Renal tract calculi Flashcards
What are the two types of renal tract stones?
Renal stones which are within the kidney and ureteric stones which are within the ureter
What is urolithiasis?
Renal tract stones
What are most urinary tract stones made out of?
Calcium oxalate
What else can urinary tract stones be made out of?
Calcium phosphate, oxalate, phosphate, Magnesium ammonium sulphate (struvite) urate and cystine
Where do struvite stones sit?
Usually fill the renal pelvis and this is called staghorn calculi
Which type of stones are radiolucent?
Urate stones
Why do renal tract stones form?
Over-saturation of urine
Why do urate stones form?
high levels of purine in the blood
What would cause high levels of purine in the blood?
red meats, haematological disorders such as myeloproliferative disease, causing increase in urate formation and crystallisation
What are cystine stones associated with?
Hypocystinuria which is an inherited defect that affects the absorption and transport f cystine in the bowel and kidneys, citrate works as a stone inhibitor so reduced amounts causes stone formation
Where are the three places stones are likely to impact?
PUJ, Crossing of the pelvic brim where the iliac vessels cross the ureter in the pelvis, VUJ
What is the most common clinical feature of renal tract stones?
Pain- ureteric colic
Sudden, severe, radiating from flank to pelvis (loin to groin) with nausea and vomiting
Why does pain occur with renal tract stones?
increased peristalsis from around the site of the obstruction
What other clinical feature might you get in renal tract stones?
haematuria
What would be present on examination with someone with renal tract stones?
tenderness in the affected flank, dehydration,
What is a differential diagnosis for someone with renal tract stones?
Pyelonephritis, ruptured AAA, biliary pathology, bowel obstruction, lower lobe pneumonia or musculoskeletal pain
What are the urine investigations for suspected renal tract stones?
Urine dip may show microscopic haematuria, and infection, if so then send urine culture
What blood tests would you send for if there were suspected renal tract stones
FBC and CRP for infection, U and E to assess renal function, urate and calcium level can assess stone analysis
What is the gold standard imaging for stones?
non-contrast CT scan of the renal tract CT KUB
What other imaging can you do for stones?
plain film abdominal radiographs however not all stones are radiopaque, also ultrasound scans can be used to asses for hydronephrosis, can also detect renal stones but not usually ureteric stones, intravenous urograms
what is a intravenous urogram?
a series of abdominal radiographs following injection of contrast to demonstrate any filling defects but these are rarely used due to high radiation exposure and superiority of CT imaging
What is the initial management for renal stones?
Fluid resuscitation, if less than 5mm will pass spontaneously hopefully, analgesia such as NSAIDs per rectum, if infection then IV antibiotics
Why would renal stones need to be admitted?
post obstructive AKI, uncontrollable pain from simple analgesia, infected stone stone >5mm
Why would a stent be inserted or nephrostomy?
obstructive nephropathy or significant infection as the obstruction must be relieved immediately to avoid renal damage
What is a retrograde stent insertion?
placement of a stent within the ureter approaching distal to proximal via cystoscopy, allows the ureter to be kept patent and temporarily relieve the obstruction
What is a nephrostomy?
tube placed directly into the renal pelvis and collecting system, relieving the obstruction proximally, if needed a stent can be placed
What are the methods of definitive management?
Extracorporeal shock wave lithotripsy, percutaneous nephrolithotomy, flexible uretero-renoscopy
What size stones is ESWL usually done?
less than 2cm, and not in pregnancy or if stone is positioned over a bony landmark
What is PCNL used for?
renal stones
What are the complications of renal stones?
infection, AKI, Recurrent stones can cause renal scarring and loss of kidney function
What advice is given to patients with stones?
keep well hydrated, eat less salt, if oxalate avoid nuts, rhubarb, sesame and chocolate, check PTH levels, if Duarte acid red meat and shellfish while taking allopurinol
When do bladder stones usually form?
when there is urine statuses within the bladder e.g. chronic urinary retention, after infections such as schistosomiasis
What are the symptoms of bladder stones?
lower urinary tract symptoms
How are bladder stones managed?
cystocopy and lithotripsy
What can bladder stones predispose you to?
TCC bladder cancer
