Small intestine Flashcards
In a study by Sumner 2019 in Vet Surg, did oversew or no oversew of stapled intestinal anastomoses (FEESA) in dogs result in a lower rate of post-operative dehiscence?
Oversewing resulted in a lower rate of dehiscence. Dehiscence in all dogs for which it was recorded occurred along the transverse staple line.
According to Duffy 2020 in Vet Surg, which closure technique for the transverse staple line of a FEESA resulted in the highest initial leakage pressures?
1) FEESA alone
2) FEESA and Cushing oversew
3) FEESA and continuous oversew
FEESA and Cushing oversew (1.8 fold increase). Both oversew techniques were associated with higher maximum leakage pressures than FEESA alone (1.4 fold)
Compare to Fealey 2020 in Vet Surg who reported no difference in initial leak pressures between handsewn anastomosis, barbed suture anastomosis, FEESA, and FEESA wth a Cushing’s oversew.
According to Larose 2020 in Vet Surg, what was the most common location for intestinal intussusception? What were the 3 most commonly observed post-operative complications? What was the rate of recurrence?
Ileocolic.
Three most common complications were diarrhea, regurgitation and septic peritonitis.
Intussusception recurred in 3% of patients.
According to Maxwell 2020 in Vet Surg, a delay of greater than 6-hours prior to surgical treatment for GI foreign body removal was associated with an increased risk for what?
Enterectomies, intestinal necrosis/perforation, greater surgery and anesthesia times.
Immediate surgery associated with earlier return to feeding and discharge.
Outcomes did not differ between groups, however.
According to Mullen 2020 in Vet Surg, which anastomosis technique was associated with the highest initial and maximum leakage pressures?
1) Handsewn
2) FEESA-blue TA
3) FEESA-green TA
4) FEESA-GIA
5) FEESA-oversew
6) Skin staples
No difference in initial or maximum leak pressures between groups
According to Culbertson 2021 in Vet Surg, what was the sensitivity of probe testing anastomoses for detection of leakage?
100% (also 100% negative predictive value).
Not all positive probe tests leaked however (79% samples had a probe drop, and only 17% leaked)
In a study by Dobberstein 2022 in Vet Surg, what percentage of dogs survived to discharge following upper GI perforation secondary to NSAID administration?
73%
According to Duffy 2022 in Vet Surg, which of the following crotch suture augmentation technique(s) when performing FEESA resulted in the greatest increase in initial and maximum leakage pressures?
1) No crotch suture
2) Simple interrupted crotch suture
3) Two simple interrupted crotch sutures
4) Simple continuous suture
Initial leakage pressures were increased with the simple continuous and two simple interrupted crotch sutures.
Maximal leakage pressures were increased with any augmentation technique as compared to no crotch suture.
In a study by Mullen 2023 in Vet Surg, did handsewn or stapled enterectomies result in improved preservation of perfusion?
Equal preservation as per dark field videomicroscopy.
In a study by Rahn 2023 in Vet Surg, administration of liposomal bupivacaine in canine gastrointestinal foreign body surgery was associated with an increased risk for what?
Wound complications, although post-operative analgesia and hospitalization times were shortened.
In a study by Williams 2023 in Vet Surg what was the primary complication of unidirectional barbed suture for gastrotomy, enterotomy and enterectomy closure?
Stricture occurred in 2 dogs 20 and 27 days after surgery.
No instances of leakage, dehiscence or septic peritonitis reported.
In a study by Miller 2024 in Vet Surg, which of the following had a higher initial leakage pressure in feline cadaveric bowel?
1) Hand sutured enterotomy
2) Skin stapled enterotomy
Was this pattern repeated for:
1) Hand sutured anastomoses
2) Skin stapled anastomoses
Hand sutured enterotomy took 8 times as long to complete but was associated with higher initial leakage pressures.
Skin stapled anastomoses were twice as fast as hand sutured and there was no difference in initial leakage pressures.
In a study by Sanders 2024 in Vet Surg, which of the following five anastomosis techniques for feline bowel had the highest leakage pressures? Which was the fastest to perform?
1) Hand sewn simple interrupted
2) Hand sewn continuous
3) FEESA
4) FEESA with oversew
5) Skin staples
No difference in leakage pressures between groups.
