Auer Ch 38 Rectum And Anus

Front 1

What is the rectal ampulla?

Back 1

retroperitoneal rectum forming dilation

Front 2

Muscular content of the anus:

Back 2

composed of the internal and external anal sphincters. The internal sphincter is smooth muscle and the external sphincter has striated muscle.

Front 3

Function of levator ani muscle:

Back 3

overcomes anal prolapse during defecation

Front 4

Origin & insertion of the levator ani muscle:

Back 4

originats from the ischiatic spine and sacrotuber ligaments and inserts under the external sphincter

Front 5

How are most rectal tears created?

Back 5

rectal wall contracts around the examiners hand or forearm, enemas, meconium extraction with forceps, sadism, dystocia, parturition, animal bites, chronic impaction at stricture, misdirection of the stallion’s penis, rectal thrombosis, or sand impactions

Front 6

Grades of rectal tears:

Back 6

Grade 1 tears involved only the mucosa and submucosa. Grade 2 tears involved only the muscle, causing the mucosa/ submucosa to prolapse through the muscle defect, creating a pocket for fecal impaction. Grade 3a tears involve the mucosa, submucosa, and muscular layers but do not involve the serosa, 3b tears are similar expect that they do not involve the mesorectum or retroperitoneal tissue. Grade 4 tears involve all layers with gross contamination of the peritoneal cavity.

Front 7

Where do most tears occur?

Back 7

dorsally and parallel to the long axis, however idiopathic tears tend to be oriented in a transverse direction

Front 8

What cause of rectal tears affects the size of the tear?

Back 8

Dystocia

Front 9

Initial treatment of rectal tears:

Back 9

reducing the activity of the rectum, gentle removal of feces, treatment for shock and peritonitis, epidural analgesia, and rectal packing, anus is closed with towel clamps or a purse string.

Front 10

When are bypass procedures used with rectal tears?

Back 10

grade 3 and 4 tears

Front 11

Describe placement of temporary indwelling rectal liner:

Back 11

prolapse ring with Dacron loop lacing around the outer circumference , rectal sleeve or arthroscopy sleeve is glued to the ring, in dorsal recumbency the liner is passed through the rectum until the surgeon can manipulate the ring and liner through a ventral midline celiotomy, past the tear. First a circumferential suture is placed around the small colon, fitting into the groove of the rectal prolapse ring, using 3 gut. Retention sutures are then placed on the dorsal, ventral, medial, and lateral aspects of the small colon, incorporating the circumferential suture, all layers of the rectum, and the Dacron loop. The circumferential suture and the retention suture is then covered by apposing the serosal surface using a Lembert pattern

Front 12

How is a temporary indwelling rectal liner removed?

Back 12

circumferential suture will cut through the rectal wall and the liner will pass in 9-12 days

Front 13

Complications of temporary indwelling rectal liners:

Back 13

sleeve tears or retraction and formation of a rectoperitoneal fistula

Front 14

Types of colostomy techniques:

Back 14

loop colostomy and end colostomy

Front 15

Why is loop colostomy preferred over end colostomy?

Back 15

easiest, quickest to create and reverse, and does not have concern for incomplete diversion of feces

Front 16

Approaches to loop colostomy:

Back 16

single incision or double incision technique

Front 17

How do single and double incision loop colostomy techniques differ?

Back 17

Single incision techniques use the exploratory incision for stoma placement and double incision technique has separate incisions for the exploration and the stoma placement

Front 18

What are the disadvantages of the single incision loop colostomy?

Back 18

colostomy is at closure weakens the closure and increases risk of prolapse or herniation

Front 19

What are the approaches to single incision loop colostomy?

Back 19

High flank approach with high flank stoma placement, low flank approach with low flank stoma placement, and ventral midline approach with ventral midline stoma placement

Front 20

What are the advantages of single incision high flank loop colostomy?

Back 20

Can be done standing

Front 21

What are the disadvantages of single incision high flank loop colostomy?

Back 21

Can’t explore abdomen or empty colon, fecal soiling of incision & skin

Front 22

What are the disadvantages of a single incision low flank loop colostomy?

Back 22

Can’t do standing, can’t explore abdomen or empty colon, risk of prolapse & herniation

Front 23

What are the advantages of single incision VMC for loop colostomy?

Back 23

Can explore abdomen and empty colon

Front 24

What are the disadvantages of single incision VMC for loop colostomy?

Back 24

GA, prolapse, herniation

Front 25

Disadvantages of performing the colostomy under general anesthesia:

Back 25

include difficulty placing the stoma because of recumbency, additional expense of inhaled anesthesia compared with standing, and risk of stoma dehiscence during recovery

Front 26

What are the approaches to double incision loop colostomy?

Back 26

High flank approach with low flank stoma placement, ventral midine approach with low flank stoma placement

Front 27

What is the advantage of a double incision high flank/ low flank loop colostomy?

Back 27

Can be done standing

Front 28

What are the disadvantages of a double incision high flank/ low flank loop colostomy?

Back 28

Can’t explore abdomen or empty colon, construction is difficult

Front 29

What are the advantages of a double incision VMC/ low flank loop colostomy?

Back 29

Can explore abdomen and empty colon

Front 30

What are the disadvantages of a double incision VMC/ low flank loop colostomy?

Back 30

GA, construction is difficult

Front 31

Where is the low flank incision made?

Back 31

between the flank fold and the costal arch, angled dorsally about 20-30 degrees

Front 32

What location in the small colon is used for the stoma?

