Module 17 Week 1 Flashcards
(Diagnostic Imaging of the Urinary System)
Why is a plain radiograph limited for imaging the urniary tract?
- Soft tissue & fluid same opacity
- Cannot distinguish between urinary fluid or renal parenchyma
- kidney and bladder may not be clearly visible esp R kidney
What are radiographic contrast studies used for?
Performed when ultrasound is unavailable
Helps assess specific structures
What structures can be assessed with contrast studies?
Intrapelvic structures
Urethral rupture
Bladder rupture
What are the types of contrast media?
Negative contrast: Air, CO₂
Positive contrast: Iodine-based contrast medium
What must be done before a contrast study?
Take plain radiographic images
Perform an enema (if remembered)
What is Intravenous Urography (IVU)?
A contrast study to visualise the kidneys and ureters
Uses an iodine-based contrast medium
How is contrast administered in IVU?
Injected intravenously into the cephalic vein
What does IVU demonstrate?
Highlights the kidneys and ureters on radiographs
What kind of contrast does a positive contrast cystogram use?
Iodine contrast medium
How do you perform a positive contrast cystogram and what does it allow you to assess?
Catheter into the bladder allowing you to assess bladder position and if there are any ruptures.
What contrast does a negative contrast cystogram use?
Air/Co2
What does a negative contrast cystogram allow you to assess?
bladder position and wall thickness
What contrast types does a double contrast cystogram use?
1-5ml contrast then air
What does a double contrast cystogram assess?
Position, luminal content and wall thickness
Who is a retrograde urethrogram performed on?
Males only
Where is the catheter placed in a retrograde urethrogram?
Distal urethra
hat structures does a retrograde urethrogram demonstrate?
The urethra
The prostate (if abnormal)
How is a retrograde urethrogram performed?
A catheter is placed in the distal urethra
Contrast medium is injected
X-rays are taken to visualise the urethra
Who is a retrograde vaginourethrogram performed on?
females only
Where is the catheter places in a retrograde vaginourethrogram
Through the vulva
What structures does a retrograde vaginourethrogram demonstrate
vestibule
vagina
urethra
How is a retrograde vaginourethrogram performed?
A catheter is inserted through the vulva
contrast medium is injected
x-rays are taken to visualise
Where should you fan the US probe when doing an renal US to view long axis?
Fanny from laterally to medially to see the entire organ
Where should you fan the US probe when doing an renal US to view short axis?
Fan through to ensure you scan the entire organ
How might you scan to view right kidney?
It can be more difficukt to image so can scan between ribs
Compare cat kindeys to dogs lol
Cats be having more mobile kidneys so variable positions
They have a more rounded outline
What should you assess when doing a renal assessment an what compnents of the kidney should you identify?
Assess: Location, Size, Shape and Margins
Components: Cortex, Medulla, Corticomedullary junction, Pelvis and (ureter)
What is Echogenicity
The ability to bounce an echo
What is echotexture?
the visualized internal composition or pattern of echoes within an individual structure
If there is diffuse parenchymal chnages what is on you DDx?
- Acute renal disease / failure
- Chronic renal disease
- Renal dysplasia
- Chronic endstage kidney
- Neoplasia eg lymphoma
If there is pelvic dilation/hydronephrosis what is your DDx
- Obstruction
- Pyelonephritis
- Neoplasia
Describe what you would see on ultrasound of a patient with acute renal disease?
rounded, hazy kidney
What conditions are associated with reduced corticomedullary definition (hypertonicity)?
Nephritis
Tubular necrosis
Acute renal failure
What might you see in a case of ethylene glycol toxicity?
Hyperechic cortex +/- corticomedullary rim sign
What changes can be seen with chronic renal disease?
- Often bilateral
- Heterogenous cortices
- Reduced cortico-medullary definition
- indentations suggest old infarcts
What chanages can be seen with renal dysplasia?
- Loss of corticomedullary definition
- Distorted outline / abnormal shape
What is pelvic dilation or hydronephrosis best seen with?
Short axis
What are key features of ureteral obstruction on imaging?
Pelvis retains a normal shape
Ureter visible up to the point of obstruction
What should you check for when assessing ureteral obstruction?
