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Y4: Urology > Renal calculi > Flashcards

Renal calculi Flashcards

1
Q

Composition of renal stones?

A
  • Calcium (80%)
    • Calcium oxalate
    • Calcium phosphate
    • Mixed oxalate and phosphate
  • Struvite (magnesium ammonium phosphate)
  • Urate (radiolucent)
  • Cystine
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2
Q

Which type of kidney stones are radiolucent?

A
  • Urate
  • Xanthine
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3
Q

Describe cystine stones?

A

Associated with familial disorders affecting cystine metabolism

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4
Q

Describe struvite stones?

A
  • Magnesium ammonium phosphate
  • Large soft stones
  • Common cause of staghorn calciuli where the stone fills the the renal pelvis
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5
Q

Describe the pathophysiology of renal stones forming?

A
  • Basis for formation is over saturation of the urine
  • Urate stones: high levels of purine in blood
    • Red meats, myeloproliferative disease
  • Cystine stones: hypocystinuria
    • Inherited defect of cysteine transport in the bowel and kidneys
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6
Q

For stones that enter the drainage system of the urinary tract, what are the natural narrowed points where stones are likely to impact?

A
  • Pelviureteric junction (PUJ)
    • Renal pelvis becomes the ureter
  • Crossing the pelvic rim
  • Vesicoureteric junction (VUJ)
    • Ureter enters the bladder
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7
Q

What are the clinical features of renal calculi?

A
  • Ureteric colic (flank to pelvis)
  • Haematuria (typically non-visible)
  • Tenderness in affected flank on examination
  • Signs of dehydration
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8
Q

Alternative differentials for flank pain?

A
  • Pyelonephritis
  • Ruptured AAA
  • Biliary pathology
  • Bowel obstruction
  • MSK-related pain
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9
Q

Investigations for someone suspected of renal calculi?

A
  • Urine dipstick
  • FBC, CRP, U&Es, uric acid and calcium levels
  • Non-contrast CT KUB (gold standard for diagnosis of renal stones)
  • AXR (only useful if stones are radio-opaque)
  • US to assess for hydronephrosis / pregnancy
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10
Q

Describe the initial management of renal coli?

A
  • Analgesia
    • NSAIDs (IM, IV or rectal) IM DICLOFENAC
    • +/- opiates
  • Alpha blocker (while drinking lots of water)
    • Relax ureteric musculature to allow stone passing
  • Specific treatments for different stone types
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11
Q

What signs from renal stones warrant intervention to relieve obstruction?

A
  • Uncontrollable pain
  • Associated fever
  • Impaired renal function
  • Obstruction > 4 weeks
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12
Q

Describe temporary stent insertion / nephrostomy procedures in patients with renal calculi?

A
  • Patients with evidence of obstructive nephropathy of significant infection
  • Retrograde stent insertion
    • Placement of stent within ureter via cytoscopy
    • Allows maintenance of ureter patency prior to definitive management
  • Nephrostomy
    • Tube placed directly into renal pelvis and collecting system
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13
Q

Describe definitive management options for renal calculi?

A
  • Used if the stones do not pass spontaneously:
    • Extracorporeal shock wave lithotripsy (ESWL)
    • Percutaneous nephrolithotomy (PCNL)
    • Flexible uretero-renoscopy (URS)
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14
Q

Describe extracorporeal shock wave lithotripsy?

A
  • Targeted sonic waves are used to break up the stone so it can pass
  • Reserved for small stones (<2cm)
  • Performed via US or X-ray guidance
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15
Q

Contraindications of extracorporeal shock wave lithotripsy?

A
  • Pregnancy
  • Stone positioned over a bony landmark (pelvis)
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16
Q

Describe percutaneous nephrolithotomy (PCNL)?

A
  • For renal stones only
    • Mostly large renal stones (staghorn calculi)
  • Percutaneous access to the kidney, with nephroscope passed into the renal pelvis
  • Stones can then be fragmented using lithotripsy.
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17
Q

Describe uretero-renoscopy (URS)?

A
  • Involves passing a scope retrograde into the ureter
  • Allows stones to be fragmented through laser lithotripsy and the fragments subsequently removed
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18
Q

Complications of ureteric and kidney stones?

A
  • Ureteric stones:
    • Infection
    • Post-renal AKI
  • Recurrent renal stones:
    • Renal scarring
    • Reduced kidney function
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19
Q

Describe the management of recurrent stone formers?

A
  • Advise to stay hydrated
  • Check serum urate and calcium levels
  • Depends on the composition:
    • Oxalate: avoid high purine and oxalate foods
    • Calcium: check PTH levels (1o hyperparathyroidism), avoid excess salt
    • Urate: avoid high purine foods, urate lowering meds (allopurinol)
    • Cystine: genetic testing for underlying familial disease
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20
Q

What are the high oxalate foods?

A
  • Nuts
  • Rhubarb
  • Sesame
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21
Q

What are the high urate foods?

A
  • Red meat
  • Shellfish
22
Q

Describe bladder stones?

A
  • Form from urine stasis within the bladder
    • Seen in chronic urinary retention or secondary to infections
  • Present with LUTS
  • Management with cystoscopy
    • Drainage or fragmentation with lithotripsy
  • Chronic irritation of bladder epithelium can predispose to transitional cell carcinoma of the bladder
23
Q

What is the gold standard for the diagnosis of renal stones?

A

Non-contrast CT scan

24
Q

What is the actual cause renal colic?

*** Important for exams

A
  • Distension of the renal capsule
  • Spasm
  • Local irritation of stone
25
Q

Describe the symptoms caused as the renal calculi approaches the VUJ?

