Extracorporeal shock wave lithotripsy (synonyms: ESWL, extracorporeal lithotripsy; Gr. lithos – stone; tribein – to pulverize) is a medical procedure for the disintegration and removal of calcium concretions (e.g., stones in the kidney, urinary bladder, ureter, gallbladder, or bile ducts).
Indications (areas of application)
- Cholecystolithiasis (gallstones).
- Choledocholithiasis (bile duct stones)
- Nephrolithiasis (kidney stones)
- Pancreaticolithiasis (stones in the ductal system of the pancreas).
- Urolithiasis (bladder stones)
- Ureteral stones (ureteral stones)
Contraindications for nephrolithiasis
- Anticoagulant or antiplatelet (anticoagulant) therapy or coagulopathy (acetylsalicylic acid (ASA) may be continued with careful indication evaluation)
- Pregnancy (unknown rate of harm to the fetus).
- Untreated urinary tract infections
- (Severe) nephrocalcinosis, boxerless (caveat: renal function impairment).
- Aneurysm in the focal zone
- Outflow obstruction distal to the stone (obstruction/occlusion).
- Newly adjusted hypertension (high blood pressure).
- Pancreatitis (inflammation of the pancreas).
Before treatment
- Before performing ESWL, knowledge of the anatomy of the region in question is essential for careful planning.
- During treatment, adequate analgesia (analgesia) should be ensured to prevent excessive respiratory excursions and thereby improve treatment outcomes.
- Routine antibiotic prophylaxis is not required during treatment.
- Regarding urinary stones: in case of infection stone, a lying foreign material for example ureteral track) or bacteriuria should be antibiotic prophylaxis or resistance therapy before action.
The procedure
Shock waves are high-energy waves generated in different technical ways, for example, by short pulses of pressure generated in water. This can be done using different physical principles:
- Electrohydraulic
- Piezoelectric (oscillations of quartz crystals).
- Electromagnetic
The sound pulses can be localized to a specific area and act there, that is, they develop their effect only at the programmed place of action. In extracorporeal shock wave therapy, the shock waves are generated outside the patient’s body (extracorporeal). Shock waves are differentiated according to their energy content, which can be varied depending on the application. When high-energy shock waves are used, anesthesia, which may be associated with a short inpatient stay, is usually necessary. Imaging must be performed before treating kidney stones, for example. Kidney stones are visible on x-ray, but they can also be localized by contrast imaging of the renal pelvic caliceal system see i. v. (intravenous) pyelogram. The patient is in a recumbent position. The disintegration of the stones is performed under fluoroscopy (X-ray film in real time) or under ultrasound control. Both systems are used to precisely locate the calculi so that the shock waves can be optimally focused. After localization, the stones are crushed with up to 4,000 ultrasound pulses. In some cases, the treatment must be repeated if the concretions have not been successfully destroyed. The destroyed kidney stones can then be excreted through the urinary tract.
ESWL for urinary stones
- Most urinary stones can be treated by extracorporeal shock wave lithotripsy (ESWL).
Factors limiting the success of ESWL treatment for urinary stones:
- Hard stone composition (brushite, cystine, calcium oxalate monohydrate), > 1,000 Hounsfield Units.
- Steep lower calyx renal pelvis angle
- Long lower calyx neck (> 10 mm)
- Narrow infundibulum (< 5 mm)
- Anatomical malformations (e.g., skeletal deformities).
- Obesity (skin – stone distance).
After treatment
- Short-term postinterventional clinical and sonographic (ultrasound) monitoring should be performed after ESWL.
- Regarding urinary calculi: Postinterventional radiographic examinations for shadowing calculi to assess disintegration and freedom from calculi (urinary tract survey) should be performed after 12 weeks at the latest.
Possible complications of ESWL of urinary stones
- A stone road may result from outgoing disintegrates (4-7%).
- Excretion of disintegrates may lead to colic (2-4%), in addition, progressive (advancing) growth of residual fragments (remnants) is described in up to 60
- Sepsis (blood poisoning) (1-2.7%).
Benefit
Extracorporeal shock wave lithotripsy is a successful and proven method for the destruction and removal of stones and calculi (e.g., kidney stones or gallstones). Patients benefit from the gentle procedure by avoiding surgery.
