Stones
STONES (CALCULI)
As all primary school children know it is not possible to form crystals in a solution unless that solution is concentrated or super saturated. The principle is the same in urine. It is unlikely that dilute urine will form stones. The children also know that in order to form crystals it is necessary to have a Nidus, such as a string dangling in a glass of concentrated salt or sugar solution.Similarly in the urinary tract often a Nidus to start crystal collection and aggregation similar to a pearl forming in an oyster.Records regarding kidney stones date back to Egyptian skeletons from over six thousand years ago.
Incidence
It is estimated that approximately 3-5% of the Australia population may well develop urinary tract stones some time during their lives.
Presentation
Presentation for a patient with a calculus is with renal colic. This is a severe pain, which usually radiates from the loin (side) to the suprapubic (bladder) region. It comes in waves and characteristically the patient cannot find any position of comfort and paces the room. It is often accompanied by sweating, nausea and vomiting and may also be accompanied by painful urination and blood in the urine. Furthermore the pain may radiate to the testis of the affected site or to the labia in the female. Some patients only present with a genital ache. Female patients who have had children will describe the pain as being worse than labour.
Treatment
Treatment is placed here before investigations because this is an extremely painful condition requiring analgesia. The quickest and most effective analgesia is usually with non-steroidal anti-inflammatory medications such as: Indomethacin, Diclofenac or similar. Indomethacin may be given as 100mg suppositories. If the patient is vomiting, then medication may be given intravenously. Narcotic analgesia is extremely effective, but in some patients does precipitate vomiting.
Laboratory Investigations
Blood test are usually carried out: FBE – a full blood picture.
Kidney Function: Urea, electrolytes, and Creatinine estimation are the most appropriate in the initial stages.
Urine Testing: The urine is usually positive for blood.If infection is suspected then the specimen is usually sent to the lab. for confirmation and antibiotics started
Imaging
Usually a KUB (Kidneys, Ureters and Bladder) abdominal film plus an ultrasound is carried out. Many departments have the ability to carry out an urgent CT Scan.
Stones tend to be held up in their progress at three positions:
1. The pelvi-ureteric junction (just leaving the kidney)
2. The portion of the ureter where it crosses over the common iliac vessels (lower abdomen)
3. At the opening of the ureter which is the narrowest point in its journey to the bladder
Conservative Management
The patient achieves adequate pain relief.
A patient should consume a fluid throughput of approximately three litres of water per day.
Approximately 30% of stones will pass within 48-72 hours. A further 30% will pass within the next 7 days. The remainder will require removal.
TREATMENT:
Kidney Stones
1. Extracorporeal Shock Wave Lithotripsy( ESWL)
90% of stones within the kidney can be treated with Extracorporeal Shockwave Lithotripsy. This is carried out with the patient sedated or under General Anaesthetic. A shock wave (sound wave) is generated and focused on the stone. When the sound waves reverberate within the solid mass, the stone is caused to crack and shatter. Sometimes in a larger calculus (> 2cm), multiple treatments may be required if this is the elective procedure of choice.Approximately 5-10% of patients may require further intervention to remove fragments of calculi, which become impacted within the ureter.
2. Percutaneous Nephrolithotomy
Prior to the development of ESWL percutaneous nephrolithotomy was the treatment of choice but now it is used for calculi which are unlikely to break up and pass down the ureter in small enough fragments to be able to clear the calculus. It is more commonly now used in Staghorn calculi. It is carried out under GA usually with the patient in the prone position and following the passage of needle into the kidney as an ante grade nephrostomy. The track is then dilated up and a telescopic instrument (nephroscope) is passed into the kidney. The stone may then be fragmented using intracorporeal lithotripsy or with laser fragmentation and the fragments removed through the telescopic track. At the end of the procedure often a ureteric stent (tube) is left in place and also a percutaneous nephrostomy(tube from the kidney through the skin draining in to a bag) in order to allow bleeding to settle and urine to pass down the ureter to the bladder.This is temporary.
3. Open Surgery
Prior to the development of the upper two methods, open pyelolithotomy was the procedure carried out. This required a large incision over the 12th rib and around the loin. The kidney was then reached and the renal pelvis opened and the stones removed that way. Sometimes in multi-branched staghorn calculi it was not possible to remove all in this manner and therefore a “cut down” on the kidney substance was used.
