Key points

Introduction

Much of the published work about urodynamics provides the best practice guidelines and standards of technique. How to appropriately apply urodynamics (when and for what purpose) remains guided mostly by expert opinion. Recent randomized controlled trials seek to guide its use in a well-defined population: women with complaints of stress urinary incontinence (SUI) who demonstrate SUI on physical examination. These important studies should be familiar to all clinicians who perform urodynamics or treat SUI. Despite a greater understanding of when urodynamic testing may be safely omitted in the evaluation of SUI, there remain many clinical scenarios in the treatment of women presenting with lower urinary tract symptoms (LUTS) in which the decision to use urodynamic testing still relies on the clinician’s judgment.

Arguments for urodynamics describe it as the best method to diagnose the underlying pathophysiology underlying LUTS. The objective data often direct therapy and help reduce unnecessary surgery or reduce the time and cost spent on unindicated treatments. Arguments against urodynamics are that the test is invasive, costly, and associated with some morbidity. A quality study also requires a well-trained clinician. However, urodynamics remains the most reliable method to confirm a presumptive diagnosis of lower urinary tract dysfunction.

In 2012, the American Urological Association (AUA) in conjunction with the Society of Urodynamics and Female Urogenital Reconstruction (SUFU) published guidelines to assist the clinician in the appropriate selection of urodynamic tests after an appropriate clinical assessment of the patient presenting with LUTS. The discussion points to the limitations of literature analysis due to the scarcity of level 1 evidence on the topic. Nineteen guideline statements are provided relating to SUI and pelvic organ prolapse, overactive bladder (OAB), urgency urinary incontinence, mixed urinary incontinence (MUI), neurogenic bladder, and LUTS.

Recent randomized controlled trials include Value of Urodynamic Evaluation (VALUE) and Value of Urodynamics Before Stress Urinary Incontinence Surgery (VUSIS2). The results clarify the use of preoperative urodynamics in a well-defined population of women with clinical pure SUI; however, this information is not generalizable to other groups of women with incontinence. High-level evidence to guide the use of urodynamics in voiding LUTS or MUI and OAB is limited. Because randomized controlled trials concern specific populations, the findings may be at odds with the priorities of the clinician who is accountable for the outcome and satisfaction of the individual patient. The decision to perform urodynamics is often based on a desire to assess risk for postoperative complications to better counsel patients on an individualized basis. Although the urodynamics information may not mitigate complications, it may help manage expectations and improve patient satisfaction even if complete cure is not achieved. When treating quality of life conditions for which surgical intervention is elective, patient expectations can be high. If conservative therapy alone is planned, urodynamics can be avoided. If surgical intervention is contemplated, urodynamics may offer valuable counseling information.

An objective diagnosis used to counsel before therapy often has value to the patient. Intuitively, the collection of objective data to establish the correct diagnosis is the first step to effective therapy. One study demonstrated that, when given a choice to have a diagnosis confirmed by urodynamics before proceeding with treatment of urinary incontinence, most women will chose to proceed with urodynamics. In this patient preference study, patients with LUTS were offered treatment based on their preference for conservative therapy based on symptoms or treatment preceded by urodynamics. Women without a preference were randomized to the two options. The investigators found that in this group of 309 women (median age 46 years), 49.4% preferred urodynamics, whereas 18.4% chose conservative therapy alone. Urodynamics did not confer any advantage in treatment response over treatment based on symptoms alone but there was a higher rate of follow-up in those who chose urodynamics. This was also true in the randomized groups. The greater rate of follow-up suggests that urodynamics may improve patient compliance with therapy. Corroborating studies are still needed.

Introduction

Much of the published work about urodynamics provides the best practice guidelines and standards of technique. How to appropriately apply urodynamics (when and for what purpose) remains guided mostly by expert opinion. Recent randomized controlled trials seek to guide its use in a well-defined population: women with complaints of stress urinary incontinence (SUI) who demonstrate SUI on physical examination. These important studies should be familiar to all clinicians who perform urodynamics or treat SUI. Despite a greater understanding of when urodynamic testing may be safely omitted in the evaluation of SUI, there remain many clinical scenarios in the treatment of women presenting with lower urinary tract symptoms (LUTS) in which the decision to use urodynamic testing still relies on the clinician’s judgment.

Arguments for urodynamics describe it as the best method to diagnose the underlying pathophysiology underlying LUTS. The objective data often direct therapy and help reduce unnecessary surgery or reduce the time and cost spent on unindicated treatments. Arguments against urodynamics are that the test is invasive, costly, and associated with some morbidity. A quality study also requires a well-trained clinician. However, urodynamics remains the most reliable method to confirm a presumptive diagnosis of lower urinary tract dysfunction.

