94.Rectum_Anus_perineum

Question 1

what anatomical structure marks the caudal aspect of the rectum

Answer 1

external anal sphincter musclelevel of 2-3 caudal vertebra

Question 2

T/Fthere is a small caudal portion of rectum that is retroperitoneal and lacks a serosal layer

Answer 2

TRUE

Question 3

difference btwn dogs and cats terminal colon/rectal blood supply

Answer 3

dogs: rely on cranial rectal artery bc middle and caudal rectal artery contributions are minimalcats: middle and caudal rectal arteries are adequately supplying rectumMUST PRESERVE CRANIAL RECTAL ARTERY IN DOGS

Question 4

zones of anal canal

Answer 4

1 cm anal canal 1. columnar zone2. intermediate zone (anocutaneous line)3. cutaneous zone (internal–anal sacs, external–perianal hepatoid glands)

Question 5

anal canal vs external anal sphincter blood supply

Answer 5

anal canal—-internal pudendal arteryexternal anal sphincter–perineal arteries

Question 6

innervation of the rectum and internal anal sphincter

Answer 6

PELVIC PLEXUS–pelvic n (PSNS)–hypogastric n (SYMP)PSNS stimulates rectum but inhibits internal anal sphincterSYMP inhibits rectum but excites internal anal sphincter

Question 7

innervation of external anal sphincter

Answer 7

pudendal nerve—perineal branch SENSORY, caudal rectal branch–MOTOR

Question 8

what is GOLYTELY

Answer 8

polyethylene glycol and electrolytes40 ml/kg x 2 doses

Question 9

approaches to rectum

Answer 9

–ventral (bilateral ischial and pubic osteotomy, pubic symphsiotomy)–dorsal (mid rectal lesions, transect rectococcygeus m +/- levator ani m CAUTION pelvic nerve plexus laterally)–rectal pull through (mid to caudal lesions; anal sacculectomies performed; removing EAS will lead to incontinence–GOAL is to preserve 1.5 cm cuff)–transanal pull through (evert rectal wall, preserves distal rectal stump)–lateral (curvilinear perianal incision; preserve caudal rectal branch of pudendal nerve to EAS)

Question 10

complications post rectal surgery

Answer 10

1. dehiscence/leakage2. infection3. stricture4. incontinence5. recurrence massfrom poor apposition, narrowed lumen, too much tension, poor blood supply, disruption of nerves/EAS

Question 11

sex and breed predisposed to congenital abnormalities of the rectum/anus

Answer 11

females 1.8 x more likelypoodlesboston terrierslook for other congenital abN

Question 12

atresia ani classification

Answer 12

I. congenital stenosis of anus===multiple bougienage or removal of stenosisII. persistent anal membrane with rectum ending immediately cranial to membrane===perforate III. anus is closed and blind end of rectum is farther cranial==perforate and bring rectum caudallyIV. terminal rectum and anus develops normally but blind pouch is in the cranial rectum within pelvic canal===abdominal approachif diagnosis is delayed—>megacolon may be irreversible

Question 13

rectovaginal fistulas

Answer 13

failure of separation of urorectal septum to separate cloacaoften associated atresia ahi type IIrectovaginal (female); urethrorectal (male)tx: fistulectomy, sterilization, +/- reconstruction

Question 14

diagnostics for rectovaginal or urethrorectal fistula

Answer 14

–history, clinical signs, PE, rectal digital exam–positive contrast retrograde urethrography +/- fluoro***–voiding cystourethrography +/- fluoro–ab films RO megacolon, urinary stones–urine culture

Question 15

complete vis partial rectal prolapse

Answer 15

partial —anal mucosa only protrudes, anal prolapsecomplete—rectal prolapse, all layers of rectum protrudeprobe will NOT pass easily (ddx intussusception)

Question 16

most common anal and perianal tumor

Answer 16

perianal land adenoma—arises from circumanal or perianal hepatoid glandsrelated to androgen concentrations—seen in older male intact dogs (if diagnosed in female—check for cushings)cytology adenoma: hepatoid (large polyhedral)tx: castrate (submit histo) and mass removal adenocarcinoma–rare, not T dependent50% Adca had previous adenoma removed

Question 17

treatment for rectal prolapse

Answer 17

—conservative if just anal or partial prolapse—complete prolapse: resection/amputation with rectal pull through technique (not recommended in cats because stricture likely), colopexy (preferred in cats) Left sided incisional or nonincisional 2.5 cm lateral to linea

Question 18

perianal adenocarcinoma and prognostic indicators

Answer 18

> 5 cm incr tumor related death 11xpresence of mets incr tumor related death 45 x>5 cm and tumor invasion increased recurrence ratesconsider castration, LN excision if metastatic, adjuvant radiation

Question 19

benign rectal tumors

Answer 19

–adenomatous polyps (single/multiple, raised, sessile, pedunculated usually distal)–can have malignant transformation 50% dogs; males Collies, WHWT–leiomyoma (intramural–good px with surgical excision); medium to large breed dogsbenign rectal tumors are NOT common in cats

Question 20

what is carcinoma in situ in relation to rectal neoplasia

Answer 20

invade intestinal lamina propria, submucosa, but NOT the basement membrane

Question 21

most common malignant rectal tumor

Answer 21

adenocarcinoma–dogsslower to met and less invasive compared to adenocarcinoma in small intestine1. pedunculated (distal)–32 mo2. cobblestone (middle)–12 mo3. infiltrative (annular lesion)–classic napkin ring, WORSE PX–1.6 moLSA–most common in cats