FEESA alone was 2 times faster to perform compared to oversewn FEESA, and 5 times faster than hand sutured anastomoses.
In a study by Thompson 2024 in Vet Surg, which of the following canine enterotomy groups had the highest initial leak pressure?
1) Hand sewn
2) Cyanoacrylate only
3) Hand sewn with cyanoacrylate
Hand sewn with cyanoacrylate had the highest initial leak pressures.
Maximal pressures didn’t differ with augmentation but was significantly less in the cyanoacrylate only group.
According to Gill 2019 in JAVMA, what was a risk factor for dehiscence following GI surgery in dogs? What were 2 risk factors for mortality?
ASA status >3 was a risk factor for dehiscence.
ASA status >3 and increased plasma lactate concentrations were associated with an increased risk of mortality.
In a study by Strelchik 2019 in JAVMA, what was the dehiscence rate following enterotomy in dogs for foreign body removal?
2%
In a study by Lopez 2021 in JAVMA, what were the dehiscence rates for enterotomy and resection and anastomosis for treatment of intestinal foreign bodies in dogs? What were 2 risk factors for increased dehiscence?
4% risk of dehiscence for enterotomy, and 18% risk of dehiscence for resection and anastomosis.
An ASA score >3 and increased age were risk factors for dehiscence.
In a study by Maggiar 2024 in JAVMA was there any difference in histopathologic diagnoses between small intestinal samples collected via needle biopsy or standard incisional biopsy techniques?
No, needle core biopsy was deemed to be safe, rapid and effective.
In a study by Miles 2021 in VRU, what percentage of dogs with suspected gastric, small intestinal, and gastric and SI mechanical obstructions resolved on 36 hour repeat radiography?
Gastric: 38%
Small intestinal: 17%
SI and gastric: 11%
Gastric obstructions had the highest chance of resolving on follow-up radiography.
In a study by Magistris 2022 in VRU, what were some imaging features on CT that helped to differentiate spindle cell tumours from lymphomas and carcinomas?
Spindle cell tumours: most commonly involved outer layer of GI. Mineralizations were common and obstruction occurred on occasion. Regional lymphadenomegaly common with leiomyosarcoma and GIST, but not with leiomyoma. Leiomyomas had a well delineated margin.
Carcinomas: may cause obstruction and regional lymphadenomegaly.
Lymphoma: associated with generalized lymphadenomegaly and multifocal disease.
Compare to a study by Lee 2023 in VRU in which spindle cell tumours tended to have large cystic portions within the tumour and lobulated growth (a ratio of greater than 6 for minimum diameter/fifth lumbar vertebral height, and lower HU postcontrast were used to differentiate these tumours from other tumour types).
In a study by Hoffman 2022 in JVECC, what two presurgical predictors were identified for enterectomy vs. enterotomy in dogs?
Vomiting severity at presentation and increase heart rate were associated with a greater risk for undergoing enterectomy.
In a study by Hiebert 2022 in JFMS, what percentage of cats undergoing GI surgery developed dehiscence? What 2 factors increased the risk of mortality?
<1% developed dehiscence.
Presence of pre-operative septic peritonitis and hypothermia post-op increased the risk of mortality. Overall mortality rate was 18%.
In a study by Gollnick 2023 in JFMS, what post-operative complication was more likely in cats undergoing linear rather than discrete foreign body removal? What was the dehiscence rate for foreign body removal in this cohort?
Cats with a linear foreign body were more likely to develop SSI (also more likely to be administered post-op antimicrobials).
No cases of dehiscence occurred.
Linear foreign body removal was associated with higher BCS, albumin, ASA score, surgery length, and total cost of visit.
In a study by Tidd 2019 in Vet Surg, what was the MST for cats undergoing surgical resection of discrete GI lymphoma?
185 days (cats with large intestinal masses lived longer; MST 675 days). Complete surgical resection was positively correlated with survival.
In a study by Cerna 2024 in JVIM, what were the most common clinical signs for cats with eosinophilic sclerosing fibroplasia (5)? What biochemical abnormalities were common? What medical treatment was most frequently used? Was survival different for medically and surgically treated cats?
Weight loss, anorexia, vomiting, lethargy, chronic diarrhea. Median duration of clinical signs was 90 days.
Eosinophilia and hypoalbuminemia were observed in 50% and 28% of cases respectively.