In 2012, the American Urological Association (AUA) in conjunction with the Society of Urodynamics and Female Urogenital Reconstruction (SUFU) published guidelines to assist the clinician in the appropriate selection of urodynamic tests after an appropriate clinical assessment of the patient presenting with LUTS. The discussion points to the limitations of literature analysis due to the scarcity of level 1 evidence on the topic. Nineteen guideline statements are provided relating to SUI and pelvic organ prolapse, overactive bladder (OAB), urgency urinary incontinence, mixed urinary incontinence (MUI), neurogenic bladder, and LUTS.

Recent randomized controlled trials include Value of Urodynamic Evaluation (VALUE) and Value of Urodynamics Before Stress Urinary Incontinence Surgery (VUSIS2). The results clarify the use of preoperative urodynamics in a well-defined population of women with clinical pure SUI; however, this information is not generalizable to other groups of women with incontinence. High-level evidence to guide the use of urodynamics in voiding LUTS or MUI and OAB is limited. Because randomized controlled trials concern specific populations, the findings may be at odds with the priorities of the clinician who is accountable for the outcome and satisfaction of the individual patient. The decision to perform urodynamics is often based on a desire to assess risk for postoperative complications to better counsel patients on an individualized basis. Although the urodynamics information may not mitigate complications, it may help manage expectations and improve patient satisfaction even if complete cure is not achieved. When treating quality of life conditions for which surgical intervention is elective, patient expectations can be high. If conservative therapy alone is planned, urodynamics can be avoided. If surgical intervention is contemplated, urodynamics may offer valuable counseling information.

An objective diagnosis used to counsel before therapy often has value to the patient. Intuitively, the collection of objective data to establish the correct diagnosis is the first step to effective therapy. One study demonstrated that, when given a choice to have a diagnosis confirmed by urodynamics before proceeding with treatment of urinary incontinence, most women will chose to proceed with urodynamics. In this patient preference study, patients with LUTS were offered treatment based on their preference for conservative therapy based on symptoms or treatment preceded by urodynamics. Women without a preference were randomized to the two options. The investigators found that in this group of 309 women (median age 46 years), 49.4% preferred urodynamics, whereas 18.4% chose conservative therapy alone. Urodynamics did not confer any advantage in treatment response over treatment based on symptoms alone but there was a higher rate of follow-up in those who chose urodynamics. This was also true in the randomized groups. The greater rate of follow-up suggests that urodynamics may improve patient compliance with therapy. Corroborating studies are still needed.

Investigating LUTS in women

LUTS are highly prevalent in men and women; rates are affected by age and ethnic or racial group. Women present with a variety of urinary complaints relating to both bladder storage (urinary incontinence, urgency, frequency, and nocturia) and emptying (urinary retention or incomplete emptying, hesitancy, straining, slow stream, intermittency, and terminal dribbling). In some cases, the presenting complaint, such as recurrent urinary tract infection, may not describe LUTS. However, further discussion of bladder symptoms when taking history may hint that a functional disorder could underlie the presenting complaint. The clinician must use the patient’s complaint, medical history, findings on physical examination, and urinalysis to develop the clinical diagnosis.

Despite best efforts at obtaining a thorough and accurate history, LUTS do not always correlate with urodynamic diagnoses. Digesu and colleagues published a systematic review of 23 clinical trials relating to 6282 women with incontinence. Results showed that urodynamics confirmed the clinical diagnosis of SUI in 75% of the cases. Clinical SUI was reclassified infrequently as MUI in 9% and as detrusor overactivity (DO) in 7% of the cases. As shown in other studies investigating the use of urodynamics in SUI, there were a small (8%) percentage of women with clinical SUI who had normal urodynamics. This review confirmed the opinion that the clinical diagnosis of SUI is usually made correctly without urodynamics.

Greater rates of change were found in women with clinical MUI, of which 46% were reclassified as SUI and 21% as DO. Based on urodynamics, rates of diagnostic change were greatest in women with clinical MUI. A full two-thirds of these women had the diagnosis changed by urodynamics. Most were found to have pure urodynamic SUI. These results point out that urodynamic findings in MUI are varied, as are the patients’ complaints. When there is disagreement between the urodynamic findings and the patient’s symptoms, urodynamics findings are not necessarily any more valid than the patient’s symptoms. Failure to demonstrate DO or SUI on urodynamics does not wholly exclude either as a source of the patient’s symptoms.

