Urinary Tract Calculi (Stones)

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Introduction

Calculi (stones) are hard masses that form in the urinary tract and may cause pain, bleeding, or an infection or block of the flow of urine.

Calculi can occur in the kidney, ureter, bladder or urethra.
Stones are different with respect to their
composition:

  • Oxalate stones
  • phosphate stones
  • uric acid stones and
  • cystine stones

Factors promoting stone formation:

  1. Obstruction to urine outflow
  2. Infection in the urinary tract
  3. Crystallization on foreign bodies
  4. Dehydration
  5. Change in pH
  6. In-born errors of metabolism

Symptoms and clinical features of stones

1. Renal and ureteric stones:

  • Sudden onset loin pain radiating to the groin
  • Haematuria
  • Nausea and vomiting

2. Stones in the bladder:

  • Urinary frequency
  • Urinary urgency
  • Difficulty in passing urine

3. Stones in the urethra:

  • Urinary retention

Differential diagnoses

Renal tumour

  • Acute pyelonephritis
  • Acute appendicitis
  • Other causes of urinary obstruction e.g. enlarged prostate, urethral strictures

Complications of urinary tract stones

  • Recurrent and intractable urinary tract infection
  • Secondary hydronephrosis
  • Progressive renal failure
  • Periurethral abscess/urethral fistula

Investigations

  • Urinalysis
  • Urine culture
  • Serum calcium, phosphate and albumin
  • Ultrasonography
  • Intravenous urography (IVU)
  • Computerized tomography (non-contrast enhanced)

Treatment for urinary tract stones

Treatment objectives

  • Relieve symptoms
  • Remove stones
  • Prevent recurrence

Non-drug treatment

  • Increased fluid intake
  • Endoscopic Short Wave Lithotripsy (ESWL)
  • Endoscopic removal of stones
  • Open surgical removal

Drug treatment

A. Analgesics

Evidence Rating: [B]

Pethidine, IM, 100 mg 4 hourly as required

Or

Diclofenac, IM, 75 mg 12 hourly

Or

Diclofenac, rectal, 100 mg 12 hourly

And

Hyoscine butylbromide, IV, 20 mg 8 hourly

Or

Mebeverine, oral, 135 mg 8 hourly may be useful

Caution

Avoid morphine as it may cause further ureteric spasm and worsening of symptoms

B. Drugs used to prevent recurrence:

Thiazide diuretics – Hydrochorothiazide 5 mg orally daily

Or:

Potassium citrate – 60 mEq orally daily

Or:

Allopurinol 100 mg orally daily.

C. Antibiotics to treat infections

See Urinary Tract Infection

Referral Criteria

Refer to a urologist or surgical specialist for definitive treatment after
initial management

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