The autologous fascial sling (AFS) surgery, a procedure where the fascial sling is tensioned to dynamically increase urethral closure pressure during raised abdominal pressure. It is a relatively common treatment option for women with stress urinary incontinence secondary to intrinsic sphincter deficiency. However, the success of the AFS relies on the optimal sling tension:  too little pressure, and SUI persists, while excessive tension can lead to voiding dysfunction secondary to bladder outlet obstruction (reported to occur in ~30% of patients at some point postoperatively). Currently, the optimal tension is subjectively determined. 

Our aim was to develop a prototype measurement system that can objectively assess the tension within an AFS intra-operatively. By measuring the pressure applied to the urethra during sling tensioning, we aim to provide real-time feedback to surgeons, enhancing the precision of AFS surgeries and offering a valuable tool for surgical training. Furthermore, this innovative approach has the potential to improve outcomes by allowing for an individualized (or patient selected) sling tension based the optimal trade-off between continence and risk of voiding dysfunction.

We developed a novel sling tension catheter (STC) catheter. As shown in Fig. 1, the STC has a lumen to drain the bladder, a balloon to anchor and reproducibly cite the catheter and five solid-state sensors to real-time pressure map the urethra. 

An ex-vivo setup was created to simulate AFS fixation at different tensions. The calculated tension was then related to pressure measured. 

AFS surgeries were performed on two cadavers by two surgeons using the STC instead of a standard Foley catheter, and the relationship between the sling tension and measured pressure by STC was assessed.

A strong linear correlation between applied AFS tension and measured pressure was demonstrated in the ex-vivo setup (Fig. 1, r2 = 0.998). Cadaveric testing demonstrated a real-time visual relationship between the sling tension and the measured intra-urethral pressure.

We successfully developed a STC prototype that can provide real-time feedback to surgeons during AFS surgery, demonstrating a strong linear relationship between STC measured pressure and AFS tension.

The novel sling tension system can measure real-time intra-operative sling tension and is a promising teaching and sling tension optimizing tool which has the potential to decrease the incidence of post-operative voiding dysfunction.