Urinary Tract Calculi

Question 1

Define nephrolithiasis

Answer 1

presence of crystalline stones (calculi) within the urinary system (kidneys and ureter).

Question 2

Where do ureteric stones originate from

Answer 2

Ureteric stones almost always originate in the kidney but then pass down into the ureter

Question 3

Epidemiology of nephrolithiasis

Answer 3

Males>females
White men
Highest prevalence between 40-60
The prevalence and incident risk of nephrolithiasis are directly correlated with weight and BMI in both genders

Question 4

Where do renal stones form

Answer 4

loop of Henle, distal tubules, or the collecting duct

Question 5

Aetiology of renal stones

Answer 5

• elevated urinary solutes (Ca2+, uric acid, oxalate, Na+)
• Decreased levels of of stone inhibitors (e.g. low citrate and magnesium)
• Low urinary volume
• abnormal urinary pH
  All of these can lead to urine supersaturation with stone forming salts and lead to stones.

Question 6

Classification of renal stones, which one is the most common

Answer 6

Calcium oxalate stones (most common)
Calcium phosphate
Uric acid stones (de to low Urinary pH)
crystine stones (caused by inborn mutation of affecting reabsorption of amino acids like cystine)
Struvite stones (aka infection stones, caused by urea splitting organisms e.g. Pseudomonas)

Question 7

Presenting symptoms of renal stones

Answer 7

• Acute, severe flank pain that may radiate to groin
• Pain can radiate to testicle
• N and V
• haematuria
• increased urinary frequency

Question 8

Risk factors

Answer 8

High protein diet
High salt diet
White
Male
Obese
Dehydrated

Question 9

Signs of renal stones

Answer 9

flank pain radiating to groin

Rare: fever, tachycardia, hypotension (these indicate urosepsis)

Question 10

1st line Investigations for nephrolithiasis

Answer 10

Bedside:
Urinalysis e.g. dipstick
Urinary Pregnancy test

Bloods:
FBC
U and Es, creatinine (check electrolyte levels and kidney function)

Imaging:
non contrast helical CT

Question 11

What do you look for in urinalysis

Answer 11

Most pts with kidney stones of microhaematuria

Signs of infection- positive nitrates, high leukocytes, bacteria

Question 12

What investigations can you consider after?

Answer 12

Plain abdo x ray KUB
renal USS (especially for pregnant pts to reduce radiation)

Question 13

1st line management for stones?

Answer 13

In any situation, 1st line management is normally conservative:
Hydration, pain control (NSAIDS e.g. diclofenac), anti emetics (ondansetron)

Question 14

How would you manage a patient with signs of infection

Answer 14

Antibiotics- trimethoprim

Question 15

How would you surgically decompress patients with obstruction

Answer 15

Stent

OR percutaneous nephrostomy

Question 16

How would you remove the stones depending on the size?

Answer 16

Small stones (<10mm): medical expulsive treatment
Alpha-blocker (e.g. tamsulosin) - relaxes ureter

Large stones (>10mm): surgical removal
1. ESWL- extracorporeal shock wave lithotripsy
2. Ureteroscopy
3. PCNL percutaneous nephrostolithotomy
These are considered first line treatments

Question 17

Complications of the surgical treatments?

Answer 17

Can cause injury to ureter leading to :
bleeding
haematoma
urosepsis

Question 18

Complications of a urinary tract calculi

Answer 18

Infection
renal damage
ureteric stricture (can be a long term sequela from ureteric injury)

Question 19

Prognosis

Answer 19

This is a lifelong disease, rate of recurrence after 1st time is 50% in 5 years.