PAUL MONIZ: What you're looking at is a patient undergoing shockwave lithotripsy. That is just a fancy name for breaking up kidney stones. If you've ever had a kidney stone, you can say with certainty you know all about pain.
I'm Paul Moniz. Thanks for being with us. Kidney stones effect some one million people in the US every year. More men than women are effected, and they can sometimes occur in men as early as their 30s. Here to talk about what treatments are available are two urologists who treat kidney stones.
Dr. Robert Salant is an Associate Professor of Urology at NYU School of Medicine and in private practice at Midtown Urologic Associates in New York City. Dr. Salant, thanks for being here.
Dr. Jon Marks is an attending urologist at Beth Israel Hospital and the Medical Director of Metropolitan Lithotriptor which are kidney stone treatment centers around our area.
Dr. Marks, let's begin with you. How is treatment determined?
JON MARKS, MD: Treatment is determined in a number of ways. The size of the stone and the composition of the stone influence that, but the average stone of modest size, perhaps less than 2 centimeters, less than about three quarters of an inch, those are stones that can be treated in general with shockwave lithotripsy.
PAUL MONIZ: Which is the procedure that we just saw.
JON MARKS, MD: That is correct.
PAUL MONIZ: That is the most common procedure right now?
JON MARKS, MD: It is. It's popularity has to do with the fact that apart from being effective, it is done under sedation. It requires no hospitalization. Patients can have it on one day and be back to work the following day. So it is advantageous in that respect.
PAUL MONIZ: Dr. Salant, take us through the procedure. How long does it take? What's involved?
ROBERT SALANT, MD: In general, the way the modern lithotripsies are done, a patient is placed on a special table, and using either X-rays or ultrasound, the stone is localized. That enables the surgeon to focus the shockwaves on the stone itself. The shockwaves pass harmlessly through the body and hit the stone, breaking the large stone up into smaller pieces. These fragments hopefully will be about the size of a grain of sand, perhaps a little bit bigger. These fragments can then pass easily through the body and out through the urethra.
PAUL MONIZ: Dr. Marks, maybe you can explain to our audience how the breakup actually occurs with these shockwaves. What's actually happening in there?
JON MARKS, MD: There are a number of different machines, but in general, the machine that we are illustrating here, there is a spark plug that sits at the bottom. It sits within a reflector. The shocks that are generated are focused at a point well above the reflector. If you bring a patient's body on top of that reflector apparatus in such a way that the stone corresponds to where the shocks are focusing, all the energy created by that spark plug discharge is focused on the stone, doing minimal damage to the surrounding tissue.
PAUL MONIZ: What does the patient feel?
JON MARKS, MD: Well, it is uncomfortable for the patient, and uncomfortable enough so that they require some sort of sedation in order to be able to tolerate the experience. There are other machines that can be used that require no sedation, but they are much less effective.
PAUL MONIZ: After the procedure is done, what happens to the stone? I assume that it breaks up. How quickly does it pass out of the system?
JON MARKS, MD: In general, and this depends on the composition and the size of the stone, but if the stone is well fragmented such that the fragments are two and three millimeters, a little bit larger than grains of sand or the size of very small BBs, these stones will gradually pass out of the patient, sometimes within the first few days, but sometimes it will take up to three months for the fragments to pass.
PAUL MONIZ: We have some shots of what those broken up pieces look like. Maybe Dr. Salant can walk us through that. Now if someone had a fairly large stone, this is just a couple of fragments or three fragments that might come out. They may have a whole bunch of them, is that right?
ROBERT SALANT, MD: Yes. After the procedure is done patients will pass several stone fragments. Literally, it could be hundreds depending on how large the initial stone was and how small the fragments had been broken into.
In general, we usually have the patients strain the urine so when the stones do come out you're able to save the fragments which can then be analyzed to see what type of stone was in the body.
PAUL MONIZ: So they have this procedure. It's about 35 minutes. Then they start passing the stones. How painful is it to pass conceivably hundreds of stones?
ROBERT SALANT, MD: Stones cause pain only under two circumstances. One, if there is active infection, and two, if the stones are causing blockage to the urine flow. If the procedure is successful the stone fragments are small enough that they should pass without causing blockage and therefore without significant amounts of pain. There may be some discomfort, but in general after a successful procedure, there should be minimal if any pain.
PAUL MONIZ: Is there a lot of blood after the procedure in terms of the urine?
JON MARKS, MD: Well, the kidney is traumatized by the presence of the shockwaves and by the entire interaction of the shockwaves with the stone. So it is not uncommon for the patients to experience what we call hematuria, which is some blood in the urine. The urine may turn light pink for a day, and then it clears up as the kidney heals.
