div class=”ChapterContextInformation”>

© Springer Nature Switzerland AG 2020
M. Drake et al. (eds.)Lower Urinary Tract Symptoms in Adults

4. LUTS Assessment

Alison Bray1  , Sophia Cashman2  , Nikki Cotterill3  , Marcus Drake4  , Mikkel Fode5  , Andrew Gammie6  , Christopher Harding1  , Dharmesh Kapoor7  , Nikesh Thiruchelvam2  , Laura Thomas6   and Alan D. Uren6  

Freeman Hospital and University of Newcastle, Newcastle-upon-Tyne, UK

Addenbrookes Hospital, Cambridge University Hospitals NHS Trust, Cambridge, UK

University of the West of England, Bristol, UK

University of Bristol, Bristol, UK

Herlev and Gentofte Hospital, Herlev, Denmark

Bristol Urological Institute, Southmead Hospital, Bristol, UK

Royal Bournemouth Hospital, Bournemouth, UK



Alison Bray


Sophia Cashman


Nikki Cotterill


Marcus Drake (Corresponding author)


Mikkel Fode


Andrew Gammie


Christopher Harding


Dharmesh Kapoor


Nikesh Thiruchelvam


Laura Thomas


Alan D. Uren


Patient-reported outcome measureLower urinary tract symptomsUroflowmetryArtefactsUrodynamicsAmbulatory urodynamics

4.1 Introduction

This chapter introduces the scope of evaluations used to reinforce the evaluation derived from clinical history and examination. These may include relevant tests if there is suspicion that all may not be as it seems, i.e., that the presentation with LUTS could actually reflect something serious, the ‘red flag’ scenarios; here the professional needs to be willing to divert care along an entirely different path and potentially refer to colleagues to pin down the exact nature of the situation.

Many questionnaires are now available of particular interest and developmental quality for the broad assessment of LUTS, the impact of LUTS on HRQL and those that target specific urological conditions. Factors which should be considered when choosing a PRO include its context of use (the condition and population to be measured), its measurement properties, the logistics surrounding its administration and other recommendations from regulatory bodies. However, there is no substitute for the location of the instrument from the developer and the careful review of its content, for an informed decision when selecting a PRO measure for research or clinical practice.

In clinical practice, a rough estimate of prostate volume can be made by DRE. This may influence choice of treatment (for medication and operation). However, the method generally underestimates the true size of the gland, and it is best suited to identify large prostates. Serum PSA value correlates well with prostate volume, and in theory, the marker provides an easy estimate of prostate volume. However, PSA has important implications in prostate cancer detection, which complicates its use in LUTS. This means that ultrasound is the modality of choice when measuring prostate volume. In this regard, the transrectal approach is more precise than transabdominal ultrasound. MRI provides an even more precise measurement of the prostate volume, but it is not routinely used in benign prostatic hyperplasia.

Free flow rate (FFR) testing is an important tool in the initial assessment of patients with lower urinary tract symptoms (LUTS). Due to the noninvasive nature of the test and the relatively low-cost equipment required for it, FFR testing is one of the simplest urodynamic tests. Although FFR or urine flow rates are rarely diagnostic, they can provide valuable information pertaining to patients’ voiding and storage symptoms.

Urodynamic assessment can identify dysfunction of the lower urinary tract in both the storage and voiding phases. It is the only way of accurately differentiating voiding symptoms due to bladder outflow obstruction (BOO) from those due to detrusor failure. Various guidelines are in place to help identify those who warrant urodynamic assessment. Urodynamics should be performed by an individual trained in interpretation of the urodynamic trace, and with a clear question to answer in mind. Test conditions should be kept as close to normal for the patient as possible in order to gain optimal study results. Free flow, filling cystometry and pressure flow studies should all be assessed. On occasion, they are done with the addition of special tests such as video studies and urethral pressure profiling. For some patients, the urodynamic question cannot be answered with standard cystometry—either the symptoms were not reproduced, or extra information is required. In these cases, special urodynamic tests can be undertaken, notably ambulatory testing. Artefacts may be experienced during the trace, which can alter the interpretation, and therefore they need to be accurately identified and noted at the time. Noninvasive urodynamic techniques have been developed, mainly concerned with attempts to diagnose bladder outlet obstruction noninvasively. The overall message about the value of noninvasive urodynamics remains unclear.

