urinary Flashcards
what is obstructive uropathy?
structural or functional hindrance of normal urine flow, sometimes leading to renal dysfunction
what are 3 epidemiological facts relating to obstructive uropathy
- 5/10 000 to 5/1000 depending on cause
Bimodal distribution (2 different age group distributions 2 different age groups it occurs)
In kids, mainly congenital
After 60 years, incidence increases particularly in men (BPH [benign prostate hypertrophy], Prostate cancer)
4% of end stage renal disease
Hydronephrosis is found in 2-4% of patients
what is the aetiology of obstructive uropathy in kids
anatomic abnormalities like stricture, stenosis or valve issues
what is the aetiology of obstructive uropathy in young adults
calculi
what is the aetiology of obstructive uropathy in older patients
BPH, tumours, calculi
what is the pathophysiology of obstructive uropathy
Dilation of the collecting ducts and distal tubules
Chronic tubular atrophy with little glomerular damage
Dilation takes 3 days from the onset of obstructive uropathy to develop; before then, the collecting system is relatively noncompliant and less likely to dilate
Obstructive uropathy without dilation can also occur when obstructive uropathy is mild and renal function is not impaired, and in the presence of an intrarenal pelvis
what are some clinical signs and symptoms of obstructive uropathy?
Less likely in chronic obstruction May include pain radiating to the T11 to T12 dermatomes Abnormal voiding Fever Oedema Haematuria Infection i.e. pyelonephritis Acute flank pain
what are some laboratory findings of obstructive uropathy
Urinalysis Serum electrolytes Creatinine Blood urea nitrogen (BUN) Bladder catheterisation
what imaging modalities are used when imaging obstructive uropathy
MCU/cystogram X-ray/KUB Abdominal ultrasound Doppler ultrasound CT pyelogram/ IVP MRI Renogram
when is MCU/Cystogram utilised in obstructive uropathy imaging
Shows reflux (scarring) and indicates pyelonephritis
Including obstruction; torturous ureters
Anatomy
Usually only if stricture in adult suspected
when is x-ray/ KUB utilised in obstructive uropathy imaging what are some positives and negatives
Often first imaging test for flank pain
May demonstrate calculi
Calculi can have varying appearances based on size, composition, location of stones
High degree of false positives and false negatives
when is abdominal ultrasound utilised in obstructive uropathy
- imaging test of choice
- aimed at detection of hydronephrosis
***Not doing this test to check for hydronephrosis. Do it to say this patient has all signs + symptoms for some sort of obstructive uropathy, let’s do a test to see if they have a stone or not.
positives and negatives of abdo ultrasound in obstructive uropathy
False-positive rate is 25% if only minimal criteria (visualization of the collecting systems) are considered in the diagnosis: normal variant for them
Absence of hydronephrosis (and false-negative results) can occur if obstruction is early (in the first few days) or mild
when is doppler us utilised in obstructive uropathy imaging
Can usually show unilateral obstructive uropathy in the first few days of acute obstruction before the collecting system dilates by detecting an increased resistive index (a reflection of increased renal vascular resistance) in the affected kidney
Useful in obesity and in bilateral obstruction
when is CT utilised in obstructive uropathy imaging
Only use CT if there is a distinct advantage over another modality due to the high radiation dose
positives of CT in obstructive uropathy
- Is sensitive for diagnosing obstructive nephropathy
- Unenhanced helical CT is the modality of choice for obstruction due to ureteral calculi: anatomic detail
- CT urography done with and without contrast is particularly useful in the evaluation of haematuria
- Thinning of the renal parenchyma suggests more chronic obstruction
why isn’t pyelogram/ IVP utilised in obstructive uropathy imaging
- High dose
- Not functional persee
- Need to be during symptoms
- Hard to justify with CT and renography
when is MRI utilised in obstructive uropathy imaging
- Anatomy
- Avoids radiation in kids or pregnant women
- Inferior for detecting calculi (to CT and US)
- Inferior to renography for function
- But nice soft tissue and “water map”
When is a renogram with 99mTc-DTPA or 99mTc-MAG3 utilised for obstructive uropathy imaging
clinical indications:
- Quantification of split renal function in either surgical planning or follow-up
- Serial examination of renal function in patients with an established clinical diagnosis i.e. patients with renal dysfunction, renal transplants, and significant previous reactions to iodinated contrast media
When is a renogram with Diuresis (Lasix) utilised for obstructive uropathy imaging
Common indications for radionuclide renal imaging with Lasix:
- Suspected uretero-pelvic or uretero-vesical obstruction; pre and post-surgical evaluation
- Hydronephrosis
- Distension of pelvicalyceal system as an aetiology of back pain
what are 5 non-medical, lifestyle treatment options offered for obstructive uropathy
- Hydration
- Quit smoking
- Eat healthy / electrolyte balance / alcohol regulation
- Regular exercise
- Control hypertension
what are 3medical management treatment options offered for obstructive uropathy
- Secondary infection prevention (antibiotics)
- Prophylactic antibiotics
- Analgesics for pain
what are 7 interventional management treatment options offered for obstructive uropathy
- Drains
- Surgery to repair anatomical defect
- Ureteral stent
- Nephrostomy tube (renal pelvis)
- Ureteroscopic removal (stone)
- Laser removal (stone)
- Pyeloplasty (PUJ obstruction)
what is renovascular hypertension?
