I would like to welcome all of you to our next installment of our virtual forum web-based lecture series. This is a series of presentations by experts in our subspecialty from across the country. The goals are not only to enhance your understanding of the FPMRS learning objectives, but also to allow you the opportunity to interact with experts in our field in real time. This presentation will then be captured and made available for view at any time on the OGS website. Upon completion of this program, as Gary mentioned, you will be given the opportunity to provide some feedback, which we do value greatly in future programming. So for this evening's presentation, it's my pleasure to introduce one of OGS and SUFU's finest speakers, clinicians, and scholars, and one of my good friends, Dr. Elizabeth Miller. She is Division and Fellowship Director of the Female Pelvic Medicine and Reconstructive Surgery Program at Loyola University Stritch School of Medicine outside of Chicago. And she is now a full professor in the Departments of Ob-Gyn and Urology. So her presentation today will be Urodynamic Evaluation of Lower Urinary Tract Symptoms. She has spoken and taught on this subject nationally and internationally, and we are really happy to have her here. So thank you, Dr. Miller. Oh, well, thank you for that, Leslie. Just hard to believe all the trouble we got into as residents, and here we are introducing each other. Hopefully there's no slides on that. No, no. There's no slides. So welcome, everyone, and I love this kind of forum, and it's small to me. I can see that there's like 17 people there. And when I was thinking about this and talking tonight, I wanted to treat this just like I would with my fellows and make this kind of an informal discussion. And I need to tell you some stories. Urodynamics have really changed, and they've really changed throughout, and their use has really changed throughout my career. For example, I remember back when we were first going to do the first, the sister trial. I don't know if you guys have talked about that much in your fellowship programs, but that was the first randomized trial that was done by the UITN, where they were randomizing people to either get a sling, a fascial sling, or a birch. And we were actually blinded to the urodynamic outcomes. We thought the study was unethical to start. We couldn't believe Dr. Brubaker had come back and told us we were going to enroll patients in it. We had had all this dogma around urodynamics. And actually at the time, we were using urodynamics to make decisions about who was going to get a birch and who was going to get a fascial sling. We uniquely did needle EMG of the urethra. We measured things like mean rectified voltage, all sorts of stuff. And we thought for sure that our formula for predicting who needed a sling and who needed a birch was pretty outstanding. And Dr. Brubaker kept saying, no, I disagree. Well, as it turns out, we went from at that time, years ago, probably doing about 10 urodynamics a day on a great big multichannel machine. I was a stinking urodynamics expert, no doubt about it. I had an engineering background. I loved all of it to where we are now, where we've seen that urodynamics, while they're a good test, really can't tell you some basic things. So let me make an analogy, and then we'll move on with the lecture. Do you know how you would use an EKG to help you decide if somebody had a cardiac issue? And you would just order it and decide if they had a block, but you could never use an EKG to decide if somebody had chest pain, could you? Well, no. And yet, oftentimes, when I ask people about why they would, what would you do here? Why do you think she's leaking? Do you think she's leaking? They'll say, let's get urodynamics. Urodynamics don't tell you what patient's symptoms are. Urodynamics help you understand what are low urinary tract symptoms. So in preparation for today's talk, one of the things I did was go back and I talked to about four people who just did oral boards, Kim Kenton, Linda Brubaker. I think I'd mentioned to Dee Fenner and somebody else, I don't remember, and asked them, tell me, what do you think that I should be teaching on this webinar? What was your experience? And here's where some of the things that were said. Just teach the basics, seriously. People don't seem to understand some of the really simple things, and I think they mean the mechanics. Talk about measures of urethral integrity, which we'll talk a little bit about today. Teach people how to know if the study is being done correctly, and I'll try to give you some clues about that today from the tracings that you can look at later. And then one comment was just what are the different types of catheters? You know, there's a technical aspect to urodynamics, and we won't be able to get into all this today. Usually when I'm teaching a urodynamics course, sometimes I'm speaking for like six hours. Aren't you glad you're not in clinic with me? That would be a drag. But actually those are kind of paid courses. So what are we going to talk a little bit about today? Well, we're going to talk about tests of lower urinary tract function. And for me, the learning objectives are first, I want to be able to teach you or make sure you understand what are the different components of urodynamic testing. People will say, well, let's do urodynamic testing, and boy, you can't get away with that around in my clinic. I'm asking you exactly what test, and I'm always asking you what's the question you're trying to answer. Understand the indications and the limitations of each of the tests, formulate a urodynamic question. Now that's important. For example, in that case, the thing I just said about the EKG, you would want to ask yourself. EKGs are actually easier to read because the technician can just do them. They have very little patient variables. Urodynamics are not quite that way. But formulate a urodynamic question, and before you order urodynamics or before you sit down for an oral board and say you're going to order urodynamics, the very first question that should come out of that examiner's mouth then is why and what is your question? Because it's only when your question has been answered that you can stop the test, and sometimes you might find that the question you're asking is really not one that could be answered by urodynamics. Lastly, state what test you would perform to answer the urodynamic question. So what are urodynamics? Well, they're straightforward. They're functional tests, and they're artificial. They're artificial. They're functional tests of the lower urinary tract, and the idea is that we're trying to capture the three components really of bladder, of the bladder, the three functions of the bladder. So one is bladder filling, two is storage, and three is voiding. And what's the role of urodynamic testing? Why do we