4.2 ‘Red Flags’

Sometimes a patient presents having been referred with LUTS, where the actual underlying mechanism turns out to be a serious underlying condition. The European Association of Urology refers to these as red flags [1], and clearly it is vital to stay alert to this possibility, to avoid serious harm coming to the patient. This issue is potentially more likely now that LUTS and the symptom syndromes are diagnoses in their own right; it seems to reduce the intellectual consideration when it is rather easy to label someone as having OAB when they report urinary urgency. A rare but crucial possibility is the presence of a neurological condition that has not yet been diagnosed. Some neurological diseases have LUTS as an early feature in their disease process [2], and this can mean that the initial referral might focus on the LUTS and miss the implication of other features. Possibilities include early-stage Parkinson’s disease, multiple sclerosis, multiple system atrophy, normal pressure hydrocephalus or spinal cord problems. If suspected, direct questioning is needed about erectile or ejaculatory dysfunction, bowel function, memory loss, loss of sensation and previous temporary symptoms (these can suggest MS, and one of the most notable features is transient unilateral vision loss, which suggests optic neuritis). Examination should evaluate speech, tremor (a unilateral 2 Hz tremor affecting one arm may indicate early Parkinson’s disease), walking, palpable/expressible bladder, weakness, impaired sensation and postural hypotension [2]. It is the responsibility of the health-care professional to tease out indicators of red flag conditions (Table 4.1) and to initiate investigation or referral with due priority.

Table 4.1

‘Red flags’ to consider

Presenting LUTS

Observation (elicited by history, examination or testing)

Implication to consider


PMH of smoking, haematuria

Bladder cancer

Dipstick haematuria

Bladder cancer or inflammation

Dipstick leukocyturia

Bladder inflammation, urethritis, STI

Dipstick nitrites



NP on bladder diary

Behavioural or medical cause

Increased daytime frequency

24-h polyuria on bladder diary

Behavioural or medical cause

Any LUTS in men

Erectile dysfunction

Metabolic syndrome or MSA

Storage LUTS in men

Tender prostate

Prostate inflammation

Any LUTS in men

Abnormal DRE or PSA

Prostate cancer

Any LUTS in women



Storage LUTS in women

Vaginal atrophy

Oestrogen deficiency

Continuous leakage in women

Previous surgery, malignancy or pelvic irradiation

Bladder or ureteric fistula

Continuous leakage in adolescent woman


Ectopic ureter

LUTS in women with prior midurethral tape

Recurrent UTIs, dyspareunia, bleeding

Mesh exposure (vaginal or bladder)

LUTS in any patient

Severe LUTS and problem of gait/speech/memory/bowels/sensation/BP/vision/erectile function

Neurological disease

This table is not comprehensive, and the health-care professional must stay alert to the possibility that a patient’s presentation with LUTS could actually be a manifestation of something unexpected and serious from a large range of possibilities. BP blood pressure (postural hypotension results from impaired regulation of vascular tone needed when changing position). DRE digital rectal examination, MSA multiple system atrophy, NP nocturnal polyuria, POP pelvic organ prolapse, PSA prostate-specific antigen, STI sexually transmitted infection

4.3 Symptom Assessment Tools

The overlap of symptoms from different lower urinary tract and voiding disorders can present a challenge for clinicians to ascertain a clinical hypothesis by history taking alone. However, there are a few ways by which a clinician may objectively capture a patient’s experience in order to formulate treatment strategies. The urinary diary (includes the frequency volume chart and bladder diary) allows a patient to record and self-report their symptoms as they occur and is accepted as an integral tool in the initial assessment of LUTS. When completing a bladder diary , the patient records information such as fluid intake, voided volume, the time of micturition and other symptoms for a few days before their visit to their clinician [3]. Clinician-completed questionnaires are available [4, 5]; however, these are not widely used, as it has been shown that interviewer administration can introduce potential bias when assessing patient responses [6, 7]. Patient-centered questionnaires are increasingly recognised as the most important way of reviewing symptoms and their impact from the patient perspective [8, 9]. A patient reported outcome (PRO) is defined by the U.S. Food and Drug Administration (FDA) as ‘any report of the status of the status of a patient’s health condition that comes directly from the patient, without interpretation of the patient’s response by a clinician or anyone else’ [10]. Over the last 20 years, there has been a large growth in the number and scope of available PRO measures for the assessment of LUTS, and their impact on health-related quality of life (HRQL). The following chapter will give an overview of the design and validation of PROs, discuss the choice of appropriate instrument and review some of the important instruments that are available for use in research and clinical practice.

