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SPC- Urology > Urinary Tract Stones > Flashcards

Urinary Tract Stones Flashcards

Describe methods for assessing and treating urinary tract stones, and their complications

1
Q

What are renal calculi and why do they form?

A

Renal stones form due to solutes precipitating within the urinary tract. This can occur when there is increasing levels of solute or decreasing levels of solvent

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2
Q

What are the most common sites for urinary tract calculi?

A

Pelvic-uteric junction
Pelvic brim- where the ureters cross over the iliac vessels
Vesicouteric junction- entry of the ureters into the bladder

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3
Q

What is the most common type of renal stone?

A

Calcium oxylate stones- these contain calcium so are radio-opaque and visible on an x-ray

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4
Q

What is a struvite stone? What can it indicate?

A

A struvite stone is also called a stag horn stone. It is formed from magnesium ammonium phosphate and they occur with infections of the urinary tract. They’re also called stag horn stones.

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5
Q

What kind of renal stones may form in patients with Gout?

A

Uric Acid Stones-

Risk factor is a diet high in purines- shelfish, beer, red meat

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6
Q

Describe the presentation of renal calculi?

A

Asymptomatic
Pain- Typically at the loin and radiating to the groin.
Nausea and Vomiting- Pain can be very severe.
Infection- Urinary stagnation increases the risk of infection and so patients may have symptoms of a UTI/Pyelonephritis (Fever, rigours, confusion, urgency). Note an obstructed infected system is an emergency requiring urgent intervention
Haematuria- Patients may complain of visible haematuria

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7
Q

For patients complaining of loin pain/lower back pain what must you rule out- how would you do this?

A

Must rule out Abdominal Aortic Aneurysm and so palpate the abdomen.

Aorta is retroperitoneal so can cause back pain.

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8
Q

How may you differentiate renal calculi pain from pain due to peritonitis?

A

Patients are unlikely to lie still with renal calculi whereas in peritonitis movement worsens the pain

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9
Q

If suspected renal calculi what investigations should be done?

A 
Urine Dip
  - Haematuria
  - Signs of UTI- White cells, protein, nitrites 
Midstream Urine Testing
  - For Microscopy, Culture and Sensitivity
Pregnancy Test-
  -Rule out ectopic pregnancy as a cause in women
Bloods
  - FBC- Increase WCC in infection
  - Inflammatory markers- CRP, EST
Renal Function
  - Serum Creatinine
  - U&Es
  - eGFR
Possible causes of the stone:
  - Calcium
  - Phosphate
  - Uric Acid
  - PTH
Imaging-
  - CT KUB (Gold Standard)- Non- Contrast and helps to rule out other causes of the acute abdomen
  - X-Ray KUB- Calcium Oxylate stones are radiolucent
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10
Q

How would you initially manage a patient presenting with a renal stone without infection?

A

Acute Management-

Analgesia-

  • Diclofenac 75mg IVIM, 100mg PR
  • If NSAIDs CI- IV Paracetamol, Opioids
  • Monitor the patients pain and step up as required

Increase Fluid Intake

  • Dehydration is a risk factor for stones
  • Assess fluid status and advice to drink more
  • IV fluids if indicated

Watchful Waiting-

  • Small stones will pass naturally and there is often no intervention needed
  • If <5mm 90-95% will pass
  • Takes approximately 31-40 days so arrange a follow up appointment for after this
  • Advise the patient that if there are any signs of infection (fever, fatigue, rigours) or severe intolerable pain then come back to hospital
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11
Q

What should be done if a patient has the presentation of renal stones with signs of infection?

A

This is an infected obstructed system which requires urgent intervention- time wasted= loss of nephrons

Make patient NBM
Blood cultures
IV ABx- according to trust guidelines- piperacillin, gentamycin, tazobactam
Senior review for urgent consideration to relieve obstruction
Relieve the obstruction- Ureteric Stenting, Percutaneous Nephrostomy

Risk of urosepsis- Do sepsis 6

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12
Q

When managing a patient with renal calculi what should prompt intervention over

A

Pain that fails to respond to analgesia
Infection- Obstructed infected system
Impaired Renal Function
- Especially if only one kidney or bilateral stones
- Risk of post-renal AKI
Social Reasons
- Young and working patients may require interventions sooner to return to normal life

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13
Q

Beyond analgesia (mainly with diclofenac) what other interventions can be considered?

A

Medical-

  • Medical Expulsive Therapy
  • Nifedipine (calcium channel blocker) or an alpha blocker (tamulosin)

Extracorpeal Shock Wave Lithotripsy (ESWL)
- If the stone is less than 1 cm, used for stone in the pelvic to the upper ureter and lower donw the bony pelvis gets in the way

Surgical-

  • Uteroscopy and stone removal using basket
  • Open surgery- very rarely done

Note- Nephrostomy and ureteric stenting relieve the obstruction (for infected obstructed system) but do not treat the actual cause.

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14
Q

What are some of the risk factors for developing renal calculi?

A 
Dehydration
Hypertension
Gout
Hyperparathyroidism
Diuretics
Calcium/Vit D supplements
Family history
Hotter Climates
Previous stone disease
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15
Q

What might be done to prevent renal calculi developing in the future?

A

Drink plenty of water
Normal calcium intake
If high levels of calcium in tubules- Thiazide diuretics reduce calcium excretion
If high oxylate levels- Pyridoine
Ig high urate levels- Allopurinol
If infection- Treat the infection (ABx) and investigate the cause of recurrent infections (could be a sign of malignancy)

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16
Q

What are the symptoms from urinary calculi?