Prednisone was the most common medical management (98%).
Surgical excision was performed in 37% of cases but was not associated with improved survival. 88% of cats were still alive at the time of writing.
At what location does the root of the mesentery attach?
The second lumbar vertebra
Which vessel supplies the majority of the small intestine?
Cranial mesenteric artery, arises beneath the first lumbar vertebra.
What is the innervation to the small intestine?
Vagus and splanchnic nerves by way of the celiac and cranial mesenteric plexuses.
What is the venous drainage of the proximal duodenum?
The gastroduodenal vein, the remainder of the SI is drained by the cranial mesenteric vein.
Describe the lymphatic drainage of the small intestine.
Majority drain to the mesenteric lymph nodes, which are clustered around the root of the mesentery. Some of the duodenal lymphatics drain to hepatic nodes. Some of the ileum drains to colic nodes.
What are the four layers of the SI?
Mucosa, submucosa, muscularis, serosa.
How frequently does replacement of the villous epithelium occur in the SI?
Every 2-6 days
What are Peyer’s patches?
Lymphoid follicles that are grouped together to form aggregated follicles (approximately 22 Peyer’s patches throughout the SI in the dog).
What are the two types of small intestinal motility?
Segmental and peristaltic. These are regulated by the parasympathetic nervous system.
What substances are absorbed in the small intestine?
What are the two methods of absorption in the small intestine?
Active (using the Na-K/ATPase pump) or passive down concentration gradients or using facilitated diffusion.
What percentage of water presented to it does the jejunum and ileum absorb?
50% and 75%, respectively.
Describe the enzymes responsible for digestion of proteins, carbohydrates and lipids in the small intestine.
Proteins: trypsin and chymotrypsin are secreted by the pancreas in response to cholecystokinin released from the duodenum.
Carbohydrates: pancreatic amylase.
Lipids: pancreatic lipase. Bile salts aid in digestion through creation of micelles (allows access of non-fat soluble lipase to the smaller fat droplets). Triglycerides are then synthesized in the enterocytes, packaged with cholesterol and lipoproteins into chylomicrons and transported in lacteals to the lymphatic system (chylomicron rich lymph).
What are common electrolyte derangements seen with intestinal obstruction?
Proximal: loss of predominantly HCl, sodium and potassium rich gastric fluids results in hypochloremic, hypokalemic metabolic alkalosis.
Distal: loss of bicarbonate, sodium and water rich pancreatic secretions may lead to metabolic acidosis.
What techniques can be used for assessment of intestinal viability?
Subjective: peristalsis, perfusion, colour, and palpation.
Objective: fluoroscein staining, surface oximetry.
How does fluoroscein staining aid in assessment of intestinal viability?
Administered IV and then the intestines are observed with a Wood’s lamp. Patchy areas of fluorescence >3mm should be resected. Probably a more accurate indicator of mucosal rather than intestinal viability, so may overestimate the bowel required for resection.
How does surface oximetry aid in assessment of intestinal viability?
If the oxygen saturation of the bowel matches that of the periphery the bowel is likely viable. However, due to the size of the probe, may miss small areas of necrosis.
Why is multifilament suture a less ideal choice for intestinal closure?
Increased drag, increased inflammation (prolonging lag phase), and may increase the risk of infection.
Monofilament absorbable, non-absorbable, barbed sutures and staples can all be used for intestinal closure.
Why is a single-layer appositional suture pattern preferred for intestinal closure?
Inverting patterns result in narrowing of the lumen, and everting patterns result in increased adhesion formation.
Single layer closures are preferred as two layer closure results in worse submucosal apposition, necrosis of the inverted cuff of tissue, and increased luminal narrowing.
What suture patterns are recommended for SI closure?
Simple continuous, simple interrupted, modified Gambee.
What are the properties of the omentum that aid in healing of small intestinal closures?
Angiogenic, immunogenic, and has adhesive properties that assist in restoring blood supply, controlling infection, and establishing lymphatic drainage.
When performing a serosal patch which layer of both segments of bowel should be engaged?
The submucosa
List some techniques for SI suture reinforcement.
Omentalization, serosal patch (gallbladder serosal patch can potentially be used for defects of the proximal duodenum).
