Infla10® Pulse™Also Known As
UPP, Urethral Pressure Profile, Urethral Profilometry, Urethrocystometry, Urethral Function Test, Urethral Pressure Measurement
Definition
Urethral Pressure Profilometry (UPP) is a urodynamic diagnostic procedure that measures and records the fluid pressure required to open a closed urethra along its entire length1. It produces a topographic curve that plots the urethral closure pressure (UCP) from the bladder neck to the external urethral meatus2. The procedure utilizes specialized catheters (such as microtip transducers or air-charged systems) that are withdrawn at a controlled rate through the urethra while continuously recording pressure measurements3.
UPP provides critical data on urethral function, including maximum urethral pressure (the highest pressure recorded along the urethra), maximum urethral closure pressure (the difference between maximum urethral pressure and intravesical pressure), and functional urethral length (the segment where urethral pressure exceeds intravesical pressure)4. These measurements help clinicians evaluate sphincter competence, identify areas of urethral dysfunction, and assess the urethral pressure distribution in three dimensions5.
The International Continence Society (ICS) standardized the terminology and technique for UPP in 2002, though technological advancements have since introduced higher-resolution systems featuring inclination sensors and improved angular resolution that can more precisely determine the location of each pressure measurement and reconstruct the spatial pressure distribution inside the urethra6.
Clinical Context
Urethral Pressure Profilometry (UPP) is primarily used in the clinical evaluation of lower urinary tract function and dysfunction1. It serves as an important diagnostic tool in several key clinical scenarios:
In stress urinary incontinence (SUI), UPP provides objective measurements that can help determine the underlying pathophysiology2. Low maximum urethral closure pressure (MUCP) has been significantly associated with SUI in multiple studies, with MUCP being 42% lower in incontinent subjects compared to continent controls3. When MUCP is below 20cmH₂O, it is suggestive of intrinsic sphincter deficiency (ISD), a condition characterized by poor urethral function4. This measurement has a specificity of 98% for diagnosing SUI5.
UPP plays a crucial role in surgical planning and outcome prediction for SUI treatments6. The National Institute for Health and Care Excellence (NICE) guidelines highlight that women with SUI and MUCP <20cmH₂O typically have poorer outcomes with supportive procedures such as colposuspension or tension-free synthetic slings7. Studies have shown that patients with MUCP in the lowest quartile demonstrate a twofold increased risk of objective failure one year after surgery8. The retropubic surgical approach has demonstrated higher success rates in women with poor urethral function compared to the transobturator route9.
In voiding dysfunction assessment, particularly in functional bladder outflow obstruction, UPP helps categorize patients based on their urethral pressure profiles10. Patients with Fowler’s syndrome, characterized by MUCP >100cmH₂O, have been shown to respond better to sacral neuromodulation11. UPP is also considered the only objective available tool for selecting patients before off-license sphincter botulinum toxin injection treatment12.
The shape of the UPP curve, beyond just pressure values, can provide valuable clinical insights13. For instance, higher pressures at the trace’s onset may indicate bladder neck hypertrophy, while a pressure dip resulting in a double hump pattern could suggest a urethral diverticulum or urethro-vaginal fistula14.
Despite its clinical utility, UPP’s predictive value and reproducibility have been criticized, and it is currently not recommended to grade the severity of incontinence in the European Association of Urology guidelines15. However, its availability, minimally invasive nature, and cost-effectiveness make it a valuable tool for comprehensive assessment of urethral function and understanding of lower urinary tract symptoms when used appropriately16.