1. Renal Tract Calculi Flashcards
(39 cards)
What are most stones composed of?
80% are calcium: - calcium oxalate (35%) - calcium phosphate (10%) - mixed (35%) Others: - Urate - struvite (magnesium, ammonium phosphate) - cystine
Which are the only stones which are readioluscent?
Urate stones
Which stones typically cause staghorn calculi?
Struvite, they are often large and soft
Why do stones form?
Over saturation of the urine which result in precipitation of solutes forming crystals
what results in Urate stones?
high levels of purine in the blood
What can result high levels of purine in the blood?
- red meat diet
- haematological disorders e.g. myeloproliferative disease
What are the most likely locations for impaction of stones?
- Pelviureteric Junction (PUJ), where the renal pelvis becomes the ureter
- Crossing the pelvic brim, where the iliac vessels travel across the ureter in the pelvis
- Vesicoureteric Junction (VUJ), where the ureter enters the bladder
What are clinical features?
- pain (ureteric colic)
- sudden onset
- flank to pelvis (termed “loin to groin”),
- associated nausea and vomiting
- haematuria typically non-visible
- tenderness on affected flank
- Concurrent infection should be assessed for, with symptoms such as rigors, fevers, or lethargy.
describe ureteric colic
sharp and usually constant
what causes pain in urolithiasis?
from the increased peristalsis and stretching from around the site of obstruction
What are possible differential diagnosis?
Differentials for flank pain include pyelonephritis, ruptured AAA, biliary pathology, bowel obstruction, lower lobe pneumonia, or musculoskeletal related pain
What investigations would you consider?
- routine bloods (FBC, CRP to test for infection)
- urinalysis (blood, ?infection)
- urine calcium and urate levels
- stone analysis if it was passed
- non-contrast CT
- USS
- Plain film abdominal radiographs (AXR)
What is gold standard imaging of stones?
Non-contrast CT
what can be detected by USS?
Ultrasound scans of the renal tract can often be used concurrently in cases of known stone disease, to assess for any hydronephrosis (they can also often detect renal stones, however not ureteric stones).
what is the disadvantage of using AXR?
not all stones are radio-opaque so limits their use, alongside their associated high radiation exposure.
Initial management?
- most stones pass spontaneously
- rehydration (secondary to reduced oral fluid intake +/- vomiting)
- analgesia
- IV antibiotics of evidence of significant infection or sepsis
risk factors for urolithiasis?
– Dehydration –> This increases the specific gravity of the urine increasing ion concentrationWhat are criteria for inpatient admission?
– Recurrent UTIs and foreign bodies which stagnate flow e.g. stents/catheters
– Diet –> May give hypercalcemia and certain foods also increase oxalate levels
What are criteria for inpatient admission?
- > 5mm stones
- infected stones
- post obstructive AKI
- Uncontrollable pain from simple analgesics
What can provide temporary relief from obstructive uropathy?
- Retrograde stent
- nephrostomy
which patients may require retrograde stent or nephrostomy?
Patients with any evidence of obstructive nephropathy or significant infection
describe retrograde stent insertion
the placement of a stent within the ureter, approaching from distal to proximal via cystoscopy . It allows the ureter to be kept patent and temporarily relieve the obstruction.
describe nephrostomy
a tube placed directly into the renal pelvis and collecting system, relieving the obstruction proximally
Definitive treatment?
- extracorporeal shock wave lithrotripsy (ESWL)
- percutaneous nephrolithotomy
- Flexible uretero-renoscopy
What does ESWL involve, what size stones is it typically used for?
Involves targeted sonic waves to break up the stone, to then be passes spontaneously. This is typically reserved for small stones (<2cm), performed via radiological guidance
