Most Urinary stones can be treated with shockwave!

Plenary Lecture at 24 Malaysian Urological Conference, Johor Baru, 21 November 2015

The "Perfect" ESWL

by Dr Clarence C M Lei

Kidney & Urology Centre, Normah Hospital, Kuching, Malaysia

Introduction:

Urinary stone management comprises at least a third of urology practice. The classical presentation is a loin to groin acute colic in a young (30 to 60 years old) man.  Prevalence is about 5 to 15%. Microhaematuria is a useful clue to diagnosis.  Imaging to confirm the stone is often possible with clinic ultrasound and plain x-ray.  Nevertheless, the gold standard investigation is a non-contrast low dose CT urography.

Methods:

ESWL, extracorporeal shockwave lithotripsy is the greatest advance in modern urology. It was first reported by Chaussy C et al in the Journal of Urology, 1982; 127: 417.  The author has been using ESWL since  1989. His personal experience with lithotripters include Siemens (GHKL, 1991 – 1995), Edap (1996 – 1997) and the Dornier Compact (since 1998).  Early experience in GHKL recorded about 2000 cases of ESWL per annum.  In more recent years, the number of cases done is about 200 per annum.

Results:

Selection of the appropriate patient and stone is the most important factor for a successful ESWL.  If the patient  has an obvious urinary tract infection, this should be treated. Parenteral antibiotics should be given during ESWL in such cases.  More than 50% of the stones would be suitable for ESWL: more than 6 mm in size, but with a maximum diameter of < 20 mm.  Upper urinary tract stones (except for the lower pole) are ideally suitable, whereas lower urinary tract stones can be treated endoscopically with a success rate of almost 100%.  The few contraindications for ESWL include: pregnancy, gross obesity, uncorrected coagulopathy, nearby vascular calcifications and a non-functioning kidney. Informed consent is should be obtained. The patient should be  aware that the overall stone free rate is about 80%. I would also not persist if there is little fragmentation after 3 sessions, usually given every other day.  The alternative options with its complications and success rates should also be made known to the patient during the informed consent process.  The patient should also be informed of the complications of ESWL, viz bleeding (1 in 178 patients with significant perinephric haematoma in the author’s series), obstruction by the stone fragments, with up to 5% of patients requiring urgent ureteric stenting especially if there is fever.

The following technical points deserve attention during the ESWL: air pockets trapped in the coupling gel between the shockhead and the patient significantly reduced the delivery of shockwave energy. Delivery of the shockwave at 60/min versus 90/min results in a stone free rate at 3 months of 91 versus 80% respectively. There should be adequate analgesia: pre-medication with analgesics, anaesthetic cream and intravenous analgesia during ESWL. With sufficient analgesia, ESWL can be delivered with maximal power and number of shocks.  Accurate localisation of the stone with x-ray or ultrasound is important and this must be continuously monitored, say, every 200 shocks.  The patient should have follow-up documentation to show that the patient is stone free or has stable stone fragments.

ESWL treatment should be part of holistic management: e.g. co-existing diabetes, hypertension and chronic kidney disease.  All the lithotripsy medical staff should be credentialed in ESWL.  Stone Clinic staff should know about stone management, treatment of complications, other treatment options and the prevention of further stone episodes. The most important prevention is the adequate intake of fluid such that the patient produces 2 to 3 litres of urine per day. Serum calcium, uric acid and urine culture should be reviewed in all patients.

Conclusion:

ESWL remains a mainstay treatment for urinary stones.  The treatment of most upper urinary tract stones less than 20 mm is rewarding.  Selection of stone size, localisation, ESWL techniques, follow-up and stone prevention are important.  Stone treatment should be given as part of the holistic management of patient.