Back 32

1 meter oral to the rectum

Front 33

Describe loop colostomy:

Back 33

small colon is folded into a loop and the loop arms are sutured together with a lambert pattern ½ way between the mesenteric and antimesenteric teniae for 8 to 10 cm. The loop is inserted into the flank incision with the proximal loop located more ventral to the distal loop and the antimesenteric teniae exposed beyond the skin edge by 3 cm. The seromuscular layer is sutured to the abdominal muscles with interrupted sutures. An 8 cm incision is made through the tenia to created the stoma, the edges are everted and sutured to the skin edges in a simple, interrupted pattern using nylon or polypropylene. An alternative is to suture the colon loop directly to the skin. At 14 days the loop is detached and oversewn at the stoma

Front 34

Why are end colostomies chosen?

Back 34

some felt there was not complete fecal diversion with loop colostomies

Front 35

Describe end colostomy:

Back 35

stoma is created by transecting the small colon, closing the aboral segment with Parker-Kerr method. Oral segment is passed through incision, the mucosa is cuffed by suturing it to the serosa, then attached to the skin

Front 36

Disadvantage of the end colostomy:

Back 36

aboral segment will atrophy which makes the reversal more difficult and predisposes to anastomosis impaction or dehiscence

Front 37

How is atrophy of the aboral portion of the loop colostomy prevented?

Back 37

flushed daily with 20L of warm water

Front 38

Why is flushing the aboral segment of the loop colostomy better than infusing luminal nutrients?

Back 38

nutrients effect only the mucosa with no effects on stretching or exercising the muscle

Front 39

When is the colostomy reversed?

Back 39

at least 6 weeks post-operatively

Front 40

Complications of colostomy:

Back 40

dehiscence, abscessation, peristomal hernia, prolapse with or without mesenteric vessel rupture, infarction, colostomy rupture, stoma obstruction or closure reversal complications

Front 41

When is liner placement selected?

Back 41

small tears

Front 42

When is colostomy considered?

Back 42

large tears

Front 43

How do liner placement and colostomy compare?

Back 43

colostomy is more expensive, is a staged procedure, and has more life threatening risks, however there is better deviation of fecal material and comparable success rates to liners

Front 44

How is suture repair performed?

Back 44

Suture repair can be undertaken by prolapsing grade 4 tears through the anus, accessing grade 4 tears through a VMC, or non-visual standing technique

Front 45

What can improve access when performing primary suture repair with rectal tears?

Back 45

Long handle instruments with pistol grips and rectal speculums are available to easy suturing. Cutting the anal sphincter and improve access and the resulting wound can be partially closure after repair of the tear or can be left open to heal by second intention

Front 46

When should primary suture repair be selected?

Back 46

best for grade 3 tears that are half or less of the rectal circumference or for grade 4 tears with very small serosal perforation only

Front 47

What qualities should suture have in repairing rectal tears?

Back 47

Suture should be long, have little memory, and resist stretch and fecal digestion

Front 48

What rectal tears can be managed with nonsurgical management?

Back 48

grade 1 and 2 tears and maybe suitable for grade 3 tears

Front 49

Complications related to rectal tears:

Back 49

stricture, diverticulum, perirectal abscess formation, mucosal or submucosal herniation, or rectoperitoneal fistula

Front 50

Survival rates for rectal tears:

Back 50

excellent for grade 1 and 2 tears, good to fair for horses with grade 3 tears and poor for horses with grade 4 tears (Claes’ paper, survival rate 100% for horses with grade 1 and 2 tears, 38% for grade 3 tears, and 2% for grade 4 tears)

Front 51

Rectal prolapse causes:

Back 51

straining due to diarrhea, dystocia, parasitism, colic, proctitis, tumor, or foreign body

Front 52

Types of rectal prolapse:

Back 52

Type 1 prolapse involves the mucosa and submucosa, type 2 is a full thickness prolapse with all or a portion of the rectal ampulla. A type 3 prolapse is a type 2 plus in addition to small colon intussusception into the rectum. With a type 4 prolapse the peritoneal portion of the rectum as well as the small colon form an intussusception through the anus

Front 53

How are type 1 and 2 rectal prolapse treated?

Back 53

educe edema with glycerin, sugar, MgSO4, lidocaine, or a mixture, Epidural anesthesia reduces straining. Purse string is performed to prevent recurrence

Front 54

How are type 3 and 4 prolapse treated?

Back 54

manual reduction, submucosal resection, or resection and anastomosis

Front 55

Describe submucosal resection of rectal prolapse:

Back 55

2- 6 inch spinal needles or IV catheters are placed at right angles to each other through the external anal sphincter and healthy mucosa to keep the prolapse in place during the dissection. Circumferential incision through healthy mucosa is made in healthy tissues cranial and caudal to the tissue to be resected. after the circumferential incision is made, a longitudinal incision is made to connect the 2 circumferential incisions, and then the abnormal tissue is resected away circumferentially, in 1/3 segments. Mucosa and submucosa is apposed in an interrupted pattern. Once all the abnormal tissue is removed the mucosa is apposed

Front 56

When is submuscosal resection of rectal prolapse performed?

Back 56

prolapse is devitalized, the prolapse recurs with medical management, or the horse continues to strain

Front 57

Described rectal prolapse RA:

Back 57

Instead of partial thickness circumferential incisions, full thickness incisions are made, again in 1/3 segments. The exposed healthy tissues are first apposed in a full thickness interrupted horizontal pattern, again in 1/3 segments, until all necrotic tissue is removed. Mucosa is then apposed

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