Abdomen Flashcards
Diagnostic imaging
Describe the systematic approach to the abdomen ?
Systematic approach to the abdomen
- Peritoneum and retroperitoneum
- Solid organ (kidney, liver and spleen)
- abdominal masses
- caudal abdomen
- Bladder and urethra
- vomiting / gastrointestinal tract
Describe the anatomical difference between the peritoneum and retroperitoneum, how could we differentiate these ?
Pertoneum and Retroperitoneum
These are 2 seperate compartments in the abdomen which do not communicate.
Pertoneum
The serous membrane lining the abdominal cavity. Most abdominal organs are inside the peritoneum.
Retroperitoneum
This is the space in the dorsal abdomen (outside the peritoneum) between the peritoneum and the dorsal abdomen
- contains kidneys, ureters, adrenals
- retroperitoneum communicates caudally with the pelvic cavity and cranially with the mediastinum
The retroperitoneum can only be assessed on lateral projection.
Identify this pathology on radiograph ?
Pathology reduced serosal detail
Identify by how well the organs are seen in the abdomen
- called serosal detail because the serosa is the outside layer of organs.
- decreased serosal detail indicates abdominal fluid but there can be imposters.
Describe what other imposters could cause decreased serosal detail ?
Describe what you could do to upon finding reduced serosal detail to determine if there truly is abdominal fluid ?
AFAST
AFAST is a point of care ultrasound that just looks for abdominal fluid
ultrasound is more sensative than radiology for abdominal fluid.
Identify this pathology and its potential causes ?
Pneumoperitoneum
This is gas in the peritoneal space
Caused by
- latrogenic laparotomy
- from the outside, bite wounds, hit by car, gun shot
- from the inside; rupture of the GI tract (other causes are uncommon)
What are the radiographic signs of Pneumoperitoneum ?
Pneumoperitoneum - radiographic signs
- Gas bubbles
In areas where there are no intrstines, in the falciform fat in the cranioventral abdomen. - Diaphragm - visualisation of both sides of the diaphragm
- due to gas against the abdominal side of D
- less common and is only usually seen when there is a greater volume of gas.
If in doubt - do a horizontal beam radiograph
Upon a lateral radiograph you suspect pneumoperitoneum, what should be your next step ?
If in doubt do a horizontal beam radiograph
You suspect pneumoperitoneum post spay; is the gas due to surgery or is new gas being introduced eg dehiscence ?
Spey
Spey healthy small incision - 24 -48hrs
exploratory laparotomy large incision and longer surgery about ten days.
The cut off is two weeks
after this time it is likely due to a new gas leak eg. dehiscence
(up to this point rely mostly on clinical signs to determine dehiscence).
Describe the technique for carrying out a horizontal beam radiography ?
Horizontal beam radiography
(carry out when we suspect pneumoperitoneum)
Technique
- X ray beam is horizontal to the floor (care)
- casette on the opposite side of the animalwith the edge of the casette on the table
- sensitive 2-5ml of free gas
- centre the beam on the diaphragm at the highest point of the animal
- place foam mat under the animal to elevate it above the cassette
- elevate chest + gently massage animal to dislodge gas
- dorsal recumbancy is most sensitive and easiest to interpret, but any recumbancy can be used.
Ensure animal has been positioned for a minimum of three minutes before taking an exposure.
Describe the steps you would take to assess the retroperitoneum ?
Assessment of the retroperitoneum on radiograph
Use the lateral view only
- how well can i see the muscles ventral to the spine
- is the normal fat opacity seen
- are the kidneys well defined (kidneys are well seen in the cat as they are surrounded by fat, this is not always the case in the dog).
Identify this pathology and its possible causes ?
Pathology = decreased retroperitoneal detail
(due to increased soft tissue opacity from fluid)
The cause (2 clinical scenarios)
1. trauma
causes are haemorrhage or urine (ruptured ureter) - next step excretory urogram
2. Spontaneous
Usually due to a bleeding adrenal gland mass
- next step abdominal ultrasound
Describe your next step when you have a patient with a history of trauma, and decreased retroperitoneal detail ?
Trauma
haemorrhage or urine (ruptured ureters).
