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Surgical Management of Urinary Lithiasis By MohammadBaghdadi Urology resident KKNGH. Kidney Stones. Historical overview :. Hippocrates :who described the symptoms of renal colic. In 1889 ,Gustav performed the first successful stone manipulation.
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Surgical Management of Urinary LithiasisBy MohammadBaghdadiUrology resident KKNGH
Historical overview : • Hippocrates :who described the symptoms of renal colic. • In 1889 ,Gustav performed the first successful stone manipulation. • In 1973, the first two modalities were described ureteroscopically: ultrasonic lithotripsy by Goodfriend1 and electrohydraulic lithotripsy by Reuter et a
Factors affect the management of renal stones • Stone factors • size • number • Composition • Renal anatomy • obstruction/stasis • hydro • UPJO • calyceal diverticulum • horseshoe / other ectopic/fusion anomalies • lower pole
Patient factors • infection • obesity • body habitus deformity • coagulopathy • age: juvenile, elderly • hypertension • renal failure • pregnancy
The indications for treatment of an :asymptomatic calyceal stone • pediatric patient • solitary kidney • high risk profession (pilots) • women considering pregnancy • Asymptomatic stones >4mm most likely will fail observation.
approach to treatment of a stone according to stone size • stones < 10mm: 50-60% of all stones • ESWL first-line, regardless of composition or location: stone-free rate 80% • PCNL, ureteroscopy only if special circumstance: ESWL failure, anatomic obstruction more invasive
approach to treatment of a stone according to stone size • stones 10-20mm • ESWL first line: stone-free rate 65% • poor result if cysteine, lower pole • PCNL, ureteroscopy: stone-free rates 89% and 72% use if stone composition, location, or renal anatomy prevent ESWL. • stones 20-30mm • PCNL first line, followed by ESWL if needed • ESWL: stone-free rate 34%, high rates (33%) of 2nd procedure if used alone. • ureteroscopy inferior to PCNL if large stone burden: 1/3 require 2nd look, high incidence of recurrences. • stones > 30mm • PCNL first line regardless of size, location, composition • ESWL stone-free rate only 27%.
Ureteral Stones • Proximal Ureteral Stones • ESWL with or without stone manipulation; ureteroscopy; PNL; and, rarely, open and laparoscopic stone surgery. • Distal Ureteral Stones • ESWL with or without a stent; ureteroscopy with extraction or intracorporeal lithotripsy; and, rarely, open and laparoscopic stone surgery .
Conservative treatment • Ureteric stone have high probability of spontaneous clearance. • According to a meta-analysis by AUA Guidelines Panel, newly diagnosed stones with diameter < 5 mm will pass up to 98%. • Passage depends on degree of obstruction, urothelial edema, and degree of impaction • Overall passage rate 25% for proximal, 45% for mid and 75 % for distal ureteric stones • Medical management • Ca antagonist + steroid Higher Expulsion rate in double blind study 79% vs 35%. • Tamsulosin • 80% vs 62%
Proximal Ureteral Stones • ESWL should be the primary approach for stones < 1 cm in the proximal ureter. • For stones larger than 1 cm in diameter, ESWL, PNL, and ureteroscopy are all acceptable choices . • A review of the literature shows excellent results for ureteroscopy lithotripsy using the holmium laser for proximal as well as distal ureteral calculi, with a mean stone-free rate of 95% associated with a low perforation and stricture rate of about 1% .
Distal Ureteral Stones • Areview of retrospective series after 1997shows that URS was optimal choice over ESWL because of superior stone free rate(85% for stone<5mm and 95% for stone >5mm with ESWL and 100% treated with URS regardless of stone size.