Bladder neck
Other kidney
What are the internal causes of ureteral obstruction?
Pyelonephritis
Neoplasia
How does neoplasia affect the renal pelvis?
Causes irregular or abnormal shape of the pelvis
Leads to disrupted architecture
What are focal renal changes?
- Neoplasia
- Calculi
- Cysts
- Abscesses
What do calculi look like on US?
Hyperchoic with shadowing
Where are calculi located?
Calyces/pelvis
How do cysts on kidneys appear? where are they located?
anechoic/cloudy and located anywhere?
Why might cysts occur in the kidney?
- Congenital
- Associated with chronic inflammation
- Polycystic kidney disease (PKD)
T/F renal abcesses are hard to Dx from cysts?
True
What should the thickness be of the echogenic wall of the bladder?
1-2mm
what are the two components of the echogenic bladder wall?
- serosal layer hyperchoic line
- mucosal layer
If there are changes to the bladder wall what is your DDx?
- Cystitis
- Mass - neoplasia or inflammatory polys
- Rupture
If the content of the bladder are abnormal what could be th causes?
- Calculi
- Blood clots
- Cell debris
What wall chanages is seen with cystitis?
Increase in wall thickness eitheri uniform or focally.
What are the two types of inflammatory polyps?
sessile (flat) or penunculated (with a stalk)
Withe a rupture in the bladder what do we see on US?
Free fluid and wall thickened or unchanged and extravasation of contrast.
Which types of urinary calculi are radio-opaque?
- Struvite
- Oxalate
Which types of urinary calculi are radiolucent?
- Cystine
- Urate
Mnemonic: “I can’t C U” (Cystine & Urate can’t be seen on radiographs)
What ultrasound feature is often seen with calculi?
Acoustic shadowing
How do urinary calculi behave in the bladder?
- Variable size and shape
- Mobile – They move and settle with gravity
What does radiography provide when assessing urinary calculi?
- An overview of urinary stones
- Helps check the urethra
Which parts of the urethra should be checked for calculi?
- Perineal urethra
- Os penis
Which stones are not visible on radiographs?
Urate & Cystine – Cannot be seen
What can cause gas in the bladder?
Latrogenic (e.g., introduced during catheterisation)
Emphysematous cystitis
How does emphysematous cystitis appear on imaging?
Small bubbles that adhere to the bladder wall
What could suspened contents be in the baldder?
Concentrated urine
Cell debris
Haemorrhage
Mucous
What must be done before performing a prostatic ultrasound?
Ensure the bladder is full
Why is a full bladder necessary for prostatic ultrasound?
It serves as a landmark
Helps move the prostate into the abdomen
What is the shape of the prostate on ultrasound?
Bilobed
How does the echogenicity of the prostate compare to other organs?
Similar to the spleen
What structures can be visualised in a prostatic ultrasound?
Capsule of the prostate
What should be noted about the prostate in castrated animals?
The prostate will be smaller
What should be assessed during a prostatic ultrasound?
Location
Size
Shape
Margins
Echogenicity
Echotexture
What are the parenchymal changes that can affect the prostate?
Benign prostatic hyperplasia
Prostatitis
Neoplasia
What fluid-filled lesions can be identified in the prostate?
Cysts
Abscess
Para-prostatic cyst
What is benign prostatic hyperplasia most common in?
Entire male dogs
How does a benign prostatic hyperplasia appear on US
Hyperechoic
How does Acute inflammation of the prostate present on US?
Hypoechoic
How is chronic inflammation of the prostate present in the US?
Hyperchoice and mottled
How does the prostate appear on US when neoplasia is involved?
Mottled
Mineralisation
Locally invasive
Where can prostate neoplasia mestastasis too?
lungs
What is prostatic cysts a commone finding with?
BPH
Do prostatic abscesses have distinct or indistinct margins?
indistinct
What do bladder abscess contents appear like on US?
Cloudy with a surrounding reaction
(Approach to Azotaemia and Acute Kidney Injury in Small Animals)
what is the main rolde of the kidneys?
To maintain the volume and balanced composition of the ECF.
What are the other functions of the kidneys?
