Urolithiasis Flashcards
Explain the gross anatomy of the kidneys and ureters
- Kidneys are paired retroperitoneal organs located between T12 and L3, covered in Gerota’s fascia.
- Ureters are 30cm long with 3 segments and 4 layers
Where are the physiological narrowing’s of the ureters?
- Pelvi-ureteric junction,
- Crossing iliac vessels at pelvic brim,
- VU junction
What are the intrinsic and extrinsic risk factors for urolithiasis
Intrinsic - Age, sex (males>females because men have high oxalate production), genetics
Extrinsic factors - Geography (hot>cold climates), more common in summer, dehydration, diet high in animal protein, salt and low in calcium salts and sedentary lifestyle
What are kidney stones commonly made up of?
- Most commonly calcium oxalate.
- Uric acid stones (form due to chronic dehydration)
- Calcium phosphate and calcium oxalate.
- Pure calcium phosphate (rare)
- Struvite (infection stones)
- Cysteine (rare, occur due to inherited disorder)
Why do renal stones form?
- Supersaturation of solute with absence of inhibitors this is an unstable state when stones form.
- In a metastable state there is supersaturation of solute but with the presence of inhibitors
What are factors which will increase risk of renal stone formation?
- Low volume, low pH, low citrate and low magnesium (citrate and magnesium are stone formation inhibitors).
- High uric acid, high calcium and high oxalate
How do patients with renal stones present?
- Can be asymptomatic so incidental finding.
- Renal colic pain which radiates from loin to groin, very severe pain.
- Restless
- Haematuria (often non visible but can be visible)
- Sepsis (uncommon)
hat are the initial investigations for a patient with kidney stones?
- History and exam,
- Bloods (U+Es, CRP and FBC)
- Urinalysis,
- Imaging - Gold standard is CT KUB (non contrast)
What are the biochemical workup investigations for patients with their first kidney stone vs recurrent stones?
- First stone - U&Es, calcium, parathyroid hormone, Vitamin D, urate, urine dip, MSSU, stone analysis.
- If patient presents with recurrent stones then do U&Es, calcium, urate, venous bicarbonate and 24 urine analysis
What are the different imaging used in investigation of kidney stones?
- CT KUB (gives info on stone diameter, skin to stone distance, no contrast used and lower radiation dose)
- Ultrasound (benefits young patients by avoiding radiation)
- Xray KUB (lower radiation dose and better for following up a known stone)
What are the medical therapies for kidney stones?
- Analgesia with NSAIDs as they reduce pain due to reduced glomerular filtration, reduced renal pressure and reduced ureteric peristalsis.
What are the surgical options for kidney stones?
- Ureteroscopy and basket or fragmentation.
- Flexible ureteroscopy
- Extracorporeal shockwave lithotripsy,
- Percutaneous nephrolithotomy
- Emergency stent or nephrostomy
When is admission required for kidney stones?
- Uncontrollable pain,
- fever/signs of sepsis,
- Solitary kidney with a ureteric stone (only one kidney)
- Bilateral ureteric stone,
- Renal failure caused by an obstructive stone
What are the differentials for an emergency presentation of kidney stones?
- Abdominal aortic aneurysm,
- Appendicitis,
- Gyn pathology such as ectopic pregnancy or torsion
- Testicular pain
What is the management of a patient with sepsis and an obstructing kidney stone?
- Urological emergency
- Implement the sepsis 6 ensuring to take cultures and give antibiotics after.
- Check bloods, renal function and inflammatory markers.
- Urgent imaging with ultrasound or CT