What volume of saline is required to achieve normal peristaltic intraluminal pressure in a 10cm segment of healthy bowel?
16-19 ml with digital occlusion, and 12-15 ml with Doyen forceps.
What are some ways that luminal disparity can be addressed during small intestinal resection and anastomosis?
Spacing of sutures, transection of bowel on an angle, spatulation of the bowel, reduction of the luminal diameter of the larger segment of bowel.
What is a potential sequelae of using a continuous pattern of polypropylene for closure of a small intestinal anatomosis?
Partial migration into the lumen can create a net which may trap ingesta creating a mechanical obstruction.
What stapling techniques have been described for small intestinal closure in dogs?
- Everting, end-to-end triangulating anastomosis with TA 30 staplers.
- Inverting end-to-end anastomosis with an EEA stapler.
- Functional end to end anastomosis (FEESA) using GIA staplers.
- Use of skin staples
Where is FEESA failure most likely to occur?
Along the transverse staple line. Recommended to offset the staple lines at the time of TA staple application. Omentalization, serosal patching, or oversew can also be used to augment the repair.
What are some complications associated with FEESA?
Anastomotic leakage and localized abscess (normally at the TA staple line). Abdominal wall incisional abscess formation has also been reported.
What are advantages and disadvantages of stapled SI resection and anastomoses:
Advantages: fast, addresses luminal disparity, reduced bowel manipulation.
Disadvantages: large size of the instrument, blunting of the knife in older versions, difficulty in certain anatomic areas (i.e. jejunoileal anastomosis).
For a GIA 60 cartridge how long is the bevelled end, and what is the significance?
23 mm. No staples are in this area, which means that need at least 60mm of bowel for the stapler to be appropriately used.
Is the bursting strength of a skin stapled resection and anastomosis comparable to hand sutured techniques?
Yes, also has a similar luminal diameter and quality of healing.
Should omentum be wrapped 360 degrees around a site of resection and anastomosis?
No, might result in intestinal obstruction.
What are three methods of intestinal biopsy collection?
Longitudinal elliptical incision, wedge excision around a stay suture, 6mm punch biopsy.
How is enteroplication performed?
Sutures are placed between the submucosa of adjacent loops of bowel (midway between the antimesenteric and mesenteric borders).
Duodenum is not included because intussusception in this area is rare.
What are some complications associated with enteroplication?
Increased morbidity reported (abdominal pain, vomiting, diarrhea, hyporexia, constipation).
Additionally, obstruction, strangulation, perforation, ileus, septic peritonitis, and intraabdominal abscess formation have been reported.
Rates of complication are often higher than rates of recurrence of intussuception.
When could enteroplication be considered?
In cases when a cause of intussusception is not identified, the cause is not easily remedied, or intussusception is recurrent.
What is the reported dehiscence rate of enterotomies or resection and anastomoses?
7-16%
Similar for biopsies (11%).
Interestingly cats seem to have a lower risk for development of post-operative peritonitis.
Compare to study by Lopez 2021 in JAVMA in dogs undergoing enterotomy or RnA: 4% risk of dehiscence for enterotomy, and 18% risk of dehiscence for resection and anastomosis.
What are some risk factors for development of post-operative dehiscence following SI enterotomy or RnA?
Hypoalbuminemia, hypotension, use of blood products, longer length of bowel resected, delayed enteral feeding post-operatively, pre-operative septic peritonitis. Foreign bodies have been a risk factor in some studies, protective in others.
Compare to study by Lopez 2021 in JAVMA in dogs undergoing enterotomy or RnA, risk factors for dehiscence included an ASA score >3 and increased age.
Why is diagnosis of post-operative septic peritonitis challenging?
Imaging results may be confounded by normal post-operative findings (air on radiographs, corrugated bowel and fluid on ultrasound), peritoneal fluid plasma and lactate values are inaccurate,
What are potential options for abdominal closure following treatment of septic peritonitis?
Primary closure, closed suction drainage, open abdominal drainage, vacuum assisted closure.
Is the severity of hypoalbuminemia and hypoproteinemia different between closed and open abdominal drainage techniques?
No.
Cause peripheral edema, depression of the immune system, delayed wound healing, and DIC.
What is the mortality rate for dogs and cats developing septic peritonitis?