- Filtration of blood & excretion of metabolic waste
- Acid-base balance
- Water/volume regulation
- Electrolyte & mineral homeostasis
- Blood pressure regulation
- Erythropoietin release- involved in creation of RBCs
What is the clinical Presentations of Kidney Disease
PUPD (Polyuria/Polydipsia)
Inappetence/Weight Loss
Depression/Lethargy
GI Signs (Vomiting/Nausea/Diarrhoea)
Ascites/Subcutaneous Oedema
Haematuria
Pain
Abdominal Mass
What is Azotaemia?
Abnormal increase in non-protein nitrogenous wastes in the blood
What does azotaemia suggest?
Suggests failure of filtration & excretion of metabolic waste.
Does Azotaemia Always Mean Kidney Disease?
No! Kidney disease ≠ azotaemia
What are the Types of Azotaemia?
Pre-Renal Azotaemia – Decreased blood flow to kidneys (e.g. dehydration, shock)
Renal Azotaemia – Intrinsic kidney disease, nephron damage
Post-Renal Azotaemia – Urinary obstruction, bladder rupture
Hoow is urea made?
Urea is made in the liver from ammonia via the urea cycle.
How is ammonia made
Ammonia is mostly made during degradation of amino acids
What Factors Affect Urea Secretion?
- Age
- Liver function
- Dietary protein content (including GI bleeding)
- Endogenous protein catabolism
- Hydration
What Factors Affect Urea Excretion?
- Renal function
- Lower urinary tract function
What is creatinine?
Creatinine is a waste product that comes from the breakdown of muscle.
What is the rate of production of creatinine?
It is produced at a constant rate which is determined by muscle mass and is then filtered in the glomerulus.
Serum concentration of creatinine is decreased with what?
Reduced muscle mass
Serum concentration of creatinine is increased with what?
- Reduced renal clearance
- Urine excretion failure (eg. urinary tract rupture)
What is the GFR?
Flow rate of filtered fluid through the kidneys
What reduces the GFR?
- Decreased renal perfusion
- Decreased renal function
- Obstruction of urine flow
Why are meaasurements of urea and creatinine used as inidrect markers for GFR?
cheap and easy tests
Describe how clinical signs work with azotaemia?
- Not all azotaemic patients have clinical signs
- Severity of clinical signs not directly proportional to magnitude of increase
- Rate of accumulation has an effect on severity of signs
What is the clinical symptoms of uraemia?
- inappetance
- Depression
- Vomiting/nausea
- Halitosis
- oral ulceration/stomatitis
- Diarrhoea
T/F All uraemic patients are azotaemic but not all azotaemic patients are uraemic
true
what are your differentials for pre-renal axotemia?
- Hypovolaemia
- Hypotension
- Aortic/renal thromboembolism
what are your differentials for renal axotemia?
- Nephron damage
- Nephron loss
What are your differentials for post-renal axotemia?
- Ureterolith
- Urethrolith
- Bladder rupture
If on history you have a animal thats not drinking and has increased losses (vom or diarrhoea) what kind of axotaemia do you potentially have?
Pre-renal
If your patients had dysuria or stranguria what kind of azotemia might you have?
Post-renal
If on history your patient they are failing to pass urine, is post-renal the only option for diagnosis?
No could be a faulure to produce urine rather than not peeing at all so renal too
If the bladder is huge and there is localised subcutaneous fluid around perineum or ventral abdomen, what type of azotaemia is most likely?
Post-renal
If there is free peritoneal fluid (urine) what kind of azoteamia is it most likely to be?
Post-renal
When should urine concentration be assessed?
Before fluid therapy
What does hypersthenuric (very concentrated) urine suggest?
Pre-renal azotaemia
Can pre-renal azotaemia have dilute urine?
Yes! If due to:
Diuretics
Steroids
Hypoadrenocorticism
What urinalysis finding suggests renal azotaemia?
Active sediment with tubular casts
What urinalysis finding suggests renal or post-renal azotaemia?
Haematuria
Whats the urine specific gravity 1.00 to 1.007 called?
hyposthenuria
Whats the urine specific gravity 1.008 to 1.012 called?
isosthnuria
Whats the urine specific gravity 1.013 to 1.055 called?
hypersthenuria
If you found a dehydrated to have hyposthenuric, isothenuric or minimla concentrated urine what would this suggest?