Next step Excretory urogram (EU)
- determine if the ureters are intact, if they are it must be haemorrhage
- contrast is injected intravenously and evaluated on radiographs or CT as it is excreted into the bladder and ureters
Two indications
- ectopic ureter evaluation
- ureter rupture post trauma
Treatment
Ureter rupture is treated surgically
Haemorrhage is treated medically
Identify the imaging modality
- is there abdominal fluid ?
- Is fluid in the retroperitoneum or peritoneum ?
- Trauma is there a ruptured ureter ?
- identify the retroperitoneal fluid without trauma ?
Answers imaging modality
- AFAST as radiographs are less sensitive
- lateral radiograph
- excretory urogram
- ultrasound, CT usually requires a specialist
Know which imaging modality (radiographs, ultrasound or contrast study) is best for which indication in the kidney ?
Kidney imaging evaluation
- Plain radiographs
- only exception for use is to view minerlisation - Ultrasound
- best modality, not difficult
- large replaced contrast procedures for the unrinary tract - Contrast study
Excretory urogram; used to assess ureters (which are not normally seen on ultrasound or radiograph).
Describe the normal location of the kidneys ?
The right kidney is more cranial, righty tighty
Left is lower
Describe how the use of the triad can help identify the kidney on a ventral radiograph ?
Triad
Right kidney is not visable in most dogs on the VD view.
Triad
Spleen
kidney
stomache
Describe how you could assess kidney size ?
Kidneys
Assess two things
- same size as each other
- normal size compared to L2
Size compared to L2
- this comparison can only be made on the VD view (kidneys are a similar view from the imaging plate).
- cat: 1.9-2.6
- Dog: 2.5-3.5
Identify this pathology and the best modality for its diagnosis ?
Radiograph minerlisation
(lateral view is best) prevents colon superimposing on the kidneys
Common in cats and dogs;
- calculi in renal pelvis
- can have no clinical significance unless calculi pass into the ureter and become stuck
- causes hydronephrosis
- ignored if renal function is normal
The significance is assessed by labwork
- renal enzymes, SDMA and USG
Identify and describe this pathology of the kidneys ?
Chronic renal insufficiency
Both kidneys are small compared to L2
Very common in cats; uncommon in dogs
- almost expected in an old cat
Identify this pathology ?
End stage kidney disease
ultrasound
usually unilateral
Identify this pathology via ultrasound ?
Renal dysplasia via ultrasound
easily diagnosed by ultrasound
- abnormal appearance of kidneys in a young dog
- appears the same as end stage kidney but in a young animal and bilateral
Degenerative kidney changes are commonly observed on ultrasound, if observed what should be our next steps ?
Renal work renal enzymes SDMA and USG
Identify and describe this pathology on ultrasound ?
Renal lymphoma
(more common in cats)
Bilateral renomegaly >4.3cm
- this may occur without disease in a large cat/ normal
- on ultrasound changes are diffuse so kidney appears normal
- hyperechoic whiter kidney
- hypoechoic black rim around them
Dx - Fine needle aspirate only usually used for masses and nodules
Identify this patholgy
Polycycstic kidney disease
large kidney with an irregular margin
Describe how we could diagnose acute renal failure / considering the kidneys appear normal on ultrasound ?
Acute renal failure
Kidneys usually look normal on imaging
- may appear smaller on follow up ultrasound images
- not detected initial ultrasound as within normal reference range
You have a case of big kidney little kidney what do you do ?
Found on ultrasound one big kidney and one small
Asymetric kidney size
Very common in cats, less common in dogs
- caused by chronic pyelonephritis or ureter obstruction
- often not detected when first kidney affected, recover after a few days and then the other kidney hypertrophies to take on extra function
- same process second kidney
- present renal failure
This process may be able to be reversed in the second kidney.
What to do
Ultrasound - to look for hydronephrosis (obstructed ureter)
Culture urine = pyelonephritis
What is pyelonephritis, and how can we identify this pathology ?
Pyelonephritis
One or both kidneys are infected.
