Urogynecology: Evidence-Based Clinical Practice 2nd ed.

4. How to Conduct Urodynamic Studies: Essentials of a Good Urodynamic Report

Kate H. Moore1

(1)

Department Obstetrics & Gynaecology, St George Hospital, Kogarah, New South Wales, Australia

Abstract

Urodynamic testing is an invasive procedure. At the minimum, a urethral catheter and a rectal balloon must be inserted. The risk of iatrogenic bacterial cystitis is about 2 %. Studies show that urodynamic testing is not cost effective in all patients with urinary leakage, because it does not always affect management. For example, women with mild stress incontinence may be rapidly cured by physiotherapy and never need urodynamic testing.

An erratum to this chapter is available at http://dx.doi.org/978-1-4471-4291-1_13

An erratum to this chapter can be found at http://dx.doi.org/10.1007/978-1-4471-4291-1_13

Who Needs Urodynamic Testing?

Urodynamic testing is an invasive procedure. At the minimum, a urethral catheter and a rectal balloon must be inserted. The risk of iatrogenic bacterial cystitis is about 2 %. Studies show that urodynamic testing is not cost effective in all patients with urinary leakage, because it does not always affect management. For example, women with mild stress incontinence may be rapidly cured by physiotherapy and never need urodynamic testing.

On the other hand, it is fair to say that performing incontinence surgery without having a urodynamic diagnosis of stress incontinence, excluding detrusor overactivity, and checking for voiding difficulty is not good medical practice at all. Several studies have shown that simply having a main complaint of stress incontinence does not equate to the patient having urodynamic stress incontinence (USI).

As is explained further in Chap. 9 (surgery for USI), the fact that a cough can provoke a detrusor contraction was a major stimulus for the establishment of urogynecology as a subspecialty. Gynecologists realized that simply operating on patients who leak when they cough is fraught with difficulty.

So one needs to take a stance midway between “urodynamics for everyone” (not warranted because of the invasiveness of the procedure) and urodynamics only for those who are surgical candidates. In practice, the real problem is that so many patients have mixed symptoms. Urodynamic results do help to dissect out the relative severity of the different components in patients with mixed incontinence and thus guide you as to the main thrust of treatment. This is described in the case history at the end of this chapter.

In general, urodynamics are very worthwhile in the following cases (in descending order):

·               Patients with failed continence surgery need detailed urodynamic studies.

·               Patients with symptoms or a past history of voiding difficulty (previous prolonged catheter or self-catheterization post-op or postpartum) need voiding cystometry.

·               Patients with mixed symptoms and cystocele who are considering surgery should have detailed urodynamics, possibly with ring pessary in situ (see “Occult” Stress Incontinence).

·               Patients with mixed stress and urge leak need cystometry at least, to determine the relative severity of the two problems.

·               Patients with pure stress incontinence symptoms who have failed physiotherapy should have cystometry with some form of imaging, to check whether there is undiagnosed detrusor overactivity or incomplete emptying.

·               Patients with pure urge symptoms who have failed bladder training and anticholinergic therapy should also have cystometry with imaging, to look for an undiagnosed stress incontinence component or incomplete emptying (the latter may be worsened by the anticholinergic drugs).

Different Forms of Urodynamic Studies

The term “urodynamics” is a general phrase, used to describe a group of tests that assess the filling and voiding phase of the micturition reflex, to determine specific abnormalities.

Some of these tests are not “physiological.” For example, inserting catheters into the urethra and a pressure balloon into the rectum, then expecting the patient to fill and empty as she normally does, may not give a “true” picture of that woman’s micturition cycle. Nevertheless, the tests have been standardized over the last 40 years, in accordance with the Standardization Committee of the International Conti­nence Society (ICS), and are performed in a similar fashion across the world. Therefore, abnormalities are interpreted in a standard way and have a common meaning in clinical practice.

The tests that are generally used include the following:

Uroflowmetry: Measuring the patient’s flow rate when voiding in private, onto a commode that is connected to a collecting device that measures the rate of fall of urine upon the device.

Simple cystometry: Inserting a single catheter into the bladder that measures pressure, with no correction for abdominal pressure, during a filling cycle, not widely used in the Western world.

Twin channel subtracted cystometry: Inserting a pressure recording line into the bladder as well as a filling catheter, along with an abdominal pressure recording line (rectal balloon), that records a filling cycle. The abdominal pressure is subtracted from the bladder pressure to give the detrusor pressure (see Fig. 4.1 and later figures).