PAUL MONIZ: How long till they can go back to work with lithotripsy?
JON MARKS, MD: As mentioned, frequently the following day.
PAUL MONIZ: Dr. Salant, if lithotripsy doesn't work, then what?
ROBERT SALANT, MD: There are some stones that are just not amenable to lithotripsy, either because of the size or the location. There are other somewhat more invasive procedures prior to doing any open surgery to address these stones. One method to get to the stones and break up the stones without making any incisions in the body is using thin telescopes that go in through the urethra and up to the level of the stone. These are called endourologic techniques. These very thin telescopes are used to directly visualize the stones. Then the stones can either be grasped in a basket and pulled out in one whole piece, or if the stones are large, they may be broken up using various sources of energy such as ultrasound, laser or electricity.
PAUL MONIZ: So you go in using what kind of an instrument? You go in through the urethra?
ROBERT SALANT, MD: We go in through the urethra using a very thin telescope which is directed up to the level of the stone. Then under direct vision, the stone is then broken up using one of the energy sources.
PAUL MONIZ: Just for our audience, the urethra is?
ROBERT SALANT, MD: The urethra is the tube where the urine comes out from the bladder. So in the male, it's through the penis, and in the female, it's just above the level of the vagina.
PAUL MONIZ: If that doesn't work, Dr. Marks, what happens next?
JON MARKS, MD: For stones that are large that reside in the kidney, these are not appropriate to be treated with shockwave lithotripsy.
PAUL MONIZ: Like this one here. If a patient came in and had this particular size.
JON MARKS, MD: This would not be appropriate to treat with shockwave lithotripsy. In years gone by, we would have done an open operation. But now we can do what's known as percutaneous nephro-lithotripsy, not to be confused with shockwave lithotripsy. That's a procedure whereby we make a small hole in the patient's back. We insert other kinds of telescopes directly into the stone under radiographic guidance using fluoroscopy. We apply various energy sources to the stone to break it up, and we physically remove large chunks of the stone through this small hole that we made in the patient's back.
PAUL MONIZ: If you have to split the kidney, as it were, in the most extreme case, there are some complications involved. Potentially.
JON MARKS, MD: The procedure that you're referring to is called anatrophic nephrolithotomy. Basically, it's a procedure whereby we make a large incision in the patient's side, we expose the kidney and see the operative field, we make an incision in the kidney itself to split it in half like the two halves of a peach that you've cut in half. The stone, like the peach pit, sits within it. Then we remove the stone by actually teasing it out from the kidney. But there can be complications.
PAUL MONIZ: Dr. Salant, let's talk about medications. Can medications be used either to dissolve some of the stones or make the symptoms less painful?
ROBERT SALANT, MD: There are two types of medications that can be used for stones. One is pain medication to mask the pain that the stone is producing. The pain medications do not dissolve the stone, but they can relieve some of the pain that the patient is experiencing. With enough hydration or fluid intake, the patient may pass a small stone on his or her own with enough pain medication in their body.
In terms of actually dissolving stones, the most common stone in the United States is a calcium oxylate stone, and that's not a stone that can actually be dissolved. However, the second most common stone, the uric acid stone, can be dissolved. The way you go about dissolving a uric acid stone is to alkalinize or make the urine more basic. In that way, the uric acid can dissolve in the base and will actually shrink in size and disappear.
PAUL MONIZ: Dr. Marks, what would your final advice be to our audience about treating kidney stones?
JON MARKS, MD: I think anyone with pain from a kidney stone would certainly be seeing a physician because of the extent of the pain. Once a determination is made as to what the composition of the stone is, or at least what it's appearance is on a radiograph, what it's location is, how large is it, then one of these various modalities would be selected by the urologist to treat the stone, and there would be a progression. If the stone failed to disintegrate with one, then you would progress to another, etc. But they need to prevent stones by maintaining vigorous hydration, keeping themselves well hydrated at all times.
PAUL MONIZ: Lots of water. They should be looking for what, two-and-a-half quarts a day of urine output?
JON MARKS, MD: We say about two to three liters a day in patients who are stone formers. In patients who are not stone formers, it's somewhat less important. But that level of hydration is important. They shouldn't use tea. They shouldn't use Coca-Cola because those things contain lots of oxylate which can actually lead to more stones.
PAUL MONIZ: Important information. Thank you very much Dr. Jon Marks and Dr. Robert Salant.
Again, remember that stones are common and they can be treated. Check with the urologist if you have pain or questions.