Normal bladder sensation
Can be judged by three defined points noted during filling cystometry and evaluated in relation to the bladder volume at that moment and in relation to the patient’s symptomatic complaints
First sensation of bladder filling
Is the feeling the patient has, during filling cystometry, when he/she first becomes aware of the bladder filling
First desire to void
Is defined as the feeling, during filling cystometry, that would lead the patient to pass urine at the next convenient moment, but voiding can be delayed if necessary
Strong desire to void
Is defined, during filling cystometry, as a persistent desire to void without the fear of leakage
Increased bladder sensation
Is defined, during filling cystometry, as an early first sensation of bladder filling (or an early desire to void) and/or an early strong desire to void, which occurs at low bladder volume and which persists
Reduced bladder sensation
Is defined, during filling cystometry, as diminished sensation throughout bladder filling
Absent bladder sensation
Means that, during filling cystometry, the individual has no bladder sensation
Non-specific bladder sensations
During filling cystometry may make the individual aware of bladder filling, for example, abdominal fullness or vegetative symptoms
During filling cystometry is a self-explanatory term and is an abnormal finding
During filling cystometry is a sudden compelling desire to void
How to Measure Sensation
Bladder sensation is measured during filling cystometry. Because sensation is inherently subjective, it requires communication between an attentive clinician and an alert, mentally competent patient .
While standardized ICS definitions exist for the various bladder sensations, ICS does not specify when and how these definitions should be communicated. Some clinicians simply ask the patient to report whatever they feel without any instruction. Others might instruct patients at the outset to report sensations and these sensations are described for the patients. Each clinician will communicate these definitions a little differently in order to achieve understanding among patients of different backgrounds. Due to the variability in the way information regarding bladder sensation is elicited, results can be difficult to reproduce across different laboratories.
Ideally, an ongoing conversation should be maintained between a clinician and patient throughout the study. The patient should be instructed to report when fluid in the bladder is first sensed. The patient is then asked to report occurrence of first desire to urinate followed by occurrence of strong desire to urinate. Finally, the patient should inform the clinician when restraining from urination is difficult to defer (urgency). The patient should also be queried as to what, if anything, is felt when any significant changes in detrusor pressure, like involuntary detrusor contractions, are noted. Many clinicians will provide everyday analogies in order to communicate to patients the differences among first desire, strong desire, and urgency. For example, first desire might be described as a sensation that would prompt a patient watching a good television show to go to the bathroom at the next commercial break while strong desire might prompt the patient to consider interrupting the show and walking to the bathroom and urgency is as a sensation that would prompt the patient to get up immediately and run to the bathroom.
Bladder sensation is subjective and a variety factors may affect the reliability of measurements of bladder sensation . These factors may include patient anxiety, non-physiologic rate of bladder filling, and irritation from the catheter. Erdem and colleagues demonstrated the subjectivity of bladder sensation measurements by showing that a significant portion of adult men who were prepped for a urodynamics study, including catheter insertion, and told that the study had commenced reported first sensation of bladder filling (83 %), first desire to void (80 %), and strong desire to void (25 %) despite lack of bladder distension with air or fluid . To investigate the impact of catheter placement on perceptions of bladder filling, another study was performed where the catheters were taped to the penile skin but not inserted . Even without catheter insertion, about half of patients reported first sensation and a quarter of patients reported first desire, although no patients reported strong desire. When the catheter was then inserted but no filling occurred in the next phase of the study, a much greater portion of patients reported first sensation (87 %) and first desire (73 %), and some patients reported strong desire (18 %). This suggested that catheter placement contributes to the perception of bladder filling but other factors also play a role. The same study performed in a group of children, however, found that they were significantly less prone to reporting sensations of bladder filling without actual bladder filling . Thus, sensations reported by children during urodynamic studies may be more reliable than those reported by adults. In terms of rate of bladder filling, there is conflicting data as to whether it affects bladder sensation [8–10].
One proposal to make assessment of bladder sensation more reproducible involves the use of an electronic keypad that allows patients to rate sensations of bladder filling between 0 (none) to 4 (desperate) . Patients can choose their starting point and go up and down on the scale as they wish throughout the test without any prompting from the clinician. The investigators found this method promising in providing reliable and repeatable results with a statistically significant increase in bladder volume at each urge level.
Studies of normal volunteers have found a consistent pattern in patients’ reports of bladder sensations [8, 11]. These studies were performed in men and women aged 18–30. In all patients, first sensation of bladder filling was followed by first desire to void, and then followed by strong desire to void. Patients describe first sensation of filling as a vague sensation derived from fluid inflow that waxed and waned and was located in the lower pelvis. Patients did not recognize this sensation from their normal daily lives. First desire and strong desire to void were recognized as they are described by the ICS. Patients identified first desire to void as being a sensation familiar from daily life that is localized to the lower abdomen. It became gradually stronger during filling. Strong desire to void was described as a constant, almost uncomfortable sensation located in the perineal region or urethra.