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Figure 4.1

Schematic diagram of twin channel cystometry

Voiding cystometry: The same as twin channel cystometry above, but the patient is asked to void into a uroflow commode while the pressure lines are in situ, so that the contractility of the detrusor muscle during the voiding phase is measured.

Videourodynamics: The same as voiding cystometry above, but radiopaque X-ray contrast dye is used to fill the bladder. The test is done in the X-ray department, and the bladder/urethra is filmed during cough and other provocation. In males, filming is continued during the voiding phase, but 60 % of women are not able to void in these public conditions. Post-void films are taken to check residual.

Voiding cystometry with ultrasound: The same as voiding cystometry, but ultrasound imaging is undertaken during cough and other provocation, and post-void image is taken.

Urethral pressure profile: Tests the function of the external urethral sphincter, performed in selected cases. Similar information is available from leak point pressure testing.

The frequency volume chart and the pad test are also part of urodynamic assessment, but these are discussed in Chap. 5 (Outcome Measures).

Practical Advice About How to Perform Urodynamic Studies

This section gives practical advice for a registrar or resident/house officer who is newly attached to a urogynecology department. For information about the medical physics of the tests, books by Abrams [1] or Cardozo and Staskin [4] are recommended.

Calibration of the Equipment

In essence, one must check that the equipment is correctly functioning and measures what it is supposed to measure.

Calibration of the urine flow machine involves pouring a known quantity of fluid into the uroflow equipment at a reasonably slow rate and then checking that the volume poured in equals the volume measured and that the computer calculated the flow rate correctly.

Calibration of the cystometry equipment involves checking that a column of fluid 100 cm high yields a pressure reading of 100 cmH2O water pressure, then zeroing the transducers to atmospheric pressure (room air) so that zero pressure gives a zero reading. For detailed discussion, see suggested further reading.

General Clinical Guidelines

When a patient presents for urodynamics studies, you need to “troubleshoot” to make sure that the test can be correctly performed on the day.

If she has symptoms of acute urinary tract infection (dysuria, foul-smelling urine, excessive frequency, strangury, or hematuria), then the test should be postponed, a midstream urine culture taken, and antibiotics prescribed. This is because instrumentation of the lower urinary tract in the presence of infection can cause septicemia.

In many units, there is a substantial delay between the first visit date and the date of the urodynamic test. In these cases, you should review the patient’s status quickly before starting the test.

If the patient was given a therapeutic trial of anticholinergic therapy at the first visit but was not given clear instructions to stop them 1–3 weeks before the test (and is still taking them), then cystometry may not diagnose detrusor overactivity, so the test may need to be postponed so anticholinergic tablets can be stopped.

If the patient had mild symptoms and has been attending a physiotherapist or nurse continence advisor in the meantime, she may be cured of her incontinence and no longer need the test.

Explaining the Test to the Patient

This is best done by the urodynamics nurse, who must form a trusting relationship with the patient. In our unit, that same nurse may have been involved in taking her initial history or will often be involved in following up the patient’s response to treatment subsequently.

Urodynamic testing does involve some minor discomfort with passage of urethral and rectal catheters, but if performed in a dignified and sympathetic manner, most patients say that it was just slightly uncomfortable. In a teaching unit, only one medical student should “watch” the procedure. Actually, we ask the student to position the lamp, type in data on the computer, and help the patient off the couch, so they do not “watch” the patient but are actively involved. Patients do not like to feel like a goldfish in a bowl, especially when they are being asked to leak.

Before starting to fill, the nurse or doctor also explains the concepts of first desire to void, strong desire to void, and maximum cystometric capacity (see below). It is important for patients to know we will stop filling if they have too much discomfort.

Uroflowmetry

Ideally, the patient should come to the urodynamics test with a comfortably full bladder, then pass urine in a private uroflowmetry cubicle. Because many patients empty their bladder just before seeing a doctor, this is not always possible (no matter what letter you send beforehand).

A normal urine flow rate (shown in Fig. 4.2) looks like a bell-shaped tracing. The maximum flow rate should be at least 15 ml/s, but this cannot be judged unless the voided volume is at least 150–200 ml. This is because flow rate depends on the volume in the bladder. For example, if you drink several pints of beer, you will pass urine rapidly. If you only drink the occasional small cup of tea, your flow rate will trickle out.

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Figure 4.2

Normal uroflow curve. Maximum flow rate 23 ml/s, average 14 ml/s, voided volume 410 ml/s, flow time 31 s

Other parameters that are measured include the total duration of flow time to empty the bladder and the average flow rate (i.e., the volume voided divided by the flow time).

