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Urinary Stones

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What is Laser Lithotripsy?

Urinary stones are a common source of discomfort and in many cases require a surgery for cure. Till 1980’s this surgery was done by open method which was morbid. After 1980’s endoscopic surgery became the standard of care. The endoscope is introduced in the urinary tract and once the stone is accessed it has to be fragmented and the fragments are then removed from the urinary tract.


Many people think that endoscopic surgery and laser surgery are the same. But this is not the case. Endoscopic surgery is a minimally invasive method of treating urinary stone. Once the endoscope reaches the stone it can be fragmented by various methods like laser, lithoclast, ultrasonic machine etc. But out of these laser is the most effective and also the safest method. Laser lithotripsy has many advantages over other methods of stone fragmentation as below


  • Fragmentation of the stone with laser can be done with precision whereas other methods are less precise.
  • In Laser lithotripsy, fine dusting of the stone can be done which improves stone clearance rates and decreases the chances of residual calculi after surgery.
  • This also reduces number of repeated introduction of the scope for removal of stone fragments. Surgical time is therefore reduced.
  • Laser can fragment all stones irrespective of the hardness, a significant advance over other methods.
  • In laser lithotripsy there is no need to impinge the stone against the wall of ureter/plevis/calyx for fragmentation. This reduces the risk of injury to the wall of urinary tract and also prevents complications like submucosal migration and perforation of the wall of urinary tract.
  • Laser lithotripsy is considered as the most efficient and safest modality for Intracorporeal Lithotripsy due to the reasons given above.

  • 1. Renal Calculi

    Till 1990’ open surgery was the procedure of choice for treatment of renal calculi. But this carried high morbidity due to the large incision, pain, late recovery and bad cosmetic result.


    Today renal stones are treatment by minimally invasive methods. The three modalities of treatment of renal stones are ESWL, RIRS and PCNL. Open surgery for kidney stone is almost never required.


    A. Extracorporeal Shock Wave Lithotripsy (ESWL)

  • It is a noninvasive treatment used to treat small kidney stones.
  • It a technique in which shock waves are generated in a machine and focused on the stone leading to its fragment fragmentation. It is done without anaethesia in adults or under General Aanesthesia for pediatric patients. The patient lies on a table and the stone is localised with the help of ultrasound or C arm image intensifier. The lithotripsy machine is connected to the patient the stone gets fragmented due to erosion and shattering by the shock waves produced in the machine. These small stone fragments can then pass out through the urinary tract with the flow of urine. This is a day care treatment and does not require admission. A repeat session may be given after a week for a maximum of 3 sessions.

  • ESWL is recommended only for small kidney stones. If it is used to fragment large kidney stones, the fragments can block the ureter a condition known as “Steinstrasse”. This can lead to pain, infection & loss of renal function if not treated properly.

  • B. Retrograde Intrarenal Surgery (RIRS)

    Renal stones < 2 cm sometimes may be unsuitable for ESWL. These can be treated by Retrograde Intrarenal Surgery (RIRS) in which a flexible ureteroscope is inserted through the urethra into the ureter. This can then access the calyces of the kidneys since it has a flexible tip. The stone once located can then be fragmented with laser. RIRS needs exclusive use of laser since the laser fibers are also flexible and can bend along with the scope.


    Patients with abnormal renal anatomy (eg. horseshoe kidney, ectopic kidney) sometimes develop renal stones. RIRS is an excellent option for these patients since it can bypass the difficulties offered by the abnormal anatomy.