Although sensation is typically part of a complete urodynamic study there has been little investigation of the clinical relevance of this information, the optimal means of eliciting the information, and the test–retest reliability of the assessments. Research has found a significant increase in volume between each sensation (see Table 13.2) [8, 11]. While volumes at which each sensation occurred varied widely among individuals and average volumes were significantly different between male and female patients, they occurred at a fairly constant percentage of total bladder volume. First sensation of bladder filling occurs at an average of 40 % of maximal cystometric capacity while strong desire to void occurs at an average 70 % of maximal cystometric capacity .
Mean volumes for bladder sensation during filling from healthy volunteers; age (years), volume (ml)
Men (n = 18)
Women (n = 32)
22 ± 3
21 ± 2
First sensation of filling
222.5 ± 151
175.5 ± 95.5
First desire to void
325 ± 140.5
272 ± 106
Strong desire to void
453 ± 93.5
429 ± 153
Cold receptors have been identified in the feline and human bladders . Cold sensation is lacking in patients who have undergone cystectomy and enterocystoplasty . While Bors described cold sensation as being felt in the skin rather than the bladder, other experts report the sensation as felt in the bladder rather than the urethra or skin . In some laboratories, room temperature fluid is used to perform urodynamic studies instead of warmed, body temperature fluid (as a matter of convenience). While the clinical significance of intact cool sensation is currently unknown, it seems reasonable to ask if the patient feels an infusion of something cool into the bladder as another test of sensation if room temperature fluid is used.
Conditions of Altered Sensation
Sensation maybe altered in a number of different conditions. The following is a list of some of these conditions:
Increased Bladder Sensation
Interstitial cystitis/bladder pain syndrome (IC/BPS) and other pelvic pain syndromes
Reduced or Absent Bladder Sensation
Sensory neurogenic bladder
Mixed Disorder of Bladder Sensation
Idiopathic overactive bladder
Interstitial Cystitis/Bladder Pain Syndrome
The Society for Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (SUFU) defines IC/BPS as an unpleasant sensation (pain, pressure, discomfort) perceived to be related to the urinary bladder, associated with lower urinary tract symptoms of more than 6 weeks duration, in the absence of infection or other identifiable causes . Since the pathophysiology is unknown and vast majority of patients diagnosed with IC/BPS have no identifiable pathologic abnormality of the bladder it is best considered to be a disorder of bladder sensation .
Urgency is a commonly reported symptom in both IC/BPS and OAB . A comparative study found that urgency is reported by 81 % of patients diagnosed with IC/BPS and 91 % of patients with OAB . The same proportion of patients in both groups (60 %) indicated that the urgency occurred “suddenly” instead of more gradually over a period of minutes or hours. In IC/BPS, however, the urgency was primarily reported as due to pain, pressure, or discomfort, whereas in OAB the urgency was more commonly due to fear of leakage. A survey of 180 IC/BPS patients from the Events Preceding Interstitial Cystitis cohort found that 65 % of patients endorsed urge to urinate in order to relieve pain whereas 21 % endorsed urge to urinate due to fear of incontinence .
Historically, urodynamic studies were included as part of the diagnostic criteria for interstitial cystitis. In the original National Institute of Diabetes and Digestive and Kidney Disease (NIDDK) criteria, the inclusion criteria and exclusion criteria included (1) cystometric bladder capacity greater than 350 ml, (2) absence of intense urgency during cystometry at a bladder volume of 150 ml, or less and (3) presence of detrusor overactivity . These criteria were intended to produce homogeneous populations for clinical research but were based only on expert opinion, and there is no evidence that any urodynamic findings have adequate sensitivity or specificity for IC/BPS. The 2011 American Urological Association Guidelines for IC/BPS recommends that urodynamics be considered if the diagnosis of IC/BPS is in doubt but this test is not necessary for making the diagnosis in uncomplicated presentations. Urodynamic studies may be helpful by identifying patients with significant detrusor overactivity, urethral or bladder neck obstruction, and urethral diverticula and other conditions that might lead to specific therapies. How selectively urodynamics should be used in the work-up of IC/BPS remains controversial among experts [20, 21].
Urodynamic studies comparing IC/BPS patient to normal patients have found that IC/BPS patients have a first desire to void at a significantly lower volume and tolerated a lower maximal cystometric capacity . Patients described bladder filling as painful. In several studies, the average first sensation was around 100 ± 50 ml and maximal cystometric capacity was found to be around 200 ± 100 ml [22–25]. The presence of Hunner’s ulcers is associated with increased bladder sensation and reduced cystometric capacity [24, 25]. As noted previously, bladder sensation measurements on urodynamics, however, are not necessary for diagnosis or management of IC/PBS; there is no evidence that measuring volumes on an urodynamic study is additive to assessing bladder function with a bladder diary.