Grades of intrinsic sphincteric deficiency (ISD) associated with female stress urinary incontinence

Intrinsic urethral sphincter deficiency (ISD) is a clinical entity that should be suspected in women with stress urinary incontinence. If it is not diagnosed prior to surgery, it poses a significant risk factor for repair failure. We propose a classification of ISD based on videofluorourodynamic (VFUD) and abdominal leak-point pressures. One hundred female patients with stress urinary incontinence due to ISD were included in this study. History and physical examination were performed on all patients. Each patient underwent a standard VFUD study with abdominal leak-point pressure (ALPP) measurement. ISD is classified into subtypes according to VFUDS and ALPP. The findings were then correlated with the clinical presentation, etiology and proposed management. Three types of ISD/SUI were identified. ISD-A, subtle/urodynamic, was present in 32 patients (32%). It is most difficult to diagnose because radiologically the bladder neck is not open at rest, and it is only diagnosed by VFUD. The abdominal leak-point pressure was less than 12 cmH2O. ISD-B was present in 45 patients (45%). This is characterized by a beak-shaped open bladder neck at rest. The abdominal leak-point pressure was less than 90 cmH2O. ISD-C was present in 14 patients (14%). It is characterized by an open, fixed non-functioning urethra (pipe-stem) with high position of the bladder neck. The abdominal leak-point pressure was less than 70 cmH2O. All the three subtypes had proximal urethral closure pressure (PCUP) less than 10 cmH2O. Based on these data, the treatment options may vary from one subtype to another. For ISD-A, initial treatment was medical, with collagen injection being used for the failed cases. For ISD-B a modified pubovaginal sling was used, as it corrects the ISD and the urethral hypermobility at the same time. For ISD-C, urethrolysis and takedown of the previous suspension was required before using a sling. Collagen injections were used in selected cases. This classification identifies different subgroups of ISD, which is important in the diagnosis and management of this condition.