Kidney stones Flashcards
Where are the kidneys located?
- Retroperitoneal
* Located between T12 and L3, right lies slightly lower than the left
What are the segments of the ureters?
- Proximal: PUJ to pelvic brim
- Mid: segment over sacral bone
- Distal: lower sacral border to UO
What are the 4 layers of the ureters?
- Urothelial mucosa
- Lamina propria
- muscular layer
- Adventitial layer
Where are the narrowings of the ureters?
- PUJ ureteropelvic junction
- Crossing iliacs at the pelvic brim
- Vesico-uritary junction
What are the risk factors for kidney stones?
- Caucasian/asian
- Age
- Men
- Family history
- Comorbid conditions: familial renal tubular acidosis, cystinuria
- Fluid intake
- Diet: high animal protein, high salt, low calcium
- higher incidence in hotter countries
- Sendentary
name the radio-opaque stones
- Calcium oxalate
- Calcium phosphate and calcium oxalate
- Pure calcium phosphate
What are the radiolucent stones made of?
- Uric acid
- Sturuvite (infection stones)
- Cysteine
When are uric acid stones more likely to form?
Chronic dehydration, in those with chronic gout or a diet too high in protein
Explain the formation of stones
- Under-saturated, no stone formation
- Supersaturate but stable - no stones
- Stones begin to form when supersaturated with spontaneous precipitation
- Saturation product: level at which no more solute will dissolve in a solution without change in pH, temp
- Formation product- level at which spontaneous formation occurs
What is the free particle model of stone initiation?
- Urine containing crystals flowing down collecting tubules
- Crystals grow and agglomerating
- Cortical particle becomes trapped in tubule
What is the fixed particle model of stone formation
- Urine containing crystal flows down the collecting tubules
- Crystals growing and agglomerating
- Particle adheres to damage site on tubule wall an other crystals agglomerate with it
What increase stone formation?
- Low volume
- low pH (acidic)
- low citrate
- Low magnesium
- high uric acid
- High calcium
- High oxalate
How do stones present?
- Incidental - imaging for another reason
- Pain - colic, radiates from spin to groin, cannot settle and unable to stay still
- Haematuria - visible or non visible
- Sepsis/infection - unknown source until imaged
What are the initial investigations in suspected kidney stone?
- History and examination
- Bloods: UEs, CRP, FBC
- Urine - haematuria
- Imaging: CT KUB (non contrast)
If it is someone’s first stone what biochemical investigations should you do?
- UEs
- Calcium
- Urate
- Urine dip
- MSSU
- Stone analysis
- PTH
What biochemical investigations should you do with recurrent stones?
- UEs
- Calcium
- urate
- venous bicarbonate
- 24 hour urine analysis
What are the benefits of CT KUB for imaging of stones?
- 94-100% sensitivity and 92-100% specificity
- Stone diameter
- Skin to stone distance
- Hounsefield units
- No contrast
- Lower radiation dose
Describe the management of kidney stones
- Analgesia - NAIDs reduce pain due to reduced glomerular filtration, renal pressure and ureteric peristalsis
- Medical expulsive therapy
What are the surgical options for stones?
- Ureteroscopy and basket
- Ureteroscopy and fragmentation
- FURS- flexible ureteroscopy
- ESWL -extracorporeal shockwave lithotripsy
- PCNL - percutaneous nephrolithotomy
- Emergency stent or nephrostomy
When is admission required for stones?
- Uncontrollable pain
- Fever or signs of sepsis
- Solitary kidney with a ureteric stone
- Bilateral ureteric stones
- Renal failure caused by an obstructing stone
What in terms of stones is a urological emergency?
A patient with sepsis and an obstructing stone (the patient may need urgent decompression of an obstructed infected collecting system by nephrostomy or ureteric stenting)
What is staghorn calculi?
- Branched stones that fill all or part of the renal pelvis and branch into several or all of the calyces
- Most often struvite
