Calculi Flashcards
(29 cards)
Definition of renal stones
Crystalline mineral deposits that from in the kidney
Classification of renal stones
- Simple
- <2cm within normal renal anatomy - Complex
- >2cm
- occurring in kidneys with abnormal anatomy
- resistant to fragmentation
Stone composition and frequency
70% calcium oxalate ~ 15% struvite 5%-10% calcium phosphate 5%-10% uric acid 1% cystine
Pathophysiology of renal stones
Normal soluble material (e.g. calcium) supersaturates the urine –> crystal aggregates anchored (usually at the end of the collecting ducts) –> incr. in size –> stone
Epidemiology of renal stones
10% of australians
2 male : 1 female
Hx of nephrolithiasis
- Often asymptomatic (in renal pelvis) until some moves into ureter
- Renal colic: severe pain, cramps, intermittent, originates in flank and radiate into lower abdo or groin
- Nausea +/- vomiting
- Microscopic or gross haematuria
- +/- dysuria
- +/- urgency and frequency
- +/- fever and chills
PMHx
- previous kidney stones and treatments
- hyperparathyroidism
- inflammatory bowel disease
- gastric bypass
- recurrent urinary tract infections
- prolonged immobilization or recent surgery to urinary tract
- gout
FHx
1. Kidney stones
PE of nephrolithiasis
- G.I - patient writhing about, unable to get comfortable. Sweating
- Vitals
- Lower abdo tenderness
- Reduced bowel sounds
- Costovertebral angle tenderness
- Urine dipstick: ++RBCs
Ix of nephrolithiasis
- CBE
- EUC
- Uric acid
- Calcium
- Coags
- Urinalysis MC&S
- Non-contrast helical CT *test of choice (except in children and pregnancy –> US)
- IV pylography option if CT not available
Broad Tx overview of nephrolithiasis
- ABCs - fluid resus
- NSAIDs for pain relief
- +/- Hydromorphone if inadequate pain relief on NSAID alone
IF UTI
- Treat or excluded prior to endourologic stone removal
- Urgent decompression with possible UTI, signs of sepsis with obstructing stones
- Antibiotics
Options for Tx
- Observe
- Medical exclusion therapy
- Active stone removal
Indications for medical expulsion therapy
- Stone likely to pass (≤6mm, mid-proximal ureter)
- Well-controlled pain
- No clinical evidence of sepsis
- Adequate renal functional reserve
Indications for active stone removal
Ureteral stones if:
- low likelihood of spontaneous passage
- persistent pain despite adequate pain medication
- persistent obstruction
- renal insufficiency (such as renal failure, bilateral obstruction, solitary kidney)
Renal stones if:
- stone growth
- stones in patients at high risk for stone formation
- obstruction due to stones
- Infection that has been treated
- Symptoms (such as pain, hematuria)
- Stones > 15 mm
- Stones < 15 mm if observation is not option of choice
- Patient preference
- comorbidities
- patient’s social situation (such as profession, traveling)
Tx of nephrolithiasis with medical expulsive therapy
- Alpha-adrenergic blockers (Prazosin 0.5mg PO BD)
- Calcium channel blockers (Nifedipine 30mg PO OD)
- Patients can be managed at home if they are able to take oral medications and fluids, and do not have uncontrollable pain or fever
- Uric acid stones (pH <6.5) can be treated with oral bicarbonate or potassium citrate supplements (alkalinize the urine)
Tx of active renal stone removal in obese
Ureteroscopy (more effective than ESWL)
What anatomic considerations to make when deciding active stone removal
RENAL
- Stone in renal pelvis / upper / middle calyx
- Stone in lower pole
UTERAL
- Proximal ureter
- Distal ureter
Define lower pole and implication on stone removal
The bottom part of the collecting system. Stones in this location are generally the most difficult to treat. Stone fragments tend to persist in this location and act as seeds of recurrent stones.
Define upper pole and implication on stone removal
The top portion of the collecting system usually drained by 1-2 infundibula and 3-5 calyces.
Define renal pelvis
The point of convergence of the major calyces and acting as a funnel for urine to drain into ureter.
Tx of stones in upper pole, mid pole or renal pelvis
> 2cm stone (in order of pref)
1. Percutaneous nephrolithotomy
1-2cm stone
- Flexible ureterorenoscopy or
- Percutaneous nephrolithotomy, or
- ESWL
<1cm stone
- ESWL
- Retrograde renal surgery
- Percutaneous nephrolithotomy
Tx of stones in lower pole
> 2cm stone
- Percutaneous lithotomy
- Retrograde renal surgery or ESWL
<2cm stone
- ESWL
- Retrograde renal surgery
- Percutaneous lithotomy
Tx of proximal ureteral stones
> 1cm stone
- Ureteroscopy (retrograde or antegrade) - stent often inserted or
- ESWL
<1cm stone
- ESWL (often needs stent)
- Ureterorenoscopy
Tx of distal ureteral stones
- Uteroscopy (transurethral stone removal/lithotripsy)
2. ESWL (not as effective)
When should renal stones be observed?
- Asymptomatic, small <1cm stones.
- Depending on comorbidities, patient preference and social situation
- Monitor at 6mo then 1-yearly with KUB x-ray/US/CT
When should renal stones be treated?
- Stone growth
- New obstruction
- Associated infection
- Acute or chronic pain
When should ureteral stones be observed?
- Newly diagnosed ureteral stone <1cm
- No indications of active stone removal
- Well controlled pain
- No clinical evidence of sepsis
- Adequate renal reserve