do it? Well, we do it when we're trying to understand the function of the lower urinary tract. Also, for example, you have a person who comes in, they've had a sling. Maybe after their sling, their bladder got over-distended a lot, let's say two liters. It's now been three weeks. They still can't urinate. Boy, it's a legitimate question. Is this coming from the sling? Now it probably happened with the sling surgery, but that over-distension injury could be making it that this woman can't urinate, and it may not be that if you cut the sling, she's going to be any better. So there are, urodynamics can really help us in that situation. Aid in the evaluation of lower urinary tract symptoms. You know, women say they leak, they say they're leaking urine. The story doesn't make much sense. And urodynamics can sometimes help. Is this overflow? Is this overactive bladder? Is this stress incontinence? Also, there are times that we do urodynamics that are not based on symptoms, but really are about surveillance. And this happens more in my world, Dr. Ricci's world, in the world of clinicians who are urologists who are taking care of women with MS, and some of you will. Some of you won't, but some of you will. And in some of those women, what can happen is that they may have no symptoms, but they also don't leak, and they could potentially put their upper tracts at harm. And so urodynamic testing might be done on a surveillance basis to just make sure they have a healthy lower urinary tract. When are they indicated? Well, when they would change treatment or decisions or affect counseling. So if you're pretty sure you're going to put somebody on medication, and medication's not permanent, there's probably not a role for urodynamics. You certainly don't need to do urodynamics to treat overactive bladder. You can just give them medication and see if they respond. And increasingly, we're feeling that way about the index stress incontinence patient, right? You have a woman who comes in. She has straightforward signs of stress incontinence. Maybe she has a filler, and you have a demonstrable sign of stress incontinence. And that woman, classically, by our organizations and the AUA practice guidelines, says we probably don't need to do urodynamics on her to prove she has stress incontinence. Sometimes though, you can treat somebody, give them medication, maybe put a pessary in. You think they have stress, or in another scenario, you're certain they have urge. And you know what? You treat them and nothing changes. And it's perplexing. And so when you're unsure after you've clinically assessed women, my favorite kind of patients that we all get, and we'll all get one a week, is the woman who just comes in and says, I'm wet. Well, when are you wet? All the time. And, you know, teasing this apart, you know, after 20 minutes of conversation, oftentimes I'll say, let's just do urodynamics. And because in that case, when they have that much mixed incontinence, and that's what I'm assuming, it's hard for me to tell which one's more difficult. I said already, if a patient doesn't respond to treatment, and increase, or probably less so than we used to, we see urodynamics being used in clinical trials and research. So let's get started. Well, the urodynamics tests that we're going to talk about, and I'm just going to go through these quickly, are uroflow, CMG, pressure flow studies, the urethral pressure profile, the leak point pressure, some stuff about EMG, and then not much about fluoroscopy. So in terms of uroflow, uroflows are really popular. In fact, there was a study that I did taking a look at the urodynamic procedures being done by all urologists in the country, and the number one, the number one urodynamic test being done is uroflow, and that's mostly being done on men. So it's a non-invasive assessment of emptying, and what happens is that a patient arrives with a comfortably full bladder, and they sit or stand to urinate, and you want them to repeat the position that they'd use most frequently, and then the flow can be observed or recorded electronically. And the classic types of uroflow devices are gravimetric, or electronic dipstick, or rotating disc, and they're required to have a 95% accuracy. Now what happens with a, what happens with, I'm trying to see my little pointer action here, there it is, okay. So uroflow, it measures flow pattern. It can measure urinary flow rate, and that's in milliliters per second, the total voided volume, the maximum flow rate, the average flow rate, and the time to maximum flow. And this is a very classic uroflow. What we have, and this is what I'd like you to all get used to and develop this habit, and that is the first thing you do is you look at the graph, you see what it says on the side, this says flow, this says volume, let's look at the scale, this is 0 to 50, the volume is 0 to 600. So we have somebody who's voided, probably it looks like 300, so a little less than 150 cc's, maybe 120 cc's, and we see that they have the majority of their, about one-third into the flow, one-third into the curve of the flow, we see that they reach their peak, and then it gradually comes downward. And that's classic, that's classic tracing. Here's another, here's the same tracing, and now what I've done is I've printed out, I've shown what the uroflow summary is that you would see on your, let's say, laboratory equipment. And it turns out that the actual voided volume was 103, I kind of guessed it, eyeballed it at 120, the maximum flow was about 12 mls per second, the average flow was 6, and how long it took for people to, took this person to urinate, how long, 16 seconds. Now, here's another uroflow, and one of the things I want to get you used to looking at is what's going on in a classic urodynamic tracing. Again, this is the same, we have 0 to 50 for the mls per second, volume 0 to 600, we see that this person, by the end of this tracing, has urinated about, it's calling it out here, 442 mls. But do you know how there's a number right here, here, and here? Those are the numbers that are being represented by this bar that's at the very end of the tracing. This is meant to represent real time, what you're seeing right now. Over here is a marker, and this marker was placed either by the machine or the technician, most likely the machine, and it's marking down what was the maximum flow rate. And you can see that here, it's saying that the maximum flow rate was 10, if you can read that number, and it occurred when there was 126 cc's that had been, that had been voided. Here's another flow, uroflow, and one of the things that I think is important is that I see the habit that a lot of people have developed of just taking the numbers off of the, off of the urodynamic equipment and never looking at the tracing, and what a drag that would be, really, in this case. Look at this person, obviously, they're