PROs, or the synonymously termed patient-reported outcome measures (PROMs), enable the capture of the subjective patient experience in an objective and measurable way. They are recognised as providing valuable information of symptoms, signs and impact on quality of life and to allow assessment of change during ongoing clinical evaluation, research or as outcome measures in clinical trials. PRO measures tend to be structured as a series of simple questions (or items) with fixed responses which patients are able to understand and answer quickly and easily. The patient is asked to remember information about perceived severity of symptoms or impact on quality of life over a recent period of time known as a ‘recall period’. The questions include a series of possible answers (response options) which allow the patient to indicate the frequency or severity by which they experience a particular symptom or impact on quality of life. These response options are usually assigned points from low to high severity, which allows the calculation of an overall symptom score. Through multiple administrations of the measure, it is therefore possible to monitor the ongoing progress of a patient, to formulate clinical hypotheses and manage treatment accordingly.

4.3.1 Development and Validation of PRO Measures

The development of a PRO questionnaire is a detailed and lengthy process involving numerous substudies, designed to demonstrate that the PRO is measuring what it is intended to measure [1114]. Figure 4.1 gives an overview of the main steps involved. There are three main measurement (psychometric) properties a questionnaire must demonstrate in order that users may have confidence in the measurements that are made: [14, 15]

  • Validity—does the instrument measure what it claims to measure in the population of interest?

  • Reliability—does the instrument measure concepts over time in a consistent and reproducible manner?

  • Responsiveness—is the instrument sensitive to treatment outcome following intervention?


Fig. 4.1

Summary of the stages in PRO develo pment

The first two, validity and reliability, are traditionally considered the fundamental characteristics that a PRO instrument must possess [14, 16, 17]. The questionnaire must be shown capable of measuring the symptoms or health-related quality of life aspects in an accurate (valid) and stable (reliable) manner [11, 13, 14]. One aspect of validity is content validity. This refers to whether the PRO instrument covers all relevant content, without omitting any important issues, but also excluding any irrelevant items [11, 14, 18]. Content validity is supported by direct patient input from the relevant clinical population using qualitative research methodology when the PRO is being developed, usually by semistructured interviews [19]. Task force reports by the International Society of Pharmacoeconomics and Outcomes Research (ISPOR) provide detailed recommendations for the demonstration of content validity in new instruments, including the development and refinement of new items by cognitive interviews [19, 20]. The third property, responsiveness (or sensitivity to change), is important if a questionnaire is to be used in clinical applications as an outcome measure to detect change in a patient’s condition. Responsiveness to change can be evaluated using percentage change in total score before and after an intervention of known efficacy. A minimally important difference (MID) can also be calculated to describe the smallest change deemed clinically useful as measured by the questionnaire [21].

Selecting PROs for Clinical Practice, Clinical Trials and Research Studies

As there are many PRO measures available for the assessment of LUTS, how does one select which is most appropriate and relevant?

  1. 1.

    Use questionnaires that have been rigorously developed and validated.

    The 6th International Consultation on Incontinence (ICI) 2016 (committee 5B) reviewed the available evidence or the psychometric properties for published self-completion questionnaires [8]. The result was a comprehensive publication and review of the measurement properties and status of validity of the published PROs relating to the assessment and screening of LUTS, and other measures relating to urgency, faecal incontinence and associated sexual function. Each questionnaire reviewed by the committee received a grade A to C based on the documented evidence of the reliability, validity and responsiveness of the questionnaire. The grading of A is given if there is ‘published evidence of validity, reliability and responsiveness to change’ and are ‘highly recommended’. Grade A+ is awarded if there is additional evidence of content validity (i.e., evidence of patient involvement in the item development process). The grading of B and C is given if there is less evidence of validity or reliability and is consequently referred to as ‘recommended’ or ‘have potential’, respectively.