Typical abnormalities of flow rate in women include intermittent prolonged flow rate with evidence of abdominal straining, suggestive of outflow obstruction. This most commonly occurs after surgery for stress incontinence that has overcompensated the urethral support. It is also seen in women with a cystourethrocele, in which the urethra may be kinked during voiding.

Normal values for flow rate in relation to volume voided have been derived from a study of several hundred normal women (Haylen et al. [7]; see Fig. 4.3). These “nomograms” allow you to determine what centile of the population a patient’s flow rate represents. Flow rates below the tenth centile are considered abnormal.

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Figure 4.3

Liverpool nomogram for maximum urine flow rate in women

The other common abnormality in elderly women is an underactive detrusor; see Fig. 4.4c. The peak flow rate is poor; the average flow rate is poor, but there is no evidence of abdominal straining. The detrusor contraction is intrinsically weak, but this needs to be proven by voiding cystometry.

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Figure 4.4

(a) Normal. (b) Abdominal straining. (c) Underactive detrusor (Reprinted with permission from Prolapse and urinary incontinence. Leader [12]; Reproduced by permissions of Edward Arnold)

Less common voiding abnormalities are described in the section on voiding cystometry (detrusor hyperactivity with impaired contractility, DHIC, seen in the elderly with mild neurological dysfunction and detrusor sphincter dyssynergia, seen only in neuropathic disease such as multiple sclerosis).

After uroflowmetry, residual urine volume is measured either by catheterization, if the patient is about to undergo cystometry, or by ultrasound. A simple “bladder scan” (Bard) may be used, which automatically calculates the residual volume. Alternatively, standard transabdominal or trans-vaginal ultrasound is used to measure the residual volume, and formulae that calculate the volume of a sphere are then used by the clinician to calculate the residual amount (e.g., width  ×  depth  ×  height  ×  0.7).

Performance of Cystometry

To pass the bladder catheters, the urethra is cleansed with sterile saline; a sterile drape is placed around the urethra; Lignocaine gel is applied to the urethra, then the filling line and the pressure recording line (similar to a central venous pressure manometry line) are inserted into the urethra. Usually, the manometry line is inserted into the distal catheter hole, so the patient only feels one line going into the urethra, then the manometry line is disconnected from the filling line by pulling it backward slightly once it is in the bladder. The vesical pressure line is then attached to the domed transducer unit, which feeds into the software of the urodynamic equipment. See Fig. 4.5.

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Figure 4.5

Bladder filling line, vesical pressure line, and rectal balloon

Some units employ a catheter that has a micro-tip pressure transducer embedded into the distal end, so that an external transducer is not needed and the slight artifactual delay encountered in the fluid-filled system is avoided. Such micro-tip transducer catheters are quite costly (1,500–1,800 Euros per catheter) and are quite delicate, so they may last roughly 6 months to 2 years of normal use. The fluid-filled pressure recording lines are single-use items, costing a few Euros per set. Each unit makes its own decision about which catheter type to use, generally on the basis of cost.

Passing the Rectal Catheter

The very small rectal balloon/transducer catheter is attached to the abdominal pressure recording line (usually prepackaged by the manufacturer). The balloon is coated in sterile lubricant, then placed into the rectum. One should not push the finger into the patient’s rectum; this is unpleasant and unnecessary. Just gently insert the balloon about 3 cm into the rectal ampulla. As an alternative, a vaginal balloon may also be used to record intravaginal pressure which is equivalent, but this is usually not successful in parous women as the balloon slips out in the erect position.

Twin Channel Cystometry

After connecting the bladder pressure recording line and the abdominal pressure recording line to the transducer domes, insert fluid into the line to exclude air bubbles, then zero the recording pressure using the software of the urodynamic program. The software program will subtract the abdominal pressure (Pabdo) from the vesical pressure (Pves) to yield the true detrusor pressure (Pdet).

The bladder is then filled with warm sterile water. Medium filling rate (10–100 ml) is advised in nonneuropathic patients. Generally a rate of 50–75 ml is used, via a peristaltic pump to prevent backflow into the bladder during a rise in detrusor pressure. The following parameters are important in a full urodynamic report:

·               Results of free uroflowmetry if available.

·               Initial residual urine volume (after the patient has performed free uroflowmetry)—normal residual  =  less than 50 ml.

·               Whether pain or resistance to catheterization is noted (may suggest urethral stenosis).

·               The first desire to void, when patient first notes that she would look for a toilet—normal FDV  =  150–200 ml.

·               Normal desire, when patient would normally stop work and go to toilet—normal desire usually  =  350–400 ml.