kind of pushing to get the urine out. We see this kind of bimodal or trimodal flow rate. You and I can both imagine that something's pushing, kind of, and that could be a valsalva. And yet, if you just looked here at the tracing, all you'd see is that the maximum flow rate is 5. This, and I have it covered, I can't really move this, but we have a low flow rate and actually a pretty low voided volume. The voided volume here was 79, but look at how long it took for this person to urinate, this small amount of fluid, a minute. And we see an elevated PBR. This is a classic picture we'd see in a woman with significant advanced prolapse. So what are the benefits of flow rates? Well, one of the nice benefits of it is that, or one of the characteristics of flow rates are they increase with voided volume. So the higher your voided volume, the higher your flow rate, up to a point. They're position dependent. You know that as well as I do. If people stand to urinate or sit, there's different flow rates. It also requires a minimum voided volume. And here is some classic work that's been around for a long time. These are based off the, typically based off the Liverpool Nomogram. That's exactly what this is. And the Liverpool Nomogram is some work that was trying to define what is normal. And I'm having some difficulty with my pointer, there it is. And what we see are that maximum flow rates, voided volumes, we don't care too much about this, but it's just trying to show that as voided volume increases, maximum flow rates go up pretty, just about linearly. Now interestingly, the Liverpool Nomograms that are used for women, and often these are the ones that have been programmed into the machinery that tells you whether or not someone's had a normal void or an obstructive void, are based in women, like a pretty lousy comparison population. It was a group of about 40 women. I don't remember the exact number. The average age was 32, and 70% of them were noliparous. So this is definitely going to overstate uroflow compared to the women that most of us are seeing in our practice. The advantages of uroflow are pretty straightforward, and that's why they're done so frequently. It's that it's non-invasive, and it's easy to perform. The limitations are that you really don't know, if someone has a low flow, why? Is it because the urethra's obstructed? Is it because they don't have a good detrusor contraction? It doesn't measure detrusor pressure, so we can't tell. And you have to remember that normal flow does not mean a normal detrusor pressure. I can tell you plenty of times that I've seen women who have a sling that's too tight. The flow comes out almost like staccato with a high flow rate, and yet once we look at the detrusor pressures that are generating that force to overcome the sling, the detrusor pressures are high. So that doesn't represent at all that it's a normal pressure. And like you're going to see with most of the urodynamic tests that we talk about, it's often not well correlated with symptoms. What do I mean by that? Well, I mean, you and I, we all have had the experience of women who say that, oh, they don't void well, they don't get all the urine out, they always feel like they have to go, and we find their PVRs are like scant, 10, 15 cc. And then we see the women who come in and say, I void great, there's no difficulty, and we see that they're walking around with a PVR of 300 cc. And that is well proven in studies in men and women that a symptom of incomplete emptying is not associated at all with high PVRs. So systematry. Well, systematry now, we're moving into what are considered to be some of the invasive tests, and it's an invasive assessment of bladder function. When performed during bladder filling and storage, it's called filling systematry. And when it's performed during voiding, it's called avoiding systematry. And it's part of a pressure flow study. And you'll hear people alternately use systematry versus systemetrogram. It's just meant to, the systemetrogram is meant to represent the tracing, the actual tracing itself. Now how does filling systematry work? Well, a patient is seated or lying down with an empty bladder. Lying down would be tragic. I can't imagine it, but I've seen it in mostly women who have neurologic disease and can't tolerate a seated position. The transurethral catheter is placed in the bladder, and then a liquid filling medium is infused into the bladder at a constant rate. And there are three different kinds, eyeball or simple, single channel, or dual channel. Now eyeball filling systematry is, hey, my picture's not showing up. That really sucks. I have a great picture. What it is, is you have, it's often what we used to do at the VA or you can do, you'll do sometimes without understanding it in the OR, you take a Foley catheter and you have the Foley catheter attached and you have the balloon blown up and then you have a piston syringe on the end of the catheter. And you just kind of balance the meniscus of, and then you start to pour fluid into the piston syringe, again, the barrel, not at all the plunger. And you align the meniscus with the pubic symphysis. And let's say you were in a third world country and you were trying to decide, does somebody have overactive bladder? Is this a valsalva induced overactive bladder or is this truly stress incontinence? And what you could do is put the catheter in, put the barrel of the piston syringe in, fill it with fluid, kind of balance it up against the pubic symphysis, cover the barrel for a minute, have the person cough, and then release the barrel. And if it's a true valsalva induced DOI, you'll suddenly start to see all the fluid move backwards and go, come out of the piston syringe. And it's one of the things, it's one of the tests that people used to do. It's like a cheap aerodynamics, or again, what they call eyeball systematry. Single-channel systematry is often done. And the reason we call it a single-channel is that you're putting a catheter into the bladder. Again, I'm trying to get my little marker thing here. You're putting the catheter into, you're putting a catheter into the bladder. It has a transducer on the end of it. We can talk about catheters later if someone brings that up as a question. And you're measuring the pressure inside the bladder. Now one has to remember that when you're measuring pressure inside the bladder, it consists of the intrinsic pressure of the bladder along with the pressure from the abdomen. And so the pressure that you're measuring is the vesicle pressure, and that has a detrusor component and an abdominal component. And so it's both. And here's a graphical representation of this. We have a tracing, and we take a look, and it says vesicle pressure. And the range is from 0 to 100. We have a very smooth tracing. But as we march along, we suddenly see an increase in the pressure that's