Urolithiasis Flashcards
pathophysiology of urolithiasis
- ↑ concentration of urinary solute
- ↓ urine volume
- Urinary stasis
most common sites to find renal stones
- Pelviureteric junction
- Crossing the iliac vessels at the pelvic brim
- Under the vas or uterine artery
- Vesicoureteric junction
renal stone types
- Calcium oxalate: 75%
- ↑ risk in Crohn’s - Triple phosphate (struvite): 15%
- Assoc. with proteus infection - Urate: 5% (radiolucent)
- Cystine: 1% (radiofaint)
factors associated with formation of renal stones
- Dehydration
- Hypercalcaemia: 1O HPT, immobilisation
- ↑ oxalate excretion: tea, strawberries
- UTIs
- Hyperuricaemia: e.g. gout
- Urinary tract abnormalities: e.g. bladder diverticulae
- Drugs: frusemide, thiazides
general presentation of renal stones
- ureteric colic
- bladder or urethral obstruction
- UTI
- Haematuria
- sterile pyuria
- anuria
features of ureteric colic
- Severe loin pain radiating to the groin
- Assoc. with n/v
- Pt. cannot lie still
features of bladder or urethral obstruction
- Bladder irritability: frequency, dysuria, haematuria
- Strangury: painful urinary tenesmus
- Suprapubic pain radiating → tip of penis or in labia
- Pain and haematuria worse at the end of micturition
urine investigations for renal stones
- dip: haematuria
- MC&S
blood investigations for renal stones
FBC, U&E, Ca, PO4, urate
imaging for renal stones
- Kidney, Ureter, Bladder (KUB) X-ray
- Ultrasound
- spiral non-contrast CT-KUB
- Intravenous Urogram (IVU)
usefulness of KUB X-ray
- 90% of stones radio-opaque
- Urate stones are radiolucent, cysteine stones are faint
what does ultrasound help to identify?
hydronephrosis
usefulness of CT-KUB
- 99% of stones visible
- GOLD standard
features of Intravenous Urogram (IVU)
- 600x radiation dose of KUB
- IV contrast injected and control, immediate and serial
films taken until contrast @ level of obstruction
abnormal findings of Intravenous Urogram
- Failure of flow to the bladder
- Standing column of contrast
- Clubbing of the calyces: back pressure
- Delayed, dense nephrogram: no flow from kidney
contraindications to Intravenous Urogram
- Contrast allergy
- Severe asthma
- Metformin
- Pregnancy
functional scans for renal stones
- DMSA: dimercaptosuccinic acid
- DTPA: diethylenetriamene penta-acetic acid
- MAG-3
prevention of renal stones
- Drink plenty
- Treat UTIs rapidly
- ↓ oxalate intake: chocolate, tea, strawberries
initial treatment of renal stones
- Analgesia
- Diclofenac 75mg PO/IM or 100mg PR
- Opioids if NSAIDs CI: e.g. pethidine - Fluids: IV if unable to tolerate PO
- Abx if infection: e.g cefuroxime 1.5mg IV TDS
conservative management of renal stones
- 90-95% pass spontaneously
- Can discharge pt. c¯ analgesia
- Sieve urine to collect stone for out-patient analysis
indications for medical expulsive therapy (MET)
- stone 5-10mm
- stone expected to pass
drugs used in medical expulsive therapy
- Nifedipine or tamsulosin
- ± prednisolone
- Most pass w/i 48h, 80% w/i 30d
indications for active stone removal
- Low likelihood of spontaneous passage: e.g. >10mm
- Persistent obstruction
- Renal insufficiency
- Infection
methods of active stone removal
- Extracorporeal Shockwave Lithotripsy (SWL)
- Ureterorenoscopy (URS) + Dormier Basket Removal
- Percutaneous Nephrolithotomy (PNL)
- laparoscopic or open surgery (rare)