  2. 2.

    Consider who (target population) and what is being assessed.

    If the intended population is of a particular demographic (e.g., gender, age or cultural origin), this will influence the choice of instrument or mode of administration. A questionnaire may also have to be linguistically validated if translated for a multinational study or for use in multicultural populations [22]. PRO instruments may be generic or condition-specific. Generic measures are designed to measure multidimensional attributes (e.g., emotional, physical and social aspects) which can be applicable to a broad range of populations or conditions [23]. Condition-specific measures have been developed and validated for use in a specific condition and population and are the focus of this chapter. The type of PRO selected is influenced by the population or outcome which is to be measured. However, both types of PROs are often selected for concurrent use in clinical trials or research, to maximize the breadth and depth of the information which is captured.


  3. 3.

    Consider the content and logistics of administration.

    Familiarity with the content, layout, scoring system and burden on patients is essential to an informed choice. The length of time an instrument takes to complete is particularly important to consider if an instrument is to be completed in a clinical setting, or administered multiple times. Administration using an electronic interface such as an iPad can have several advantages, such as the reduction of data entry workload and accuracy [24, 25], and usually have high patient acceptance [26]. However, while scores from traditional paper-based versions be equivalent, this cannot be assumed [27], so a validated electronic version should be sought from the instrument developer.


  4. 4.

    Has the questionnaire been successfully used and is it recognised by regulatory bodies?

    There are considerable advantages if the questionnaire has already been successfully used in clinical practice or research studies in the countries where it will be administered. For example, patient-reported symptom assessment tools are recommended in guidelines for initial investigation of patients presenting with LUTS and incontinence by the UK National Institute of Clinical Excellence (NICE). The regulatory requirements for the intended use of the instrument should be also considered. For example, if the PRO measure is to be used in clinical trials, the extent to which their published properties comply with the standards required by the U.S. FDA: ‘Guidance for industry for PRO measures: use in medical product development to support labeling claims’ [10].


4.3.2 PRO Measures for the Assessment of LUTS

To restrict the included questionnaires to those of highest developmental quality, the questionnaires included in this chapter have been given an ICI grading of A or A+, or are of particular interest to the assessment of LUTS in research or clinical practice. Table 4.1 gives the broad concepts/symptoms which are measured by the included PROs. However, it is highly recommended that the user should contact the developer for access to the instrument and translations that are available, to understand fully their structure and content. B-SAQ (Bladder Self-Assessment Questionnaire)

This is an 8-item tool designed to assess storage symptoms in women and was validated for men in 2014 [28, 29]. This aims to be a concise, screening tool rather than assessing broad LUTS. The items were generated following literature review and input from a European panel of experts and showed good reliability and responsiveness. Individual symptoms and bother scores are summated, giving an overall symptom and bother score which can be used to advise whether medical help is required. The questionnaire has been translated and validated in more than 14 languages. DAN-PSS-1 (Danish Prostatic Symptom Score)

This 12-item tool was designed in Denmark to assess voiding problems and associated bother in men with LUTS suggestive of benign prostate hyperplasia (BPH) [30, 31]. It has also been validated for LUTS in men after stroke [32] and used for LUTS in patients with Parkinson’s disease [33]. A score is generated by multiplying the bother score with the symptom score to attain a total score out of 108. It has also been validated in electronic format (albeit in 2001) [34]. ICIQ-MLUTS (ICIQ-Male Lower Urinary Tract Symptoms)

This is a 13-item tool to assess a wide range of LUTS with associated bother in men [35, 36] and was derived from the original long-form ICS male [36]. It is part of the International Consultation on Incontinence Questionnaire (ICIQ) modular group (www.​iciq.​net) [37] which offers a range of psychometrically robust instruments for the self-assessment of lower urinary tract dysfunction. Content validity was evidenced by in-depth interviews with patients and consultation with an expert clinical panel. Aspects of reliability and responsiveness to change have been evidenced following surgical and drug treatments [38]. The paper -based version has recently been validated for its equivalence in electronic format [39]. ICIQ-FLUTS (ICIQ-Female Lower Urinary Tract Symptoms)

