Sx of the Rectum, anus and Perineum Flashcards
Describe the anatomy of the rectum
- Pelvic inlet → ventral to 2nd/3rd caudal vertebrae→ beginning of the anal canal
- Short segment retroperitoneal before it joins the anal canal
- Lacks serosa (healing)
- Dorsal to reproductive organs, bladder and urethra
Blood suppky go rectum?
cranial rectal artery
What are the 4 layers fo rectum?
mucosa, submucosa, muscularis, and serosa
What is the mesorectum?
continuation fo mesocolon
What are some indications for surgery of the recum ansu and perineum
- Rectal prolapse
- Stenosis/stricture
- Neoplasia
- Congenital abnormality
- Anal sac disease
- Anal Furunculosis/Perianal fistulae
- Rectal perforation
- Perineal hernia
- Diagnostic biopsy
What is a differential for rectal prolapse?
LI intussuception
Cause of rectal prolapse?
anything causing tenesmus
Surgical maangement of rectal prolpase?
- Manual reduction & purse string suture (3-5 days) (tx of underlyign cause too)
- Colopexy; if recurrence despite tx the underlying cause
- Rectal amputation; if non-reducible/necrosis (cats high incidence of strictures forming)
how to do a purse string method?
Where does colorectal stenosis happen?
At the anorectal junction
Colorectal stenosis can be one of two things:
- Acquired - secondary to chronic inflammation , trauma, anal furunculosis, colorectal tumour
(adenocarcinoma) or previous surgery - Congenital - atresia ani
CLs of colorectal stenosis?
tenesmus, dyschezia, haematochezia or narrowed/flattened faeces, megacolon
Diagnosis fo colorectal stenosis?
- Rectal examination
- Positive contrast recto-colonography
- Biopsy: to rule out tumour (adenocarcinoma)
Tx of colorectal stenossis?
»Treatment; dilate manually under GA
* Balloon dilatation or bougiennage (more common) +/- tramincinnolone injections
* Stent or resection can be attempted
Compare and contrast rectal neoplasia in dogs vs cats
Clinical signs of rectal neoplasia?
tenesmus, dyschezia and haematochezia, weight loss, diarrhoea and vomiting
Diagnosis & tx of rectal neoplasia?
Diagnosis; rectal palpation or colonoscopy + biopsy
Treatment; surgical resection with wide margins (often not possible)
➢risk stricture formation
Describe benign adenomatous polyps as rectal neoplasia?
- Single/multiple, raised or prudnuculated
- Usually distal rectum or anorectal junction
CS of Benign Adenomatous Polyps ?
haematochesia, tenesmus, abnormal faeces, dyschesia, and D+
Who do we see these in?
MALEs & collies and WHWT predisp
Malignant transformation can occur
How do we get rid of benign adenomatous polyps?
- Most easily prolapsed through anus for removal
- Full thickness excision is not usually necessary
- At least biopsy
How do we remove cranial rectal masses?
caudal laparotomy and pelvic osteotomy
How to we approach mid-distal rectal passes?
Rectal pull through/anal approach
Post -op mass rmeoval?
give meloxicam (anti-neoplastic)
Is resection of rectal neoplasia currative?
- Resection curative for adenocarcinoma and leiomyosarcoma (slow to met)
- Local recurrence with incomplete resection
Survival after resection?
6m-2yrs
annular edenoC=> less than 2 months
Cats - longer survival if subtotal colectomy and chemo (if no mets 6-8m)
Why might we resect rectum?
- Masses – benign or neoplastic
- Polyps/neoplasia
- Traumatised or necrotic tissue
- Prolapse/fistula
- Strictured segments
What different approaches may we use?
Ventral
Dorsal
Rectal pull-through
Anal approach
What pre-op considerations for Rectum sx?
- Peri-op Abs
- Pain relief – opioids/epidural
- Do not perform pre op enema
- Can do up to 12 hours before
- Low residue diet 2-3 days prior to surgery
- Longer starve (24 hours)
- Manually evacuate bowel after anaesthesia
What max amount to resect of the rectum?
6 cm max
Describe the Ventral approach to the rectum?
- Access to cranial rectum and caudal colon/colorectal junction
- Caudal ventral laparotomy
Descrieb Dorsal approach to the rectum?
- Lesions in caudal or mid rectum but not anal canal
Describe rectal pull-through approach?
Distal colonic/midrectal not approachable by abdomen
* Too large for anal approach
* High risk of stricture
Describe the anal approach?