significant. And you and I cannot say, what's that due to? Is that person moving in the chair a bit? Or is this an uninhibited, is this a detrusor contraction? We cannot tell. Because it could be either coming from an abdominal, an increase in abdominal pressure, or an increase in the bladder pressure. That's why dual-channel systematry was invented. And with dual-channel, what happens is that we have a catheter that comes in, we have pressure, we have the vesicle pressure being measured. We also have the abdominal pressure, but then we measure the abdominal pressure separately. And we take the vesicle pressure, we subtract the abdominal pressure, and it leaves us with the detrusor pressure. In women, the places that we can try to get surrogate for the abdominal pressure is by placing the catheter in the rectum and getting up and to high enough that you're past the rectal reflection, at the level of the rectal reflection, or at the top of the vagina if they don't have prolapse. Now here's the tracing that's a good example of that. First, let's talk a little bit. Usually I have a slide presentation that I do for about an hour before this one. But we're going to have to try to cram it all in. So let's start. So this is a classic multi-channel urodynamics tracing. And we see that we have the pressure vesicle, we have the abdominal pressure, we have the detrusor pressure, urethral pressure, and the closure pressure. And this is just at the beginning of the study. And what I'm trying to demonstrate to you is how, at the start of the study, all of the catheters were zeroed. And then they were turned on and allowed to be running and measuring. And the first thing that the operator did was have the patient cough. And with that cough, we see a rise in the vesicle pressure. That's because abdominal pressure is being transmitted to the bladder. We see the appropriate rise in the abdominal pressure. That makes sense. And we see a beautiful subtraction. And that tells us that technically, this detrusor pressure can be trusted. Interestingly, the urethral pressure also goes up. And actually, that's one of the reasons why we're continent when we cough or lift a refrigerator or things that are heavy, because the same abdominal pressure that goes to the bladder goes to the proximal urethra and is part of our continence mechanism. In prolapse, when that urethra, or after childbirth, when that urethra drops down behind the pubic bone, it may not see that transmission of the abdominal pressure. And hence, the birth urethropexy was always thought of as a repositioning procedure, not a procedure for the sphincter itself. Okay. And we see closure pressure, which we'll talk a little bit more about. So what I want to say about this study is first, what I want to say about this slide is that it's critical that you see that at baseline, the catheters were zeroed. And then the patient, again, like I reviewed, the patient was asked to cough, and the subtraction is checked. And look how nice that is. Now, here's the same tracing that I had shown you earlier, but now we have the added information of the abdominal pressure. So we see first that as this pressure went up in the vesicle channel, that the abdominal pressure stayed flat. And as a result, this vesicle pressure subtracting out the abdominal pressure leaves us with the detrusive pressure. And we know now that those were uninhibited contractions of the bladder. And I'm just asking you to take a look and see at the mathematics of it that the calculations are correct. So 41 minus 28 truly does give you 13. Okay. Oh, here we are. This is a microtip catheter, and a microtip catheter has the transducer in the catheter itself. So this is a strain gauge that measures pressure. These are less likely used by most of you who are in on this talk tonight, and that's because the catheters are really expensive. They're probably about $1,500 a piece, and they're washed in between. But what's nice is they're very sensitive. Another kind of catheter is the water-filled catheters, which are disposable, but they have some issues that come from having a column of water transmitting the pressure. And we'll show some of that in the tracing where there can be a bit of a delay. Now what most people are using in their clinical practice, and this is true now for urologists and urogynecologists, are air-charged catheters. Anyway, when you go to measure urethral pressures, of course you want to measure them in the urethra. And, oh, the thing I wanted to show about this is that here we're measuring, we have a strain gauge vesicle with the catheter that's in the bladder, and also with the catheter that's positioned in the urethra. So when this is properly positioned, and that doesn't mean jammed all the way into the damn bladder where you would get both being the same, but when it's properly positioned, you'll have this port, or this transducer in the bladder, and this one in the urethra. So that's measuring the urethra. Another way that you can do it is just kind of pull the vesicle, pull the vesicle channel out through the urethra, and that's the way people have done it for years if they didn't have a dual lumen. So when you're measuring urethral pressures, it's very similar. It's a urethral closure pressure is a calculated pressure. Oh, and that's one thing I didn't say. Detrusor pressure is calculated. So let's say that again. Detrusor pressure is not directly measured. It's calculated, right? It was PVES minus P abdominal. Well, any time something is calculated, something can get screwed up. And so you'll want to remember that when we're interpreting tracings, and we'll want to remember it when we're doing studies. And same thing with closure pressure. So urethral pressure is directly measured, but urethral pressure is calculated. It's the urethral pressure minus the vesicle pressure. And you would always know that that makes sense because you would never have a calculated pressure being based off another calculated pressure. So urethral pressure is measured, vesicle pressure is measured, and urethral closure pressure is calculated, and detrusor pressure is calculated. And that's what I'm trying to show here. The three things that are actually measured are PVES, P abdominal, and P urethra. So let's talk a little bit about measuring urethral pressures. First thing to note here is, again, we're looking at a, I've only cut out a portion of the tracing. So you can see up at the top that we have the vesicle pressure. We have the abdominal pressure, scales are 0 to 100, 0 to 100. The calculated detrusor pressure is 0 to 100. And look at how pretty that subtraction is all the way through. Very good quality tracing. And we have P urethra and P closure. and we see that tracing also. You can't see because it doesn't go to zero like the other one does, but you can tell that it's a good tracing. Now, notice how as