    C. Percutaneous Nephrolithotomy (PCNL)

  • It is an Endoscopic Surgery for Kidney Stones. It is the treatment of choice for kidney stones >2cm. This also applies to staghorn stones. Success rate of PCNL is not affected by stone size.
  • The gravity dependant position of the lower pole impedes the passage of the stone fragments. Hence for lower polar calculi > 1 cm, PCNL is preferred over ESWL especially if the anatomy of lower calyx is not favorable for passage of stone fragments.
  • The procedure starts with cystoscopic placement of a ureteric catheter under C-arm guidance.
  • A foley catheter is kept per urethra. Pt is made prone. Retrogarde pyelography is done by injecting radio-opaque contrast in the ureteric catheter.
  • A tract is created into the desired calyx. Nephroscope is passed through the tract and the stone is fragmented with pneumatic lithoclast or laser and the fragments are removed with forceps.
  • A nephrostomy tube is kept in the tract and X ray is done next day to see for any residual fragments. If stone clearance is complete the nephrostomy tube is removed after 48 hrs and patient is discharged. If residual stone fragments are present then a 2nd stage PCNL or ESWL are planned depending on the stone size.
  • For staghorn stones multiple tracts may need to be created for complete stone clearance.
  • The most common complication during PCNL is bleeding and this may require blood transfusion.

  • Advantages of PCNL:

  • Minimal morbidity
  • Fast recovery and early return to work
  • Obvious Cosmetic advantage

  • 2. Ureteric Calculi

  • For a major mart of the 20th century, ureteric stones were treated by open surgery but this had many disadvantages like high morbidity, longer hospitalization, late recovery and a post operative scar giving poor cosmetic result
  • Today the treatment of choice for ureteric stones is by endoscopic surgery namely Uretero-Renoscopic Lithotripsy ie. URSL. After anaesthesia, the patient is given lithotomy position. The ureteroscope is introduced in the urethra and then into the bladder. It is then advanced into the ureter
  • Once the stone is reached it is fragmented with the lithotrite of choice to tiny fragments small enough to be extracted by forceps or basket
  • A ureteric stent is kept to prevent colic or obstruction in the post operative period and is removed after 2 weeks under local anesthesia.

  • What is Flexible Ureteroscopy/Retrograde Intrarenal Surgery (RIRS)?

    Ureter is a tube that carries urine form kidney to the urinary bladder. Many urinary stones get trapped in the ureter and cause obstruction to the urine flow. This can lead to excruciating pain. Many such patients need to undergo surgery. In today’s era this surgery is done with ureteroscope. Ureteroscope are of two types rigid and flexible. Rigid urteroscope many times cannot access the upper ureter and also cannot access the calyces of the kidney. A flexible ureteroscope does not have these limitations and can access the upper urinary tract with ease.


    Lihtotripy with flexible ureteroscope is called Retrograde Intrarenal Surgery (RIRS). RIRS needs exclusive use of laser since the laser fibers are also flexible and can bend along with the scope. Many upper ureteric stones migrate into the kidney during fragmentation and cannot be accessed by a rigid ureteroscope. These migrated stones then need additional treatment like ESWL or PCNL for clearance. Flexible ureteroscope can clear these stones transurethrally in the same sitting without an incision.


    Many patients have abnormal anatomy of the kidney or ureter which limits the use of rigid scopes. Flexible ureteroscope can bypass these difficulties of abnormal anatomy of the upper urinary tract eg. horseshoe kidney, ectopic kidney.


    Advantages of URSL/RIRS :

  • Minimal morbidity
  • Painless
  • Fast recovery and early return to work
  • Obvious Cosmetic advantage
  • Extremely low complication rate
  • Excellent Stone-free rates: Stone-free rates for URSL for lower ureteric stones are > 95% and 80-90% for upper ureteric stones. In 10-20 % cases of upper ureteric stones, there is a risk of migration of the stone into the kidney during stone fragmentation. These patients require ESWL post operatively to fragment the migrated stone.

  • Important factors to consider while deciding treatment for ureteric stones.