A 
Flank pain- Radiates from loin to groin
Colickly pain
Decreased urine output
N+V
Urinary stasis---> Infection
Fever, Fatigue, Confusion, Rigors
Haematuria- may be visible, likely invisible
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17
Q

What condition must be ruled out for patients presenting with lower back/loin pain?

A

Abdominal aortic aneurysm must be ruled out

Examine for a pulsatile, expansile mass in the abdomen

18
Q

How feature in the patient presentation would help you to differentiate between peritonitis and urinary calculi?

A

Patients with peritonitis will lie very still as movement causes pain
Patients with urinary calculi, experience radiating pain from loin to groin, are unlikely to lie still

19
Q

What is the most common type of urinary calculi?

A

Calcium oxylate

20
Q

What type of kidney stone is visible on an X-ray?

A

Calcium oxalate stones

21
Q

What type of kidney stone is more likely to form in patients with a UTI/ascending infection?

A

Struvite stone

22
Q

What type of kidney stone is more likely to occur in patients with gout or tumour lysis syndrome?

A

Uric acid stone

23
Q

What are some risk factors for urate stones?

A

Same as risk factors for gout
Diet high in beer, red meat, shelfish

(High in purines)

Note- Tumour lysis is also a risk factor as it causes release of DNA which is broken down to produce urate.

24
Q

What is a risk factor for the development of calcium oxalate stones?

A

Hypercalcaemia

Hyperparathyroidism- Primary or may be secondary to CKD
Malignancy
XS Vitamin D

25
Q

What initial investigations would you do if suspecting urinary calculi?

A

DO AN ABDOMINAL DIP TO RULE OUT AAA

Urine
Urine dip- Haematuria + Proteinuria +White Cells +Nitrites (If infection signs send do MSU and send for culture)–> Infected obstructed system requires urgent percutaneous nephrostomy
- Pregnancy test in women

Bloods

  • FBC, ESR, CRP
  • Creatinine, eGFR
  • Calcium, PTH, Uric acid, Phosphate
26
Q

What test should be done in women presenting suspected urinary calculi? Should be done for any acute abdomen in women

A

Pregnancy test

27
Q

After initial investigations (Urine, Bloods) what investigations would you request for suspected urinary calculi?

A

X-Ray- KUB- Only calcium containing stones (~75%) will show up on X-ray

CT-KUB (Non Contrast)- This is the gold standard investigation

28
Q

What is the gold standard investigation for suspected kidney stones?

A

CT- KUB (Non Contrast)

29
Q

What important features directs the immediate management of a patient with suspected UTI?

A

Is this an infected obstructed system?

Signs of infection- Fever, Raised WCC, Raised ESR + CRP, Urine dip, Urine culture

Percutaneous nephrostomy or ureteric stenting
IV ABx (e.g. Piperacillin + Tazobactam, Gentamicin)
Requires senior review

30
Q

What is the initial management for urinary calculi?

A

Analgesia-
Diclofenac 75mg IV/IM or 100mg PR
If NSAIDs CI give opioids

Fluids-
Assess fluid status and give IV fluids if need, encourage patients to drink plenty to wash stones out

31
Q

Why might no intervention be needed for urinary calculi?

A

Small stones will pass on their own in the majority of cases. This takes around 31-40 days

32
Q

What is important to advise the patient if they are being discharged for urinary calculi to pass on it’s own?

A

If you develop any signs of infection (fever, fatigue) or intolerable pain come back to hospital

Discharge with pain relief

33
Q

What should be done if there is an obstructed infected system?

A

IV ABx- Piperacillin + Tazobactam, Gentamicin (check trust guidelines
NBM
Senior review
Percutaneous nephrostomy

34
Q

When should surgical intervention be considered for

A

Pain fails to respond to analgesia
Infected obstructed system
Social reasons - e.g. urgent return to work in young patients
Reduced kidney function or a single kidney

35
Q

How long does it normally take for a stone to pass on its own?

A

31-40 days

36
Q

What is the management for an infected obstructed system?

A

NBM
IV ABx- Piperacillin + Tazobactam, Gentamicin
Senior review
Relieve obstruction- Percutaneous nephrostomy or Ureteric stenting

37
Q

If it is decided that patients will benefit from intervention what methods may be used?

A

Rigid or flexible ureteroscopy with basket/ laser

Extracorporeal shockwave lithotripsy (if stone less than 1cm)

38
Q

What are some indications for urgent surgical intervention in urinary calculi?

A 
Infected obstructed system
Extreme pain
Solitary kidney
Reduced kidney function
Bilateral stones
Social reasons- need urgent fix
39
Q

What does medical expulsive therapy involve?

A

Nifedipine or alpha blocker such as tamsulosin

But it’s not really recommended anymore

40
Q

What are some risk factors for developing urinary calculi?

A 
Dehydration
Hypertension
Gout
Hyperparathyroidism
Hypercalcaemia
Tumour lysis
Vitamin D excess
Hot climates
Previous stone disease
41
Q

How can renal calculi be prevented?

A

Stay hydrated and drink plenty of water

If due to high urate- Allopurinol

If due to high phosphate- Phosphate binders

If PTH overactive- Phosphate binders, Parathyroidectomy,, Bisphosphonates

If struvite stone- treat infection and investigate for causes of recurrent UTI.

SPC- Urology (8 decks)

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