this patient is going from probably about 0 to 300 cc of volume, that detrusor pressure is remaining nice and stable. That's a sign of a really nicely compliant bladder. But look at this. Look how the urethral pressure, when the transducer is placed in the correct place, is picking up this rise in the urethral pressure. You know what we call that? That's called the guarding reflex. And what happens is that the signal, the afferent signal coming out of the bladder, sends an interneuronal connection as a spinal reflex. And as a result, the pudendal nerve, we have an increase from onus nucleus, a signal sent through the pudendal nerve, and we have an increase in that sphincter tone. And again, that's called the guarding reflex. And we can see it easily in aerodynamics. And boy, we can really hear it if you do needle EMG, where you'll hear that urethra really firing more as the bladder continues to fill. And we also see the urethral pressure increasing. Now, a CMG measures compliance. We just saw a beautifully compliant pressure. In fact, we saw a change in volume that was about 300 cc, and we saw no rise in that detrusor pressure. What a perfectly compliant bladder. In fact, if we looked at compliance, we would say the change in volume was 300 divided by zero. It's infinite. Another thing that we can measure, it's not something we can measure, it's something that we can ask the patient about and then write down on the tracing, is what was the first sensation? What was the first desire to void? When did they have normal and strong desires to void? And what was the most they could hold? And we can measure pressure and stability. We can, we of course, measure and talked about this a lot now, that we're measuring directly the vesicle pressure, the abdominal pressure, and the urethral pressure, and that we have the detrusor pressure that's calculated. Now, one of the things I wanted to share with you is of all these measures that are here, do you know the one that is the most predictable is actually compliance? And that's probably because it really is a function of the bladder physiology itself. Meaning that if I did urodynamics one day on somebody, and the next day on that same person I did urodynamics, the only variable that would probably stay the same is the compliance. And that's just been shown in clinical trials. Actually, when people do urodynamics and you do them back to back, people accommodate so nicely, and we often find that the first desire to void and maximal capacities continue to increase as people have more urodynamics, and they're just getting accommodated to it. Again, here's compliance. A little slide on compliance. And there are values that are considered to be normal. A low-compliant bladder tolerates very little, and a calculation of it would be less than 10 mils per centimeter of water. The one we just saw was approached infinity, so any number over 20 is considered normal. So here's the tracing, and boy, it's busy, isn't it? So let's just start from the beginning. If I start with this tracing, the first thing I like to do is come up here. I haven't talked about this before, and just look at what amount of time am I looking at, and this is five minutes. And I don't, I'll show you examples of tracings that have like 18 minutes on one tracing, but that totally sucks, and it's impossible to see. So when I'm doing urodynamics and I'm going over it with the fellows or I'm doing a teaching case, I always try to print it out so that I have six minutes per page so that I can see some of the nuances. What I'd like to do, have you do, is focus on the start, like I am. Here I am with PVAS and P-Abdomen, and as we start this study, which here's the start because here's the volume that's being infused, we see that it truly is a good subtraction. P-Deb is essentially zero, and we consider anything plus or minus five centimeters of water to be a good start. As this person is filling, let's go from here, from zero to 52 cc, so please, 52 cc is like stinking nothing. A cup is 250 cc, so one-fifth of a cup, what is it, like three tablespoons. We see no real rise in the bladder pressure. Things are nice and steady. Now we're going to go ahead and we see this first kind of blip in the detrusor pressure, and your habit always has to be that the first thing you do is come up and look at these two channels, because remember, this is subtracted, and this blip could be caused by a rise in the vesicle pressure like we see here, but also by a decrease in the abdominal pressure. So we see a rise at the same time that the patient is reporting a first sensation that someone has marked here. It's kind of classic DO. And as we continue to march along, at only 69 cc's, 100 cc's, 110 cc's, we start to see this bladder really starting to go a little nutty, right? In fact, I should say that what happens here is that the patient is so full at 100 cc's that they stop the study, strong urge, uninhibited contraction, they don't tell us whether or not this person is leaking, and they actually give them permission to urinate. And it says uroflow started. So now this contraction that we see here is at the capacity and the patient is told they can urinate, and we see a detrusor contraction with some resultant uroflow. We're not trying to make a diagnosis off this tracing. In fact, you and I can't do that without being in the room and knowing what was the urodynamic question. I'm just trying to show you some of the ways that I think through a tracing when I'm looking at it. Let's go to the next one. So what's the value of performing systometry? Well, it really allows us to see a continuous assessment of bladder pressure. It allows us to see, provide information on bladder storage disorders. You can see with that woman that we just took a look at her tracing that she could barely tolerate any fluid in her bladder. Her sensations were low, and she started having, you know, overactive bladder contractions. It also allows us to correlate it with lower urinary tract symptoms, and it allows us to see if there's a risk for upper tract injury. And I won't talk much about that now, but that's something that, you know, if they had me back, we could talk a little bit more about what are other things you watch for. Women, we really don't worry as much about upper tract injury. Women pop off at the urethra. What I mean by that is that they leak, and very few women present with renal failure due to obstruction. If they did, we would be the group that's seeing them because the most common reason probably for women to have obstruction is advanced prolapse. And yet, we see very little upper tract damage usually because the prolapse goes away at night, and then women get up and urinate. It's also easy to perform, and it's well-tolerated. Well, what are the limitations of systematry? Well, it's artificial. Come on. I mean, nobody's getting their bladder