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Year 3 Conditions: Renal and Urolgy > Urinary tract calculi (Complete) > Flashcards

Urinary tract calculi (Complete) Flashcards

1
Q

What are the main types of renal calculi?

A

Calcium oxalate (85%)

Uric acid (5-10%)

Calcium phosphate (10%)

Struvite (2-20%)

Cystine (1%)

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2
Q

What is the most common type of renal stone?

A

Calcium oxalate (85%)

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3
Q

What are the main features of calcium oxalate stones?

A

Most common type of renal stone (85%)

Radiopaque (appear white on x-ray)

Hypercalciuria is major risk factor

Form in variable urine pH

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4
Q

What are the main features of calcium phosphate stones?

A

10% of stones

Radiopaque

Typically occurs in renal tubular acidosis type 1 & 3 [causes high urine pH which supersaturates calcium and phosphate]

Form in high urine pH (normal-alkaline)

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5
Q

What are the main features of cystine stones?

A

1% of stones

Semi opaque “ground glass” appearance (due to presence of sulfur)

Caused by inherited recessive inborn errors of metabolism which leads to disruption of cystine transport and decreased absorption from renal tubule.

Multiple stones may form

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6
Q

What are the main features of uric acid stones?

A

5-10% of stones.

Radiolucent.

Uric acid formed from purine product metabolism

Can be caused by diseases which result in extensive tissue breakdown (e.g. malignancy)

Precipitated when urinary pH is low.

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7
Q

What are the main risk factors for urate forming renal stones?

A

Gout

Ileostomy (loss of bicarbonate and fluid results in acidic urine, causing the precipitation of uric acid)

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8
Q

Why does ileostomy increase risk of urate renal stones?

A

Loss of bicarbonate and fluid results in acidic urine, causing the precipitation of uric acid

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9
Q

What are the main features of struvite stones?

A

2-20% of stones

Radio opaque

Formed from magnesium, ammonium and phosphate.

Occur as a result of urease producing bacteria, associated with chronic UTIs (ureaplasma, proteus).

Crystals precipitated in alkaline conditions

Tend to form staghorn calculi

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10
Q

Summary of urine pH conditions for precipitation of different types of stones

A
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11
Q

What are the main risk factors for renal stones?

A

Modifiable:
Obesity

Dehydration (urinating 1 litre a day increases risk vs 2 litres)

Diet

Non-modifiable:

Previous stone disease

Anatomical abnormalities of the collecting system

Family history

Hyperparathyroidism

Renal tubular acidosis

Myeloproliferative disorders

All chronic diarrhoeal conditions

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12
Q

What is renal tubular acidosis?

A

Syndrome characterized by hyperchloremic metabolic acidosis with a normal serum anion gap.

Results in buildup of acid in blood

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13
Q

What is the main presentation of renal colic?

A

Acute/subacute onset of severe pain

Pain radiates from loin to groin (testes or labia)

Colicky

Patients often unable to get comfortable and pace around/ hunch over in pain

Nausea

Vomiting

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14
Q

What investigations should be considered in patients with renal colic?

A

Bedside:

Basic obs: Check for sepsis signs such as hypotension

Urine dipstick and culture: Show very positive haematuria and may aid in determining type of stone

Urine pregnancy test: Rule out ectopic pregnancy

Bloods:
FBC: Check for inflammatory response (WCC) in case of infection such as UTI and pyelonephritis

Blood culture: If features of sepsis

CRP: Check for infective causes such as pyelonephritis or UTI

U&Es: Check for any subsequent renail impairment

Calcium: Check underlying cause hypercalaemia

Uric acid: Check for underlying cause hyperuricaemia

Clotting factors and G&S: If percutaenous intervention is planned.

Investigations:

Non-contrast helical CT KUB: gold standard

Renal ultrasound: If pregnant or child

Abdominal X-ray: Useful to check for visible stone which would require extracorporeal shockwave lithotripsy.

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15
Q

Should renal colic be ruled out if no evidence of haematuria on urine dipstick?

A

Should not rule out

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16
Q

What is the gold standard investigation for renal stones?