Ureteric Stones
Stones in the upper ureter may be treated with:
a) ESWL insitu.
b) Pushing the stone back to the renal pelvis with a retrograde catheter, putting a stent in place and then ESWL, so called “push/bang”
c) Ureteroscopy with either a flexible ureteroscope and laser disintegration or rigid ureteroscopy, disintegration (intracorporeal lithotripsy or laser)and extraction.
Lower Ureteric Stones.
These stones are best managed by ureteroscopy which is carried out by passage of the instrument into the bladder via the urethra. It is then passed into the ureter and onto the stone. In that position the stone may be grasped and removed or alternatively if too big, may be broken up using either inracorporeal lithotripsy or with laser. At the end of the procedure a retrograde pyelogram (X-ray) is carried out and if there is free flow of contrast back to the bladder it may not be necessary to insert a stent. If the Urologist has any doubt about the ability of that kidney to drain then a ureteric stent is usually inserted.
STENTS
A stent is a small tube with a curl at the top end to stop it from falling out and a curl at the bottom end to stop it moving up the ureter. It is inserted over a guide wire, which is a finely coiled flexible spring which is inserted up the ureter. It is left in place temporarily for 3-4 weeks following the procedure. Under no circumstances must patients take Ural or Citravescent or any other form of urine alkaliniser while a stent or any other foreign material is in place within the urinary tract as these substances can cause phosphate to precipitate on the material and prevent its removal because of the encrustation.
The stent is removed by carrying out a cystoscopy and grasping the lower end and withdrawing it. The upper loop uncoils to allow easy removal.
All procedures to remove calculi are covered with intravenous antibiotics.
Occasionally it is not possible to remove the calculus because it is too impacted or vision is obstructed. Under those circumstances the stent is likely to be left in place and a further attempt made at a later date.
If endoscopic procedures fail then open uretero-lithotomy or laparoscopic uretero lithotomy are alternative procedures. In both cases the ureter is approached through the skin of the abdomen. A stent is usually left in place after opening the ureter to allow it to remain decompressed in order for swelling to settle and the urine flow to resume. Often a drain tube is placed beside the ureterotomy site and left on free drainage for 3-5 days post operatively to allow removal of any “seepage” or urine through the incision.
BLADDER STONES
Usually bladder stones form primarily in place rather than being ureteric stones, which have passed into the bladder but not beyond. They may also form in diverticula or on foreign bodies including catheters. Approximately 15% of patients with bladder calculi will have upper tract calculi as well.
Presentation
These patients usually present with pain or bleeding at the end of urination or sudden stoppage of urine with the “ball valve” affect of the calculus lodging in the bladder neck. Often the patient finds that lying down allows the stone to roll out of the opening and urine flow to be resumed.
Calculi are often formed with chronic indwelling catheters present, usually the result of phosphate deposits and contributed to by alkaline urine. The treatment for prevention is to keep the urine dilute and acidic.
Treatment
Bladder stones 2cm or less are best managed endoscopically. Under General Anaesthesia a telescopic instrument is placed down the urethra, the stone is visualised with and then grasped with an instrument called a lithotrite and the procedure of cystolitholapaxy carried out. The stone is crushed and the fragments evacuated.
Alternative methods are:
Intracorporeal lithotripsy using a small “jack hammer” type of intracorporeal lithotripter or laser treatment. The use of laser may be increasingly expensive as fibres can only be used once and not all hospital operating theatre departments have those.
Open Surgery
Open surgery is carried out and the procedure of cystolithotomy performed. The Surgeon makes an incision on the lower abdomen The stone is removed from the bladder through an incision in the bladder and the bladder is closed At the end of the procedure a catheter is left in place for 5-10 days to enable to bladder to remain decompressed and therefore the wound to heal. Often a drain tube is left outside the bladder through a stab incision of the lower abdomen in case the catheter becomes blocked with small clot and urinary leakage occurs through the cystotomy.
N.B.
