal rectal a.
* Ventral perineal a.
* Dorsal artery of penis
Internal iliac a.
--\> Caudal gluteal
* Gluteal branches
* Lateral caudal a.
* Dorsal perineal a.
* AND branch running ventrally to semitendinous
115
Name a breedpredisposed to perineal hernia
Peke
Boston
Corgi
Boxer
Poodle
Bouvier
Old english
116
List 6 factors proposed to be involved in perineal hernia aetiology
* **Rectal** **abnormalities**
* **Androgens**
* Risk of recurrence x2.7 if entire
* Lower number of androgen receptors in pelvic diaphragm muscles in perineal henria dogs (whetehr catsarted or not)
* **Gender-related anatomic differences**
* Females have larger, broader levator ani muscle, larger sacrotuberous ligament, more cranial boundary to peritoneal cabity
* **Relaxin**
* Increased relaxin receptiors in perineal hernia pelvic diaphragm muscles (primarily produced in prostate - high concentration in prostatic cysts)
* **Prostatic disease**
* 25-59% have concurrent prostatic disease
* Testicular abnormalities in 70% of dogs with perineal hernia (seminima \> interstitial cell \> seminoma)
* **Neurogenic atrophy**
* High incidence of spontaneous potentials on EMG of pelvic diaphragm muscles
117
WHat are 3 most common clinical signs of perineal hernia
PErineal swelling, straining to defaecate, constipation
118
What % of perineal hernias are bilateral
Side predilection
50%
R
(10% develop hernia on other side within 3 years from sx on first side)
119
In what % of perineal hernia cases is bladder retroflexed?
20-29%
(Do cystopexy if bladder retroflexed. One study found reduced recurrence wit cystopexy. Can stage that vs perineal hernia sx)
120
How is megacolon dx?
1.5 x length L7
121
List surgical options for management of perineal hernia
* Traditional herniorrhaphy
* Internal obturator muscle transposition
* Superficial gluteal transposition (has been reported in combo with internal obturator transposition)
* Semitendinosus transpositioon
* Prosthetic mesh
* Biomaterials
122
Label the diagram
Final appearance after traditional herniorrhaphy (caudolateral view).
1, External anal sphincter;
2, coccygeal muscle;
3, superficial gluteal muscle;
4, ischial tuberosity;
5, internal obturator muscle elevated from ischial table
6, retractor penis muscle.
123
List 2 benefits of internal obturator transposition over traditional heriorrhaphy
* Reduced tensionon closure
* Brings in more blood supply
124
What is the cranial limit of internal obturator elevation and why?
Caudal edge of obturator foramen to prevent damage to obturator nerve and artery
125
How is tendon of internal obturator recognized
Where is it cut during internal obturator transposition?
Three bands that converge as tendon as it crossed over the lateral edge of ischium
Cut it medial to the lateral edge of ischium to avoid sciatic nerve damage (and N.B. a blood vessel runs immediately cranial to tendon)
126
What vessel needs to be preserved during superficial gluteal transposition?
Caudal gluteal artery
127
When is semitendinous transposition used in perineal hernia repair
As salvage when other techniques have failed
Ventral hernia (= between ischiourethralis, ischiocavernosus and bulbocavernosis)
128
What are the major blood vessels supplyign proximal semi-tendinous muscle (i.e. must be preserved!)
What vessel supplies the distal half of the muscle?
Where is muscle transected during transposition?
Prox supply: Caudal gluteal artery and vein
Distal supply: Distal caudal femoral artery
Transect midbelly or closer to stifle if nec.
129
Describe a modification of the semitendinous transposition
* Split *contralateral* muscle longitudinally in half
* Transect medial half of the muscle proximal to popliteal LN
* Rotate dorsomedially and pass ventral to anus and into hernia defect
* Suture to coccygeus and sacrotuberous lig and external sphincter + internal obturator, ischiourethralis and periosteum
Technique reduced muscle bulk which can make closure difficult
130
Name an important intra-op step when using prostetic mesh for perineal hernia repair
Check orientation of mesh
Polypropylene mesh will accomodate significantly higher load and energy yo yield when longitudinal ords are oriented parallel to tension axis
131
What is most significant complication after use of mesh for perineal hernia repair
Suture sinuses
Removal of suture --\> resolution
80% cure, 12.5% recurrence (with concurrent internal obturator transposition)
132
What biomaterial performed best in biomechanical testing for perineal hernia?
Fascia lata \> polypropylene mesh \> multilaminate SIS \> single layer SIS
Porcine dermal collagen also reported 60% success only
133
What was most common complication after fascia lata autograft for herniorraphy?
Lameness
7/7 success (clinical series)
134
List 3 organopexy r=techniques to augment perineal hernia repair
Colopexy, cystopexy, vas deferens pexy
135
When is colopexy for perineal hernia indicated
If pre-exisiting rectal dilation or prolapse or bladder retroflexion
136
Where is cystopexy performed
Right bladder neck to R lateral abdo wall
137
What additonal procedure has to be performed with vas deferes pexy
Castration (open! so that artery and vein are ligated separately from vas deferens)
138
Brefly describe vas defernsopexy
* Each previously ligated and transected vas deferens is retrieved from the inguinal canal.
* After careful separation of the vas deferens from the testicular artery and vein, a stay suture (e.g., 3-0 polypropylene) is placed on its severed end. Each vas deferens, with its associated vascular supply, is dissected from the peritoneal attachments to the level of the prostate gland.