·               Maximum cystometric capacity, when patient would not tolerate any more fluid. Although the patient should not be pushed to the point of bladder pain, we use the example that if she were driving in the country, she would get out of her car and go behind the bushes to void—normal MCC  =  450–500 ml.

·               The filling line is then removed (because it has a diameter sufficient to obstruct the outflow of urine during the next steps).

·               A supine cough is performed, while the urethra is visually inspected to look for a stress leak. Reassure the patient that there is only sterile water in the bladder and that all linen is discarded after each test, so her leaking will not spoil the linen. At this point, a cough-provoked detrusor contraction may be seen.

·               Supine tap water provocation is performed, while asking if urgency is increased by the sound of running water (and rise in detrusor pressure is checked for).

·               The patient then stands erect.

·               The transducer levels are readjusted so that they remain at the level of the symphysis pubis (e.g., raise them for a tall patient).

·               Erect tap water stimulus is performed (as for supine).

·               Erect cough is performed, with the legs widely apart. Reassure the patient again that if any fluid escapes, it is only sterile water; there is no urine in the bladder, and this is an important part of the test.

·               The patient then sits down on the uroflow commode; the transducers are lowered so they remain at the symphysis pubis, and voiding cystometry commences.

Urodynamic Diagnoses Available from the Filling Phase

The diagnoses that may be made during the filling phase Abrams et al. [2] are as follows:

Urodynamic stress incontinence (USI) is the involuntary leakage of fluid during increased abdominal pressure, in the absence of a detrusor contraction (Fig. 4.6).

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Figure 4.6

Urodynamic stress incontinence, with a normal FDV, SDV, and MCC, no detrusor contractions (Pves and Pdet remain flat) but obvious leak of fluid with cough

Detrusor overactivity is a urodynamics observation characterized by involuntary detrusor contractions during the filling phase which may be spontaneous or provoked. The most common picture is that of systolic detrusor pressure waves, seen during the filling phase (Fig. 4.7). The same picture is seen when the sound of running tap water provokes a detrusor contraction.

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Figure 4.7

Detrusor overactivity with systolic waves of detrusor contractions, seen at FDV and at MCC. Stress leak does not occur

A less well-understood phenomenon is detrusor overactivity seen as a gradual linear rise in bladder pressure (Fig. 4.8) that persists after filling stops, in association with urgency. This is often termed “low compliance DO.

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Figure 4.8

Low compliance detrusor overactivity

Finally, two less common but important variants of systolic overactivity are cough-provoked DO and erect-provoked DO. Cough-provoked DO is usually quite clearly seen on the tracing (Fig. 4.9).

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Figure 4.9

Cough-provoked detrusor overactivity

But erect-provoked DO often needs careful scrutiny to exclude artifact. A common problem is that the abdominal pressure transducer is not readjusted when the patient stands up (it is not repositioned to the level of the pubic symphysis). If a short patient stands up from the table, her pubic bone may drop to well below its original site when she was lying on the couch; Pabdo then becomes negative. Because Pves minus Pabdo equals Pdet, if you subtract a falsely negative Pabdo, you will get a falsely positive Pdet when the patient stands (see Fig. 4.18 given as part of the case history at end of this chapter).

What Is Sensory Urgency, Now Termed Bladder Oversensitivity?

For many years, patients who suffered from frequency, urgency, and nocturia, in whom urodynamic testing revealed a stable bladder but a very early first desire to void (less than 100–150 ml) and a small maximum cystometric capacity (less than 400 ml), were diagnosed as having sensory urgency Jarvis [10]. These patients often found bladder filling unduly uncomfortable. More recently, the International Continence Society has termed such patients as being on the mild end of the spectrum of “bladder pain syndrome.” The severe end of the spectrum is frank interstitial cystitis (see Chap. 12, these patients mainly complain of suprapubic pain). The milder end of the spectrum is now called bladder oversensitivity.

A problem arises in that repeat twin channel cystometry (and ambulatory cystometry, a research tool) will reveal detrusor overactivity in at least one third of cases of “sensory urgency.”

The management of patients with a small capacity stable bladder is therefore usually empirical. One starts out treating as for detrusor overactivity, because they do meet the clinical criteria for the symptom complex of overactive bladder. If the patient does not respond, then cystoscopy to look for features of interstitial cystitis is reasonable. This area is controversial.

Features of the Atonic Bladder During the Filling Phase

Patients with a very late FDV (more than 400–500 ml) and a very large MCC (more than 650–750 ml) have characteristics of an atonic bladder, but this condition should not really be diagnosed until voiding cystometry has been performed, to prove that the detrusor is underactive.

Before going on to describe voiding cystometry, a summary of videourodynamic testing and twin channel cystometry with ultrasound imaging is given.