Problem with renal
What is renal disease?
Damage or functional impairment of kidneys with varying severity
What is renal insufficiency?
Functional impairment not severe enough to cause axotaemia but sufficient to cause loss of renal reserve
What is renal failure?
Functional impairment severe enough to cause azoteamia and urine concentrating ability is usually impaired
What is acute kidney injury?
It is a sudden and often reversible reduction of the elimination and metabolic function of the kidneys
Why are kidneys at such a high risk to being damaged?
- High blood floe
- Toxins may be secreted/reabsorbed by tubular cells
- Potential concentrating effects of toxins in urine
- Play a role in biotransformation of drugs/toxins
What things can lead to reduced renal perfusion and, ultimately, acute kidney injury?
- Dehydration
- Hypovolaemia
- Decreased cardiac output
- Hypotension
- Shock
What nephrotoxic drugs can cause acute renal injury?
- NSAIDs
- Aminoglycosides
- Doxorubicin
- Cisplatin
What infections can cause acute renal injury?
- Leptospirosis*
- Borreliosis (Lyme disease)
What toxins can cause acute renal injury?
- Lilies (cats)
- Grapes/raisins (dogs)
- Ethylene glycol (anti-freeze)
Describe the initiation phase of acute renal injury?
Something damages part of some of the nephron leading to dysfunction
Describe the extension phase of acute renal injury?
Ischemia, hypoxia, inflammation & cellular injury result in cell death & further nephron damage.
Describe the maintenance phase of acute renal injury?
Ongoing cell death occurs with cell recovery and early repair
Describe the recovery phase of acute renal injury?
Gradually reversible renal lesions are repaired & viable nephrons hypertrophy
What can you find on clinical examination of patient with acute renal injury?
- Often dehydrated
- May have uraemic ulcers
- halitosis
- Usually normal to large kidneys and could be painful
- There should also be urine produaction
How should you diagnose acute kideny injury?
- Collect blood and urine before fluid therapy
- Identify azotaemia
- rule out post-renal causes by history and clinical exam
- identify reduced urine conc ability via urinalysis
- differentiate acute from chronic kidney disease
How would you differentiate acute from chronic kindey dosease? and why?
- history, clinicale xamination, lab findings
- It affects treatment and short to long-term prognosis
What are other typical clinopathological abnormalities see with acute kidney injury?
- Initial hyperkalaemia
- Initially normal phosphate then hyperphosphataemia
- Total calcium may be high, low or normal but if marked high consider hypercalcaemia as cause
- PCV may be increases due to dehydration
What is anuria?
No urine production
What is oliguria?
output less thatn 0.25ml/kg/hr
What is polyuria?
more than 2ml/kg/hr
What is normal urine output?
1-2ml/kg/hr
What are the general principles for treating acute kidney injury?
- Remove the inciting cause
- Restore renal perfusion
- Monitor urine output and consider drugs to increase urine output
- Monitor electrolytes, acid-base balance, hydration status
- Treat uraemic complications & provide nutrition
- Investigate underlying causes
(Approach to and Management of chronic kidney disease in Small Animals)
What is chronic kindey disease?
It is a loss of functional renal tissue due to prolonged process. It is usually progessive and irreversible
Is chronic renal failure a end-stage process?
Yes obvs die
Why is CKD important?
- Prevalence of 1-3% in cats, 0.5-1.5% in dogs
- Affects animals of all ages
- Incurable diseases
- Treatment can modify disease progression
- Prolonged survival is common (especially in cats)
What are the degenrative causes of CKD?
- Chronic interstitial nephritis
- Renal infarcts
what are the developmental causes of CKD?
- Familial renal dysplasia
- Polycystic kidney disease
What are the metabolic causes of CKD?
Hypercalcaemia
What are the neoplastic causes of CKD?
- Renal lymphoma
- Renal carcinoma
What are the iatrogenic causes of CKD?
Vitamin D supplememtaion
Nephrotoxic drugs
What are idiopathic causes of CKD?
renal amyloidosis
primary glomerulopathies
What are immune-mediated causes of CKD?