Often found to appear normal on ultrasound
- small amount of fkuid within the renal pelvis (pyelectasia)
There are however many causes for pyelonephritis
IV fluids, renal insufficiency, PU/PD
How do you identify hydronephrosis on ultrasound and what are its potantial causes ?
Hydronephrosis
Identify
- severe dilation of the renal pelvis
- ultrasound
- excretory urogram
Causes
- obstruction downstream of pelvis eg calculus in the ureter
Describe the role of radiography, ultrasound and CT in the evaluation of the liver and gall bladder ?
Modality for liver assessment
Radiography
- used to assess gastric axis and liver size
Ultrasound
- nodules and masses, may not be seen in radiographs
- diffuse liver disease
- gall bladder
Biopsy
- diffuse parenchymal disease
CT
- parenchymal disease (mass, abscess)
- helps assess if liver masses are surgically retractable
- portosystemic shunts
Describe the role of ultrasound when it comes to evaluation of the liver ?
Describe which image modality is most appropriate for assessment of the kidney, ruptured ureter, obstructed ureter and ectopic ureter ?
The best image modality
Kidney = ultrasound
Ruptured ureter = excretory urogram
obstructed ureter = ultrasound specialist
ectopic ureter = CT
Describe how you could assess the size of the liver ?
Assess the liver size through the gastric axis
(lateral radiograph)
Gastric axis = line between the fundus and pylorus.
- pylorus must be seen to make a gastric axis (not always possible)
- location of the fundus can be presumed if not seen (cranial dorsal abdomen next to diaphragm) held there by the oesophagus
Normal axis
- perpendicular to the spine
- or parallel with the ribs
- any change in the axis is only due to change in the location of the pylorus - pendulum.
Describe all factors which could influence your interpretation of the size of the liver ?
Liver size
The gastric axis may appear different
- on right vrs left lateral
- conformation eg barrel chested dogs (brachys it appears larger) or deep chested dogs
- young animals liver is relatively larger
- obese
- geriatric (stretching of the ligaments that attach the liver to the diaphragmso the liver sags further caudally in the abdomen)
Identify this pathology ?
Hepatomegaly
- caudal displacement of the gastric axis
- rounding of the caudoventral margin
- subjectively more liver on the ventral view (greater distance between the diaphragm and stomach)
- U shaped stomache on ventral view
Great you have identified hepatomegaly, what is your next step ?
Hepatomegaly and your next step
It can be normal for a patient so assess your
Blood work
Ultrasound liver for masses and nodules
- Test for Cushings clinical signs + bloodwork
FNA
- can be used to rule out lymphoma
- masses and nodules to rule out neoplasia and fungal granulomas.
Identify this pathology ?
Microhepatia
- cranial displacement of the gastric axis
- subjectively less distance between the diaphragm and the stomach on VD
Great you have identified microhepatia, what should you do now >
Microhepatia
It is usually normal for the patient
- cirrhosis ultra specialist
- portosystemic shunt CT specialist
- if there is no indication of these diseases on blood work, then it is normal.
What is a portosystemic shunt and what is the best image modality ?
Porto systemic shunt
CT - specialist
Describe this change ?
Minerlisation of the biliary tract
(liver opacity)
Normal liver opacity is soft tissue opacity
- minerlisation of the wall of the biliary tract
- mineral opaque branching structures
No clinical significance
Identify and describe this pathology ?
Hepatic abscess
Predisposed
- diabetes mellitus
- biliary disease
- pancreatitis
25% have gas producing bacteria - and gas can be seen on radiograph
Describe the location of the gall bladder in a cat and dog ?
Gall bladder location
Cat
- ventral margin sometimes seen / ventral to the liver
Dog
- not seen
- ventral right side of spine central
- ventral on a lateral view in the centre
Identify this pathology ?
Cholelith
- calculi in the gall bladder are common
- no clinical significance
Describe how you would determine the thickness of the wall of the gall bladder ?
Ultrasound
hypoproteinaemia
portal hypertension RSHF
Identify and discuss this pathology ?
Gall bladder Mucocoele
A semi solid mucoid material replaces normal bile in the gall bladder
Dogs only
- ultrasound
- 7-44% unsymptomatic
- TX = surgery even if they are asymptomatic
Describe the location of the spleen in cats and dogs ?