- Small, non invasive, pedunculated polyps which can be
exteriorised via anus - Caudal rectum or anal canal
- Perforations
- Can resect annular lesions and anastomose
What complications of preianal and rectal sx?
- Infection
- Dehiscence
- Tenesmus
- Rectal prolapse
- Haematochezia
- Incontinence (temporary or permanent)
- Anal stricture
- Haemorrhage
- Recurrence/metastases
- Nerve damage (pudendal, sciatic, femoral)
Describe risk of faecal incontinence post-op?
- Removal of distal 1.5 cm of rectum (terminal rectal cuff) even if no damage to sphincter
- Greater than 4-6 cm rectum resected
- More than half of external anal sphincter damaged/resected
- Perineal nerve damage
Prognosis for benign rectal polyp?
Good
Some top tips for rectal sx?
- Use peri-(and post?) op antibiotics in this area
- Consider epidural and opioids for pain
- Rectal prolapse not uncommon
What are the three zones of the anus?
: columnar, intermediate, cutaneous (internal & external zone)
What is in each zone of the anus?
- Anal glands - columnar and intermediate zones
- Anal sacs - Internal zone of cutaneous zone and in between internal & eternal anal sphincter
- Internal anal sphincter – thickening of circular smooth muscle
- External anal sphincter – circumferential band of skeletal muscle
blood supply of the anus?
internal pudendal and perineal arteries
Innervation of the anus?
Pelvic plexus (pelvic and hypogastric nerves)
What major innervation to external sphincter?
pudendal nerve
What are some pre-anal sac sx considerations?
- Positioning
- Purse string suture
- Bowel prep -> reduce faecal flow during/after sx
- AMs: antibiotics peri- and post op (reduce intraluminal bact load)
What other consideration?
Faecal incontinence=> copious lavage before closure, absorbably monofilament & non-abs mnofil (SC & skin)
describe Atresia any
- Congenital
- +/- recto-vaginal or recto-urethral fistulae
Describe types of atresia ani?
- Type I: Congenital anal stenosis
- Type II: Persistence of anal membrane; rectum ends as blind pouch
- Type III: Imperforate anus with blind pouch at level of rectum
- Type IV: normal anus and distal rectum,
blind - pouch at proximal rectum
How does Type 1 present?
t at weaning with tenesmus, constipation, perineal swelling
How do types 2-4 present?
; normal for 2-4 weeks and failure to thrive, anorexia, abdominal enlargement, absence of
* defecation
Tx for Atresia ani?
- Type 1; bouinage or resection
- Types 2-4; surgical repair
Prgnosis of atresia ani?
POOR, high morbidity and mortality, high complication rate
describe localising anal sacs
- Invaginations of inner cutaneous zone
- Between external and internal anal sphincter muscles
- Dog: opening at anocutaneous junction
- Cat: opening 0.25cm lateral to the anus
What kind of anal sac disease might we see?
- Impaction, sacculitis, abscess
CS of anal sac dx?
Clinical Signs; scooting, licking, biting tail base/perineum, pain on
* sitting/defecation, draining tracts
Tx for anal sac dx?
manual expression, cannulation and lavage, lance and drain abscesses, pain relief +/- antibiotics
=> for refractory cases - sacculectomy
What are the common perianal tumours?
- Adenoma (benign)
- Adenocarcinoma (malignant)
What two types fo glands do perianal tumours arise from?
- Anal sac apocrine gland neoplasms
- Perianal (circumanal) glands (hepatoid glands)
Can you get other skin tumours?
YES -> MCT, melanoma
Prevalence of anal sac gland adenoC?
2% of all tumours in dogs
What sign is seen with anal sac adenoC? what about metastases?
- 27-90% hypercalcaemia and hypophosphatemia
- Paraneoplastic (PTHrp)
- 50% -80% metastatic at diagnosis
How does anal sac adenoC spread?
- Sublumbar LNs>lungs>spleen>lumbar vertebrae
Differentials for this?
- Differential diagnosis: Primary Hyperparathyroidism
- This produces true PTH
T/F corticosteroids help reduce signs of hyperca?
true
When should we be performing rectals?
ANY older dog that is polydipsic
CLS of adenoC?
palpable mass (rectal exam) mass
effect (tenesmus, dychezia, swelling) or
hypercalcaemia (PU/PD, weakness, V+, anorexia constipation)
Diagnosis ?
FNA, biopsy
* Staging: rectal exam, haem/Ca2+ serology, thorax/abdo rads + US
Compare and contrast causes of hyperCa?