The indications for intervention for ureteral stones • intractable sx • infection • Patients who fail ESWL. • Patients with a history of cystine stones. • Patients with distal obstruction. • Patients with impacted stones. • Obese patients. • Patients with bleeding diathesis. • When ESWL is not readily available. • Stone unlikely to pass spontaneously
ESWL VS Ureteroscopy
The AUA Ureteral Stone Guidelines Panel meta-analysis showed ESWL to have: • Stone clearance of 74% for stones < 1cm • Stone clearance of 46% for stones 1-2 cm • More than 1 session of is often required • Success rate decreases after subsequent re treatments • Pace et al. in a series of over 1500 pts treated with Dornier MFL 5000 lithotripser, showed: • Superior success rate for upper/ mid ureteric calculi comparing to lower calculi • Initial stone free rate of 68% decreased to 46% on 1st re treatment and 31% on 2nd re treatment
The AUA Update series (2006) concluded that Uretroscopy is highly efficient and minimally invasive for all proximal, mid & distal stones. • The article focused that the 1st line treatment for managing ureteral stones should not only depend on stone free rate • Additional variables include efficiency, invasiveness, symptoms, pt satisfaction and morbidity
ESWL • non invasive . • can be performed with sedo-analgesia in OPD. • high pt tolerance. • possible cost advantage • has higher re-treatment
Extracorporeal Shockwave Lithotripsy • Technical aspects : • All lithotripsy machines share 4 basic components: • an energy source (the shockwave generator) . • a focusing system . • imaging or localization unit . • a coupling mechanism .
Shockwave generator • An electro hydraulic, or spark-gap, technology. • The piezoelectric method . • An electromagnetic generator
Localization systems • Imaging is employed to localize the stone and direct the shockwaves onto the calculus. • The 2 methods commonly used to localize stones are fluoroscopy and ultrasonography. • Real-time imaging without interrupting the treatment can be obtained with in-line fluoroscopy, which also allows continuous adjustments during a treatment session to pinpoint shockwave placement onto the stone.
Localization systems • Ultrasound localization allows the visualization of both radiopaque and radiolucent renal stones in the absence of fluoroscopy (without intravenous contrast administration) • Most second-generation lithotriptors can employ this imaging modality, whose costs are much lower than radiographic systems. • Although ultrasonography has the advantage of avoiding exposure to ionizing radiation, ureteral calculi are frequently very difficult to localize with sonography alone because of interposed air-filled intestinal loops. Smaller stones may be particularly hard to identify with ultrasonography. • In addition, urologists are often more familiar with fluoroscopic localization.
Localization systems Advantages of fluoroscopy include: • identification of both renal and ureteral calculi . • Tracking of migrating fragments in the ureter. Fluoroscopy, however, employs ionizing radiation and fails to visualize radiolucent or minimally radiopaque stones unless contrast is administered. • The administration of intravenous iodine-based contrast during treatment can be useful in localizing these stones with fluoroscopy. • Alternative methods of stone visualization include the insertion of a ureteral catheter before the procedure and the direct injection of contrast into the collecting system retrograde ureteropyelography.
Coupling mechanisms • A coupling system is needed to transmit the energy that is created by the shockwave generator across the skin surface, through visceral tissues, and ultimately to the stone itself. • Traditionally, this has been accomplished by placing the patient in a large (1000 L) water bath (e.g., with the first-generation device, the Dornier HM3 lithotriptor). • The second- and third-generation lithotriptors, however, small water-filled drums or cushions with a silicone membrane are used instead of large water baths to provide air-free contact with the patient's skin.
Mechanisms of Stone :Comminution • Four potential mechanisms for ESWL stone breakage have been described: • (1) compression fracture. • (2) spallation. • (3) acoustic cavitation. • (4) dynamic fatigue.
Contraindications: Absolute • contraindications to ESWL include: • Acute urinary tract infection. • Uncorrected bleeding disorders. • Pregnancy. • Sepsis. • Uncorrected obstruction distal to the stone.
Relative contraindications include the following: • Altered mental status. • Body weight greater than 300 lb. • Orthopedic or spinal deformities, renal ectopy, or renal malformations (including horseshoe and pelvic kidneys)
Poorly controlled hypertension Preexisting • Pulmonary and cardiac problems. • Before ESWL, oral anticoagulants, such as clopidogrel (Plavix) and warfarin (Coumadin) must be discontinued to allow normal clotting factors to resume.
Stenting and extracorporeal shockwave lithotripsy • The cystoscopic placement of a ureteral stent ensures upper urinary tract drainage. • Prevents transient obstruction from fragment migration after ESWL. • Helps localize ureteral calculi. • Employed to push back a stone from the ureter into the kidney, where treatment may be easier and more successful.