* The bladder is emptied, and a craniocaudal tunnel, 1.5 to 2.5 cm long, is created on each side under the transversus abdominis muscle at the level of the apex of the empty bladder. Using curved mosquito forceps, each vas deferens is pulled in a caudal to cranial direction through the tunnel and then turned backward and sutured to itself using three or four monofilament sutures (e.g., 3-0 polydioxanone or 3-0 polypropylene) in an interrupted pattern.
* In small dogs concurrently undergoing colopexy, vas deferensopexy is performed after colopexy.
139
What is most common complication of organopexy?
Tenesmus
140
Define a complicated perineal hernia
* Significant rectal dilation
* Concurrent surgical prostatic disease
* Retroflexed baldder
* Recurrent
141
List 2 sx options for treatment of ventral perineal hernia
* Semitendinous transposition
* New perineal body may be formed by suturing the two levator ani muscles together (ventral to anus). In females these muscles are then attached to the dorsal wall of the vagina to reinforce the repair.
142
List 6 complications after perineal hernia sx (6 points)
* SSi
* Faecal incontinence
* Sciatic nerve injury
* Urinary tract complications
* Tenesmus (/rectal prolapse 0 - 17%)
* Recurrence
143
In what % of perineal hernia cases is post-op faeceal incontinence reported
0 - 33%
Permanent in 10 - 15%
(SSi reported in similar number)
144
What is rate of sciatic n injury after perineal hernia repair
What c/s.
What is tx?
What are salvage options if function doesnt return?
5%
C/s:
* Marked pain
* Paresis
* Lameness (NWB)
* Extended tarsus, flexed toes
* Lack of withdrawal digits 2-5
Tx:
* Caudolateral approach to hip to remove suture asap
Salvage:
* Talocrural arthrodesis
* Long digital extensor tendon transfer to vastus lateralis
* Amputation
Approach to caudal aspect of hip Piermattei p. 350
A. The curved incision is centered on the caudal surface of the greater trochanter. It starts near the dorsal midline, continues caudal to the trochanter, and extends through the proximal one fourth to one third of the femur.
B. The subcutaneous fat is undermined and retracted with the skin. The fascia of the biceps muscle is incised along the cranial border of this muscle, beginning proximally at the sacrotuberous ligament, and extending distally to the end of the skin incision.
C. The tendinous insertion of the superficial gluteal muscle is transected near its attachment on the third trochanter, and the incision is continued into the deep leaf of the fascia lata. The tensor fasciae latae muscle is now retracted craniodorsally and the biceps femoris caudally to expose the external rotator muscles of the hip.
D. With the femur internally rotated, the combined tendon of insertion of the internal obturator and gemelli muscles is cut close to its attachment in the trochanteric fossa.
E. A stay suture in the tendon of the internal obturator and gemelli muscles will aid in its retraction. As it is retracted, it also retracts and protects the sciatic nerve as the obturator fossa of the ischium is exposed. A Hohmann retractor placed ventral to the femoral head will help retract the external obturator and quadratus muscles. Care must be taken to protect the sciatic nerve and circumflex femoral vessels. For improved local exposure of the ischium, the cranial portion of the origin of the gemelli muscles is elevated from the bone, all the way to the ischiatic spine dorsally. Where the tendon of internal obturator muscle crosses the ischiatic spine, there is a thin-walled bursa that is 1 to 2 cm wide surrounding this tendon. Incision of this bursa allows the internal obturator muscle to be retracted further caudally. For caudal acetabular fractures, this increased exposure allows for the application of a bone plate that extends caudally to a point halfway along the body of the ischium. To avoid undue retraction of the sciatic nerve, the nerve is moved cranially during plate application. Screws can be inserted through the interval between the gemelli and internal obturator muscles dorsally, and the external obturator and quadratus femoris muscles ventrally. For local enhancement of the exposure of the acetabular labrum more cranially, a portion of the origin of the deep gluteal muscle is elevated.
145
What bladder complication may be seenwith bladder retroflexion
Bladder atony (10 - 29%)
146
List 3 possible urinary tract complications after perineal hernia sx
* Bladder atony (partic if bladder been retroflexed)
* Urinary incontinence (nerve damage or atony)
* Urethral obstruction (suture through urethra)
* (Bladder necrosis)
147
What should be performed after perineal hernia sx before waking patient up
Rectal exam
148
List factors that have been associated with recurrence of perineal hernia (7 points)
What is recurrence ate of tranditional herniorrhaphy vs internal obturator transposition?
* Surgeon experience (70% recurrence if inexperienced, 10% experienced)
* Surgical technique
* Previous surgical repairs (83% if prev repair, 43% if not)
* Type of suture material used
* Local tissue strenght at time of repair
* Ongoing predisposing factors
* Neutered vs intact
Traditional 27% recurrence, internal obturator 11%
149
List 3 differences in presentation of perineal hernia in cats compared with dog
How is it managed
What factor was asociated with failure in cats?
* Geater proportion of females in cats (25% cats bs 7% dogs)
* Bilateral disease more common
* Perineal swelling less common
* Bladder entrapment rare (2.5%)
In cats, treat just predisposing factor if present. Surgery if symptomatic for perineal hernia
Sx:
* Traditional
* Internal obturator
* Semitend
Factor associated with failure
* Perineal swelling presnet pre op
* (all the other factors listed for dogs not significant in cats)
