Description and classification of lower urinary tract dysfunction and pelvic organ prolapse


The purposes of any classification system are to facilitate understanding of disease etiology and pathophysiology, to help establish and standardize treatment and research guidelines, and to avoid confusion among those who are concerned with the problem. Classification systems for voiding disorders and pelvic organ prolapse have been based on various symptoms, as well as anatomic, radiographic, and urodynamic findings. This chapter reviews the classification of voiding dysfunction in women, as well as the differential diagnosis of urinary incontinence using up-to-date terminology from the International Continence Society (ICS). Pelvic organ prolapse terminology, quantitative assessment, and staging are also reviewed. Lastly, the ICS classification system of vaginal prostheses and graft complications is presented. It is hoped that the nomenclature used in these classification systems will become more widely understood and used, and that further research will be aimed at defining their clinical applicability.

Classification systems of lower urinary tract dysfunction

International continence society classification

In 1973 the ICS established a committee for the standardization of terminology of lower urinary tract function. Over the subsequent decades, reports from this committee and its subcommittees have been considered the gold standard in establishing terminology related to lower urinary tract function and dysfunction. In 2010, the ICS terminology for lower urinary tract dysfunction was updated and incorporated into a report on terminology for female pelvic floor dysfunction (published jointly by the International Urogynecological Association [IUGA] and the ICS). In 2018, more focused ICS terminology reports were published related to nocturnal lower urinary tract function and underactive bladder. Each report highlights the importance of basing diagnoses for pelvic floor disorders on the correlation between a woman’s symptoms, signs, and relevant diagnostic investigations. The following sections summarize terminology and classifications for female lower urinary tract dysfunction based on the 2010 IUGA/ICS report, as well as the ICS terminology updates from 2018.

The lower urinary tract is composed of the bladder and urethra, which work together as a functional unit to store and excrete urine. Symptoms, signs, urodynamic observations, and conditions are separate categories with unique but overlapping terminologies. Although a complete urodynamic investigation is not necessary for all symptomatic patients, some clinical or urodynamic assessment of the filling and voiding phases is essential for each patient. It is useful to examine bladder and urethral activity separately in each phase. If urodynamic studies are performed, results should clearly reflect the patient’s signs and symptoms.

Filling and storage phase.

The ICS classification of abnormalities of the storage and voiding phases is outlined in Box 8.1 and diagrammed in Fig. 8.1 . Cystometry measures the pressure/volume relationship of the bladder during filling and storage and assesses bladder function in terms of bladder sensation, detrusor activity, bladder capacity, and bladder compliance.

Box 8.1

The International Continence Society Classification of Lower Urinary Tract Dysfunction

Storage phase

  • A.

    Bladder function during storage

    • 1.

      Detrusor activity

      • a.


      • b.


    • 2.

      Bladder sensation

      • a.


      • b.

        Increased (oversensitivity)

      • c.


      • d.


      • e.

        Nonspecific bladder sensations

      • f.

        Bladder pain

      • g.


    • 3.

      Bladder capacity

    • 4.

      Bladder compliance

  • B.

    Urethral function during storage

    • 1.


    • 2.


    • 3.

      Urethral relaxation (instability)

Voiding phase

  • A.

    Detrusor function during voiding

    • 1.


    • 2.


      • a.


      • b.


  • B.

    Urethral function during voiding

    • 1.


    • 2.


      • a.

        Bladder outlet obstruction

      • b.

        Dysfunctional voiding

      • c.

        Detrusor sphincter dyssynergia

Fig. 8.1

Abnormalities of storage and voiding phases. SUI, Stress urinary incontinence; ISD , intrinsic sphincter deficiency.

Detrusor activity may be normal or overactive. Overactive detrusor function is characterized by involuntary detrusor contractions during filling. These contractions may be spontaneous or provoked and cannot be suppressed completely. Overactive detrusor function in the absence of a known neurologic abnormality is called idiopathic detrusor overactivity, and overactivity caused by disturbance of the nervous control mechanisms is called neurogenic detrusor overactivity. These conditions are often associated with the symptom of urinary urgency. Urgency, with or without urgency incontinence, usually with frequency and nocturia in the absence of urinary tract infection or obvious pathology, is described as overactive bladder (urgency) syndrome. Terminology used to describe overactive bladder is provided in Box 8.2 .

Box 8.2

International Urogynecological Association/International Continence Society Terminology for Overactive Bladder

Increased daytime urinary frequency

Complaint that micturition occurs more frequently during waking hours than previously deemed normal by the woman. Seven episodes of micturition per day is felt to be the upper limit of normal, although some variations between populations may exist. a

Complaint from a patient who considers that she/he voids too often by day. b

Nocturia c

Complaint of interruption of sleep one or more times because of the need to micturate. Each void is preceded and followed by sleep. a

The number of times urine is passed during the main sleep period. Having woken to pass urine for the first time, each urination must be followed by sleep or the intention to sleep. b


Complaint of a sudden, compelling desire to pass urine that is difficult to defer. a , b

Overactive bladder (urgency) syndrome

Urinary urgency, usually accompanied by frequency and nocturia, with or without urgency urinary incontinence, in the absence of urinary tract infection (or other obvious pathology). a , b

Urgency (urinary) incontinence

Complaint of involuntary loss of urine associated with urgency. “Urgency” replaces “urge” as accepted terminology per the International Continence Society. a