filled with 300 cc's in six minutes. If you are, that's odd. The fill rate's weird. The mediums that we use are weird. There's a presence of a catheter. The environment, I mean, really, you can urinate with someone staring at your crotch. And also the technical concerns. One of the things that I think is very interesting and I see happen a lot, you know, you have a woman come in, you have a urodynamic question. Maybe the urodynamic question on this woman is, does she truly have stress incontinence? She never complains of having a low bladder capacity. She says she can go three or four hours without urinating, and suddenly you bring her in to do urodynamics, and this woman cannot tolerate anything in her bladder and can't tolerate the catheter. Is that a sign that she's having overactive bladder or she has a painful bladder? No, it's a sign she can't tolerate this artificial test. It's important to not give patients diagnoses from urodynamic findings unless you also have patient symptoms that match the finding. Another great example that I've had women referred to me who have stress incontinence and at the time of the urodynamics, they couldn't urinate. Well, please tell me which woman seriously can urinate when you're staring at her and someone else is staring at her in a room. And so a woman who's never had a problem with urinating in her life, the very first time she comes into the office to be seen, her post-flood residual is 50 cc's. Now suddenly has urodynamic testing and has the diagnosis of urinary retention. No way. Again, patient symptoms have to match the urodynamic findings for them to be significant. So pressure flow studies. Well, pressure flow studies, the idea is that you want to assess the bladder and the urine flow characteristics during emptying, and it's rare for someone to order these by themselves. I do, but it means that you're just going to fill them up right away and not look at the filling part of the tracing. And for the most part, when we do urodynamics, we do a complete set. We'll fill and then do the pressure flow study. But in your testing and in questions, people may ask about these separately. So pressure flow studies are usually performed after filling systematry. The patient's been filled to MCC, their maximum capacity, and then been repositioned or put in a position where they can urinate. They're given permission to urinate and asked to identify when the voiding is completed. And we record vesicle and abdominal pressures along with the uroflow and the aim of pressure flow studies. And of course, all urodynamic studies are to reproduce the patient's symptoms. So what do pressure flow studies, what kind of measures do we get out of it? Well, we get the pre-micturition pressure. Hardly anybody talks about that really. What it's meant to say is that we just get the equipment all zeroed and do a cough test again to make sure it's a good quality procedure. We get what is the maximum voiding pressures and we can say whether people are normal, underactive, or acontractile bladders. We measure the detrusor pressure at the maximum flow. And there's some studies, granted they're limited, but that's one of the ways that we can diagnose obstruction in women. There's something called the Blavis-Grotz nomogram. Again, it has limitations, but it's published and it's a nice place to start. And we can look at flow rate parameters. Classic pressure flow study, normal values, we don't talk about this much in urogyne, is female 20 to 30 centimeters of water. But it's very dependent on what you also see as the flow rate. So now let's look at this and talk a little bit about a pressure flow study. So we have a tracing. And again, now we're looking at the vesicle channel. I've cut off the markers that are up here that the nurses have said, permission given devoid. So you're just going to have to take my word for it. And we see a vesicle pressure. We see a rise in the p-vest. You know what, we see a little bit of relaxation in the abdominal. And I see this frequently. And I think if you look closely, you'd see it too. And that's because when people relax their pelvic floor, it decreases the pressure in the abdomen. And so here's someone who's about to urinate, and they're relaxing the pelvic floor. And we see a rise. So even though this is dropped, and you know, probably dropped on the order of five centimeters, the rise in the abdominal pressure, I mean, the rise in the ves- detrusor pressure, that follows the curve of the rise in the vesicle pressure. And so this trivial rise that's coming from the subtraction from the abdominal pressure is meaningless really. And we see resulting urine flow. And avoided volume of 280 mils. Now the value of performing a pressure flow study, I think this is very helpful. It's one of my favorite studies. It's kind of my go-to for when I'm trying to decide, you know, women who can have a sling that's too tight and have a normal PBR. Let me say that again. A woman who's young, especially, can have a sling that's obstructive and still be able to empty their bladder. Over the months that it's been in, they absolutely can push past the obstruction of that sling. But there's nothing about their bladder function that's normal. And that's why there's studies. There's a nice study by Wendy Lang out of Michael Chancellor's group years ago that showed that women who develop urgency incontinence symptoms, worsening urgency, all of a sudden a lot of leakage symptoms about a year or so after their sling, if you take a look, you'll find that they have obstruction. And if you're not careful and keep that as a diagnosis, you can go on to harm that bladder. The changes that occur in the bladder wall are not easily reversible. And the greatest predictor of whether or not those symptoms will go away once the sling is cut is based on how long that woman was in that condition. So pressure flow can be used when you have a suspicion that a woman is having symptoms following her surgery months or years later, and your concern is that her worsening urgency incontinence might be related to her sling. And you check her PVR and it's normal, doesn't mean a thing. Especially if she reports symptoms with burning, with urination, things like that. So this is a very nice study and very straightforward to do. And it's well tolerated. What are the limitations? Again, it's artificial test, presence of a catheter, requires a physical condition and specific equipment. We're going to talk about the urethral pressure profile, and then I'm going to leave some time to answer questions. So the urethral pressure profile is a graphical representation of the interluminal pressure along the length of the urethra. And I showed you this slide earlier, vesicle pressure, urethral pressure. It's measured in the urethra, but you can also take a vesicle catheter and pull it through the urethra. The closure