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%
- Triple phosphate (struvite): 15%
- Urate: 5%
- Cystine: 1%
Calcium Oxalate stones ass with?
crohns
What are struvate stones ass with?
proteus infection
X ray appearance of Urate and cystine stones
Urate radiolucent
Cystine radiofaint
factors associated with formation of renal stones
- Dehydration
- Hypercalcaemia: 1O HPT, immobilisation
- ↑ oxalate excretion
- UTIs
- Hyperuricaemia: e.g. gout
- Urinary tract abnormalities: e.g. bladder diverticulae
- Drugs
Drugs leading to stones formation
furosemide
thiasides
Food with high amounts of oxalates
strawberries
tea
chocolate
General presentation of renal stones
- bladder or urethral obstruction
- UTI
- Haematuria
- sterile pyuria
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
Storage/voiding sx
Suprapubic pain radiating → tip of penis or in labia
Pain and haematuria worse at the end of micturition
Blood investigations for renal stones
Ca
PO4
Urate
Imaging for renal stones
- Kidney, Ureter, Bladder (KUB) X-ray/CT
- Ultrasound
- 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 serialfilms 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
or MAG-3)
prevention of renal stones
- Drink plenty
- Treat UTIs rapidly
- ↓ oxalate intake: chocolate, tea, strawberries
Initial treatment of renal stones
- Analgesia
- Fluids
- 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
NOT USED ANYMORE
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)
Side effects of Extracorporeal Shockwave Lithotripsy (SWL)
renal injury may → ↑BP
Contraindications to Extracorporeal Shockwave Lithotripsy (SWL)
pregnancy
AAA
Bleeding diathesis
Treatment of patient who is febrile with renal obstruction
- Surgical emergency
- Percutaneous nephrostomy or ureteric stent
- IV Abx: e.g. cefuroxime 1.5g IV TDS
Treatment for stone in renal pelvis
- >20mm = PNL or URS
- <20mm = SWL
Treatment for stone in proximal ureter
- >10mm = URS or SWL
- <10mm = SWL
Treatment for stone in distal ureter
- >10mm = URS
- <10mm = URS or SWL
