Gastrointestinal Tract Flashcards
Normal stomach anatomy:
What is highlighted in this stomach? What other structure is seen?
fundus
accumulation of gas outlines rugal folds
What is highlighted in this stomach? In what projection is it better visualized?
gastric body
VD - gas is not gravity dependent
What is highlighted in this stomach?
pylorus
What is the normal anatomy of the stomach on the left lateral projection?
- fundus dependent (down) = fluid-filled
- pylorus and proximal duodenum non-dependent (up) = gas-filled
What is the normal anatomy of the stomach on the right lateral projection?
- pylorus dependent (down) = fluid-filled
- fundus non-dependent (up) = gas filled
What is a pyloric pseudomass? How can it be ruled out?
seen on right lateral projection when the pylorus is fluid-dilled and resembles a mass
take a left lateral and VD radiograph, where it will be gas-filled
How does the normal feline stomach compare to canines?
slightly to the left of midline with the pylorus slightly to the right on VD
How does the small intestine position differ in felines?
lack of segments within the left abdomen due to increased fat deposits
What is being pointed to in this radiograph?
wet hair artifact - likely due to a previous ultrasound
What is being pointed to in this radiograph? How is it comfirmed?
normal fat within gastric submucosa that can resemble a FB, best seen on an empty stomach
- CT = hypoattenuated fat
- U/S = hyperechoic
What is the normal size of the canine small intestine?
< 1.4x height of L5
< 2x minimal small intestinal diameter
When is the canine small intestine considered dilated? When is mechanical obstruction of high concern?
1.4-2.4x height of L5, 2-3.4x minimal small intestinal diameter
> 2.4x height of L5, >3.4x minimal small intestinal diameter
What is the normal size of the feline small intestine? In what way is it different than canines?
12 mm in width from serosa to serosa
- very little gas - not as aerophagic as dogs
- lack of size variation in felines makes ratios not necessary
What unique feature of the feline small intestine is observable on radiographs?
normal segmentation and peristalsis = “string of pearls”
Are obstructions common in the colon?
no - if an FB made it this far, it will likely be excreted with feces
- contrast studies help with observation
What positive contrasts are commonly used for colon studies? What are the 2 indications for performing this?
barium and iodine —> radioopaque
- vomiting
- suspected dysmotility
What are 2 contraindications for performing positive contrast used for colon studies?
- intractable vomiting - aspiration risk
- possible GI rupture
What are 2 negative contrasts used for colon studies?
- room air - readily available and safe
- CO2 - more commonly used for urinary tract
What are 5 uses of contrast studies?
- can more accurately view mucosal surface
- allows evaluation of GIT wall
- visualized motility
- locates regions of GIT
- located obstructions
What is occurring in this radiograph?
double contrast gastrogram - barium + air
- lack of positive contrast in fundus, likely due to some kind of FB (intraluminal filling defect)
- can observe normal striation of feline esophagus
- can observe normal rugal folds in the pylorus
Feline upper GI study:
- normal gastric filling with positive contrast
- normal string of pearls = peristalsis
What 2 specific large intestinal contrast studies are performed?
- pneumocolon - sedation, delineates path of colon to rule in/out gas dilation of small intestine on survery radiographs
- barium enema - heavy sedation or GA, barium sulfate suspension through Foley catheter and enema bag
Pneumocolon:
room air differentiates it from small intestine
What is the primary differential for vomiting patients?
GIT obstruction - animals love to eat things they shouldn’t!
Normal canine stomach:
LL = fluid in fundus, gas in pylorus
RL = fluid in pylorus, gas in fundus
What is mechanical ileus? What is the most common cause?
FOCAL - dilation of a segment of the GIT
obstructions of the GIT - luminal, mural, extra-mural
What is functional ileus? What is the most common cause?
GENERALIZED - more mild dilation of the entire GIT
GIT paralysis or decreased motility caused by infection, inflammation or toxins
GIT, Roentgen signs:
What Roentgen signs are associated with distension of the GIT? Mechanical vs functional ileus?
SIZE - anatomy, measure diameter, use ratios
SHAPE - relaxed, hairpin turns, stacking, plication
LOCATION - segments affected
NUMBER - amount of segments affected
What are the 3 major etiologies of mechanical obstruction?
- LUMINAL - FB, intussusception
- MURAL - neoplasia, infection, inflammation, stricture
- EXTRA-MURAL - infarction, intestinal volvulus, external compression
What is pyloric outflow obstruction? What are 3 common causes?
mechanical obstruction of the stomach leading to gastric distention
- luminal FB
- hypertrophic gastropathy (mural) common in small breeds
- mural neoplasia
What is likely occurring in this radiograph?
- stomach full and extending beyond the 13th ribs
- contraction at pylorus with thickened walls
- no contrast beyond the contraction = decreased outflow
PYLORIC OUTFLOW OBSTRUCTION
What are the 3 radiographic signs of gastric dilatation volvulus? What is a common secondary sign?
- craniodorsal displacement of pylorus over fundus
- ventral displacement of fundus
- compartmentalization = soft tissue band caused by folding of gastric wall between the 2 gas-distended stomach compartments
vascular congestion = splenomegaly
What is considered the gray zone of segmental intestinal dilation?
1.4-2.4x height of L5
between 2-3.4x minimum small intestinal diameter
- need further testing, like repeated radiographs or U/S
What are the 2 populations of small bowels with mechanical obstruction?
- distended portion orad to obstruction
- normal small intesting aborad to obstruction
What is seen in this contrast study?
normal aborad movement of contrast until it abruptly stops at a dilated segment, creating concave a filling defect indicative of a luminal, round FB
What is seen in these radiographs?
all of intestine is uniformly dilated with no indication of peristalsis = functional ileus
What is megacolon? How is it differentiated?
functional disease common in cats, causing the development of a feces-filled colon
- NORMAL = <1.28x length of L5
- MEGACOLON = >1.68x length of L5
- CONSTIPATION = 1.48x length of L5
What is colonic torsion?
colon twists around its longitudinal axis, causing severe dilation and mal-positioning of the colon
- surgical emergency
- common in dogs
How do patients with linear foreign bodies typically present? What is seen on their radiographs?
vomiting, anorexia, abdominal pain
NOT CLASSICAL SIGNS OF MECHANICAL ILEUS
- no dilation
- tortuous, irregular margins
- abrupt changes in direction
- plication: focally gathered/bunched
Where are linear foreign bodies most commonly anchored?
- CATS = base of tongue
- DOGS = pylorus