A

Non-contrast helical CT KUB

17
Q

Non-contrast helical CT KUB is contraindicted in which patients? Which imaging is therefore prefered?

A

Pregnant women

Children

Urgent renal ultrasound instead

18
Q

What pH values may be seen in dipstick which is suggestive of each type of calculi?

A

N.B. Mean is calculated as pH is effected prandially (meals can make pH fall due to purine metabolism)

19
Q

What is the management plan for renal stones?

A

Conservative management if stone <5mm

Manage sepsis ASAP before treating stone if present

Medication:

Analgesia:
NSAIDs
Parenteral analgesics (e.g. Intramuscular/rectal diclofenac): If severe pain for rapid relief.

Medical expulsive therapy: Can speed up passage of stone

Surgery:

Nephrostomy: For emergency situations

Retrograde stent insertion: For emergency situations

Shockwave lithotripsy

Ureteroscopy

Percutaneous nephrolithotomy

20
Q

Renal stones measuring less than 5mm in maximum diameter will typically pass within how many weeks of symptom onset?

A

4 weeks

21
Q

List examples of types of medical expulsive therapy options.

A

Tamsulosin

Doxazosin

N.B. they relax the ureter to aid passage

22
Q

Medical expulsive therapy is only used in which types of patients?

A

Patient is of the following:

Not spetic

Normal renal function

Stone is visible on AXR

23
Q

What analgesia is reccomended for patients with severe renal colic?

A

Parenteral analgesia

E.g. Intramuscular diclofenac

24
Q

What presentation of renal colic is considered a surgical emergency?

A

Stones together with infection (e.g. sepsis)

25
Q

Which presentations of renal colic indicates more urgent and intensive treatment is required in these patients?

A

Presence of ureteric obstruction with subsequent renal impairment

Renal developmental abnormality such as horseshoe kidney

Previous renal transplant.

26
Q

What surgical options are used in renal colic in a septic patient?

A

Nephrostomy

Retrograde stent insertion

27
Q

What is a nephrostomy?

A

Radiological procedure where access to the renal pelvis is gained through the skin.

A drain is then inserted to decompress kidney

Antegrade stent can then be inserted to ensure kidney drains urine into bladder (can be inserted at same time as nephrostomy or later date)

28
Q

What is retrograde stent insertion?

A

Stent inserted via urethra access to decompress kidney

29
Q

What surgical options are offered in non-emergency management of renal stones?

A

Extra corporeal shock wave lithotripsy

Percutaneous nephrolithotomy

Ureteroscopy

30
Q

What is shockwave lithotripsy?

A

Shock wave is generated external to the patient

Causes cavitation bubbles and mechanical stress which fragments the stone

31
Q

Shockwave lithotripsy should be offered in presentations of renal stones?

A

Stone burden of less than 2cm in aggregate

This is because there is fragmentation of larger stones can cause ureteric obstruction.

32
Q

What are some complications of shockwave lithotripsy?

A

Ureteric obstruction (if done on large stones)

Solid organ damage

Pain (Require analgesia during and post-procedure)

33
Q

What is ureteroscopy?

A

Ureteroscope is passed retrograde through the ureter and into the renal pelvis

Stones can be removed by using a basket, or breaking it into smaller pieces using a laser.

34
Q

When is ureteroscopy indicated?

A

Stone burden of less than 2cm in pregnant females or in patients in which lithotripsy is contraindicted.

35
Q

What is percutaneous nephrolithotomy?

A

Involves accessing the renal pelvis via a percutaneous approach through the loin.

Stones can then be broken up and removed.

36
Q

When is percutaneous nephrolithotomy indicated?

A

Complex renal calculi and staghorn calculi

37
Q
A
38
Q

What medications can be considered in patients with reccuent kidney stone disease to reduce risk?

A

Calcium stones: Thiazide diuretic (increases calcium reabsorption)

Oxalate stones: Cholestryamine or pyridoxine

Uric acid stones: Allopurinol or oral bicarbonate

Year 3 Conditions: Renal and Urolgy (13 decks)

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