Urothiliasis Flashcards
What is renal colic?
Abdominal pain caused by urolithiasis (stones in the kidney + urinary stones
Describe renal colic pain?
In the flank
Radiates to the hypochondrium or the groin
On and off
Where is the hypochondrium?
Just below ribcage
On either side
What is urolithiasis?
Formation of a stone anywhere in the urinary system
What 3 sub-categories of urolithiasis are there?
Nephrolithiasis: stones in kidney
Ureterolithiasis: stones in ureters
Cystolithiasis: stones in bladder
What age-group is most commonly affected by urolithiasis?
25-45
Where in the urinary system can you get stones?
Anywhere!
Collecting duct to urethral meatus
What are the risk factors for getting urolithiasis?
Anatomical abnormalities:
- horseshoe kidney
- PUJO
- spina bifida
Trauma, obstruction
Excess quantities of stone-forming substances in the body
Dehydration
Infection
Poor diet, excess salt + protein
High BMI, inactive lifestyle
What is PUJO?
Pelvic-ureteric junction obstruction
Describe the mechanism of stone formation?
Nucleation theory:
Crystals form in supersaturated urine
These crystals form stones
What can stones be made from?
Calcium phosphate, calcium oxalate
Uric acid
Struvite
Cystine
What are stones most commonly made from?
Calcium
What is the link between smoking and urolithiasis? Why?
None!
What is the link between dairy foods and urolithiasis? Why?
More dairy is better
Calcium in dairy binds to oxalate which means it can’t form stones
In what conditions do uric acid stones form?
Acidic urine
How can you reduce the risk of getting calcium stones?
Reduce dietary salt Reduce dietary proteins Over-hydration Reduce BMI Be active
How can you reduce the risk of getting uric acid stones?
De-acidify urine
How can you reduce the risk of getting cystine stones?
Over-hydration
Urine alkalisation
Cystine binders
Genetic counselling
What causes cystine stones?
Genetic condition causing excessive excretion of cystine
There’s a lot of cystine in the urine so it forms stones
How does infection cause stones?
Occurs in UTIs caused by urease producing organisms
Excess urease, urease hydrolyses to ammonia which raises the pH of the urine
Results in stones made of ammonium, magnesium, calcium
What causes uric acid stones?
Low urine pH, any cause
What is the link between ileostomeis and stones?
Ileostomies increase the risk of uric acid stones
Because, ileostomies cause a loss of bicarbonate, so lower urine pH
What are the clinical features of urolithiasis?
Can be asymptomatic
Loin pain: side between ribs and hips
Renal colic
UTI symptoms: dysuria, urgency
Urinary tract obstruction
Recurrent UTIs
Haematuria
Why is renal colic pain on and off?
Due to peristalsis of the ureters
Investigations of suspected urolithiasis?
Urine dip to check for infection
Mid stream urine sample for culture
Bloods: serum urea, electrolytes, creatinine, calcium
CT
History: could indicate what type of stone is likely
Which stones are visible on CT?
Fully radiopaque
- Calcium phosphate and oxalate
- Magnesium stones
Cystine mildly radiopaque
Uric acid not at all
Management of urolithiasis?
Analgesic: NSAIDs such as diclofenac are best, morphine if necessary
Anti-emetic
Increase fluid intake
Can give alpha blockers (tamsulosin) or Ca Ch blockers (amlodipine)
Give patient 3 weeks to pass themselves before offering surgical (unless signs of infection or obstruction)
Interventions:
Electrical shock wave lithotripsy (shockwaves to break up stone so can pass fragments)
Percutaneous nephrolithotomy (remove stone by sticking big needle into kidney)
Ureteroscopy (using lasers to break stone)
Open surgery
What are the indications for urgent intervention?
What would you do?
Signs of: Obstruction and Infection
Because infection + obstruction = pyonephrosis
Can go into renal failure within 24 hours
Or get sepsis, leading to septic shock
IV antibiotics (cefuroxime or gentamicin)
Percutaneous nephrostomy to drain urine
Stent to relieve obstruction
What is pyonephrosis?
Infected hydronephrosis (urine backed up into kidney)
Infection of the collecting ducts of the kidney
Pus accumulation in the renal pelvis
And kidney distention
Can result in AKI, renal failure, sepsis
Management of a patient with infection + a kidney stone?
IV antibiotics cefuroxime, gentamicin
Urgent intervention:
- stenting
- percutaneous nephrostomy
What is a percutaneous nephrostomy?
An artificial opening created between the kidney and the skin which allows for the drainage of urine
In most cases, what are spiky stones made of?
Calcium oxalate
In most cases, what are large, staghorn stones made of?
Infection related stones
Magnesium ammonium phosphate
In most cases, what are yellow, crystalline stones made of?
Cystine
Indications for stone analysis?
First time stone formers
Early recurrance after stone removal
Frequent stones despite pharmacological therapy
Prevention of further stones?
Drink plenty of water
Keep eating Ca foods (dairy)
Lifestyle
Calcium stones: thiazide diuretics to decrease Ca2+ excretion
Uric acid stones: allopurinol
Calcium citrate: for Ca oxalate stones
