MANAGEMENT OF RENAL CALCULI

INTRODUCTION

Urolithiasis is one of the most ancient diseases known to mankind. Urinary stones have been detected in Egyptian mummies preserved for over 70 centuries. Sushruta-the pioneer of medical writings in India has vividly described “ kidney pain” due to stones in one of his original papers. Urinary calculi constitute one of the commonest surgical affliction in our country. By conservative estimates there are about 5-7 million stone patients in India. 1/1000 of our population needs hospitalisation due to urinary calculi and more than 5 lakhs operations are done every year for this malady associated with great pain and suffering. Obstructive uropathy due to calculi is the second commonest cause (14%) of End Stage Renal Disease and is the commonest reversible cause of Chronic Renal failure.

The management of urolithiasis has undergone a revolutionary change since the beginning of this decade. Till then conventional major operative intervention was the only available method of treatment. The patients had no choice but to resort often desperately to invasive surgery. Many recent advances have swung the pendulum convincingly in favour of non-invasive management of urolithiasis. It may not be an exaggeration to state that description of open stone surgery may only be found in the medical history books of the 21^st century. However, at present, 90% of cases of Renal calculi can be managed by ESWL and PCNL in our country.

EXTRA CORPOREAL SHOCKWAVE LITHOTRIPSY

The dream of a totally non-operative treatment for urolithiasis was turned into reality with the advent of ESWL in 1980. Lithotripsy being a totally non-invasive procedure is the ideal method of treatment of majority of stones. This method pulverizes urinary stones without any injury to the adjacent tissues. The stone is reduced to fragments which are passed out spontaneously by the patient through his normal urinary passage.

Principle of ESWL

Shock wave lithotripsy acts via a number of mechanical and dynamic forces on stones resulting in fragmentation. Lithotripter shockwave are mechanically generated waves that have a relatively high energy and an extremely steep peak of ascent. These are very powerful yet highly localised in nature and are based on the electromagnetic principle. They are very powerful, yet highly localised, in nature. There are several different ways in which shock waves can be generated:

· Electrohydraulic (EHL)

· Electromagnetic (EMG)

· Piezoelectric (PZE)

Clinical fragmentation of stones in the urinary tract is dependent on three factors:

1. Correct localisation of the stone (either by fluoroscopy or ultrasonography)

2. Application of appropriate energy to the stone for fragmentation

3. Spontaneous passage of fragments of sufficiently small size to cause minimal symptoms.

The treatment commences with the precise localisation of the stone at the intersection of two planes. This is done by means of two sets of x-ray generators and image intensifiers. The patient is positioned by computer controlled table movements so that the stone comes in the exact focus of the shock wave generator after which the shock waves are initiated. Shock waves are triggered by monitoring the respiration/ECG of the patient. Sharply and accurately focussed shock waves break the stone by precise and selective targeting and reduce it to fine gravel which is passed out with urine. An average sized stone needs about 4000 shock waves and is fragmented in 30-40 minutes.

Advantages of ESWL

The numerous inherent advantages of Lithotripsy are obvious:

1. Absolutely non-invasive procedure – requires no long muscle cutting incisions or late ugly scars.

2. Unparalleled safety – A recent world-wide review of detection of complications of lithotripsy by serial radio-isotope renal scans, CT scans and NMR imaging has revealed that lithotripsy has minimal side effects or complications. Functional renal tests with I 131 Hippuran have shown significant improvement in renal function after lithotripsy and stone removal

3. Minimal hospitalisation –average hospital stay is 48-72 hours. In most cases the patient is ambulatory and eating normally immediately after the treatment.

4. Very early resumption of normal activities-average 4-5 days with great socio-economic impact.

5. No need for General Anaesthesia in vast majority of cases hence no associated anaesthetic complications. Most patients need only local anaesthesia or light sedation.

6. Blood transfusion not required-avoids serious transfusion hazards e.g. haemolytic reactions, hepatitis and AIDS.

7. Method of choice for recurrent stones (30% incidence after surgery). Repeat stone operations not only need multiple blood transfusions but also carry higher incidence of major complications. Nephrectomy may be essential in about 20-30% of such cases.

8. Ideal modality ` for poor risk cases for surgery e.g. poor cardiac or respiratory status, diabetes mellitus, chronic renal failure, advanced age (oldest patient treated is 102 years).

9. Bilateral urinary calculi are specially suitable as bilateral invasive surgery Is prevented.

Results

In over 5 lakh treated patients all over the world success rate varies from 86%-98%. Stone particles passed in urine vary in size from 0.1 to 1.1 mm. Majority pass the fragments without any discomfort while about 25% have colics needing antispasmodics. Transient mild haematuria responding to conservative measures occurs in about 30-70% of cases. The time taken for the debris to pass out varies between 2-8 days but may take up to 3 months rarely. Residual concretions usually in a dilated lower calyx can be detected in about 7-9% of cases but pass out spontaneously. Fragment impaction warranting PCN or URS occurs in about 8-10% of cases.