Immune-complex mediated glomerulonephritis
what are the infectious causes of CKD?
pyelonephritis
borreliosis
What could CKD be a sequel too?
Urinary obstruction or acute renal failure
Descrine the pathophysiology of CKD?
CKD leads to nephron damage and kidneys have limited ways to respond. Nephrons cannot regen or replicate as nephrons are lost, remaining nephrons have to filter more blood leading to glomerular hypertension and hyper filtaration.
What can prolonged nephron injury lead to?
- infiltration of inflammatory cells
- profibrotic cytokine production
- Hypoxia leading to further injury
If number of fephrons falls below a third of normal amount what happens?
The urine concenrating ability becomes impaired
If number of nephrons falls below a quarter of normal amount what happens?
azotaemia develops
What are consequences of CKD?
- Azotaemia and uraemia – due to reduced GFR
- PUPD – due to tubular damage & fewer nephrons
- Hyperphosphataemia
- Increased PTH (renal secondary hyperparathyroidism)
- Hypokalaemia
- Anaemia
- Haemorrhage
- Hypertension
- Proteinuria
- Metabolic acidosis
What is hyperphosphatemia?
Phosphate excreted vua filtration through glomeruli
What is Hyperphosphatemia
Hyperphosphatemia is a condition in which you have too much phosphate in your blood
How is hyperphosphataemia a consequence of CKD?
Phosphate excreted via filtration through glomeruli and due to reduced Glomeruli filtration rate with CKD phospahte retained in blood.
What are the effects of Hyperphosphatemia?
unlikely to directly cause clinical signs but it does drive secondary hyperparathyroidism which leads to disease progression and reduced survival
What are the neuro effects of hyperparathyroidism?
Neurological: Likely uraemic toxin leading to depression
What are the skeletal effects of HYperparathyroidism
Skeletal: Can lead to osteopenia, tooth loosening, pathological fractures
What are the renal effects of Hyperparathyroidism
Renal: Causes renal cell tubular damage
What are the causes of hypokalaemia in CKD?
Reduced intake, reduced renal potassium reabsorption, renal tubular acidosis.
What are the clinical signs of hypokalaemia in CKD?
Neuromuscular weakness (ventroflexion of neck), arrhythmias, metabolic acidosis, anorexia, weight loss.
What is hypokalaemic nephropathy?
A condition where low potassium levels promote PU/PD and worsen kidney function in CKD patients.
What type of anaemia is seen in CKD?
Non-regenerative, normocytic, normochromic anaemia.
What are the causes of anaemia in CKD?
Erythropoietin deficiency, reduced RBC lifespan, nutritional abnormalities, chronic GI haemorrhage, iron deficiency.
What are the effects of anaemia in CKD?
Lethargy, inappetence, possible disease progression due to renal hypoxia.
What are common causes of haemorrhage in CKD?
Ocular haemorrhage, GI haemorrhage secondary to ulceration.
Why does hypertension occur in CKD?
Impaired sodium excretion, activation of the renin-angiotensin-aldosterone system (RAAS).
What organs can be damaged by hypertension in CKD?
Kidneys, eyes, brain, cardiovascular system.
Why does proteinuria occur in CKD?
Increased glomerular capillary pressure and fewer tubules to reabsorb protein.
Why is proteinuria concerning in CKD?
It contributes to CKD progression and is a risk factor for mortality.
What causes metabolic acidosis in CKD?
Reduced excretion of H+ ions, retention of phosphate and organic acids, increased loss of chloride (vomiting).
Why is CKD a progressive disease?
Ongoing triggers, systemic and glomerular hypertension, mineral imbalances, proteinuria, renal fibrosis, inflammation.
What are important targets for CKD treatment?
Hypertension, phosphate control, proteinuria reduction, reducing inflammation and fibrosis.
What are common clinical signs of CKD?
PUPD, weight loss, depression, dehydration, haematuria, oedema, acute blindness, fractures.
What findings are seen on clinical examination of CKD patients?
Dehydration, poor body condition, small kidneys, pale MM, hypertensive retinopathy, fractures.
What laboratory findings indicate CKD?
Azotaemia, reduced GFR, low urine specific gravity, hyperphosphataemia, hypokalaemia, anaemia.