Detrusor overactivity

The occurrence of involuntary detrusor contractions during filling cystometry. The contractions may be spontaneous or provoked and produce a wave form on cystometrogram of variable amplitude and duration. No minimum requirement is known for the amplitude of an involuntary detrusor contraction. Detrusor overactivity, with or without urgency and/or urgency incontinence, may be phasic or terminal. Detrusor overactivity may be further qualified if the cause is known: neurogenic, when there is a relevant neurologic condition; and idiopathic, when the cause is unknown. a

(Modified from a Haylen BT, de Ridder D, Freeman RM, et al. An International Urogynecological Association (IUGA)/International Continence Society (ICS) joint report on the terminology for female pelvic floor dysfunction. Neurourol Urodyn. 2010;29:4. b Chapple CR, Osman NI, Birder L, et al. Terminology report from the International Continence Society (ICS) Working Group on Underactive Bladder (UAB). Neurourol Urodyn. 2018;37:2928. c Hashim H, Blanker MH, Drake MJ, et al. International Continence Society (ICS) report on the terminology for nocturia and nocturnal lower urinary tract function. Neurourol Urodyn. 2019;38:499.)

Urethral function during storage can be assessed clinically (direct observation of urine loss with cough or Valsalva maneuver), urodynamically (urethral closure pressure profilometry and leak point pressure measurements), or radiographically (cystourethrography with or without video). The urethral closure mechanism may be competent or incompetent. An incompetent urethral closure mechanism is one that allows leakage of urine during activities, which may raise intraabdominal pressures in the absence of a detrusor contraction. Involuntary leakage during filling cystometry may occur during increased abdominal pressure, in the absence of a detrusor contraction (urodynamic stress incontinence), or because of urethral relaxation in the absence of raised abdominal pressure or detrusor overactivity (urethral relaxation incompetence). The definition and significance of the latter condition await additional data.

Urinary incontinence is the complaint of any involuntary (urethral or extraurethral) leakage of urine. Urinary incontinence is a symptom, a sign, and a condition. Urinary incontinence as a symptom means that the patient states that she has involuntary urine loss. Types of incontinence symptoms include stress incontinence, urgency incontinence, mixed incontinence, nocturnal enuresis, situational incontinence, and continuous incontinence. In each specific circumstance, urinary incontinence should be further described by specifying relevant factors such as type, frequency, severity, precipitating factors, social impact, effect on hygiene and quality of life, the measures used to contain leakage, and whether or not the individual seeks or desires help because of urinary incontinence. The sign of stress incontinence denotes the observation of urine loss from the external urethral meatus synchronously with physical exertion such as a cough or Valsalva maneuver. Because symptoms and signs of urinary incontinence are sometimes misleading, accurate diagnosis often requires urodynamic investigation in addition to careful history and physical examination.

Voiding phase.

During the voiding phase, the detrusor muscle may be normal, underactive, or acontractile. Normal voiding usually is achieved by an initial voluntary reduction in intraurethral pressure (urethral relaxation) followed by a continuous detrusor contraction that leads to complete bladder emptying within a normal time span, and in the absence of obstruction. Detrusor underactivity during micturition is defined as a contraction of reduced strength and/or duration, resulting in prolonged bladder emptying and/or a failure to achieve complete bladder emptying within a normal time span. An acontractile detrusor is one that cannot be demonstrated to contract during urodynamic studies, resulting in incomplete bladder emptying.

During voiding, urethral function may be normal or abnormal. Abnormal urethral function may be caused by uncoordinated or involuntary urethral contractions, urethral stricture, or obstruction from an anatomic abnormality such as severe pelvic organ prolapse or changes after a stress incontinence procedure.

Simultaneous measurement of intravesical or detrusor pressure and urine flow is necessary to determine whether the patient’s voiding is obstructive. In general, high detrusor pressures with low flow rates suggest an obstructive problem, whereas low detrusor pressures with low flow rates imply that the problem is one of detrusor underactivity or acontractility. Simultaneous external urethral sphincter electromyography is necessary to determine whether an obstructive voiding pattern is secondary to urethral overactivity or mechanical obstruction.

Differential diagnosis of urinary incontinence

Among women complaining of urinary incontinence, the differential diagnosis includes genitourinary and nongenitourinary conditions ( Box 8.3 ). As previously mentioned, genitourinary disorders include problems of bladder filling and storage, as well as extraurethral disorders such as fistula and congenital abnormalities. Nongenitourinary conditions that cause urinary incontinence generally are functional conditions that occur simultaneously with normal or abnormal urethral and bladder function. These conditions are most common in elderly women.

Box 8.3

Differential Diagnosis of Urinary Incontinence in Women

Genitourinary etiology

Filling/storage disorders

  • Urodynamic stress incontinence

  • Detrusor overactivity (idiopathic)

  • Detrusor overactivity (neurogenic)

  • Mixed types


  • Vesical

  • Ureteral

  • Urethral


  • Ectopic ureter

  • Epispadias

Nongenitourinary etiology

  • Functional

  • Neurologic

  • Cognitive

  • Psychologic

  • Physical impairment

  • Environmental

  • Pharmacologic

  • Metabolic

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Nov 27, 2021 | Posted by in GYNECOLOGY | Comments Off on Description and classification of lower urinary tract dysfunction and pelvic organ prolapse
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