Spleen location
Head
- VD view only
- every cat and dog
- use the triad stomache and left kidney to identify it
Tail
- only seen on lateral view
- normal to be seen or not seen in dogs
- should not be seen in cats (it indicates splenomegaly)
Identify this pathology and describe its causes ?
Splenomegaly
Assessed subjectively
Dog
- ‘normal’ size is variable
Cat
- less variable, if tail visable splenomegaly
- ultrasound >12mm FNA to rule out neoplasia/ lymphoma
Describe the potential causes of splenomegaly ?
Causes of splenomegaly
- normal in some breeds eg German sheperd
- anaesthesia/sedation
- neoplasia / lymphoma
- torsion - rare
Provide a definition of organomegaly, mass and nodule ?
How can we different these ?
Definitions
Generalised organomegaly
- the whole organ is enlarged eg renamegaly, hepatomegaly
Mass
- A mass is a focal enlargement >2cm
Nodules
- These are a focal enlargement < 2cm, often undedectable on radiographs due to their small size
Sometimes on radiograph it is difficult to differentiate between organomegaly or a focal mass may require referrel for CT.
Define mass and mass effect ?
Definitions
Mass
The actual mass itself > 2 cm
Mass effect
The displacement of organs away from their normal location by the mass. The intestines are the most mobile so easiest to see.
The displacement of organs can be used to indicate the mass location.
Identify the location of this mass ?
How to identify the location of a mass through the mass affect -
Mass / mass affect
- mass affect can see intestine displaced to the right on VD
- mass visable in left mid abdomen
Visability of suspected organ
- head of spleen is visable no summation not this organ
- left kidney is not visable in contact with the mass possible summation, indicating the mass is likely in this organ.
Further imaging ultrasound, CT or exploratory laparotomy is usually required to definitively determine the location.
You have found a mass, but what are they possible differentials ?
Ddx mass = Chang
C = cyst
H = haematoma
A = abscess
N = neoplasia
G = granuloma
Disscuss how you could accurately describe a mass ?
Use the Roentgen signs
- Size
- Shape
- Margins
- Opacity
- Number
- Location
Use your knowledge of the Roentgen signs to describe this mass ?
Mass description
1. Size, usually measured
2. Shape oval
3. Number = one
4. Margins definitive margin ventrally
5. Opacity fat opacity, which is unusual as most masses are soft tissue opacity.
6. Location = dorsal right abdomen, potentially retroperitoneal
What radiographic signs would be seen to identify a cranial mass ?
Cranial mass
- mass in the cranial abdomen
- caudal displacement of the stomach
- if the mass is in the stomach or caudal to the stomach then the stomach will not be caudally displaced, but the small intestine will be caudally displaced.
Describe the differentials of a identified cranial mass on radiograph ?
Cranial abdominal mass Ddx
- liver (most common)
- dilated stomach
- stomach wall mass, gall bladder, pancreas but these are extremely rare
Identify the location of this mass ?
Liver mass in the right side of the liver
- cranial mass
- displacement of stomach caudally and to the left
Identify the location and pathology ?
Dilated stomach
- know mass is cranial
- caudal caudal caudal to locate liver margin
- stomach is not displaced
- intestine displaced to the left and caudally
What are the radiographic signs of mid abdominal mass ?
Mid abdominal mass
Mass observed mid abdomen
- small intestine displaced cranially, caudally and dorsally
- loss of serosal detail due to haemoabdomen can be present due to a bleeding splenic mass.
What are the four locations within the abdomen we can view a mass ?
What are the differentials for a mid abdominal mass ?
Mid abdominal mass Ddx
- spleen (most common by far
- pedunculated hepatic mass - connected to liver by a stalk
- uncommon intestine + usually present with GIT signs
(caecal masses may not present with GIT signs) - mesenteric mass (usually very large mesenteric lymph nodes (central abdomen on all views).
Why can we not use displacement of the gastric axis to find to identify the location of a mass?
Identify the mass ?
Splenic mass
- displacement of intestine caudally, cranally and dorsally
- visualisation of mass
You identify a splenic mass what your next step ?
