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Ureteric calculi

  • Form from crystalline aggregates of organic molecules
  • Factors favouring formation
    • Increased urinary concentration of constituents
    • Presence of promoter substances
    • Reduction in concentration of inhibitors
  • Life time risk of developing a ureteric calculus is about 5%
  • Recurrence rates are close to 50%
  • Occur most commonly in men aged between 30 - 60 years
  • 90% are idiopathic
  • 10% are due to:
    • Hyperparathyroidism
    • Vitamin D excess
    • Primary hyperoxaluria
  • Recurrence rate at 10 years is about 50%

Chemical composition

  • Calcium oxalate (40%)
  • Calcium phosphate (15%)
  • Mixed oxalate / phosphate (20%)
  • Struvite (15%)
  • Uric acid (10%)

Clinical features

  • Stones usually present with pain due to obstruction of urinary flow
  • May cause few symptoms or may present with typical ureteric colic
  • Ureteric colic typically is severe colicky loin to groin pain
  • Pain may radiate into scrotum in men and labia in women
  • May also cause frequency, urgency and dysuria
  • Pain may settle with passage of the stone or if stone fails to migrate
  • Abdominal examination is usually unremarkable
  • Microscopic haematuria is often present

Differential diagnosis

  • The differential diagnosis included renal and non-renal causes
  • Non-renal causes include:
    • Appendicitis
    • Diverticulitis
    • Ectopic pregnancy
    • Salpingitis
    • Torted ovarian cyst
    • Abdominal aortic aneurysm
  • Renal causes include:
    • Tumour (clot colic)
    • Pyelonephritis
    • Retroperitoneal fibrosis
    • Stricture
    • Papillary necrosis

Investigation

  • The following investigations should be considered
    • Midstream urine specimen
    • KUB plus ultrasound
    • Intravenous urogram (IVU)
  • CT scanning is replacing IVU as the investigation of choice
  • Has higher sensitivity for the detection of stones
  • Also allows identification of other causes of loin pain
  • Radiation dose from IVU = 1.5 mSv
  • Radiation does from CT scan = 4.5 mSv

KUB showing left ureteric calculus

IVU showing left ureteric calculus

Pictures provided by H Houng, Epsom General Hospital, United Kingdom

Complications

  • Complications of ureteric calculi include:
    • Obstruction
    • Ureteric strictures
    • Infection
  • Acute infection in an obstructed kidney is a urological emergency
  • Patient is usually unwell with loin pain, swinging pyrexia and dysuria
  • Without drainage, rapid renal destruction may occur
  • Requires emergency percutaneous nephrostomy
  • Chronic infection with urease-producing organisms (e.g. Proteus) precipitates stone formation
  • Magnesium ammonium phosphate or staghorn calculi result
  • Large staghorn calculi may be asymptomatic
  • Staghorn calculi can lead to a deterioration in renal function

Staghorn calculus

Indication for urgent intervention

  • Presence of infection with urinary tract obstruction
  • Urosepsis
  • Intractable pain or vomiting
  • Impending acute renal failure
  • Obstruction in a solitary or transplanted kidney
  • Bilateral obstruction stones

Management

  • Initial conservative treatment with oral fluids and adequate analgesia
  • Check serum electrolytes and calcium
  • Urinalysis will normally show microscopic haematuria
  • IVU to confirm diagnosis and ureteric obstruction
  • Most stones < 5 mm  in diameter pass spontaneously
  • If more than  5-10 mm in diameter and fail to pass spontaneously consider:
    • Upper third of ureter - extracorporeal shock wave lithotripsy (ESWL)
    • Lower third of ureter - ureteroscopy (USC) + lithotripsy
    • Middle third of ureter - either ESWL or USC
  • If total obstruction occurs in the presence of infected urine need urgent decompression 
  • Decompression usually achieved with percutaneous nephrostomy
  • If large stones in renal pelvis or upper ureter consider percutaneous nephrolithotomy.
  • Particularly if stone more than 3 cm in diameter or a 'staghorn calculus'
  • Less than 1% patients with stones require open surgery - uretero- or nephrolithotomy

Plain abdominal x-ray showing a right staghorn calculus

left ureteric calculus on CT KUB

Lithotripsy

  • Is the use of shock waves to break up stones
  • Lithotripsy requires:
    • An energy source - spark-gap electrode or piezoceramic array
    • A coupling device between patient and electrode - water bath or cushion
    • A method of stone localisation - fluoroscopy or ultrasound 

Indication for metabolic evaluation

  • Family history of urolithiasis
  • Bilateral stone disease
  • Presence of inflammatory bowel disease, chronic diarrhoea or malabsorption
  • History of bariatric surgery
  • Medical conditions associated with urolithiasis
    • Primary hyperparathyroidism
    • Gout
    • Renal tubular acidosis
  • Nephrocalcinosis
  • Osteoporosis or pathological fracture
  • Stones formed from cystine, uric acid or calcium phosphate
  • The patient is a child

Components of metabolic evaluation

  • Analysis of stone composition
  • Two 24 hour urine collections for:
    • Volume
    • pH
    • Calcium
    • Oxalate
    • Citrate
    • Uric acid
    • Ammonium
    • Magnesium
    • Phosphate
    • Creatinine
    • Cystine screen
  • Serum
    • Calcium
    • Bicarbonate
    • Creatinine
    • Magnesium
    • Phosphate
    • Uric acid
  • Blood urea nitrogen

Bibliography

Kennish S J,  Wah T M,  Irving H C.  Unenhanced CT for the evaluation of acute ureteric colic:  the essential pictorial guide.  Postgrad Med J 2010:  86:  428-436

Miller N L,  Lingeman J E.  Management of kidney stones.  BMJ 2007;  334:  468-472.

Moe O W.  Kidney stones:  pathophysiology and medical management.  Lancet 2006;  367:  333-344.

Westenberg A,  Harper M,  Zafirakis H,  Shah P J.  Bladder and renal stones:  management and treatment.  Hosp Med 2002;  63:  34-41.

Whitfield A H N, Whitfield H N.  Is there a role for the intravenous urogram in the 21st century.  Ann R Coll Surg Engl 2006;  88:  62-65.

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