50%
Is the mortality rate different between primary abdominal closure or closed/open abdominal drainage technique in patients with septic peritonitis?
No, so long as the source of peritonitis is corrected, the peritoneum is aggressively lavaged, and appropriate supportive care is instituted.
What factors increase the likelihood of adhesion formation?
Ischemia, hemorrhage, foreign bodies and infection.
What percentage of bowel needs to be resected for short bowel syndrome to occur in dogs? Is proximal or distal bowel resection better tolerated?
50% (although some dogs have clinically tolerated up to 85% resection).
Proximal bowel resection is better tolerated. Distal bowel resection results in steatorrhea because the absorptive functions of the ileum cannot be assumed by the jejunum.
What are the causes of maldigestion and malabsorption associated with short bowel syndrome?
What occurs with intestinal adaptation?
Reduced mucosal surface area, decreased transit time, small intestinal bacterial overgrowth (SIBO), gastric and intestinal hypersecretion.
Intestinal adaptation involves an increase in the number and size of enterocytes, bowel diameter, height of the villus, crypt depth.
What dietary changes are recommended to treat short bowel syndrome?
Recommend feeding small frequent meals of highly digestible diet. Fiber (10-15% on a dry matter basis) is very important in modulating motility, stimulating adaptive changes, increasing water absorption, and binding to bile salts.
Fat may also need to be included and is trophic to enterocytes, decreases gastric emptying and provides crucial energy. Animals may require injections of fat soluble vitamins.
What drug can be used to treat persistent diarrhea in cases of short bowel syndrome?
Loperamide (anti-diarrheal)
What antimicrobials can be used to treat SIBO secondary to short bowel syndrome?
Amoxicillin, metronidazole, tetracylines, tylosin.
What are some options for medical management of ileus?
Metoclopramide, cisapride, mirtazapine, erythromycin.
What is the mechanism of action of erythromycin on small intestinal motility?
Has similar effects to the hormone motilin and stimulates gastric emptying.
What is the mechanism of action of mirtazapine on small intestinal motility?
Tricyclic antidepressant that might stimulate GI motility and appetite.
What are some factors that might affect the prognosis of a patient with short bowel syndrome?
Amount and location of intestinal resection, presence of the ileocecal valve, degree of adaptation, health of the remaining gastrointestinal system, preoperative condition of the animal, and willingness of the owners to pursue prolonged intensive medical management
What is thought to be the cause of post-operative ileus?
Overactivity of the sympathetic nervous system.
In what percentage of linear foreign bodies is it anchored around the tongue in cats?
50%
What are some methods of assessing degree of small intestinal dilation in cases of suspected foreign body obstruction in dogs and cats?
Dogs: SI diameter as compared to height of the 5th lumbar vertebra. Ratio <1.6 = unobstructed, ratio >2 = obstructed. A more accurate measure has also been proposed (see image).
Cats: SI diameter as compared to the height of the cranial endplate of L2. Ratio <2 = unobstructed, ratio >3 = obstructed.
Cannot differentiate between mechanical and functional causes of distension.
How long might contrast take to highlight distal foreign body obstructions?
24 hours (typically 6 hours for proximal small intestinal obstructions).
What technique might be used to expedite closure when multiple enterotomies are required (as in linear foreign body)?
Use of a skin stapler (although the fate of the staples remains unknown). They can also be used to close the gastrotomy after initial simple continuous closure of the mucosa/submucosa with suture.
In what percentage of cats was conservative management (cutting of the string) of linear foreign bodies anchored under the tongue in cats successful in one cohort?
47%. Remaining cats were taken to surgery with 1/3 having perforations.
What percentage of dogs with linear foreign bodies have septic peritonitis at the time of surgery?
40% (40% also require resection and anastomosis).
What is the reported mortality rate in dogs/cats after foreign body removal?
1 - 8%. Financial concerns and sepsis are the most likely reasons for euthanasia.
What is the prognosis for dogs and cats with linear foreign body?
Generally considered good in cats due to low rates of perforation (18% mortality in study by Hiebert 2022 in JFMS).
Prognosis worse in dogs due to high rate of perforations at presentation. The need for multiple enterotomies or extensive small bowel resection may be associated with higher mortality.
What is chronic intestinal pseudo-obstruction?