Splenic mass
Not all are haemagiosarcoma or a death sentence
Do not euthanase without histopathology
- 1/3 benign haematoma
- 2/3 malignant usually haemangiosarcoma
- many different types of masses can bleed
- all large masses in any organ should be removed even if benign, especially cavitated masses
FNA in solid mass lymphoma can be treated medically
cavitated mass remove entire mass due to high risk of bleeding
Identify this pathology ?
Mesenteric mass
- central abdomen on all views
- rarely get this large
- usually due to a huge mesenteric lymph node
Identify this pathology ?
Retroperitoneal mass
Left renal mass
- opacity soft tissue
- location mid right dorsal abdomen
- displacement of colon ventrally
- summation with left kidney
What are the radiographic signs of a retroperitoneal mass ?
Retroperitoneal mass
Dorsal aspect of abdomen even when the mass becomes large
- ventral displacement of colon
- kidney and adrenal most common
Discuss the differentials for a retroperitoneal mass ?
Retroperitoneal mass
- kidneys, neoplasia, hydronephrosis
- adrenal glands, neoplasia
- retroperitoneal fluid often causes a mass effect, ventrall displacing the colon and small intestine
Discuss the differentials for a caudal abdominal mass ?
Caudal abdominal differentials
Sub lumbar lymph nodes
Colon
Uterus / uterine stump
Bladder
Prostate
The assessment of the caudal abdomen
- always work dorsal to ventral
- location of colon entering the pelvic inlet (should be half way between the spine and pubis.
- small intestine displaced cranially
Describe how you should assess the caudal abdomen ?
Assessment of the caudal abdomen
Main points
- assess each organ from dorsal to ventral
- assess the location of the colon at the pelvis inlet (should be half way between spine and pelvis)
- assess for a caudal abdominal mass effect eg cranial displacement of intestine
Identify this pathology ?
Sublumbar LN enlargement
- soft tissue opacity
- ventral displacement of the colon (if large enough)
- usually caused by neoplasia - metastasis or multicentric neoplasia (such as lymphoma)
What are the radiographic signs for a enlarged prostate, and what are the main differentials ?
Prostateomegaly
Identification
- colon displaced dorsally
- caudal abdominal mass effect - intestine + bladder displaced cranually
Differentials
- entire dog naturally has a larger prostate
(in entire dogs prostate neoplasia = normal sized prostate as their prostate is normally small in size as it occurs usually in neutered dogs).
- benign prostatic hyperplasia, entire dogs only
- prostatitis usually entire dogs
- prostatic neoplasia = neutered dogs
Ultrasound is the best imaging modality for the prostate can also guide FNA.
Identify and disscuss this pathology ?
Prostatic neoplasia
Radiographic support of neoplasia (usually neutered dog)
- sublumbar lymph node enlargement
- periosteal new bone (metastasis) on the vertebrae and sacrum
- minerlisation in the prostate
You observe a ventral caudal abdominal mass in a female dog - discuss the differentials ?
Differentials for Uteromegaly
- pyometra
- pregnancy (no minerlisation < 45 days)
Identify this pathology ?
Pyometra
What is the best imaging modality to detect pyometra or prostatic neoplasia ?
Ultrasound
What is the best imaging modality to detect pregnnacy and provide a foetal number estimation ?
Pregnancy diagnosis
- Ultrasonud best - as early as day 10 cat / dog (usually reccomned 30 days post mating)
- radiographs must wait 45 days for the foetus to become minerlised
Foetal estimation
best to use a radiograph > 50 days most accurate, but must ensure the foetuses are well minerlised
- take two views
- count by heads and spines
When assessing the bladder what are the best imaging modalities ?
The best imaging modality to assess the bladder
- Ultrasound is the best
- inexpensive and easy
- detects bladder pathology except rupture
Plain radiographs
- most pathology is not detected on radiograph
- calculi only
Contrast studies Cystograms
- almost entirely replaced by ultrasound
- bladder rupture positive contrast cystogram to determine the size of the rupture
- more invasive, more risk
- if you have no access to an ultrasound you will have to use contrast studies
What is the best imaging modality to detect cystitis, neoplasia, calculi and rupture in the bladder ?