A
  • Lower quadrant pain
  • Uregency, frequency, dysuria
  • Can mimic cystitis
26
Q

Normal frequency of urine in an individual?

A
  • 3-5 during the day
  • 0-1 during the night
27
Q

Specific presentation of struvite renal stones?

A
  • Recurrent UTIs
  • Malaise, weakness
  • Loss of appetite
28
Q

Presentation of complicated renal stones?

A
  • Pyuria, fever
  • Leucocytosis, bacteriuria
  • Potential for infected obstructed kidney or pyonephrosis
29
Q

Differentials for renal colic?

*** Common exam question

A
  • Pyelonephritis
  • Bacterial cystitis
  • Lobar pneumonia, rib fractures
  • Acute abdomen
    • Bowel, biliary, pancreas, AAA
  • Gynaecological
    • Ectopic pregnancy, ovarian cyst, ovarian torsion
30
Q

Features of renal colic from examination?

A
  • Patient moves around to find comfortable position
    • Acute abdomen => board like rigidity
  • Lower abdominal / costovertebral angle tenderness
  • +/- fever
31
Q

What is the diameter of the ureter?

A

5-7mm

32
Q

Which type of stones are most and least likely to pass?

A
  • Proximal ureteric stones
    • Least likely to pass spontaneously
  • Distal ureteric stones
    • Most likely to pass spontaneously
33
Q

Signs of breast cancer from physical examination?

A
  • Firm mass
  • Axilllary lymphadenopathy
  • Skin changes
  • Nipple discharge
34
Q

Who does the American Cancer Society recommend has annual MRI screening?

A
  • BRCA1/2 mutation
  • First degree relative with BRCA1/2 mutation
  • Had radiotherapy of chest between 10 and 30 years old
  • Li-Fraumeni & Cowden syndromes
35
Q

Case presentatins of primary invasive breast cancer

A
36
Q

Findings on mammography suggestive of breast cancer?

A
  • Irregular spiculated mass
  • Cluster micro-calcifications
  • Linear branching calcifications
37
Q

Differentials for Primary invasive breast cancer?

A
  • Fibrocystic changes
    • US can differentiate cysts from solid lesions
    • Biopsy can confirm diagnosis
  • Fibroadenoma
    • Smooth, well demarcated and mobile
    • Biopsy can differentiate
38
Q

Describe the surgical options of renal calculi?

A
  • Least to most invasive
  1. ESWL
  2. PCNL
  3. Ureteroscopy
  4. Cystoscopy
  5. Open surgery
39
Q

Describe ESWL?

A
  • Extracorporal shockwave lithotripsy
  • High energy shockwaves break down the stones
    • Small enough to be excreted
  • Non-invasive
40
Q

Indiciations for ESWL?

A
  • Stones <2cm
  • Favourable anatomy
41
Q

Contraindications for ESWL?

A
  • Pregnancy
  • Distal obstruction
  • Uncorrected coagulopathy
  • Consult cardiologist if patient has a pacemaker
42
Q

Describe PCNL?

A
  • Percutaneous nephrolithotripsy
  • Small puncture wound in the skin followed by shockwaves
  • Minimally invasive
43
Q

Indication for PCNL?

A
  • Stones >2cm
  • Staghorn calculi
  • Multiple stones >1cm
  • Proximal urethral stone >1cm
44
Q

Contraindications for PCNL?

A
  • Active infection
  • Pregnancy
  • Uncorrect coagulopathy
  • Adhesions from previous surgery
45
Q

Describe ureteroscopy?

A
  • Scope is passed up the urethra, through the bladder and into ureter
  • Stones are distintegrated using 1 of the following modalities:
    • Laser
    • Ultrasonic
    • Electrohydraulic
    • Pneumatic
46
Q

Indications for ureteroscopy?

A
  • Pregnancy
  • Coagulopathies
  • Stones which can’t be visualised by fluoroscopy
47
Q

Describe the use of cystoscopy?

A
  • Used for bladder stones
  • Lithotripsy or litholopaxy
48
Q

A 73-year-old lady is undergoing chemotherapy for treatment of acute leukaemia. She develops symptoms of renal colic. Her urine tests positive for blood. A KUB x-ray shows no evidence of stones.

What is the most likely composition of her stone(s)?

A

Uric acid

49
Q

A 16-year-old boy presents with renal colic. His parents both have a similar history of the condition. His urine tests positive for blood. A KUB style x-ray shows a relatively radiodense stone in the region of the mid ureter.

What is the most likely composition of his stone?

A

Cystine

50
Q

A 24-year-old woman presents to the emergency department with a 2-hour history of left-sided flank pain radiating down towards her groin. The pain is constant and unrelieved by changes in position. She feels nauseous and has vomited once. Her past medical history is unremarkable and she takes no regular medications.

On examination, she is tender over the left costovertebral angle. There is evidence of guarding but no rebound tenderness. Her observations are heart rate 112/min, blood pressure 120/76mmHg, temperature 38.1ºC, respiratory rate 14/min, saturations 97%.

An ultrasound scan of the kidneys demonstrates dilation of the renal pelvis on the left. CT scan of the kidneys, ureters and bladder shows a 4mm stone in the left ureter. What is the most appropriate management?

A

Surgical decompression due to signs of obstructive urinary calculi and infection

51
Q

A 44-year-old female, 32 weeks pregnant, is referred to a nephrology consultant by her general practitioner for querying renal stones. She has a past medical history of hypertension and ischemic heart disease.

A CT-KUB report shows a renal stone, approximately 1.5cm in size.

Which one of the following is the preferred definitive management in this lady?

A

Ureteroscopy is preferred in pregnant women

52
Q
A

Y4: Urology (12 decks)

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