HOW TO TREAT ANAL SAC ADENOC?
wide surgical excision + radiation +/- chemotherapy
* stabilise hypercalcaemia prior to surgery
* large tumours with no mets can shrink with chemo prior to sx
* segmental resection of anal sphincter
* remove metastatic sublumbar/intrapelvic LNs
When would we need radio/chemo ?
if failure to acheive wide margins & high metastatic rate
Persistent hyperCa?
= failure to excise or mets
* Check levels regularly for recurrence
* Persistent hyperCa+ can result in renal failure - biochem
Survival /prognosis?
- Small and no mets = 3-4 years; large and not mets 2 years, mets 12-24 months ?
- Negative prognostic indicators; metastasis, larger tumour size and hypercalcaemia
How can we do an anal sacculectomy?
Closed vs open
What steps foto sacculectomy?
- Insert something into sac to aid identification
- Umbilical tape, gel, foley catheter, instrument/probe
- Dissect as close to sacs as possible; reduces damage to rectal artery, nerve and external anal sphincter
Complications of sacculctomy?
draining tracts if not fully excised, infection, incontinence, anal stricture, dehiscence,
tenesmus
What are common perianal (circumanal gland) neoplasia?
Adenoma -> PErianal (prepuce, scrotum, tail base vulval … single or multiple +/- ulcerated
T/F circumanal glands under hormonal control?
- entire males +/- testicular tumour
- decrease in size after neutering
Dx of circumanal gland tumour?
signalment and location
* Adenocarcinomas can occur – BIOPSY
* [NOT hormone dependant – metastasize – need wide excision]
Tx for perianal (cirumanal gland) neop?
- Treatment; castration +/- surgical excision
- May regress after castration
- Will recur without castration
Describe what anal furunculosis/ anal fistulae are?
- Suppurative, deep, ulcerated tracts
- Begins sterile → contaminated with bacteria
- Aetiology is unknown (likely immune-mediated cause)
Who is predisposed to furunculosis?
GSH - >broad based tail wit low carriage
Dx?
clinical presentation +/- histopath
Tx for furunculosis?
- Surgical: significant complications and recurrence
- Medical: nor always 100% effective, costyl
Medical dx for furunculosis?
SX tx for furunculosis?
When. dowe see perineal hernias?
- Weakness of muscles of pelvic diaphragm
- Dilatation & deviation of rectum
- Caudal protrusion of organs
Who is predisposed to perineal hernia?
- Entire males
- Castration prevents recurrence
- Concurrent prostatic dx is common
Any condition causing straining may predispose
Anatomy of the perineal hernia?
-> Pelvic diaphragm contains: external and sphincter msucle, coccygeus, levator ani
-> Ischiorectal fossa -> potential space b/w diaphragm and skin
-> Internal pudendal vessels & nerves -> run along. the internal obutrator nerve
-> Caudal rectal nerve= sole motor supply to external anal sphincter
Where do we commonly see hernias?
between levator ani, coccygeus and external anal sphincter muscles
Clinical signs. foperineal hernia?
- Soft, fluctuant mass in perineal region - reducible
- Unilateral or bilateral
- Faecal tenesmus
- Rectal dilatation or deviation upon rectal exam
- Loss of the pelvic diaphragm on rectal exam => Hook finger around external anal sphincter muscle into ischiorectal fossa→Diagnostic
- Retroflexion of bladder into hernia -> dyuria)
What medical management of perineal hernia?
- High fibre diet, add moisture
- Stool softeners (Lactulose)
- Manual evacuation of faeces may be
necessary - Success rates of surgery reasonable, little
justification for medical management
Surgical options for perineal hernia?
- Internal obutrator transposition
- Castrate
- Colopexty if marked rectal dilation / deviation
- Cystopexy if retroflexed bladder
What most common hernial contents?
- Rectal flexure
- Rectal sacculation
- Prostate
- Fluid
- Omentum
- Fat
- Bladder
How woudl we go about an internal obutrator transposition?
- Consider epidural analgesia
- Antibiotics
- Manually evacuate rectum and anal purse string suture
- Sternal recumbency with pelvic limbs hanging over the end of the table
- Incised from tail base to ischial tuberosity
What complications from perineal hernia?
-> Faecal tenesmus most common (may lead to rectal prolapse
-> Faecal incontinence (uncommon)
- Sciatic nerve injury when doing tenotomy of obutrator M
- Detrusor atony/urinary dysfunction if bladder retroflexion
- Damage to ureters
- Haemorrhage/infection
- Reccurence