Videourodynamics

Videourodynamic Testing

This involves installation of a radiopaque dye (e.g., Hypaque) dissolved in warm water, while screening intermittently using a fluoroscopy unit with image intensifier in the radiology department. A fluoroscopy table that rises to the erect position is needed, with a platform on the bottom of the table, so that the erect patient can turn to the side for filming of the lateral view of the bladder neck and urethra (see Fig. 4.10). This study is termed videocystourethrography (VCU) where a videotape can be made of the screening images that most software packages can superimpose upon the cystometry tracing and store for later review.

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Figure 4.10

Patient in erect position during screening on videocystourethrography

Because VCU involves exposure to X-ray and installation of iodine-containing medium which patients may be allergic to, not to mention the costs of using the fluoroscopy unit, it is only needed in selected cases.

VCU was the initial “gold-standard” urodynamics test and is still important for male patients in whom prostatic outflow obstruction needs to be delineated from simple detrusor overactivity. In men, the voiding phase is always screened. Also, in men with neurogenic incontinence, VCU allows clearer definition of any contribution from prostatic outflow obstruction. Finally, VCU allows detection of vesicoureteric reflux which may threaten the upper urinary tract.

In the female, studies have shown that about 60 % of women cannot void in the upright position on a screening table with a collecting funnel between their legs.

During a cough, the bladder neck may be slightly open, forming the shape of a bird’s beak, with fluid entering the proximal urethra (called “beaking”; see Fig. 4.11). In more severe cases, the urethra may open widely in the shape of a funnel during cough (called “funneling”). In the worst-case scenario, as soon as the patient stands, the bladder funnels open widely, and fluid pours out onto the floor. These findings have been classified using various grading systems Herschorn [8].

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Figure 4.11

“Beaking” on VCU

VCU is very helpful in women with failed previous continence surgery. In the anteroposterior view, typical features of previous colposuspension or sling can be seen, with slightly “dog-ear”-shaped indentation just lateral to the bladder neck. Sometimes although these lateral indentations are partly evident, the urethrovesical junction may still be hypermobile on the lateral view, suggesting that the sutures are no longer effective.

The patient in Fig. 4.11 had undergone Macroplastique injections to the midurethra, which explains the slightly asymmetrical picture of the “beak.”

In other cases, the sutures are very evident; the bladder neck does not open appreciably, but fluid still leaks out. This is typically suggestive of intrinsic sphincteric deficiency; that is, the urethral musculature is intrinsically weak. Many clinicians would seek to quantify this by performing an abdominal leak point pressure or a urethral pressure profile (see below).

Value of VCU in Cystocele

In patients symptomatic of cystocele (often worse at the end of the day, not when you examine them in the morning clinic), a cystocele may be very evident in the erect position with a full bladder that was not clearly seen when examined in the supine position. At the end of the voiding phase, you may also see urine trapping in the cystocele (when screening in the erect position to check post-void residual; see Fig. 4.12).

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Figure 4.12

Urine trapping in a dependant cystocele after voiding

“Occult” Stress Incontinence

One problem in urogynecology is that a patient with cystocele but no appreciable incontinence may begin leaking after an anterior repair. This is because the cystocele may involve the upper portion of the urethra, so when the cystocele descends during cough, the urethra is kinked off, masking the incipient incontinence. It is very disturbing when the patient comes to the postoperative visit complaining of stress incontinence for the first time. This is known as “occult” stress incontinence. The likelihood of this occurring ranges from 7 to 28 %, depending upon the publication (for review, see Haessler et al. [6]).

Such patients may have to replace their cystocele manually before they can have a good stream of urine. If they do not digitate the cystocele, they can have initial hesitancy, need to strain to start, and have terminal dribble. In such cases, it is worthwhile to conduct VCU (or twin channel cystometry) with a ring pessary in situ, as this is likely to unmask the occult incontinence. This allows one to incorporate a specific procedure for incontinence into the repair operation (for example see Schierlitz et al. [15]).

Ultrasound

Because of the costs and X-ray exposure involved with VCU, ultrasound imaging has become popular as part of urodynamic testing.