pressure is calculated. And a urethral pressure profile is done when a patient is seated or supine with a pressure catheter in the bladder. The catheter is held with something called a prophyllometer and pulled through the urethra at a constant speed. And then the resulting pressure tracing is analyzed. So here's a prophyllometer, and as this catheter, this arm stays steady, this is in the urethra, and this is withdrawing at a rate of one millimeter per second. That used to match the rate that the graph paper was being printed out, and that way you could calculate out urethral length. So the measurements that we get from this are the maximal urethral pressure, the maximal urethral closure pressure, and the total urethral length, and something called the functional urethral length, which we're not going to get into. Now here's an actual tracing, and I'm going to walk you through this. So I have things pretty pointed out here. So you have, again, we have a tracing. We have nice subtraction. Look at this. We have we have p-ves here. We have p-abdominal here. The subtraction is beautiful. This is happening while the patients have been filled to their maximal capacity, and now we're doing this urethral pressure profile. The urethral catheter has been advanced into the bladder. You can tell this because the two pressures are identical, and as a result, the closure pressure is just about zero. Then what happens is we have that prophyllometer attached, and as we start to pull the prophyllometer catheter out, and it's withdrawing at one millimeter per second, and the closure pressure also rises, and then we have the peak urethral pressure, which in this instance is over 100, and note the bladder pressures are staying nice and stable. This isn't an overactive bladder contraction. This is a urethral pressure profile, and we continue to withdraw the urethral catheter until it starts to come out of the urethra, and that time when the closure pressure is greater than zero is called the functional urethral length. It's the length that contributes to the pressure where we see a rise in the pressure, and then we don't just take one measurement. What we do is we reinsert the catheter back into the bladder, and that's why we see that sudden rise again, but real quick because we're doing it faster, and then again we do another closure pressure, and we average the two. So urethral pressure profiles have been associated with continence status and outcomes after continence surgery, so it's a pretty reliable measure, and it's the only study that directly measures urethral pressure. Now you'll have access to my slides, so what are the limitations? It's subject to inner artifact. It requires a profilometer. It's very dependent on bladder volume, catheter type, and orientation, and it has a poor test retest reliability, but it does have some benefit. Anyway, I'm going to stop at this point, and you can look at my slides for the rest of the information kind of on leak point pressure and the, you know, valsalva leak point pressure, but I want to make a point right now that I think is an easy point of confusion. A valsalva leak point pressure is very different from a urethral pressure. This urethral pressure profile that we just talked about was done static, meaning the person is laying there doing nothing, and it's being measured in the urethra, which has a much different pressure, a much higher pressure than in the bladder. A valsalva leak point pressure is a dynamic test, and it's actually you're measuring the pressures inside the bladder, not the urethra. The two are not related, other than to say low pressures suck for the patient, but other than that, the two cannot be really equated. Okay, I'm going to stop it there since we only have like seven or eight minutes for questions, and ask Leslie to help us or to see if there's any kind of question. Yeah, so we do have a few coming up here. One is asking about the issue when the, you know, the p-ves, the vesicle or abdominal catheter can get extruded during the pressure flow study and makes the study uninterpretable. Do you have any tips to prevent that? Oh, sure. Well, you know, you'll become a master at taping catheters. Another thing is that, you know, even though it's not perfect, you can kind of tell from the uroflow. You won't have all the information you need, but sometimes a person can conjecture. But if you can't, if you, if you don't, let's say that your, your dynamic question was absolutely dependent on getting that vesicle pressure. For example, let's say it's the case I was telling you about. I have a woman who after a sling, I think there's a problem. I have to have that vesicle pressure. I would take a Foley catheter, I would refill her bladder, and I would repeat the test because I don't consider the test to be done until I've answered the question. Okay. And then there is another question also about, I guess, artifacts that you can see from Valsalva during a pressure flow study and any tips to prevent that. I'm not. Well, a pressure flow study, there's very few people who are younger than me or who are at the age of our fellows who would be thinking of trying to do a dynamic urethral pressure profile. That was from years ago when people would divide the urethra up into quartiles and look at pressure transmission ratios. So a urethral pressure profile is done static. And so there shouldn't be a Valsalva being done during a urethral pressure profile. That doesn't make much sense to me. I guess it's just the patient that's, it's straining during it, you know, but again, it's not really artifact, just it is what it is, right? Well, it's a static test. So it should be done in a static condition. So in that case, let's say you have a woman who you've overfilled and now you're trying to at MCC, almost most centers do a urethral pressure profiles at MCC. You're trying to look at that urethral pressure and she's so miserable and uncomfortable, she can't wait. I would let her void, get the voiding part of the study. And then when her bladder was emptied, I would repeat the urethral pressure profile because urethral pressure, you saw the rise in the urethral pressure as it went from zero to 300, but that rise was trivial, maybe 10 CCs or 10 mils of pressure. Nothing like, nothing like what you're really trying to answer the question. And that is like, is there an obstructive sling? Is this urethral pressure profile up at 200? So for me, I would just repeat the, for me, I would just repeat the, I can't, I would just try to repeat the urethral pressure profile when her bladder is empty. Okay. What about, and I think the question was maybe more directed at the pressure flow study, when someone's Valsalva-ing during a pressure flow study and that creating artifact. Although I guess, so I'm not exactly sure of the nature of the question. If you're there watching, then you know it's