Best imaging modality
Cystitis = ultrasound + cystocentesis
Neoplasia = ultrasound + catheter biopsy
Calculi = radiogrphy or ultrasound
Rupture = positive contrast cystogram for location + ultrasound guided collection of fluid in abdomen for analysis to determine if it is urine.
Demonstrate an understanding of the pathology of cystitis in dogs and cats ?
Cystitis
Dog
- bacterial
- most common in bitches
Cat
- idiopathic cystitis (sterile), bacterial cystitis is uncommon
- both females and male cats
- male cats may obstruct, a common presentation in practice
Describe what you would see and imaging modality used to detect cystitis ?
Cystitis = ultrasound
- often the bladder appears normal
- thickened bladder wall - cranioventrally (where the urine sits)
- sediment sludge in the urine, sometimes seen
Radiographs are useless bladder appears normal
Describe how you would identify neoplasia in the bladder ?
Neoplasia bladder - imaging findings
Ultrasound required
- irregular thickened wall
- most urothelial cell neoplasms are located in the trigone region (must always ultrasound to assess if the mass has obstructed the ureters).
Must confirm diagnosis
- ultrasound guided catheter biopsy
- no FNA
Describe how you would identify a bladder rupture ?
Bladder rupture
Best AFAST - free abdominal fluid (appears as a normal empty bladder)
Radiograph - loss of serosal detail
Confirmation of a ruptured bladder
Positive contrsat cystogram = location
Abdominocentesis = creatine to potassium ratios
Describe the pathology and imaging modality to identify calculi in the bladder ?
Bladder calculi
Both dogs and cats, may be located in the kidneys, ureters, bladder or urether
- often obstruct in the narrowest region of the urinary tract
Ultrasound best - can detect all calculi
Radiograph - mineral opacity
+ urate are the most common type of calculi (soft tissue opaque and effece with urine)
+ dalmation dogs or portosystemic shunt
Describe a double contrast cystogram ?
Double contrast cystogram
Indications = calculi not detected on radiograph or ultrasound
- both air and positive contrast agent (iohexol) is instilled into the bladder
- contrast settles in dependant part of bladder
- diplacement of calculi ‘filling defect
You identify a calculis, but are unable to distinguish its location between the colon and bladder - what to do ?
Compression study
To seperate the colon and small intestine
- prevents superimposing the colon on the bladder
- bone colon - calculi bladder
- apply gentle pressure with a wooden
Describe the normal anatomy of the urethra ?
Normal anatomy of urethra - dog
Divided into three parts
- prostatic
- membranous
- penile
What is the best imaging modality for assessment of the urethra ?
Urethra imaging
Ultrasound t
- proximal and intraabdominal urethra is visable cranial to the pelvis
- the portion within the pelvis is invisable as it becomes shadowed by the bony pelvis
Plain radiograph
- well visualised urethral calculion well positioned radiograph
- cats (iodiopathic cystitis is rarely seen on radiographs, but imaging is sometimes performed to screen for calculi).
Positive contrast urethrogram
The best imaging modality to assess the entire urethra
- rupture
- obstruction, especially not seen on radiograph
- commonly performed in male dogs / rarely cats or bitches
Identify this pathology ?
Urethral obstruction
Normal lateral view
- usually observable if the majority of the perineum is included.
Bum view
- legs pulled cranially so that they do not superimpose on the urethra
Describe the indications and procedure for a urethrogram ?
Normal urethrogram
positive contrast is injected into a Foley catheter that is inserted inside the urethra
- completely fill catheter prevent air bubbles
prostatic narrower
membranous wider
Indications
filling defect some type of obstruction
- neoplasia, calculi, stricture
- extravasation indicates a rupture of the urethra
What is the best imaging modality to identify a bladder calculi, urethral calculi, urethral rupture, bladder neoplasia, bladder rupture and prostatic disease ?
The best imaging modality
Bladder calculi = ultrasound
Urethral calculi = positive contrast
Urethral rupture = positive contrast
neoplasia of the bladder = ultrasound
bladder rupture = positive contrast cystogram
prostatic disease = ultrasound
