Extracorporeal shock wave lithotripsy (ESWL) was introduced in the early 1980s as a completely noninvasive therapy to break up stones within the kidney and ureter. The Department of Urology at the University of Florida was one of six sites within the United States to investigate the efficacy of ESWL lead by Dr. Birdwell Finlayson, a world renowned expert in stone disease.
ESWL accomplishes stone fragmentation by utilizing shock waves generated by a sophisticated spark plug electrode housed within a lithotripter device. These shock waves are generated by the lithotripter outside of the human body and the energy generated travels through the body converging onto the stone resulting in fragmentation. The resulting tiny fragments then pass out of the urinary system over the course of several weeks. This obviates the need for surgical incisions or invasive devices required to break up and extract these stones. ESWL, however, is only used in select stones in the kidney and ureter and therefore is not applicable for all stone types or locations.
Vincent G. Bird, MD
Department of Urology
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Benjamin K. Canales, MD, MPH
Department of Urology
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Russell S. Terry, MD
Director of MIS Education and New Technologies
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Prior To the Procedure
What to expect during your initial consultation:
- It is important that prior to your initial clinic consultation that all Xray films and their reports (e.g. CT scans, intravenous pyelogram or IVP, sonogram, or MRI) are compiled and brought to your appointment for careful review by your surgeon. These films can be requested along with the radiology report from the facility that performed the Xray. A review of your medical history and a physical examination will be performed along with blood and urine tests if needed. If your surgeon determines that you are a candidate for ureteroscopy, you will then meet with a Surgery Scheduling Coordinator to arrange for the date of your procedure.
What to expect prior to surgery:
- Prior to undergoing ESWL, you must make an appointment to have preoperative testing done at the Florida Surgical Center within one month prior to the date of surgery. The Surgery Scheduling Coordinator will assist with scheduling this appointment.
- Depending on your age, medical history, medications and overall degree of health, the following tests may need to be performed prior to your procedure:
- EKG (electrocardiogram)
- CBC (complete blood count)
- PT / PTT (blood coagulation profile)
- Comprehensive Metabolic Panel (blood chemistry profile)
- Urine culture
Preparation for Procedure
Medications to Avoid Prior to Surgery:
- The following is a list of medications to avoid at least 7-10 days prior to surgery. Many of these medications can alter platelet function or your body’s ability to clot and therefore may contribute to unwanted bleeding during surgery. Please contact your surgeon’s office if you are unsure about which medications to stop prior to surgery. Do not stop any medication without contacting the prescribing doctor to get their approval.
- Aspirin, Motrin, Ibuprofen, Advil, Alka Seltzer, Vitamin E, Ticlid, Coumadin, Lovenox, Celebrex, Voltaren, Vioxx, Plavix
- A formal list of these medications and others will be provided to you by our Surgery Scheduling Coordinators.
Signs and Treatment of Urinary Tract Infection Prior to Surgery:
- It is very important that your urine remain free of infection prior to ESWL. Therefore if you suspect that you may have a urinary tract infection (burning on urination, blood in the urine, urinary frequency and urgency, fevers), please notify your surgeon immediate so that proper cultures and treatment may be provided.
For the vast majority of patients, ESWL is performed on an out-patient basis with no need for hospital admission following the procedure. ESWL procedures typically last approximately one hour. ESWL can be performed either under general anesthesia or under intravenous sedation. Once the patient is anesthetized, the lithotripter machine is positioned in contact with the patient’s flank on the side of the stone. A series of up to 2,000 shock waves are delivered to fragment the stone. ESWL is performed under Xray guidance to accurately target the stone in efforts to maximize stone fragmentation while minimizing adjacent organ injury. On occasions, a ureteral stent may be required to dilate the ureter, avoid stone obstruction, and facilitate stone passage down to the bladder.
Potential Risks and Complications
Although ESWL has proven to be very safe over decades of use and experience, there are potential risks that patients must be aware of which include:
- Bleeding and Transfusion: A small amount of bleeding will occur as a result of ESWL and often manifests by visible blood in the urine following the procedure. Rarely, bleeding can occur in and around the kidney (called a hematoma) that may require a transfusion. Nevertheless, transfusion rates for ESWL are generally <1%.
- Infection: Although patients receive a dose of intravenous antibiotic immediately prior to ESWL, occasional infections within the urinary system can occur resulting in high fevers and chills. Although most infections are treated successfully with oral antibiotics, in rare cases patients may require readmission to the hospital for intravenous antibiotics.
- Adjacent Tissue/Organ Injury: Although uncommon, injury to surrounding skin, tissue, nerves, muscles and organs (liver, spleen, small and large intestines, pancreas, and kidney) may occur following ESWL. Most injuries are minor, resolve spontaneously and require no further intervention.
- Ineffective/Incomplete Stone Fragmentation: Although ESWL has proven to be an effective treatment for kidney and ureteral stones, the success of ESWL is dependent upon many variables including the size and especially the composition of the stone. All stones are made of slightly different composition, which may impact on the density of the stone and hence responsiveness to ESWL fragmentation. Other factors that affect ESWL success are the location of the stone within the urinary tract, function of the affected kidney, medical condition of the patient, time since ESWL treatment and the ability to accurately target the stone during ESWL treatment. For some stones, multiple ESWL treatments may be required to adequately fragment the stone. Unfortunately in some cases the stone may be resistant to fragmentation with ESWL despite multiple attempts.
