Extracorporeal Shock Wave Lithotripsy (SWL)


Extracorporeal = “outside of the body

Shock Wave = “using waves of a specific type of energy

Litho = “stone”

Tripsy = “breakage or fragmentation”

Urinary tract stones are either located in the kidney, in the ureter (the tube that attaches the kidney to the bladder) or in the bladder itself. SWL may be used to fragment stones that are inthe kidney or in certain parts of the ureter. The success rate of breakage depends on the size of the stone, the location within the kidney or ureter, the composition or make-up of your particular stone, and the number and energy level of the shocks employed. The second part ofsuccess is whether or not the fragments pass out of your system. This will depend on the original location of the stone, the size of the fragments, and on the particular anatomy of your urinary tract.

There are different types of SWL machines throughout the world. They use different types of energy and have different powers. Regardless, they all have the same goal of fragmenting a stone employing non-invasive technology. This is NOT a form of laser technology. Lasers are only used to fragment stones with the minimally invasive procedures in which scopes are inserted into the urinary system.


It is necessary, as with any procedure or operation requiring anesthesia, that you have not eaten for at least eight hours prior to the scheduled time. In order to assist us with visualizing your stone, we may ask you to clean out your intestines and colon the night before. You should plan a very light dinner (perhaps around 5-6:00 p.m.) the evening prior and avoid vegetables or other foods that typically cause gas. Approximately one hour after, you should take a laxative(available over the counter). Depending on your particular digestion, it will “clean you out.”You may drink for the rest of the evening, but do not eat. Not all patients will be asked to take a laxative, although the light dinner and the avoidance of gas-producing foods is usually a good idea.

As with any procedure in which anesthesia is administered, you will be asked not to eat or drink anything after midnight on the evening prior to your surgery. You may brush your teeth in the morning but not swallow the water. If you are on medications that must be taken, you will have discussed this with us and/or the anesthesiologist and instructions will have been given to you. The procedure will not be performed if you are currently taking, or have recently taken any medication that may interfere with your ability to clot your blood (“blood thinners, aspirin, anti-inflammatory medicines, etc.”). The most common of these medications are aspirin and all related pain relievers or anti-inflammatory compounds (whether prescription or over-the-counter).

Please refer to the attached list and tell us if you took any of these within the past 10 days.

If your new medication is not on the list, alert us immediately so that we may ensure optimal procedure safety. We will have reviewed all of your current medications with you during the pre-operative/pre-procedure consultation. You are obligated to inform us if anything has changed (medication or otherwise) since your previous visit.

*If you are a patient with high blood pressure (hypertension) and your pressure has been poorly controlled recently, please let us know as it is important that your primary care physician get your pressure back to normal prior to this procedure.

*Patients who are being treated for abnormal heart rhythm (i.e. atrial fibrillation or patients with pacemakers) can have this procedure, but it is important that we know so that we may communicate with your cardiologist and possibly make special preparations with the SWL machine and with the anesthesiologist.


You will be placed lying on your back (or less commonly face-down on your stomach) and the stone will be localized with real-time x-rays (fluoroscopy) and/or ultrasound technology. Some machines necessitate that you be partially submerged in a water bath and others do not. Once we are satisfied that your stone can be accurately targeted with the shock waves, you will be given light sedation by the anesthesiologist. Rarely, some patients may require general anesthesia. Shock waves are aimed precisely at the stone. The maximum energy level used and the number of shocks administered will depend on how your stone responds to the shocks. There is, however, a maximum level at which point we will terminate the procedure. In addition, for safety reasons, your heart rate and rhythm may dictate the way in which we administer the shocks. At the end of the procedure, we often have an idea as to its success, but we too, are sometimes fooled. A stone that appears well-fragmented during the procedure can often be found to be unchanged on the follow-up x-rays weeks later. Alternatively, a stone that appeared unchanged during the procedure is sometimes not seen at all on follow-up x-rays due to successful fragmentation and passage.

At the termination of the shock waves, you are easily awakened and observed in the recovery room until the sedation has completely worn off. Almost all SWL procedures are done on an ambulatory basis, and it is quite rare that a patient needs to be admitted.

Post Procedure

After the procedure, you will be in the recovery room until you are ready to be discharged. It is uncommon for a patient to be admitted to the hospital afterward, but certain circumstances could make admission necessary.

It is common and even expected to have some discomfort in your back on the treated side. Over the next day or two, your urine may appear dark or amber which represents the presence of blood. You may have no blood in the urine, mild blood, or even what appears to be a significant amount of blood or small clots. It is rare for the blood to not disappear within a day or two. You may also notice stone fragments passing in the urine, and this is the desired result. Because they are small, a patient typically does not feel them as they pass in the urine but they can be visible as sand or very small pebbles.

Expectations of Outcome

The intent of SWL is to completely fragment the stone and have all pieces pass out in the urine. Unfortunately, this is not always the case. Sometimes, the stone does not break at all, or there is incomplete fragmentation and only part of the stone breaks.

In this regard, we may suggest another SWL at a later date. Sometimes the stone fragments quite well, but the pieces never leave the kidney. This is most common with stones that are in the lower half of the kidney. The combination of the sharp angle and gravity holding them in the lower half make it less likely that they move into the ureter.

Occasionally, and more common to larger stones, a large fragment can get caught in the ureter and temporarily block the kidney. In this situation, we may elect to observe (if you are comfortable and the fragment is of a size that may permit spontaneous passage) or we may recommend placement of a stent.If necessary, we might recommend a ureteroscopy procedure (putting a small telescope into the ureter) to further fragment and/or remove the large piece.

Possible Complications of the Procedure All surgical procedures, regardless of complexity or time, can be associated with unforeseen problems. They may be immediate or even quite delayed in presentation. While we have discussed these and possibly others in your consultation, we would like you to have a list so that you may ask questions if you are still concerned. Aside from anesthesia complications, it is important that every patient be made aware of all possible outcomes which may include, but are not limited to:

We provide this literature for patients and family members. It is intended to be an educational supplement that highlights some of the important points of what we have previously discussed in the office. Alternative treatments, the purpose of the procedure/surgery, and the points in this handout have been covered in our face-to-face consultation(s).

The information contained in this document is intended solely to inform and educate and should not be used as a substitute for medical evaluation, advice, diagnosis or treatment by a physician or other healthcare professional. While UUANJ endeavors to ensure the reliability of information, such information is subject to change as new health information becomes available. UUANJ cannot and does not guaranty the accuracy or completeness of the information contained in this document, and assumes no liability for its content or for any errors or omissions. Please call your doctor if you have any questions.


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