The presence of systemic hypertension due to a stenotic or obstructive lesion within the renal artery
what are 3 renovascular hypertension epidemiological facts?
- Atherosclerotic lesions > 60% found in the kidney in 6.8% of population above age 65
- Renal artery stenosis (RAS) found in 20% of patients with coronary disease
- RAS found in 35% of patients with peripheral vascular disease
what is the aetiology of renovascular hypertension
- The most common and problematic cause is atherosclerotic renovascular disease
- Atherosclerosis constitutes 84% of patients identified with renal artery stenosis
- The two most common causes of RVH are:
• Atherosclerotic renal artery stenosis (ARAS) = 90%
• Fibromuscular dysplasia (FMD) = 10%
• Possible for injury, tumour and clots
what is the pathophysiology of renovascular hypertension?
- stenosis in the renal artery
- this causes an increase in renin and increased secretion of angiotensin II
- this results in vasoconstriction as well as aldosterone being released from the adrenal cortex
- aldosterone increases the blood volume
- increased blood volume and vasoconstriction leads to hypertension
what are some signs and symptoms of renovascular hypertension
- High blood pressure
- Headache
- Fatigue
- Nausea and vomiting
- Chest pain
- Vision problems, confusion, anxiety
- Excessive perspiration, pale or reddened skin
- Sudden pain in the side
- Bloody urine or clot in urine
- sometimes no symptoms at all
what are 3 clinical presentations of hypertension
- abrupt onset/ sudden worsening of well-controlled hypertension
- refractory to medical treatment with more than 3 drugs
- age and sex (young women suggestive of FMD; older men suggestive of ARAS)
- malignant or accelerated hypertension
- no fam history of essential hyertension
what are 3 clinical presentation of renal problems
- azotemia induced or worsened by antihypertensive medications: ACE inhibitors or ARBs
- unexplained azotemia
- discrepancy in kidney sizes by more than 1.5cm with cortical scanning
- bilateral small kidneys with cortical scanning
- low-grade proteinuria with bland urinary sediment
clinical presentation of other associated findings related to renovascular hypertension
- laboratory evidence of persistent RAAS activation i.e. chronic hypokalemia
- abdominal or flank bruit or both on physical examination
- unexplained CHF symptoms or ‘flash’ pulmonary oedema
- evidence of systemic atherosclerotic vascular disease i.e. CAD
- smoking
- severe retinopathy
- left ventricular hypertrophy
what are some laboratory markers used to diagnose renovascular hypertension
- Tests to eliminate other renal disease:
• Serum creatinine levels assess renal function
• 24-hour urine collection for proteinuria
• Urinalysis to eliminate RBCs in urine
• Serologic tests for systemic lupus erythematosus or vasculitis
-Peripheral renin may be elevated (but also in essential hypertension and ischaemic nephropathy)
-Renin levels pre and post captopril
what imaging modalities are utilised when imaging for renovascular hypertension
angiography/ arteriography doppler US CTA MRA scintigraphy
when is angiography/ arteriography used for imaging renovascular hypertension and what are the advantages and disadvantages?
-Gold standard
-Invasive
-Radiation dose
-Risk of contrast-induced nephropathy
-Not used routinely unless
• Concurrent therapy with angioplasty, +/- stent
-The quality of images with DSA is not as good as with conventional angiogram
when is doppler ultrasound used for imaging renovascular hypertension and what are the advantages and disadvantages?
- Direct visualisation of the renal vascular tree
- Assess blood flow velocity and pressure wave forms
- Inter-operator variability
- Useful when positive
- Looking for major flow accelerations in a renal artery
when is CTA used for imaging renovascular hypertension and what are the advantages and disadvantages?
- 3D reconstruction of the vascular tree
- Excellent sensitivity and specificity to see RAS
- RAS anatomy
- Potentially nephrotoxic
- Radiation dose
when is scintigraohy used for imaging renovascular hypertension and what are the advantages and disadvantages?
-Captopril-enhanced
-Non-invasive
-Assess functional status
-? bilateral RAS
-Not great in significant renal insufficiency
-Functional, not anatomical, diagnosis of RAS
-No direct visualisation of the renal arteries
-Interpretation, changes from baseline after ACEI:
• 10% change in cortical uptake
• 15% increase in cortical retention
• 2min+ increase in time to peak
• 2min+ delay in visulaisation of collecting system
-Curve that:
• Change in differential function
• Delayed time to peak
• Flattening of the curve
• Delayed clearance
when is MRA used for imaging renovascular hypertension and what are the advantages and disadvantages?
- Non-invasive
- Excellent visualisation of the renal vasculature
- Gadolinium contrast
- High cost
- Potential for nephrogenic systemic fibrosis for those with renal insufficiency
what are some lifestyle changes used as treatment options for renovascular hypertension
• Quit smoking • Eat healthy • Regular exercise • Weight control • Control hypertension, hyperlipidaemia, diabetes These are the same for atherosclerosis
what are some medical management treatment options for renovascular hypertension
management of risk factors:
- ACE inhibitor for BP (ramipril, lisinopril for example)
- (or ARB) +/- diuretic
- Beta blocker for cardiac workload / BP
- Calcium channel blocker relieves symptoms
- Aspirin or anti-platelets (clopidogrel) reduces CV risk
what are some interventional treatment options for renovascular hypertension
- Stent
- Surgery (rarely needed)
• Bypass
• Renectomy