Originally the Bristol female lower urinary tract symptoms questionnaire [40, 41], the recommended version as part of the ICIQ modular group is a scored 12-item tool which assesses female LUTS (with an emphasis on urinary incontinence), and associated bother [37]. The instrument has been used for outcomes and epidemiological research [42, 43]. It has good levels of reliability, validity and responsiveness [40, 41] and is valid in electronic format [39]. LUTSS (Lower Urinary Tract Symptom Score)

This is a 14-item tool that a ssesses a range of LUTS in men and women, developed in the United States in 2015 [44]. In particular, the aim is to provide a more ‘nuanced’ assessment of urgency and incontinence compared to those provided by other existing PRO measures. Items that cover post micturition dribbling and the ‘persistent awareness of the need to void’ are not included by the developers, due to a perceived lack of relevance to clinical practice (though this may have been misguided), and to reduce patient burden. Other Condition-Specific Measures

When selecting a PRO measure to assess LUTS, one must consider the instrument’s ability to assess broad LUTS versus specificity to a particular urological condition, such as overactive bladder, bladder outlet obstruction or urinary incontinence. For example, the International Prostate Symptom Score (I-PSS) [45] is widely used in research and clinical practice as an 8-item screening tool for capturing the severity of symptoms relating to BPH. However, the I-PSS does not include some LUTS which have considerable burden, most notably urinary incontinence (Table 4.1) [46]. Its ICI grading of B reflects that patients were not involved in its development. Others target incontinence, such as the ISS (Incontinence Symptom Severity Index) [47], or overactive bladder such as the OAB-SS (Overactive Bladder Symptom Score ) [48].

4.3.3 PRO Measures for the Assessment of LUTS HRQL

HRQL PROs collect information on aspects (or domains) that relate to the impact of a condition on a patient’s life. Fo r exam ple, questionnaires may cover the impact on emotions, work-life, sleep, physical, sexual activities or family life. These domains will vary according to the focus of the particular questionnaire. Similar to symptom PROs, HRQL questionnaires may be generic or condition-specific. Condition-specific instruments for the assessment of LUTS on HRQL include the ICIQ-LUTSqol (Lower Urinary Tract Symptoms—quality of life) [21, 4951], formerly known as the King’s Health Questionnaire (KHQ) . This is a 21-item comprehensive tool to assess the impact of LUTS and associated bother on HRQL for men and women. It has demonstrated validity and reliability and responsiveness to change, has an ICI grading of A+ and is available in over 30 languages [52]. It is also recommended for use in the initial assessment of LUTS by NICE. Other questionnaires target the impact of specific urological conditions on HRQL, for example, the ICIQ-OABqol (ICIQ Overactive Bladder questionnaire) [53, 54], or nocturia such as the ICIQ-Nqol (ICIQ Nocturia Quality of Life Questionnai re) [55].

4.3.4 Novel PRO Measures

Owing to the large number of questionnaires available (Table 4.2) and the complex, and lengthy process required to design a new questionnaire, it is prudent to avoid reinventing the wheel. Indeed, the ICI recommends that no further questionnaires are developed [56]. Nevertheless, there is scope for additional PROs for specific urological conditions (e.g., the ICIQ-Underactive Bladder) [57]. The recently developed LUTS tool (Lower Urinary Tract Symptoms Tool) [58, 59], although yet to be psychometrically validated, shows promise as the first questionnaire for the assessment of LUTS to be in development with published evidence of content validity according to FDA regulatory standards [10].

