Rigi10™ Malleable Penile Prosthesis
Also Known As
Type III stress urinary incontinence, Urethral sphincter incompetence, ISD
Definition
Intrinsic Sphincter Deficiency (ISD) is a medical condition characterized by a weakness of the urethral sphincter, the muscle that controls the release of urine from the bladder. It represents a specific type of urethral deficiency where the urethra fails to function effectively as a seal, leading to involuntary urine leakage, particularly during activities that increase abdominal pressure, such as coughing, sneezing, or exercising (a condition known as stress urinary incontinence). ISD occurs when the urethral sphincter cannot generate or maintain enough resistance to hold urine in the bladder, even if the bladder neck and surrounding structures are well-supported. The underlying cause involves a combination of anatomical and physiological problems within the urethra itself, rather than issues with bladder contractions or hypermobility of the urethra in some cases. Its primary purpose in urology is to identify a key factor contributing to stress urinary incontinence, guiding appropriate diagnostic and treatment strategies.
Clinical Context
ISD is clinically relevant in patients presenting with stress urinary incontinence (SUI).1 It is particularly suspected when SUI is severe or persists despite previous surgical attempts to correct urethral hypermobility.1 Patient selection criteria for diagnosing or considering ISD often involve a thorough history, physical examination, and urodynamic studies. Urodynamic testing might reveal low Valsalva leak point pressure (VLPP) or low maximum urethral closure pressure (MUCP), which are indicative of a weakened sphincter mechanism.1 While ISD can occur with or without urethral hypermobility, its presence often influences treatment choices. For instance, patients with ISD might be considered for procedures like pubovaginal slings, transvaginal tape (TVT), transobturator tape (TOT), or periurethral bulking agents, which aim to increase urethral resistance.1 Expected outcomes after treatment for SUI in the context of ISD vary depending on the chosen intervention and patient factors, but the goal is to restore continence and improve quality of life.1 The diagnosis of ISD helps clinicians tailor surgical strategies, as some procedures may be more effective than others when significant sphincter weakness is present.1