BLAdder Shape Test: Medium-fill Cystometry and Trans-abdominal Assessment of Bladder Shape in Women With Overactive Bladder

This study hypothesises that bladder shape changes associated with involuntary contractions of the detrusor muscle, might be detected using trans abdominal ultrasound, which could itself form the basis of a novel diagnostic test for detecting involuntary contractions associated with overactive bladder syndrome and urgency incontinence.

The detection of involuntary bladder contractions currently relies on invasive internal pressure measurement, commonly termed Urodynamics. This is an invasive test involving the placement of pressure measurement catheters, usually via the urethra into the bladder and via the anal canal into the rectum. In its normal healthy state, the bladder remains a contractile throughout filling and is compliant, meaning that there is minimal or zero increase in pressure as it fills. During Urodynamics, the bladder is filled artificially, using a pump, with water or contrast medium via a urethral catheter, whilst abdominal pressure is measured via a rectal catheter introduced anally. Differences between pressure measurements in the bladder and the abdomen are used to detect involuntary detrusor contractions; termed 'detrusor over activity when detected during Urodynamics. Patients often report Urodynamics as being uncomfortable and undignified, and the test carries a risk of introducing urinary tract infection. Furthermore, there are significant issues relating to the sensitivity of Urodynamics in the detection of abnormal bladder contractions in the context of Overactive Bladder.

Variations in bladder shape have been observed in association with detrusor over activity during video-Urodynamics, when fluoroscopic images are captured during filling with contrast medium. At one extreme, women with neuropathic overactive bladder have been observed to have tense, spherical or dome-shaped bladders with trabeculations 'fir tree' or 'Christmas tree' bladder. In women with normal detrusor muscle function, the bladder outline appears relaxed and a contractile, following the contours of the pelvis when assessed by cystography.

Although conventional Urodynamics has previously been regarded as the 'Gold Standard' in the assessment of lower urinary tract disorders, it is also well recognised as having issues of sensitivity, patient acceptability and cost. The test is commonly employed to diagnose and better understand the underlying pathophysiology of incontinence and is often deemed necessary, particularly prior to invasive forms of treatment. The requirement for urodynamic equipment, including its purchase, maintenance, associated training and size restricts its use to specialist hospital facilities, rendering it relatively inaccessible as a diagnostic tool. In addition to this patients have reported finding Urodynamics embarrassing and uncomfortable and with the inclusion of x-ray screening (video-cystometry) which is part of the procedure which aims to contemporaneously evaluate lower urinary tract structure and morphology, involves exposure to ionising radiation and is of unproven benefit. Therefore, there is a patient & clinical need to objectively assess lower urinary tract function with less invasive, sensitive, reproducible and more widely available tests.

A pilot study will now be performed to establish the use of bladder shape testing as a new investigation for the assessment and diagnosis of lower urinary tract disorders. It is anticipated that this pilot will lead to the development of a new healthcare product that can be used in the primary care setting as an alternative to urodynamic assessment in the acute secondary care environment.