Initially, ultrasound imaging of the pelvis used transabdominal scanning which gave poor definition of the bladder neck. The next step was to use trans-vaginal scanning, which allowed better definition of the bladder neck but could not be performed during a stress provocation test (because the vaginal probe interfered with urethral leakage). In the last decade, trans-perineal scanning has allowed good visualization of the bladder neck. See Fig. 4.13. Using this technique, one can assess the following:

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Figure 4.13

Determination of bladder neck descent and retrovesical angle: ultrasound images show the midsagittal plane at rest (a) and on Valsalva (b). S symphysis pubis, U urethra, B bladder, Ututerus, V vagina, A anal canal, R rectal ampulla, L levator ani (From: Dietz [5], with permission)

Hypermobility of the bladder neck region

Fluid in the proximal urethra (Fig. 4.13)

Beaking and funneling of the urethra

The main difficulties are that:

·               Ultrasound scanning is not easy to perform in the erect position.

·               Trans-perineal scanning does not easily yield a lateral view that is helpful in previous failed continence surgery.

Therefore, trans-perineal scanning occupies an intermediate position in terms of accurate anatomical assessment of complex incontinence (somewhere between simple “eyeballing” of leakage on twin channel cystometry and full radiological imaging with VCU).

Voiding Cystometry

During voiding cystometry, the patient sits on the uroflow commode with the pressure transducers in situ. All staff leave the room while she voids in private (Fig. 4.14). The maximum and average flow rates (Q Max and Q Ave) are measured, as in a free uroflow, but the maximum detrusor pressure at the point of maximum flow (Pdet at Q Max) is also measured. The findings may be as follows.

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Figure 4.14

Voiding cystometry

In outflow obstruction, Q Max and Q Ave are low, but the detrusor pressure is high (the detrusor is trying to overcome the obstruction, so Pdet at Q Max is high, called “high pressure, low flow”).

Also in outflow obstruction, abdominal straining may be seen on Pabdo channel.

In an underactive detrusor, the Q Max and Q Ave are low, but the detrusor pressure at Q Max is also low (called “low pressure, low flow”), which is a feature of the atonic bladder.

Diagnoses Made After Voiding Cystometry

Outflow Obstruction

In women, the most common cause of obstruction is previous continence surgery or prolapse kinking the urethra (see Fig. 4.15). The high detrusor pressure with the low flow rate is typical. If sufficient voiding efficiency can be generated (often with abdominal straining, giving an intermittent pattern), then the residual may be minimal.

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Figure 4.15

Obstructed voiding pattern on voiding cystometry. Note detrusor contracting vigorously, then abdominal straining added, to achieve bladder emptying. Although flow was intermittent and prolonged, the residual was 90 ml (Qvoid  =  flow rate, ml/s)

Atonic Bladder

As mentioned, some features of bladder atony (large volume at FDV and MCC) are seen during filling, but during voiding, the most important feature emerges, of low detrusor pressure with low flow rate. Generally, there is a substantial residual. In women, this may be seen with diabetic autonomic neuropathy, or it may be a marker of a neurological lesion at the level of the sacral cord.

Detrusor Hyperactivity with Impaired Contractility (DHIC)

This is another cause of an underactive detrusor in elderly women. During the filling phase, there may be mild detrusor overactivity (see Fig. 4.16). During voiding, there is an initial burst of detrusor activity at the start of flow (detrusor hyperactivity), but it is not sustained through the whole flow (impaired contractility). This condition is thought to be due to atherosclerotic changes of the blood vessels supplying the spinal cord, so that there is relative impairment of the coordination of the micturition reflex Resnick and Yalla [14].

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Figure 4.16

Detrusor hyperactivity with impaired contractility. Note detrusor overactivity during filling phase, but poorly sustained contractility during voiding. Q Max 8 ml/s, Q Ave 3.5 ml/s, and residual volume was 120 ml

Detrusor Sphincter Dyssynergia (DSD)

In women with multiple sclerosis or spinal cord injury, you may see severe detrusor overactivity during the filling phase, then during voiding, very high detrusor pressures and an intermittent flow rate without abdominal straining, due to intermittent spasm of the urethra. It is due to poor coordination of the spinal relays of the impulses that signal the command to void. These should evoke synchronous relaxation of the urethra with contraction of the detrusor, but in DSD the synchrony is impaired due to spinal cord pathology (for review, see Jung and Chancellor [11]).

Special Urodynamic Tests

Urethral Pressure Profilometry

With about 200 ml fluid in the bladder, a double lumen fluid-filled manometry catheter or a flexible micro-tipped pressure recording catheter with one transducer mounted at the end and one 6 cm along is withdrawn from the bladder into the urethra. A mechanical puller device is used so that withdrawal occurs at about 5–10 cm/min. First, a resting urethral pressure profile (UPP) is made, to record the rise in pressure as the catheter at the 6 cm position passes through the ­urethral sphincter area. See Fig. 4.17. The urethral closure pressure equals urethral pressure (Pura) minus the bladder pressure (Pves). In a continent woman, Pura exceeds Pves. In most continent women, the urethral closure pressure is greater than 60 cmH2O pressure (although the UPP has been criticized because there is no absolute cutoff between continence and incontinence for this test). A resting closure pressure of less than 20 cmH2O is considered very low and is one indicator of intrinsic sphincteric deficiency (ISD).