Distension of the small intestine with no sign of luminal obstruction. Generally poorly responsive to medical management. If focal can be resected, otherwise prognosis is grave.
What is a common cause of mesenteric thromboembolism in cats?
Hypertrophic cardiomyopathy (most clots, 90%, lodge in the aorta, but sometime may lodge in the mesenteric vessels).
If only a localized segment of jejunum is affected the prognosis is good.
How is mesenteric thromboembolism diagnosed?
Mesenteric angiography.
How can intussusception protruding from the anus be differentiated from rectal prolapse?
Ability to pass a probe between the prolapsed segment and rectum indicates intussusception.
What causes the clinical signs associated with intussusception?
Invagination of the intussusceptum into the intussuscipiens results in obstruction of venous outflow. Continued arterial blood supply results in intramural hemorrhage, loss of blood into the intestinal lumen, and bloody diarrhea.
What is the typical underlying cause of intussusception?
Young dogs: enteritis.
Old dogs: neoplasia.
What is shown in the image?
Intussusception
What type of contrast study might be particularly useful in identifying ileocolic intussusception?
Barium enema (rather than upper GI contrast study).
What is the reported recurrence rate of intussusceptions?
6-27%
Compare to Larose 2020 in Vet Surg, in which a 3% recurrence rate was reported.
What imaging finding might indicate intussusceptions that are manually reducible or might undergo spontaneous reduction?
Documentation of blood flow within the intussusception on ultrasound. May be prudent to re-ultrasound these patients after GA and before surgery in case spontaneous reduction occurs.
Which sections of the small intestine are affected by mesenteric volvulus?
From the distal duodenum to proximal descending colon.
What patients are most at risk for mesenteric volvulus?
Young, adult, male, large breed dogs. German shepherd most frequently reported.
What are the most common clinical signs associated with mesenteric volvulus?
Abdominal distension and hematochezia. Signs are typically peracute or acute.
On bloodwork hypoproteinemia, hypoalbuminemia and hypokalemia are common.
What might cause a delayed intestinal perforation following abdominal trauma?
Avulsion of a section of mesentery resulting in ischemic necrosis of the bowel.
What is the accuracy of blunt probing wounds to assess for intra-abdominal penetration?
60%. Abdominal imaging usually recommended for further assessment.
What are the most commonly diagnosed small intestinal tumours in dogs?
Adenocarcinoma, lymphoma, leiomyosarcomas, GISTs, leiomyomas.
What is the most commonly diagnosed small intestinal tumour in the cat?
Lymphoma
Large cell (intermediate/high grade) lymphoma often has a focal mass and multicentric involvement.
Small cell (low grade) often diffusely thickened to normal appearing intestines.
What paraneoplastic syndromes have been reported in association with intestinal neoplasms?
Lymphoma: hypereosinophilia.
Smooth muscle tumours: hypoglycemia and nephrogenic diabetes insipidus.
What are the surgical margins recommended for treatment of small intestinal neoplasia?
3cm
What is the preferred treatment of lymphoma?
Large cell: CHOP
Small cell: prednisone and chlorambucil.
What is the MST for dogs with intestinal lymphoma undergoing surgery +/- chemotherapy?
14 days
Which drug might be effective in the treatment of GISTs? Why?
Tyrosine kinase inhibitors, because GISTs express c-kit mutations.
What is the MST for cats with SI lymphoma?
Large cell: 5-7 months
Small cell: 22-25 months
What is the prognosis for dogs with completely excised SI smooth muscle tumours?
Can be good, with long term control reported.
What is feline gastrointestinal eosinophilic sclerosing fibroplasia?
A nodular proliferative inflammatory lesion associated with gastrointestinal tract and alimentary lymph nodes.
Etiology is unknown, potentially develops in genetically predisposed cats in response to bacterial or fungal antigens in the intestinal wall.
What treatment is recommended for feline eosinophilic sclerosing fibroplasia?
Prednisone or surgical excision.
In a study by Cerna 2024 in JVIM there was no difference in survival between groups.
What is the difference between intestinal diverticula and duplication?
Diverticula are outpouchings of the intestinal wall. Duplications are lined by intestinal mucosa and contain smooth muscle in their walls but do not directly communicate with the intestinal lumen (either in the wall or directly adjacent).
Surgical excision of either condition is expected to be curative.
