Ch 47 Small intestine Flashcards
What is the normal diameter of canine small intestine?
- ≤2 times width of rib
- <1.6 narrowest height of L5
What is the normal diameter of feline small intestine?
- ≤12 mm
- < 2.0 endplate height L2
Which parts of the duodenum are fixed (as opposed to mobile)?
Cranial duodenal flexure; attached to the caudal R liver with the hepatoduodenal ligament
Proximal ascending duodenum; attached to the colon with the duodenocolic ligament
Canine pseudoulcers are located at the antimesenteric wall and are caused by depressions in the mucosa at sites of submucosal lymphoid follicles. One or more may be present
What does an inner hyperechoic mucosal band in the small intestine represent?
the intestinal villi; dog in image had mild lymphoplasmacytic inflammation, but can be found in asymptomatic patients.
What does an outer hyperechoic mucosal band in the small intestine represent?
the lamina propria
What does a thin hyperchoic mucosal band in the ileum represent?
submucosal lymphoid follicles
What would a hyperechoic thin line in the muscularis layer of the small intestine represent?
In one study, histologically this was correlated with fibrous tissue in the myenteric plexus located between the inner circular and outer longitudinal components of the muscularis propria.
What does an asymmetrically positioned hypoechoic extra layer (APHEL) in the submucosa of the feline distal jejunum and ileum represent? In which age category is it more common?
normal lymphatic tissue (Peyer’s patches) in the lamina propria and submucosa
More common in young cats, unknown clinical relevance
What is speculated as the likely cause of mucosal echogenicities immediately post-prandial?
a) Physiologic lacteal dilation
b) Reflections and/or mixture of mucus and food in the lumen
c) Inflammation of the bowel
d) Increased blood flow
b) Reflections and/or mixture of mucus and food in the lumen
In one study, at 60 minutes post-prandial, how were hyperechoic speckles distributed in dogs fed a high-fat meal?
a) Few and close to the luminal portion
b) Scattered and irregular
c) More numerous and uniformly distributed throughout the mucosal layer
d) Absent
c) More numerous and uniformly distributed throughout the mucosal layer
How are small intestinal wall thicknesses expected to differ in puppies compared to adult dogs of similar weight?
Should be thinner; “In normal 7- to 12-week-old beagle puppies ranging in weight from 2.3 to 5 kg, the bowel wall thickness was less than in adult dogs of similar weight.”
Beagles 7–12 weeks of age with weight range 2.3–5 kg:
duodenum 3.8 (3.2–4.8)
jejunum 2.5 (1.2–3.4)
What is the normal wall thickness (max width) of the duodenum and jejunum in dogs <20kg?
duodenum ≤5.1
jejunum ≤4.1
What is the normal wall thickness (max width) of the duodenum and jejunum in dogs 20-30kg?
duodenum ≤5.3
jejunum ≤4.4
What is the normal wall thickness (max width) of the duodenum and jejunum in dogs >30kg?
duodenum ≤6
jejunum ≤4.7
What is the normal wall thickness (max width) of the duodenum in cats?
2.51mm
What is the normal wall thickness (max width) of the jejunum in cats?
2.67 mm
What is the normal wall thickness (max width) of the ileum in cats?
3.59 mm
Normal diameter of jejunal lymph nodes in cats?
5mm
Ionic iodinated contrast media are not recommended for oral administration in young and debilitated patients and especially dehydrated patients, because___________________________.
the resultant fluid shift can worsen any hypovolemic state
Most ionic contrast media are hypertonic and cause an influx of fluid into the gastrointestinal tract.
________________________ is one of the most frequent causes for a nondiagnostic barium study.
Failure to administer an adequate volume of contrast medium; The intestine should be distended to its reasonable physiologic maximum.
At what time intervals will these structures be seen in a barium or iodinated contrast study in a cat ?
When will orally administered contrast reach the duodenum in the dog? and the colon?
15 min (duodenum)
4 hours (colon)
Contrast enhanced ultrasound with microbubbles can be used to evaluate _____________.
tissue perfusion
cat given BIPS 12h ago; retention in the duodenum. This is highly indicative of an obstruction. There is reduced serosal contrast in the mid-right abdomen. Ultrasonographically, there was plication of the jejunum. At surgical exploration, several perfora- tions had been caused by fishing line foreign material.
what can zinc cause if ingested (FB)?
hemolytic anemia from acute zinc toxicity. Hemolytic anemia from Zn toxicity is characterized by the formation of Heinz bodies. e.g. dice, u.s. coins
An acid pH is necessary for release of free Zn to cause the toxicosis, which can occur over a period of just a few days. Importantly, by the time of radiography the foreign objects may have moved into the small bowel, which decreases the suspicion for Zn toxicity.
How does mechanically obstructed bowel generally differ from functionally obstructed bowel?
- it’s larger
- contains both fluid/gas (functional usually just gas)
- there are 2 populations (functional, usually uniformly abnormal)
How does mechanically obstructed bowel generally differ from functionally obstructed bowel?
a) Mechanically obstructed bowel is smaller in diameter
b) Functionally obstructed bowel is fluid-filled
c) Mechanically obstructed bowel is usually larger in diameter
d) Functionally obstructed bowel contains both gas and fluid
c) Mechanically obstructed bowel is usually larger in diameter
obstructed or not?
yes, >1.6x L5 body height
ratio of 1.95 (SI diameter:L5 height)
gives what probability of obstruction?