Table 4.2

Summary of the concepts/symptoms measured by the selected questionnaires for the assessment of LUTS

Item concepts









Daytime urinary frequency





Contact developer

Slow stream



Postmicturition dribble

Incomplete emptying

Bladder pain

Continence aids

Questionnaires: B-SAQ Bladder Self-Assessment Questionnaire, DAN-PSS-1 Danish Prostatic Symptom Score, ICIQ-MLUTS ICIQ-Male Lower Urinary Tract Symptoms, ICIQ-FLUTS, ICIQ-Female Lower Urinary Tract Symptoms, LUTSS Lower Urinary Tract Symptom Score, OAB-SS Overactive Bladder Symptom Score, ISS Incontinence Symptom Severity Index, I-PSS The International Prostate Symptom Score

4.4 Bladder Diaries

Frequency refers to the number of voids observed in a defined time period, and this is most reliably identified by asking the patient to complete a record. The simplest is a micturition time chart, which records only the times of micturitions for at least 24 h [60]. A frequency volume chart (FVC) also records the volumes voided, as well as the time of each micturition, day and night, for at least 24 h. A bladder diary is the most informative, as it records the times of micturitions and voided volumes, and additional information which can be selected to give the most important features for the patient being investigated. The type of information could include fluid intake, incontinence episodes, pad usage, the degree of urgency and social activities. Instructions need to be clear, and patients must be encouraged to write in waking and sleeping times, as these are often overlooked—which makes interpretation difficult.

Three-day diary durations are generally used in clinical practice [61], as a balance between gathering sufficient information to be meaningful, and not so much of a burden that the patient refuses to complete it. The only validated diary currently available was prepared by the International Consultation on Incontinence Questionnaires team [3, 62]. This diary captures the time of drinks and voids, the volume of each drink and void, the type of fluid drunk each time, and whether pads were used. They need to write ‘wake’ and ‘sleep’ times. The patient is also asked to write how their bladder felt when they went to the toilet using these codes;

  • 0—if you had no sensation of needing to pass urine but passed urine for ‘social reasons’, for example, just before going out, or unsure where the next toilet is.

  • 1—if you had a normal desire to pass urine and no urgency. Urgency is different from normal bladder feelings and is the sudden compelling desire to pass urine, which is difficult to defer, or a sudden feeling that you need to pass urine and if you don’t you will have an accident.

  • 2—if you had urgency but it passed away before you had to visit the toilet.

  • 3—if you had urgency but managed to get to the toilet, still with urgency but did not leak urine.

  • 4—if you had urgency and could not get to the toilet in time so you leaked urine.

Interpretation requires a systematic approach, and a checklist of parameters can help (Fig. 4.2). An example of how to derive the values is given in Fig. 4.3.


Fig. 4.2

Parameters to consider when reviewing a bladder diary. This checklist is detailed, and helps discern key elements. Average values are taken across the three days and put in the ‘Documented’ column, indicating that this is the analysis of the values given by the patient. The ‘Comment’ and ‘Target range’ columns are useful for giving feedback to the patient, so they can identify where the values are outside desirable range, and what they should aim for. The ‘wake/sleep times’ row is to make sure they have been marked. UTC/NR/N/A may be used for any missing information


Fig. 4.3

How to examine a bladder diary. This patient completed a three-day diary, of which two are illustrated. Interpretation of the first day is given; the arrows indicate waking and sleeping time; the filled blue arrow is the waking time of the studied period (8 a.m.), the open blue arrow is the start of the night phase for the period (10 p.m.) and the black filled arrow is waking for the start of the following day (7 a.m.). The drinks of the first 24-h period are covered by the green rectangle; they were all in the daytime, totalling 2150 mL. The nature of the fluid is clearly documented and includes tea, coffee and alcohol—they would be advised to adjust this in view of the obvious nocturia. Daytime frequency was 7 (red rectangle including the dashed red line), including the first void on waking. Nocturnal frequency, i.e., nocturia, was 3 (solid orange rectangle). Most of the voids were either normal sensation (1) or urgency (2), but at bedtime, this patient passed urine without a particular desire to void (0), presumably as they were heading to bed. The 24-hour voided volume is derived by adding the volumes voided in the solid red, solid orange and dashed orange boxes, i.e., 2060 mL. Nocturnal urine production comprises the voids in the orange boxes (solid and dashed), i.e., 890 mL. The nocturnal polyuria index is the night production expressed as a percentage of the 24-h volume (890/2060 × 100 = 43%). The same analysis is done for each fully completed day, to get the indicators for the patient. Note that a 3-day diary does not give the volume of the first void on the 4th day (or any nocturia episodes after 5 a.m.), so the 24 hour and nocturnal voided volumes cannot be calculated for the 3rd day