Contraindications

1. Uncorrected bleeding disorders

2. Uncontrolled hypertension

3. Radiolucent calculi

4. Untreated distal urinary obstruction

5. Untreated uro-sepsis

6. Radiation contra-indications e.g. pregnancy

7. Calcified renal artery or aneurysm on side of stone

8. Gross obesity above 150 kg

9. Bladder stones

10. Non functioning kidney

PERCUTANEOUS NEPHROSTOMY (PCN) NEPHROLITHOTOMY (PCNL)

The starting of PCN and PCNL was an important landmark in the changing trends in management of renal calculi. This was the first step in non-invasive technique of stone removal.

Principle

This technique warrants elaborate radiological and endoscopic facilities including a urological table with image intensifier. Essentially the procedure involves formation of a direct percutaneous access to the stone bearing part of the renal collecting system followed by endoscopic stone removal.

Procedure

The initial puncture of the renal pelvicalyceal system is done with a fine needle under ultrasonic or radiological control. Retrograde contrast filling up of the pelvicalyceal system greatly facilities the initial puncture. Thereafter a guide wire is introduced and the tract is dilated with telescoping dilators over which the endoscopic sheath viewing lens is passed. After locating the stone it is removed under vision. A large variety of baskets, loops or forceps are available and used depending on the number, size and location of the stone. Larger calculi can be fragmented under vision by ultrasonic energy transmitted by ultrasonic burrs. Electrohydraulic probes are best avoided in the kidney. Multiple tracts may be needed for larger, multiple and complex stag horn stones. A nephrostomy tube is left in situ for 48 hours. PCNL represents a considerable improvement over surgery but still carries with it risk of complications e.g. Access difficulties, bleeding, infection, residual fragments, liver and spleen injuries, perforation of kidney, fluid extravasation.

URETERORENOSCOPY (URS)

URS is an indispensable adjunct to non-invasive management of urinary calculi especially lower ureteric calculi.

Procedure

Preliminary cystopanendoscopy is mandatory. The ureteric orifice is dilated by passing dilators over a guide wire and then the ureterorenoscope is introduced into the ureter. The stone is visualised and removed with the help of different types of forceps and baskets, larger stones are fragmented with ultrasonic probes. Ureteric stricture, previous ureteric surgery, enlarged prostate may render this technical difficult.

THERAPEUTIC STATUS OF ESWL, PCNL AND URS

ESWL monotherapy is currently the treatment of choice for the management of stones up to 2 cms. In size. Stones larger than 2.5 cms. and partial or complete staghorn stones need repeated sessions of ESWL or may need adjuvant PCNL or URS. Preliminary PCNL in such cases with big stone mass results in debulking of the stone mass and is followed up with lithotripsy for residual fragments. Radioluscent calculi and very hard calculi are not amenable to lithotripsy and may need PCNL. With the availability of these new modalities, open surgery shall be rarely required.

CHEMOLYSIS

Chemolysis involves chemical dissolution of urinary calculi usually done by irrigation through the nephrostomy tube. Optimum inflow and outflow channels allowing irrigation at low intrapelvic pressure are essential. This method finds relatively restricted application in management of residual stones after ESWL or PCNL, infection, uric acid and cystine stones. Large variety of irrigant solutions, e.g., Hemiacidrin, EDTA, THAM, etc. are available.

OPEN SURGERY

Although technical advances have changed the manner in which urologic surgeons approach renal calculi, the basic indications for intervention remain the same. These include obstruction, pain, infection, significant haematuria, or stone growth despite appropriate medical therapy. Within these settings, the indications for open operative intervention are much more confined and include :

1. An associated anatomic abnormality requiring open operative intervention.

2. A stone so large and extensive that in the judgement of an experienced urologic surgeon, a single operative procedure would, with less risk and cost, more likely render the patient stone-free than would the option of multiple percutaneous and ESWL procedures. The cost is an important factor in our country.

3. Failure of or contraindication to both ESWL and PCNL.

Types and choice of open surgery

· Simple pyelolithotomy

· Extended pyelolithotomy

· Anatropic nephrolithotomy

· Partial nephrectomy

· Nephrectomy

The choice of open surgery depends upon the configuration, size and function of the kidney. For example, for renal stones, pyelolithotomy is indicated in cases which are not suitable for ESWL and PCNL, or are associated with PUJ obstruction requiring pyeloplasty. For partial and complete staghorn calculi with extrarenal pelvis, extended pyelolithotomy is the treatment of choice. For inferior calyceal calculi, with dilated calyx and poorly functioning inferior pole, lower pole nephrectomy can be done. Nephrectomy is advised in cases with nonfunctioning kidney with calculi. Retroperitoneal laparoscopic nephrectomy can be done in these cases with minimum morbidity, reduced hospital stay and a mini scar.