Ultrasound evaluation of anterior compartment defects

Transperineal ultrasound (TPUS) is recognized nowadays as a gold standard technique in the diagnosis of urinary incontinence (UI) and voiding dysfunction (VD) and is a very useful method, which allows overall assessment of all anatomical structures (bladder, urethra, vaginal walls, anal canal and rectum) located between the posterior surface of the symphysis pubis and the ventral part of the sacral bone.
Urinary incontinence (UI) has been defined by the International Urogynecology Association and the International Continence Society as: “involuntary loss of urine”. This condition is exceptionally common and more than 40% of women over 40 are estimated to experience UI. The most common types of UI are: 1) Stress Urinary Incontinence (SUI), defined as the involuntary loss of urine during increased abdominal pressure. It is thought to be due to a poorly functioning urethral sphincter muscle (intrinsic sphincter deficiency) or to hypermobility of the bladder neck or urethra; 2) Urge Urinary Incontinence (UUI), defined as the complaint of involuntary urinary leakage accompanied or immediately preceded by urgency, due to detrusor overactivity. The key to understanding female UI is an assessment of the anatomy and physiology of the lower urinary tract. Ultrasonography can provide essential information in the management of SUI. Tunn et al. recommended the measurement of the retrovesical angle with TPUS in patients with SUI. For quantitative evaluation of urethral mobility, the Valsalva maneuver is preferable to the cough test. In patients with SUI or UUI, funnelling of the internal urethral meatus may be observed on Valsalva and sometimes even at rest. Marked funnelling has been shown to be associated with poor urethral closure pressures. Schaer et al. reported that TPUS allowed the quantification of depth and diameter of bladder neck dilation in incontinent women. Using Endovaginal Ultrasound (EVUS) to measure bladder wall thickness, Khullar et al. found that women with urinary symptoms and detrusor instability had significantly thicker bladder walls than women with SUI. Another study confirmed that bladder wall thickness greater than 5 mm at EVUS was a sensitive screening method for diagnosing detrusor instability in symptomatic women without outflow obstruction. TPUS and EVUS allow comprehensive evaluation of many abnormalities of the female urethra such as urethral diverticula, abscesses, tumors, and other urethral and paraurethral lesions. Multiplanar EVUS also gives the opportunity to assess the vascularity of the urethra which is believed to contribute to continence. Wieczorek et al. demonstrated that urethral vasculature is different along its entire length, with the mid-urethra, which includes the RS muscle, having the greatest intensity of perfusion. In females with SUI, urethral perfusion appeared significantly reduced.
Ultrasonography also allows the evaluation of tapes used in anti-incontinence surgery as improper positioning or dislodgement may be associated with failed surgery. Dietz et al. performed 3D-TPUS to assess the effectiveness of suburethral slings (TVT™, IVS™, Sparc™). All three tapes were visualized by ultrasound and showed comparable short term clinical and anatomical outcomes. Using 3D-TPUS, Ng et al. found that the midurethral position of the tension-free vaginal tape (TVT) may not be essential in restoring continence, a finding confirmed by Dietz et al., and that the TVT once inserted may not always remain in the midurethral position, likely due to shifting of the tape in the immediate postoperative period. Actual tape migration weeks, months or years after implantation, however, seems unlikely. It has been shown that over-elevation of the bladder neck after Burch colposuspension is associated with postoperative symptoms of the overactive bladder, and this is also observed after obstructive TVTs. Tighter placement of transobturator tapes seems to be associated with less UUI postoperatively, at least in the medium term.
Ultrasound is particularly useful in the assessment of postoperative voiding dysfunction. The minimal gap between implant and SP on maximal Valsalva seems the single most useful parameter in the postoperative evaluation of suburethral tapes as it is negatively associated with voiding dysfunction and positively associated with both SUI and UUI.

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