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Figure 4.17

Urethral pressure profile test in stress incontinence

Next, the catheter is reinserted into the bladder and withdrawn through the urethra while the patient gives a series of short hard coughs (a stress UPP). Even while coughing, Pura should exceed Pves. In the incontinent woman, the Pves repeatedly exceeds the Pura during the cough, yielding a “negative stress profile.”

Abdominal or Valsalva Leak Point Pressure Test

At a volume of 200–250 ml, with a simple manometry line in the bladder (as for cystometry setup), the patient is asked to give a series of progressively harder coughs or Valsalva maneuvers. The intravesical pressure required to produce leakage from the external meatus (in the absence of a detrusor contraction) is called the leak point pressure (LPP). An LPP of less than 60 cm is thought to indicate intrinsic sphincteric deficiency: 60–100 cmH2O is equivocal, and a pressure of more than 100 cm is often taken to indicate that the leak is due to urethral hypermobility. The test is controversial because test–retest reliability has been difficult to document and correlation with other measures of incontinence severity is not high.

Triple Lumen (Trantner) Catheter Test for Urethral Diverticulum, Now Replaced by MRI

The triple lumen catheter test, with radiological screening, was previously the standard test for diagnosis of urethral diverticulum. The catheter had two balloons; the smaller balloon was filled with 8 ml water and compressed gently against the internal urethral meatus. The larger balloon was filled with 20 ml of water and compressed against the external urethral meatus, so that fluid could not escape the urethra. Radiopaque dye injected into the urethra would be forced into the urethral diverticulum, thus delineating it on X-ray screening.

In the last 5 years, urogynecological MRI and ultrasound imaging have improved, so that these are the preferred diagnostic test for detection of urethral diverticulum. See Fig. 4.18, for ultrasound image of diverticulum.

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Figure 4.18

MRI of urethral diverticulum (arrow)

Although excluding the diagnosis of urethral diverticulum is an important part of urogynecology investigation, the condition is not commonly encountered (about 3 % of women with recurrent UTI and post-micturition dribbling). Therefore, it is not further discussed in this “practical” text (but see Nichols and Randall [13] or Cardozo [3] for full review).

Note Regarding Diagnostic Tests for Vesicovaginal Fistulae

Because vesicovaginal fistulae are not common in the Western world, details of diagnosis and management are outside the scope of this text. For full review, see Hilton [9].

Example of Report

Case History, with Example of a Full Urodynamic Report, Illustrating Contribution of Urodynamic Studies to Management

Mrs. Brown is a 47-year-old para 2  +  0 lady. Twelve years ago, after her second delivery (Kielland’s forceps), she noted ­leakage with standing up from the sitting position, with mixed stress and urge incontinence. She had twin channel cystometry elsewhere; results are lost. Afterward, she was given 6 weeks of Ditropan 5 mg TDS, which she did not tolerate because of dry mouth. Pelvic floor physiotherapy was not performed. She told the doctor she did not want any more tablets but would like an operation. She underwent a colposuspension and went home with a suprapubic catheter for 10 days.

She was dry for about 2 years but did notice persistent daytime urge with nocturia. Since then, she has had gradually increasing leakage when arising from a sitting position. She often has to go back to the toilet to revoid.

On examination, with bladder partly full, stress leak is not seen. The anterior vaginal wall is not hypermobile. The retropubic area is rather fixed to the back of the pubic bone, more so on the left than the right. She had a weak 2-s pelvic floor contraction.

Summary, provisional diagnosis: This patient may have failed continence surgery with recurrent stress leak, or she may have an overactive bladder, or she may have both. Obstruction is also a possibility to explain her need to revoid. Clearly, careful urodynamics are essential.

Urodynamic Result

Initial Residual: 90 ml. First desire to void  =  190 ml. Strong desire to void  =  230 ml. Maximum capacity  =  380 ml.

During filling phase, systolic detrusor contractions were seen, Max P det of 21 cm. Supine tap water  =  increase in Pdet to 28 cmH2O. Supine cough  =  no stress leak. Erect provocation  =  increased detrusor pressure to Pdet 35 cmH2O with leak.

During multiple erect coughs, the patient leaked a small amount of fluid; on screening, asymmetrical beaking of the bladder neck was seen, with fluid leak.

In lateral view, the bladder neck did not descend.