24-h (or ‘global’) polyuria is th e measured production of more than 2.8 L of urine in 24 h in adults [63]. Nocturnal polyuria (NP) is present when an increased proportion of the 24-h output occurs at night. For the case illustrated in Fig. 4.3, the nocturnal polyuria index was 43%—being above a third (33%), that does indicate this patient had NP. If polyuria or nocturnal polyuria is present, the observation of a high voiding frequency may reflect a cause other than lower urinary tract dysfunction, notably behavioural factors such as a high fluid intake, or a medical condition affecting fluid balance. An example of 24-h polyuria is illustrated in Fig. 4.4; importantly, this patient was not intentionally drinking excessively due to a mistaken impression that high fluid intake is healthy. The patient was actually losing water as a result of diabetes insipidus (DI) , meaning they had to drink a lot to avoid severe dehydration. For this reason, fluid advice to restrict intake must not be given if the patient responds in the affirmative when asked about constant thirst; review is needed beforehand to check for DI.


Fig. 4.4

24-h polyuria. Extrem ely high fluid intake and urine output, with the intake driven by thirst. The cause was diabetes insipidus

A diary that includes fluid intake and urine output measurement generally shows the former exceeds the latter each day (the difference is because some water is lost in the breath and some in the faeces, neither of which is measured for the diary). However, on some days, there may be fluid output greater than intake. Such discrepancies generally even out if the diary is completed over a longer time, but it could be a consequence of failure to fill in the diary accurately, or eating foods with a high liquid content (salad, fruit, soup or pasta).

From a bladder diary, abnormalities in the circadian rhythm of urine production may be detected, and psychogenic voiding patterns might be identified. In addition, it has been shown that certain patterns suggest particular types of bladder or urethral pathology (Table 4.3) [64].

Table 4.3

Classifi cation of bladder diaries [60]


4.5 Free Flow Rate Testing

Multiple sources recommend urine flow rates as a baseline assessment for individuals experiencing LUTS [1]. Within the clinical setting, these tests can also be useful in patients for whom pressure flow studies have provided inconclusive or abnormal results—such as unusual flow patterns or incomplete bladder emptying. They may also have a role in the monitoring of patients started on anticholinergic medications, who have a history of difficulties emptying and postvoid residuals. Although fairly universally accepted as a standard assessment for patients with LUTS, the true predictive value of free flow rate tests (FFRs) is still to be debated. Further research into the parameters recorded and their cutoff values are essential for informing practice guidelines.

There are two commonly used measurement systems for testing a patient’s urine flow rate. Both are heavily tested and validated, but need to be regularly calibrated to ensure reliable results. Calibration checks can be performed easily and should be conducted every morning before clinic. If these checks highlight any problems, then full calibration should be performed.

  1. 1.

    Weight transducer: the weight of urine voided is measured over time. The rate of change in weight of urine is used to establish the urine flow rate.


  2. 2.

    Spinning disk: this relies on the measurement system maintaining the disc’s rotation at a constant speed. Urine hitting the disc makes it heavier, and the amount of additional power needed to maintain its steady speed of rotation is converted into flow rate.


4.5.1 Process of FFR Testing

Pretest preparation— urine flow rates should be as representative of the patient’s normal voiding habits as possible. A standardised bladder diary is a valuable indicator of the patient’s normal voiding behaviour, providing information on the average voided volume as well as frequency of voiding and the amount and type of fluid they are drinking. A precompleted bladder diary can therefore be used to determine whether flow recorded in the clinic setting is characteristic of your patient’s normal volumes. As part of the FFR test, urinalysis should also be performed and recorded along with other reported parameters.

During the test—It is important to understand the direct impact circumstances surrounding the test, as well as the volume voided, can have on the FFR. As such it is important that these procedures are conducted in a private setting where the patient feels at ease, being encouraged only to pass urine when they have a normal desire to do so. Patients are advised to arrive in clinic well hydrated and prepared to stay for as long as it takes to produce two representative voids.