A physician must expertly listen and observe during the history and physical examination to recognize symptoms, physical findings, and patterns that point to a high likelihood of a functional urinary disorder. Although there is a role for empiric treatment of many LUTS, when there is a very high clinical suspicion for a functional disorder that may be best treated surgically, diagnostic urodynamic testing may be the prudent next step. Urodynamics is also relied on when empiric treatments fail to provide the expected satisfactory results and the clinician wishes to confirm the clinical diagnosis.

Urodynamic tests used to investigate LUTS

Uroflow is a noninvasive screening test for patients with LUTS. It may be used when any voiding abnormality is suspected. A normal flow curve is a smooth arc-shaped curve. The kinetics of the detrusor contraction accounts for the uroflow pattern observed. Abnormal flow curves may suggest obstruction or a weak detrusor but they cannot diagnose the true pathophysiology. The uroflow may be altered by a low voided volume or if the patient feels inhibited during voiding; therefore, the clinician should repeat the uroflow in these situations.

Filling cystometrography (CMG), the urodynamic investigation of the pressure-volume relationship of the bladder during filling, provides assessment of bladder sensation, the presence of DO, bladder compliance, and bladder capacity. Urethral function studies may also be undertaken during filling CMG. In clinical practice, the presence of altered compliance, DO, or other urodynamic abnormalities detected during CMG may alter the treatment decision, particularly when invasive surgery is planned. Women in whom there is a high index of suspicion for these urodynamic findings should have a CMG performed, including those with urinary urgency incontinence (UUI), retention, neurogenic disease (known or occult), pelvic radiation, or radical pelvic surgery.

A pressure-flow study (PFS) examines the relationship of bladder pressure and urine flow rate during the voiding phase. A PFS is useful to diagnose bladder outlet obstruction (BOO)or impaired detrusor contractility in a patient complaining of voiding symptoms and urgency incontinence.

An electromyogram (EMG) is a test of perineal muscle function and measurement of the striated sphincteric muscles of the perineum. In normal voiding, relaxation of the pelvic muscles occurs before the detrusor contraction. Therefore, increases in EMG activity during the voiding phase suggest dysfunctional voiding or detrusor sphincter dyssynergia. EMG is a useful adjunct to PFS to help diagnose voiding dysfunction.

Videourodynamics refers to the simultaneous fluoroscopic imaging of the lower urinary tract during multichannel urodynamics for the purpose of obtaining anatomic data. It may be particularly useful to diagnose a pop-off mechanism of vesicoureteral reflux in the patient with low compliance of the bladder or to determine the level of obstruction in BOO. For the diagnosis of primary bladder neck obstruction, confirmation is made exclusively by fluoroscopy.

Although urodynamic tests are described as separate entities, a thorough urodynamic investigation of a patient with LUTS includes both CMG and PFS. Because clinical symptoms do not predict urodynamic findings, it cannot be relied on that a patient with storage symptoms needs only CMG and a patient with voiding symptoms needs only PFS. The importance of attention to the voiding phase in women is highlighted by a study of women with LUTS in which urodynamic results of CMG were compared with results of CMG and PFS. The investigators found that PFS added relevant information in 33% of women. Seventy percent of the women with PFS findings had normal a CMG. An interesting and thought-provoking finding is that five women initially classified as dysfunctional voiders were later reclassified as having detrusor-external sphincter dyssynergia (DESD) after a neurologic evaluation. All five had also shown DO on CMG. The investigators caution that increased sphincter activity during voiding and DO, especially if associated with DO incontinence in a woman younger than 40 years, should prompt consideration of a neurologic referral. This study emphasizes that storage and voiding symptoms are related, and that voiding abnormalities may result in storage abnormalities, such as low compliance, DO, change in sensation, and change in capacity.

Urodynamic testing in female LUTS

Multichannel urodynamics is the gold standard study for the evaluation of complex LUTS and identification of functional urinary abnormalities. Urodynamic testing is not a screening tool for LUTS. It is a diagnostic tool meant to be applied with precision to patients who have already been identified as having LUTS. Specifically, urodynamics is used to answer a particular question or series of questions regarding the patient’s symptoms. The validity of the test to answer these questions is predicated on the ability to reproduce the clinical symptoms during the test. The results should confirm a diagnosis when there is clinical doubt or when therapy may be altered by the findings. If conservative therapy alone is planned, urodynamics may be avoided because there is little risk to the patient from conservative, nonsurgical therapies. Urodynamics may be more helpful before surgical intervention.

Like other diagnostic tests, urodynamics is not infallible nor is it therapeutic or capable of generating a therapeutic decision. Its quality is affected by operator expertise at set up, performance, and interpretation. It is also subject to patient factors, such as the ability to relax and perform to the degree that what she experiences at home can be demonstrated during the study. Assuming ideal operator and patient factors, urodynamics can provide the clinician with data that may change the diagnosis and choice of therapy. It is a commonly held belief that the objective data obtained by urodynamics is superior to clinical impressions and are more important, particularly when the previous clinical diagnosis changes. However, it is not clear that all urodynamic findings are relevant, particularly in the case of DO.