- Steinstrasse: Steinstrasse, or an accumulation of a large number of unpassable stone fragments within the ureter, occurs in 1-4% of patients who undergo SWL, increasing to 5-10% for stones >2 cm in size, and up to 40% in patients with partial staghorn calculi.
- Diabetes/Hypertension: New onset hypertension, primarily diastolic, is a potential consequence of SWL, with the development likely being dose dependent. Despite multiple retrospective reports, three prospective randomized trials in this area failed to demonstrate SWL-mediated changes in blood pressure. In a recent retrospective, case-control study, development of diabetes and hypertension was found to be higher in patients who underwent SWL in 1985 (odds ratio of 3.23 and 1.47 respectively) than in control patients who were treated conservatively. Despite the study limitations and methodologic biases, the results of this analysis must be viewed as significant potential long-term complications of SWL, and patients should be counseled appropriately.
What to Expect After Surgery
- Flank Pain: Most patients experience some degree of discomfort for a day or two after ESWL. The pain is usually described as a dull ache or soreness over the kidney or flank area, and is typically at its worst the evening following surgery. The pain lessens over the following days.
- Blood in Urine: It is normal to see visible blood in the urine for days to several weeks after surgery. It is important during this time of bleeding that you avoid strenuous activity, blood thinning medications, and drink plenty of fluid.
- Fevers: Low grade fevers are not uncommon following any surgical procedure and anesthesia. If you have fevers >101o F, please notify your surgeon or call352-265-0111 and ask to be connected to the urologist on call.
When to call your Doctor
Although adverse events are rare following ESWL, it is important for patients to recognize these events and know when to contact their surgeon. You should contact your surgeon or primary care doctor immediately if any of the following occur:
- Worsening pain over the ensuing days following ESWL procedure. If this pain continues to escalate despite the use of oral pain medication, this may indicate obstruction of the kidney from a large stone fragment lodged within the ureter, hematoma around the kidney or infection of the kidney.
- Large amounts of blood clots in the urine that may lead to difficulty with voiding and fully emptying the bladder.
- Fevers >101o F may indicate a serious infection within the urinary tract.
- Nausea and vomiting
- Chest pain or difficulty breathing
Frequently Asked Questions (FAQs)
What is the advantage of ESWL as compared to other stone treatments?
- The primary advantage of ESWL is that it is completely non-invasive in that there are no skin incisions required or invasive instrumentations used to treat the stone. Instead, the energy from shock waves is used to fragment the stone into smaller pieces that will then pass down the ureter and out the bladder.
Are there disadvantages?
- Unfortunately not all stones will fragment successfully with ESWL as the fragility of the stone is dependent on many factors including size, location, and stone composition. Therefore on theoretical disadvantage to ESWL as compared to more invasive stone procedures is that more than one ESWL treatment may be required to adequately fragment the stone to small enough fragments to allow for spontaneous passage through the urinary tract. In addition, rare complications may occur following ESWL as described above.
Which patients are good candidates for ESWL?
- ESWL is well suited to patients with small kidney stones (generally < 1cm) that can be easily seen by x-ray. Certain stones within the upper portion of the ureter may be treated with ESWL as well. Those that are further down the ureter are often approached by ureteroscopically.
What patients are not good candidates for ESWL?
- Patients who are pregnant, have active urinary infection, obstruction of the kidney or are on blood thinning medications that can not be discontinued are not ideal candidates for ESWL treatment. Patients with particular known stone composition including cystine and certain types of calcium phosphate stones are not ideal candidates as these stone types may not fragment well with ESWL due to their dense nature.
Can multiple stones be treated simultaneously with ESWL?
- Multiple stones can be treated; however, the number of shock waves delivered may be distributed amongst the stones therefore limiting the energy delivered to any one stone for fragmentation. Your surgeon will determine if there are too many stones for ESWL therapy and whether alternative treatments should be considered.
Will I need placement of an indwelling ureteral stent following ESWL?
- Not all patients who undergo ESWL will require a ureteral stent. Based upon stone size, location, or presence of any abnormalities in the drainage system of the kidney, placement of a ureteral stent may be required to aid in passive dilation of the ureter to help facilitate passage of stone fragments following ESWL. This is usually placed at the time of the ESWL while you are under anesthesia. Our surgeons will make this decision with each patient prior to surgery based upon each individual’s case. For stent related questions, please refer to Ureteroscopy FAQs.
What is the overall success rate with ESWL?
- The success of ESWL is dependent on many factors such as stone composition, stone location within the urinary tract, patient body habitus (obesity), kidney anatomy, and type of ESWL machine used. Our surgeons carefully consider all of the aforementioned variables and will discuss this with you in order to maximize success and determine if ESWL is right for you. Overall stone free success rate is 67% at our center.
How do I know if ESWL was successful?
- Following ESWL, your surgeon will determine whether the treatment was successful based upon X-ray findings. This may be in the form of either an abdominal Xray or CT scan. With these Xray tests, the surgeon can determine the degree of stone fragmentation and whether any fragments remain within the kidney or ureter. If stone fragments remain within the urinary tract, more time may be required to allow for spontaneous passage, which often takes several weeks. Alternatively your surgeon may recommend further treatment with repeat ESWL, ureteroscopy, or percutaneous nephrolithotomy.
Can ESWL be repeated?
- Yes. Often due to stone density or size, fragments may at times remain in the urinary tract that are too large to pass spontaneously. In such cases, repeat ESWL may be considered.