Voiding cystometry—Q Max 25 ml/s; Q Ave 9 ml/s. Flow rate was intermittent and prolonged, with abdominal straining. Pdet at Q Max was 45 cmH2O; final residual was 110 ml.

See Fig. 4.19

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Figure 4.19

Urodynamic study of Mrs. Brown

Comments

Mrs. Brown has a reduced bladder capacity (380 ml), with detrusor contractions provoked by filling, supine tap water, and erect provocation to a maximum of 38. She does have some stress incontinence with an asymmetrical appearance of the urethra, in keeping with findings on examining the retropubic vagina. Her maximum flow rate is fine, but her average flow rate is poor, with abdominal straining ­suggesting relative outflow obstruction, in keeping with initial and final residuals of 90 ml/110 ml.

Diagnosis: Marked Detrusor Overactivity (DO) with Mild Degree of Obstruction; Mild Stress Incontinence Management

Treat the DO with bladder training, including pelvic floor muscle physiotherapy. Teach double emptying techniques. At 6 weeks, start anticholinergics, for example, tolterodine (less dry mouth), but recheck post-void residual 6 weeks later. If increased, you may need to consider clean intermittent self-catheterization. After this therapy, if stress incontinence persists, consider collagen/Macroplastique.

Note: If this patient had undergone pelvic floor training initially, with alternative anticholinergic therapy, the current situation may not have arisen.

Conclusions

Urodynamic testing requires careful attention to detail, both in the selection and counseling of the patient during the test, in performance of the provocation maneuvers, and in analysis of the results, to obtain precise diagnoses of the components of the continence disorder. Unlike an ECG that can be performed by a technician, this test requires a trained clinician in order to yield the maximum information.

References

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Abrams P. Urodynamics. 3rd ed. London: Springer; 2006.

2.

Abrams P, Cardozo L, Fall M, Griffiths D, Rosier P, Ulmsten U, et al. The standardisation of terminology of lower urinary tract function: report from the standardisation Sub-committee of the International Continence Society. Neurourol Urodyn. 2002;21:167–78.PubMedCrossRef

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Cardozo L. Urethral problems. In: Urogynaecology. New York: Churchill Livingstone; 1997. p. 377–86. Chapter 24.

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Cardozo L, Staskin D, editors. Textbook of female urology and urogynaecology. Thirdth ed. London: Martin Dunitz; 2010. p. 257–304. Chapters 29–32.

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Dietz HP. Pelvic floor imaging in incontinence: what’s in it for the surgeon? Int Urogynecol J. 2011. doi:10.1007/s00192-011-1402-7.

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Haylen BT, Ashby D, Sutherst JR, et al. Maximum and average urine flow rates in normal male and female populations – the Liverpool nomograms. Br J Urol. 1989;64:30–8.PubMedCrossRef

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Herschorn S. Videourodynamics. In: Cardozo L, Staskin D, editors. Textbook of female urology and urogynaecology. London: Martin Dunitz; 2001. p. 264–74. Chapter 24.

9.

Hilton P. Surgical fistulae and obstetric fistulae. In: Cardozo L, Staskin D, editors. Textbook of female urology and urogynaecology. London: Martin Dunitz; 2001. p. 691–720. Chapters 55, 56.

10.

Jarvis GJ. The management of urinary incontinence due to primary vesical sensory urgency by bladder drill. Br J Urol. 1982;54:374–6.PubMedCrossRef

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Jung SY, Chancellor MB. Neurological disorders. In: Cardozo L, Staskin D, editors. Textbook of female urology and urogynaecology. London: Martin Dunitz; 2001. p. 837–53. Chapter 65.

12.

Leader LR, et al. Handbook of obstetrics and gynaecology. 4th ed. London: Chapman & Hall; 1996. p. 406.

13.

Nichols DH, Randall CL. Urethral diverticulum and fistulae. In: Vaginal surgery. 4th ed. Baltimore: Williams and Wilkins; 1996. p. 422–5. Chapter 18.

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Resnick NM, Yalla SV. Detrusor hyperactivity with impaired ­contractile function: an unrecognized but common cause of incontinence in elderly patients. JAMA. 1987;257:3076–81.PubMedCrossRef

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Schierlitz L, Dwyer P, Rosamilia A, Murray C, Thomas E, Fitzgerald E, Hiscock R, De Souza A. A prospective randomised controlled trial comparing vaginal prolapse repair with and without tension free vaginal tape (TVT) in women with severe genital prolapse and occult stress incontinence: long term follow up. Int Urogynecol J. 2010;21(Suppl):S2–3.