What urine-specific gravity suggests CKD in dogs and cats?
Dogs: 1.008-1.020, Cats: 1.008-1.030
Why is proteinuria monitored in CKD?
It increases risk of mortality and contributes to renal injury.
What imaging methods help diagnose CKD?
Ultrasonography (small kidneys, renal lymphoma), Radiography (mineralization, uroliths)
Why is blood pressure measurement important in CKD?
Hypertension can cause kidney damage and target organ damage.
What are the main treatment goals for CKD?
Treat underlying causes, improve quality of life, slow disease progression.
How is hypertension managed in CKD?
ACE inhibitors (dogs), Amlodipine (cats), ARBs, moderate salt restriction.
How is dehydration managed in CKD?
IV fluids (short-term), oral fluids, subcutaneous fluids, feeding tube if needed.
What medications help control nausea in CKD?
Maropitant, metoclopramide, ondansetron, H2 antagonists, proton pump inhibitors.
What are treatment options for anaemia in CKD?
Erythropoietin therapy (rHuEPO or darbepoietin-α), iron supplementation, treating underlying causes
Why is phosphate restriction important in CKD?
Prevents secondary hyperparathyroidism and slows disease progression.
What are common phosphate binders used in CKD?
Aluminium hydroxide, calcium carbonate, Ipakitine, Pronefra
How do ACE inhibitors benefit CKD patients?
Reduce glomerular pressure, proteinuria, sodium retention, and renal fibrosis.
What is Telmisartan used for in CKD?
Reduces proteinuria and treats hypertension in cats
Why are renal diets beneficial in CKD?
Reduce uraemic crises, prolong survival, improve quality of life.
What nutrients are controlled in renal diets?
Phosphate, protein, sodium, potassium, omega-3, antioxidants, B vitamins.
How should a diet change be introduced for CKD patients?
Gradually over 3-4 weeks, not during uraemic crisis or hospitalization.
Why is long-term monitoring important in CKD?
To track disease progression, manage complications, and adjust treatments.
How often should CKD patients be monitored?
Depends on severity, but regular check-ups are essential.
What is ‘acute on chronic’ kidney disease?
An acute worsening of CKD due to another illness, dehydration, UTI, or obstruction.
What is the typical prognosis for CKD?
Dogs: months to a few years; Cats: often ~2 years, depending on treatment and stage.
How would a patient present who has a kidney disease?
- PUPD
- Inappetence/weightloss
- Depression
- GI signs like vom/naus/diarrhoea
- ascites/subcut oedema
- haematuria
- pain
- abdominal mass
what is proteinuria?
It is an increase in the amount of protein in the urine
What are physiological/transient causes of protienuria?
Strenuous excercise, seizure, fever and stress
What are pre-renal causes of proteinuria?
Abnormal concentration of protein presented to kidney
What are renal causes of proteinuria?
Defective renal function or inflammation of renal tissue
What are post-renal causesof proteinuria?
Inflammation in the ureter, bladder, urethra or prostate
What are the presenting signs of proteinuria?
- none and have to detect on dipstick
- Could be signs of underlying disease such as neoplasia , infection or renal failure
- Could be signs kdure to low serum levels so weight loss, lethargy, poor appetite, ascites and pitting oedema
What protein is a dipstick more senstive than others?
Albumin
Why might a dipstick give a false positive result for proteinuria?
If urine is alkaline or contaminated
How would you identify pre-renal causes of proteinuria?
Haem and biochem that bitch
How would you identify physiological causes of proteinuria?
Via history and clinical examination
Why might a dipstick give a false negative result for proteinuria?
If the urine is acidic or bence jones proteinuria
How would you identify post-renal causes of proteinuria?
History, clinical exam, urinalysis and imaging
How would you identify a renal or post-renal inflammation as the cause of proteinuria?
Examine urine sediment for inflammatory cells and perform urine culture and sensitivity
Why should you quantify proteinuria?
- To evaluate severity of renal lesions
- assess disease prgression
- assess response to treatment
How should you quantify proteinuria?
24hr urine protein measurement is gold standard but difficult so like okay whatev so urine protein:creatinine ratio da fuck
What can renal inflammation cauas einterms of protein?
Cause protein to leak into filtrate