77-80%
Which ratio (SI diameter:L5 height) gives a probability of 86-90% of obstruction?
2.07
Which ratio (SI diameter:L5 height) usually rules out obstruction?
<1.4-1.6
In a series of cats, when the maximum small intestinal diameter to L2 vertebral endplate height was _______ gastrointestinal disease was present, and at a ratio of _____, the most likely abnormality was intestinal obstruction
> 2.0 (GI disease/ function ileus)
> 2.5 (mech obstruction)
Which presents a greater diagnostic challenge and why - acute or chronic mechanical obstructions?
Acute; distension may not have developed yet, and if vomiting and proximal still, fluid/gas may reflux into the stomach and outwards.
What is the gravel sign?
accumulated dessicated ingesta within intestine orad to a chronic partial obstruction
gravel sign in a cat with distended ileum due to ileal adenocarcinoma
In vomiting dogs, ultrasound findings of a jejunal serosa-to-serosa measurement of more than ______, with normal wall layering, and a fluid-filled or gas-filled lumen should prompt careful interrogation of the bowel for an obstructive lesion
1.5 cm
cat with a linear foreign body.
For which species are linear FBs twice as fatal?
dogs (compared to cats)
which species is more prone to secondary intussusceptions following linear FBs?
dogs
Where do the majority of intussusceptions occur?
ileocolic or cecocolic junction
What is commonly pulled into the intussuscipiens and appears hyperechoic, making the whole intussusception structure slightly asymmetrical?
mesenteric fat
linear foreign body in a cat
a) fat cat with a linear FB
b) fat cat without a linear FB
fat in fat cats causes relative clumping, but look at the serosal border of cat A - it’s more undulating. contrast studies can help.
What can Doppler blood flow tell you about the intussusception?
Good blood flow to the intussusceptum is a good predictor of reducibility.
What US parameter can tell you about the reducibility of an intussusceptum?
Doppler / blood flow - good blood flow, better outcome
US, cat with linear FB
dog with an ileocolic intussusception; This intussusception has not caused jejunal dilation, probably because the obstruction is not complete. The leading edge of the intussusceptum (black arrows) is visible in this patient as a round mass contrasted by colon gas. This appearance could be caused by a colonic foreign body but is more typical of an intussusception, and ultrasound should be performed for confirmation.
What is the SI:L5 ratio in CT that gives a 79% sens / 72% spec?
2.5
What causes functional ileus (broadly)?
vascular or neuromuscular abnormalities
Chronic mechanical obstruction can lead to functional ileus - true or false?
True; the previously ‘ normal ‘ intestine becomes fatigued.
Mesenteric volvulus results in occlusion of the ______________ (which vessel).
cranial mesenteric artery
Which layer is affected in chronic intestinal pseudo-obstructions in dogs and cats?
tunica muscularis - fibrosis and atrophy
(apparently not involving myenteric plexus)
What is the appearance of the GI tract in dysautonomia?
focal or diffuse GI dilation
transit time (contrast) is markedly delayed
US findings of parvovirus
- fluid-filled small bowel
- absent peristalsis
- decreased thickness and hyperechogenicity of the MUCOSA
- indistinct jejunal wall layers
- normal jejunal lymph nodes.
Benign adenomatyous polyps of the duodenum are found in what cat breeds?
Asian
Asian cat breeds are overrepresented for which types of lesions in the duodenum?
benign adenomatous polyps
What percentage of cats with alimentary lymphoma have the mass form?
75%
In 150 dogs, _____________ was the most predictive feature for differentiating between enteritis and neoplasia.
loss of wall layering (more common in neoplasia)
What percentage of cats with alimentary lymphoma have mesenteric lymphadenomegaly?
about 50%
what may help with distinguishing ibd from lymphoma in cats?
lymphoma cats are older, more commonly have thicker muscularis and lymphadenomegaly
Which intestinal changes are caused by Heterobilharzia americanum?
Canine schistosomiasis causes focal SI wall mineralisation. Identified dogs have been reported to be hypercalcemic.
How is PLE distinguished from idiopathic IBD or food-responsive enteropathy, on US?
Mucosal hyperechogenicity due to vertical striations, caused by lymphangiectasia
(plus, secondary findings: effusion, pancreatic edema)
(compared to hyperechoic speckles, being oriented in a horizontal or focal dot pattern, found in IBD/food-resp)
What kind of GI lesions does Pythiosis produce?
Pyogranulomatous lesions cause localized thickening of the intestinal wall that frequently extends through the serosa, along the mesentery, and into the mesenteric lymph nodes. The sonographic features are like those of intestinal neoplasia.
both have mucosal hyperechogenicity, but the left has vertical striations that represent dilated lacteals, consistent with PLE. unknown diagnosis on the right.
Which types of drugs, when ingested, might cause metastatic calcification in the GI tract from hypercalcemia?
- cholecalciferol-based rodenticides
- human antipsoriasis ointment containing calcitriol analogues
3 criteria for a duplication cyst
- an intimate association with the gastrointestinal tract
- a well-developed muscular layer (which is continuous with the associated bowel)
- an epithelial lining
but the lumen does not communicate with the intestinal lumen
*usually on the mesenteric side
how is a diverticulum different from a duplication cyst?
Typically the wall of the diverticulum contains the expected wall layering (rather than just muscle and epithelium) AND the lumen of the diverticulum communicates with the bowel.
also diverticulae are usually found on the antimesenteric side.