Valsalva. You can, I don't know what you would do. I would maybe try to ask the patient, just don't strain, just see what happens when you don't strain, but do you have any advice for? I do. I do. One of the things that we didn't have a chance to talk about, again, these are higher level discussions. Do you know, right, when people are going to urinate, what happens to the urethra? The urethra is supposed to relax. And so a detrusor contraction occurs with a urethral relaxation. So you can often, I can often tell, even if someone's Valsalva-ing, well sometimes, I would first instruct them not to Valsalva, Valsalva, and then I would also look at the urethral pressure and see if there was any component of urethral relaxation detrusor contraction. And then, again, if your question is not answered, you repeat the study. It's not a one-shot deal. Okay. And then I have another question about, we had an issue when urethral pressure wouldn't record on UPP, any tips? I'm assuming this was an air-filled catheter. It doesn't say exactly what kind of catheter, but those, I think, are the most common right now. But the urethral pressure wouldn't record. Well, that's a technical issue. And I think that that's not, that's beyond the scope of us talking here today. The first thing I would do, though, is I would take the catheter that, I would take the transducer that you're using to measure abdominal pressure and switch the two out and just see if the issue's happening at the level of the transducer, the side of the box. So I switch catheters around all the time. Just switch the transducer and see now if on the bladder port are you seeing the pressure, because certainly it's not that the urethral pressure is zero or... Right. And I have a question about, of my own. Okay. What do you consider, you know, when you're doing the pressure flow study, and especially if you're trying to rule out obstruction, like rule it out and rule it in after a, you know, otherwise we just don't see it that much in women. But, you know, what pressure flow combination is too, what pressure is too high for you and flow too low? Okay. That's a great question. Well, I think the first thing is everything's a guideline, right? I mean, it'd be like blood pressure. You're certainly not going to admit somebody to the ER with a blood pressure of 130. So it really is about the, even though that's an abnormally high pressure, it's not urgent. So there are, there's a guide. The first thing is all of us should be able to tell that a pressure, a detrusor pressure that's greater than 40, 50, that's high. A way, the best way to diagnose obstruction is this guideline. And this guideline is off the Blavis-Grotes Nomogram. P dot at Q max. So you go and you look, let me go find a slide. Give me just a second. Let me see. Where am I? Pressure flow study. Oh, let me see. That sucks. It's important to me to show this though. Go up here. This will do. Okay. So do you see how, can you see me on this Leslie? Yes. Okay. So do you see how this is Q max? Yes. Okay. So Q max here is 13. Now you go up to P dot, which is here. So classically, P dot Q max greater than 25 or 30, many times I'll use 35, when the flow rate is less than 12 or 15. So many times I'll see people who have really sucky flow rates like five, but the P dot's only like 10. There's no way that's obstructed. There's other times when I've seen people who have flow rates that are 15 or 20, which pretty good, but the detrusor pressure is 200, you know? So it's not a specific number, but in the scenario where you have somebody, and the other thing you can do, I think a sling is very helpful with this. You can pinpoint where the obstruction, you know how we've all been to the OR and cut a sling and you cut it and just bounces back and it's almost C shaped. If you do, if you do ultrasound, you can see that curve. It's like one point where it's absolutely like two millimeters, just absolutely smashed into that urethra. It looks that way on urethral pressure profile. Have me back with tracings to look at things like this. And you can actually pinpoint exactly where in the urethra it's tight. And in a woman who has a high detrusor pressure, low flow, and a urethral pressure profile that's high and a story that fits, that's an obstructed sling. So typically the cutoff again is P dot Q max, 30, 35 when the flow rate is low and low flow rates would be 12 to 15. Okay. And that's pretty much what I use again. It's just for, there's a lot of fellows on, it's difficult, you know, because you're also using the clinical picture. So I think that's important also. That's right. But, and I think we have time for one more question. So somebody asked, and I don't know if the exact answer to this, is there any evidence that a woman's estrogen status affects her MUCPs? I know age does. I don't know about estrogen status. I haven't seen that. Age is such a proxy for estrogen status. You know, it'd be hard to pull the two apart, but I haven't seen anything like that. So here's another example. If we can look at this slide, do you see here? I have a flow. Here's the P dot Q max. Do you see how that flow says 33? And if you go up to P dot, it's 49 here. Well, this woman has a high pressure, but that flow rate is so good. So there's no way that that's obstructed. Right. Okay. Right. Okay. So I think we are going to wrap it up. So I just want to really thank Dr. Miller for that presentation. I think we learned a lot. There's a lot of nuances when it comes in and to interpreting neurodynamics. And I just have to agree with her that you really need to look at the tracings and not really the numbers. I think there's a tendency just to look at the printout with the numbers. And I always like to look at the tracings myself and actually write my own little report no matter who's doing it. So I just want to thank Dr. Miller for all those tips. I want to thank you also to all of our participants on the call for carving out time in your days to participate with our speaker and with each other. I do want to remind everybody that we have, sorry, let me find this. Adrian was kind enough to send me. Yes, our next webinar is going to be May 25th at 7 p.m. Eastern with Dr. Lennox Hoyt. And he's going to be talking about robotic sacrocopalpexy with relevant anatomy and kind of tips and tricks and complications management. So mark your calendars May 25th, 7 p.m. with a robotic sacrocopalpexy inspired talk. So I think until then, remember to provide feedback for future programming. And again, we appreciate everybody's participation and especially for Dr. Miller for taking the time to put this together and answer all of our questions. Thanks again.

urodynamic evaluation

lower urinary tract symptoms

virtual forum

urodynamics

uroflow

pressure flow studies

bladder function

symptom evaluation

correlation with patient symptoms

diagnosing obstruction