Diagnostic testing does not always predict response to therapy and urodynamics is no different. This is often held up as the rationale for more limited use of urodynamics; however, caution should be used when interpreting this as a repudiation of its use. As pointed out by a committee of experts, “UDS [urodynamic] results are often compared to diagnosis based on clinical symptoms but there is no ‘gold standard’ to compare to; therefore, estimates of sensitivity, specificity, positive and negative predictive value of UDS are misleading.” Quality and value, as they relate to urodynamic testing, have not been clearly defined nor is there a consensus of thought. Stakeholders (physicians, patients, and third-party payers) probably would not have identical definitions in any case.

Storage LUTS: SUI

The application of urodynamics has changed more in SUI than any other category of female LUTS. Results of randomized controlled trials published by the Urinary Incontinence Treatment Network (UITN) support the recommendation that urodynamics is not necessary in the preoperative evaluation of pure SUI. When SUI is described clearly by the patient, urine leak is seen with cough or Valsalva on examination (supine or standing) and there is no sign or symptom of urinary retention, SUI is diagnosed without the need for confirmatory urodynamics. Urodynamics in this situation is thought to only increase cost and delay treatment.

Whether the same recommendation can be made for the patient with persistent or recurrent SUI is not known. Although not specifically addressed in these trials, by similar reasoning, the patient who reports persistent SUI after incontinence surgery and demonstrates leakage on examination may not need urodynamics before undergoing a secondary incontinence procedure, particularly if the treating physician is confident in the clinical diagnosis. However, recurrent SUI in which the patient had a previously successful incontinence procedure but later becomes incontinent may warrant urodynamics before deciding on any future invasive therapy.

Measuring urethral competence tests of abdominal leak point pressure (ALPP) and maximal urethral closure pressure (MUCP) fell out of widespread use with the advent of midurethral polypropylene slings and changes in concepts of intrinsic sphincter deficiency (ISD). Contemporary concepts of ISD recognize it as a spectrum rather than absolute. Because not all women with urethral hypermobility leak, those women who do must have some degree of ISD. Data from the Stress Incontinence Surgical Treatment Efficacy Trial (SISTEr) found that ALPP did not predict surgical outcome, but the Trial of Mid Urethral Slings (TOMUS) results found a higher rate of SUI postoperatively at one year. Women with ALPP or MUCP were in the lowest quartile. Although clinicians may still use the sign of leakage with cough or Valsalva to confirm SUI on urodynamics, the absolute pressure required to cause the leak rarely plays a role in the choice of surgery nor does it predict response. Even with urethral bulking agents for SUI, outcomes data support its use in women with urethral hypermobility as well as in the ISD patient. Despite changes in the understanding of SUI within clinical practice, documentation of an ALPP less than or equal to 100 cm water is still routinely required in order for the Center for Medicare Services to approve a bulking agent for SUI. Therefore, if a Medicare patient with SUI desires a bulking agent as treatment, she will require urodynamics first.

It is well documented that urodynamics fails to diagnose urodynamic incontinence in a small percentage of women with SUI symptoms. Almost 12% of women in SISTEr and TOMUS had absence of urodynamic SUI (USUI) despite clinical symptoms and a positive standardized empty bladder stress test. In TOMUS, prolapse reduction testing was not performed, which certainly affected the rate of USUI detection.

In a secondary analysis of these studies, high-grade pelvic organ prolapse (stage 3–4) was strongly associated with the absence of USUI. The investigators noted that the urodynamic bladder capacity (maximum cystometric capacity) in these women was lower, which may reflect that they did not reach the volume at which they leak in their own environment. Given the supraphysiologic filling and room-temperature fluid for urodynamics, some women do not accommodate as large a bladder volume as they do naturally, thus they fail to demonstrate leakage. Management of women with clinical SUI but no USUI is problematic. These patients were at higher risk for postoperative urgency urinary incontinence in a secondary analysis of the VALUE trial.

When clinical SUI exists with pelvic organ prolapse, demonstrable with or without prolapse reduction, urodynamics is not needed to confirm or guide the treatment of incontinence. The decision to treat is based on the patient’s reported bother from incontinence. More controversial is the use of urodynamics to diagnose occult SUI in women who have no symptoms of SUI. Methods of prolapse reduction are not standardized and results can be affected by the method used. Currently, clinicians must be guided by their own level of comfort in the possibility of de novo SUI versus a potential complication from a sling that may not have been necessary.