Most male patients form bladder calculi because of outlet obstruction secondary to prostatic hyperplasia and in order to prevent further stone formation they will require surgical management such as TURP. Occasionally that is carried out at the same time as the cystolitholapaxy, however with multiple manipulation and prolonged procedures there is usually a prolonged period of recovery.
Incidental asymptomatic calculi
Occasionally stones are found in the upper tracts incidentally upon ultrasound or CT Scan for investigation of other abdominal procedures. It is often not known how long those stones have been present. The need for treatment depends on the age and general health of the patient, the position and size of the calculi, as well as the presence of adjacent renal damage.
In addition, small intra renal calculi may also be managed expectantly, but after small (< 5mm).
INVESTIGATIONS OF PATIENTS WITH URINARY CALCULI
On first presentation of a patient with a single < 5mm diameter calculus which passes spontaneously further investigation other than routine haematology and biochemistry, serum calcium and urate levels is not warranted.
Approximately 30% of patients with calculi will have a further calculus sometime in their lives. Generally speaking if a further calculus presents within 12-18 months further investigations should be carried out in order to attempt to reduce the incidence of further calculi.
Any calculus passed or removed should be analysed biochemically prior to further investigation.
| Stone Composition | % |
| Calcium Oxalate | 50 |
| Calcium Oxalate + Phosphate | 20 |
| Uric Acid |
1 |
|
Triple Phosphate |
14 |
| Cystine | 1 |
PREVENTION OF STONES
1. Uric Acid stones - This maybe done with the assistance of allopurinol and alkalinisation of the urine.
2. High fluid intake can significantly reduce the occurrence of urinary calculi. The association between animal protein intake and increased stone risk has not been clearly demonstrated in randomised trials. Severe calcium restriction should be discouraged.
Coffee, Tea, Beer and Wine seems to be associated with reduced risk of stone formation. Cranberry Juice has offered no specific protection against Calcium Oxalate calculi.
Sodium
A high sodium intake may increase urinary calcium and pH and decrease urinary citrate which is more significant for urate stones but not so for calcium oxalate stones.
To reduce urinary calcium and sodium urate saturation sodium intake should be limited to 2000-3000mg per day.
Animal Protein Intake
There is no conclusive information on studies on animal Protein intake. It appears that a high fluid throughput is more important.
Dietary Calcium
As calcium is the most common component of urinary calculi it may seem that dietary calcium is important in stone forms. Unfortunately there is a lack of direct link between high urinary calcium and calcium stone formers and it is important to consider the possibility of development of osteoporosis in people on low calcium intake. This is not the only factor in osteoporosis as general health, muscle bulk, exercise and androgen and oestrogen levels(hormones) play roles.
Oxalate
Absorption of oxalate depends on passive absorption across the intestine with the greatest amount in the colon. It depends upon calcium binding, presence of fatty acids and bile salts and obviously the amount of oxalate presented. Vitamin C (ascorbic acid) may increase the urinary oxalate levels and intake should be limited to less than or equal to 1000mg daily in patients with stone disease.
Note that increased oxalate absorption may occur in diseases of the bowel such as Crohn's Disease. Dietary sources of oxalate are tea, coffee, chocolates, spinach, rhubarb and strawberries.
CONCLUSIONS
For stone prevention
1. High fluid intake
2. Mild salt restriction
3. Association between animal protein increase stone risk is not clearly demonstrated
4. Severe calcium restriction should be discouraged
URETHRAL CALCULI
It is very rare that a stone is formed within the urethra. Usually they occur in the male because they have been unable to pass completely from the bladder.
In the female quite often the calculus in the region of the urethra is within a urethral diverticulum which has resulted from a blockage of a paraurethral gland enabling urine to enter the duct and a calculus to form.
PROSTATIC CALCULI
These are often seen on plain x-ray film or ultrasound for examination of the prostate. They often occur as a result of the corpora amylacea increasing in frequency and size. Other calculi in the prostate tend to occur between an enlarged prostatic adenoma (non-cancerous enlargement) and its “capsule”. It may be that calculi are formed from the inspissated secretions and may be the result of having had a previous infection. Generally they are found incidentally and may also be found upon investigation of blood in the ejaculate. They do not require specific treatment.