Question 22

% of rectal masses felt on digital examination

Answer 22

63% of dogs with colorectal adenocarcinoma had palpable masses on digital rectal examcircumferential lesion is very suggestive of rectal adenocarcinoma

Question 23

histological type of endoscopically biopsied colonic masses

Answer 23

incorrect in 30% with surgical biopsies revealing a more malignant diagnosis

Question 24

most common complication following EEA stapling transrectally for colonic R& A based on Banz et al 2008

Answer 24

40% complicationsstricture and transient colitis most common

Question 25

px for rectal tumors

Answer 25

polyps, leiomyoma, carcinoma in situ good with resectionpolyp recur 17%carcinoma in situ 55%

Question 26

surgical options for fecal incontinence

Answer 26

–nerve from biceps femurs created onto EAS–neuromicrovascular free transfer from latissimuss–semitendinous muscle flap–clockwise rotation following rectal resection 225 degrees

Question 27

why is there speculated to be lower incidence of anal sac disease in cats vs dogs

Answer 27

cats have more sebaceous glands in their anal sacs (have a more sufficient amount of lipid–to help avert occlusion of duct and secretions are not to viscous)

Question 28

incidence of apocrine gland adenocarcinoma of the anal sac

Answer 28

diagnosed incidentally on PE in 40% dogsbilateral tumors < 10%incidence of paraneoplastic hypercalcemia 27%>50% (36-96%) have mets at time of presentation (check sub lumbar LN)not common in cats but poor px

Question 29

4 systemic signs and 2 bloodworm abN associated with apocrine gland adenocarcinoma of anal sac

Answer 29

PU/PDweaknessvomitingconstipationhyperCa, hypoP

Question 30

negative prognostic indicators for survival in dogs with apocrine gland adenocarcinoma

Answer 30

–lack of therapy–presence of LN or distant mets–primary tumor size > 10 cm 2 worse–hyperCa (controversial)

Question 31

MST for apocrine gland adenocarcinoma

Answer 31

OVERALL 544 dayssx alone (sign shorter than with multimodal tx) 402 daysmultimodal tx 548 days

Question 32

anal sacculectomy

Answer 32

avoid trauma to EAS and caudal branch of pudendal nerve to maintain continenceclosed, modified open, or standard open approachesmore complications noted with open approachoverall complications: scoot, inflm, drainage, seroma, incontinence (permanent if longer than 3-4 mo, bilateral damage), fistulation/infection (incomplete removal–open tech), stricture

Question 33

4 medical options for perianal fistulas (sinuses)

Answer 33

1. cyclosporin 8.8 weeks 70-100% success (many patients have recurrence with discontinuation rx); + ketoconazole (inhibits p450 cytochrome enzymes resulting in incr cyclosporin concentration decr dose 75%, incr saving 60%)2. GCC (prednisone)3. Tacrolimus (topical, $$$)4. azathioprine–metronidazole (may not cause complete resolution but more economical)

Question 34

types of perineal hernia

Answer 34

1. caudal (btwn levator ani, internal obturator, EAS)–MOST COMMON2. dorsal (btwn levator ani and coccygeus)3. ventral (btwn ischiocavernosus, ischiourethralis, bulbocarvernosus)4. laterally (btwn coccygeus and ST ligament) aka sciatic perineal hernialevator ani is the most commonly atrophied muscle

Question 35

castration at the time of perineal hernia repair recommendations

Answer 35

NEUTERrisk of recurrence was 2.7x greater for intact dogsneutering reduced recurrence rate from 43% to 23%

Question 36

concurrent prostatic disease incidence in dogs with perineal hernia

Answer 36

25-60% concurrent prostatic disease

Question 37

unilateral vs bilateral perineal hernia

Answer 37

unilateral 60% (RIGHT IS MORE COMMON–70%)bilateral 40%other side may still be “weak” in pararectal fossa

Question 38

bladder retroflexion in cases is perineal hernia

Answer 38

20-30%

Question 39

surgical treatment for perineal hernia

Answer 39

T-I-S-S-PT—– traditional primary herniorraphyI —– internal obturator flapS —-semitendinous muscle transposition (ventral hernia)S —-superficial gluteal muscle transpositionI —– implants (Prolene mesh, SIS, fascia lata)+/- pexy procedures (cystopexy, colopexy, vas deferens vasopexy)

Question 40

blood vessels crossing caudomedially over internal obturator muscle

Answer 40

internal pudendal vessel and pudendal nervegive rise to casual rectal vessels and nerve

Question 41

length of elevation of the internal obturator muscle for perineal hernia repair

Answer 41

DO NOT proceed farther cranially than the caudal edge of the obturator foramento avoid damage to the obturator nerve

Question 42

complications following perineal hernia repair

Answer 42

1. seroma2. wound infection/drainage/abscess3. incontinence4. straining/tenesmus ~50% (esp with colopexy)5. sciatic nerve injury < 5%6. fistulation < 15%7. urinary dysfunction (bladder atony)8. recurrence

Question 43

recurrence rate of perineal hernia with experienced surgeon vs inexperiences surgeon

Answer 43

70% inexperienced10% experienced

Question 44

recurrence rate of traditional herniorraphy vs internal obturator transposition

Answer 44

traditional 10-50%internal obturator 0-40%