    1. Stone Burden (ie. size & no) Width of the stone is the most imp factor affecting the likelihood of stone passage. 5-mm is the breakpoint. For stones < 5 mm, conservative management is considered. For ureteric stones greater than 5mm URSL is recommended


    2. Duration of Stone Presence any ureteric stone has the potential to cause irreversible loss of renal function. Symptoms and stone size don’t predict loss of renal function. For stones > 5mm patient should be properly counseled about the risks associated with waiting. If the stone is small it is safe to wait for 2-3 weeks provided the degree of backpressure changes are minimal.


    3. Pain Majority of the patients present with pain in the flank which occurs due to obstruction to the upper urinary tract. Pain not getting controlled with oral analgesics is an indication for URSL.


    4. Infection associated with ureteric stones is potentially life threatening and a urologic emergency. Patients may have fever, renal angle tenderness or may have signs of septic shock eg hypotension. Urgent drainage of obstructed upper urinary tract by ureteric stenting or by a nephrostomy tube is required in such cases. Appropraite antibiotics should be started. Definitive treatment of the stone is delayed till urine cultures are negative and patients has recovered completely from the infection.


    5. Solitary Kidney: Ureteral stones in surgically/functionally solitary kidney demands prompt treatment to prevent renal failure.


    3. Urinary Bladder Calculi

    Etiology

    Disease processes resulting in urinary stasis in the bladder eg. due to enlarged prostate, stricture urethra, bladder diverticulum or neurogenic problem eg spinal cord injury. They may also be due to the introduction of a foreign body in the bladder eg. a non absorbable suture used in a previous surgery. Characteristic symptoms are Dysuria, Intermittency & Hematuria. Other symptoms which may be present are Freq, reduced stream, lower abdominal pain. Diagnosis requires an X ray KUB & USG on full bladder.


    Treatment

    The primary goal of surgical stone management is to achieve maximum stone clearance with minimal morbidity. Treatment of bladder calculi depends on the size of the stone with 3 cm being the cut off. For stones < 3 cm Transurethral cystolitholapaxy is recommended. The picture above shows a Mauer Mayer stone punch which is used to crush the stone. This procedure is not recommended for larger stones as the procedure then takes a long time, increasing the future risk of a urethral stricture.


    For large bladder stone ie > 3cm options are either an percutaneous/Open cystolithotomy.


    Per Cutaneous Cystolithotomy (PCCL) is a minimally invasive technique which involves creation & dilatation of a suprapubic tract in a distended bladder. An Amplatz sheath is used to maintain the tract. A nephroscope is passed through the sheath & stone is fragmented using pneumatic lithoclast. A suprapubic catheter is kept after the surgery & pt is discharged the next day with the catheter which is removed after 3-4 days. This technique eliminates the risk of trauma to the urethra from repeated passages of instruments in case of a large stone.


    Open cystolithotomy is another option for a large vesical stone but it is not favoured due to the need of prolonged catheterization, increased length of hosp stay, longer time for recovery and poor cosmesis. It is done only if the stone is very large and not amenable for Per cutaneous cystolithotomy (PCCL)


    The most important thing is to treat the cause of bladder stone formation to avoid recurrence. This may be a

  • TURP for prostate enlargement
  • OIU or urethroplasty for Stricture urethra
  • CIC for neurogenic bladder

  • Risk of Recurrence

    First time stone formers have a 50% risk of recurrence within the next 10 yrs. Hence all of them are provided empiric fluid & dietary recommendations as below

  • Restriction in the animal protein & sodium in the diet along with a high fluid intake.

  • Older recommendations to significantly reduce calcium intake actually increases oxalate absorption & this is no longer recommended. However a moderation in the intake of calcium rich food is advisable.
  • The actual benefit of avoidance in oxalate rich food is unclear as <10% of urinary oxalate is derived from diet.
  • Urinary Alkalisers are used rampantly owing to a popular misconception that they dissolve urinary stones. However these do not dissolve an already formed stone. They are recommended to prevent a recurrence once definitive treatment for an existing stone is over. For prevention of recurrence they should be taken for a long duration ie. a minimum of 3 yrs.