Urinary Tract Stones

URINARY TRACT STONES

INTRODUCTION:

Malaysia lies in the “stone belt”.  This is probably related to chronic dehydration from the hot weather, as well as the diet.  The prevalence of stones in male is about 15% whereas it is only about 1/3 of this in female.  Again, this is probably related to the outdoor activities of men in general and possibly from the longer urinary tract in men.  Stones can form in any part of the urinary tract: kidney, ureter and bladder. The stones can occasionally get impacted in the urethra, causing urinary retention.

PRESENTATION:

Ureteric colic is the most severe pain a man can experience.  If the stone is in the kidney, there may be not much  symptoms.  If the patient has a bladder stone, he may present with intermittent gross haematuria and difficulty in urination. Stones can often cause infection giving rise to high fever. 

Pain relief is important for ureteric colic and the most efficacious is that of a NSAID e.g. Diclofenac.

One also has to consider the differential diagnosis of a ureteric colic: if in the right side, this may be an ectopic pregnancy or appendicitis.  In older persons, one has to consider perforated diverticulitis and aortic aneurysm.

INVESTIGATIONS FOR STONE DISEASE:

The following investigations need to be done:

(1)    Urinalysis, urine culture

(2)    KUB, this picks up about 80% of the radio opaque stones.  Uric acid stones are not radio opaque.

(3)    Ultrasound is a simple screening test which can pick up stones easily in the kidney upper ureter and the bladder.

(4)    CT, non-contrast: this is useful in acute setting to rapidly diagnose stones in the ureter to clarify the diagnosis of loin pain.  One has to be careful with the use of intravenous contrast as this may give rise to fatal anaphylaxis.  In patients with renal impairment, the intravenous contrast may be nephrotoxic and should be avoided if the eGFR is <35 min.="" ml="" nbsp="" o:p="">

NATURAL HISTORY OF STONES:

Large kidney stones will be associated with infection and formation of pus.  Stones in the ureter can cause obstruction, also giving rise to sepsis as well as kidney failure. 

METABOLIC INVESTIGATIONS FOR STONES:

To prevent stone formation, one would need to try to find out the underlying cause.  This may be infection.  The blood should be sent for analysis of serum calcium and uric acid.  A raised serum calcium may be due to a hyperactive parathyroid gland, which may need surgical treatment.  Stone formation is part of the presentation of hyperparathyroidism.

MEDICAL MANAGEMENT OF URINARY STONES:

(1)    The most important management is to drink liquids to produce 2 litres of urine a day.

(2)    The dietary management could involve taking low salt diet, normal calcium diet, low uric acid diet and a low oxalate diet (namely, less chocolate, less nuts).

MANAGEMENT OF URINARY STONES:

Stones which are less than 6 mm and not causing significant obstruction or infection may be treated conservatively. This involves taking sufficient fluids and analgesia.  If the patient has uric acid stones, such stones can be dissolve by taking urinary alkaliniser e.g. Potassium Citrate.

MET, MEDICAL EXPLUSIVE THERAPY:

MET is used if the stone is in the lower ureter.  An alpha adrenergic blocker (e.g. Terazosin) can be used to relax the lower ureteric orifice and the bladder neck to encourage the passage of stones.

SURGICAL INTERVENTION

Stones which are in the kidney and upper ureter and are less than 20 mm may be treated by ESWL, Extracorporeal Shockwave Lithotripsy.

Stones in the bladder and in the lower ureter may be treated by endoscopic means.  Treatment of the stone in the ureter is with ureteroscopic lithotripsy and that in the bladder, by vesicolithotripsy.  The stone may be fragmented by an energy source e.g. laser or mechanical Lithotrite. 

Big stones in the kidney may be treated by PCNL, Percutaneous Nephrolithotripsy.  It is important to cover PCNL with antibiotics as a percutaneous tract may be complicated by infection (and also by bleeding). 

SUMMARY:

Urinary stones are common, often a cause of severe loin pain in young men.  Smaller stones can often be treated by pain relief, ESWL, Extracorporeal Shockwave Lithotripsy and drinking sufficient fluids to prevent further formation. Bigger stones can be treated by endoscopic lithotripsy.

Written by:

Dr Clarence Lei Chang Moh, FRCS Urol, FEBU

Consultant Urologist

email: clarencelei@gmail.com

4 September 2013