The traditional general indications for ureteralstenting before ESWL include : (1) large, dense stone burdens (>10-15 mm). (2) completely obstructing stones, impacted stones, or both. (3) poorly visualized stones, where the stent is required to aid in localization.
Renal complications • Perinephric, Subcapsular,intranephric hematoma may be associated with severe pain. • Unexplained or unusually severe pain, • significant bleeding, or any unusual drop in blood pressure may suggest a hematoma. • Hemorrhagic complications after ESWL rarely necessitate transfusion, embolization, or nephrectomy, although any of these are possible.
Hematuria occurs in the majority of patients and clears within the first few postoperative days. • Passage of many clots and urinary clot retention occur infrequently. • Post-ESWL sepsis is infrequent if the preoperative urine is sterile.
Hypertension is an unusual complication of ESWL, but it may occur as a sequela of a large perinephric hematoma. • Older patients with abnormal renal perfusion may develop hypertension within 26 months after the ESWL session. • Patients who receive ESWL at higher risk to develope hypertension and diabetes than patients who underwent other therapies for stone removal.
Steinstrasse:2% to 10 % post ESWL • Patients with asymptomatic and nonobstructingsteinstrasse are monitored closely with serial imaging. • Asymptomatic or mild symptomatic steinstrasse with mild dilation of the upper urinary tract can be managed conservatively with antibiotics and analgesics as needed. • If fragments are not passed after 3-4 weeks, ESWL or endoscopic lithotripsy may be repeated.
steinstrasse • Obstructing, infected, or symptomatic steinstrasse requires either percutaneous nephrostomy drainage or ureteroscopic treatments with stenting to ensure drainage.
The RF for developing acute renal side effects after ESWL • age: children and elderly • obesity • coagulopathies • thrombocytopenia • DM • CHF • hypertension • increased thromboplastin time • use of ASA
The acute and chronic histologic changes seen in kidneys after ESWL • Acute • venous thrombi • mild tubular necrosis • tubular dilation and cast formation • damaged veins and small arteries • rupture of glomerular and peritubular capillaries • Chronic • nephron loss • dilated veins • streaky fibrosis • diffuse interstitial fibrosis • Ca and hemosiderin deposits
Factors increase the degree of renal trauma in animals • Number of shocks • Period of shock wave administration • Accelerating voltage (higher voltage increases damage) • Type of shock-wave generator • Kidney size • Preexisting renal impairment
Intracorporeal lithotriptors: • How does EHL work? • fragments stones w/ shock waves generated by an underwater electrical discharge • underwater spark plug w/ 2 concentric electrodes of different voltage polarities separated by insulation • current supplied to overcome insulative gap spark produced • spark discharge causes explosive formation of a plasma channel and vaporization of the water surrounding the electrode
EHL • rapidly expanding plasma causes hydraulic shock wave, then cavitation bubble formation • depending upon the proximity of the probe to the stone surface, the collapse of the cavitation bubble may be symmetrical (~1mm from stone), resulting in a strong secondary shockwave or asymmetrical (~3 mm), leading to the formation of high-speed microjets • shock wave not focused (unlike ESWL), therefore, the stone must be placed where the shockwave is generated • may use saline irrigation
What are the advantages and disadvantages of EHL? • Disadvantages: • narrow margin of safety due to risk of ureteral perforation expansion of cavitation bubble • high risk of perf w/ impacted stones • retrograde propulsion of stones • large number of fragments produced. • Advantages: • cheapest intracorporeal device • successful in 90% rough stones break easily • flexibility of probes
laser = light amplification by stimulated emission of radiation. • Lasers have become a trusted weapon in the urologists' arsenal in treating stone disease. • The holmium:YAG laser has revolutionized intracorporeal lithotripsy: • wavelength of 2100 nm with a pulse duration of 250-350 ms. • The optical laser fibers available for use with the holmium: YAG lasers • are composed of flexible low-OH silica and available in diameter sizes ranging from 200,365,550 and 100mm. • The 365mm fiber is most often employed for the majority of lithotripsy procedures .