An ideal voided volume (as an indicator of a suitable state of bladder filling when the void is started) is reported to be greater than 150 mL and less than 550 mL; outside of this range, the maximum flow has been shown to be artefactually reduced. Above 550 mL, the bladder becomes overfull and is not able to empty as quickly as normal. Detrusor contractility is therefore affected by being both over or under filled; however, an acceptable voided volume is always dependent on what is normal for the patient, and this should be determined through their bladder diary.

The patient should ideally void a minimum of twice while in clinic, passing urine into a flow meter which then produces a measurement pertaining to urine flow rate and pattern. Following each void, the patient’s postvoid residual (PVR) is assessed, most commonly via ultrasound scan. Connections have been made between PVR and conditions such as recurrent urinary tract infections as well as upper urinary tract concerns. They may also play a role in urinary frequency and urgency due to the volume of urine retained artefactually reducing bladder capacity [65]. Accurate measurement of PVR is therefore an important part of FFR testing.

4.5.2 Parameters Assessed

The most valuable information obtained from urine flow rates comes from comparing multiple, consistent and representative voids. Urine flow rate is usually displayed graphically and described in terms of parameters such as volume voided, maximum flow rate (Q max), flow time and pattern of flow. A good report is one which accurately describes the observed parameters in conjunction with the clinical history and bladder diary.

  • Voided volume—this is the volume of urine that the patient passes into the flow meter and is commonly presented on a flow rate nomogram.

  • Maximum flow (Q max)—normal ranges have been set through the collection of voiding data from large populations of asymptomatic individuals. Maximum flow rates can be presented on nomograms whereby the relationship with voided volume is examined. When Q max is significantly lower than expected, there are a number of possible explanations; bladder outlet obstruction, poor bladder contractility, low/high voided volume or unrepresentative void.

  • Nomograms—nomograms display the relationship between two variables; voided volume or bladder volume and maximum flow rate. They are produced to illustrate the likelihood that the recorded maximum flow and voided volume are normal. Nomograms are not diagnostic but, if used correctly, can be a useful screening tool for LUT dysfunction. Patient age and gender will have a bearing on which nomogram should be used.

  • Pattern of flow—for some patients, the possibility of reaching 150 mL is a daunting and quite frankly an unlikely possibility. For these individuals, the pattern of flow may provide valuable insight. Four of the most common flow patterns seen during FFR clinics are displayed in Figs. 4.5, 4.6, 4.7 and 4.8.

  • Postvoid residual—this volume is most commonly measured through an ultrasound scan of the bladder and should be conducted as soon after the patient has voided as possible. It refers to the volume of urine left in the bladder following an attempt from the patient to empty their bladder fully. Within the literature, there are various definitions of what is considered to be a chronic PVR, with reported volumes ranging from 100 to 500 mL [6668].


Fig. 4.5

A normal ‘bell shape’ flow pattern with a maximum flow rate of 24 mL/s, a voided volume of 323 mL and a minimal PVR


Fig. 4.6

The above trace has a fairly constant Q max of 7 mL/s and a voided volume of 421 mL. It is also worth noting the prolonged flow time of approximately 85 s and the flattened appearance of the flow curve. This plateau ‘constrictive’ pattern is strongly suggestive of a urethral stricture. There is likely to be a PVR


Fig. 4.7

A nonsustained flow rate where voiding initiates and then halts, returning back down to baseline when voiding ceases. Patient has voided 278 mL with an artefactual Q max of 7 mL/s. Correct Q max should be achieved by adjusting the annotation point to prevent it being taken from a sharp peak. There is likely to be a PVR


Fig. 4.8

A fluctuating flow rate must be interpreted with caution, as automatically calculated Q max is likely to be artificially high (vertical dashed line), and adjustments may need to be made (added black curve, showing that the manually corrected Q max is lower than the one derived automatically by the machine. Blue arrow indicates terminal dribble. There may be a PVR

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Mar 23, 2021 | Posted by in ABDOMINAL MEDICINE | Comments Off on Assessment

Full access? Get Clinical Tree

Get Clinical Tree app for offline access