LAUSR

Approximately 10,000 patients undergo cystectomy with ileal conduit diversion annually in the USA, of which ∼ 50% will subsequently develop a parastomal hernia (PSH) at 2 years. Due to the knowledge gap between urostomy surgical factors and abdominal wall forces, we developed a silicone and ex-vivo human cadaver fascia-based model for study. Our objective was to measure the relationship between incision size/type/material and axial tension force (ATF) as a surrogate for herniation force. Using incisions (linear, cruciate, circular) ranging 1 to 3 cm (0.5cm increments) in clamped 3″x3″x0.020″ silicone or cadaveric sheets, a dynamometer was hooked to a Foley catheter at the drainage aperture and pulled using a motorized positioning system at 20 millimeters/minute. Balloons were hydrated to 125% incision dimension. Upward ATF was recorded until balloon herniation and repeated up to N=5 membranes/size. As limited cadaveric fascia was available, a single incision size was used. Controlling for silicone incision size, linear incision ATF was highest. With an average 3cm incision herniation force of 18.58, 8.48, and 2.36 Newtons (linear, cruciate, and circular respectively), linear was greater than cruciate herniation force (p<0.0001), and cruciate was greater than circular (p=0.0039). This was true in cadaveric fascia for linear vs cruciate (p=0.0001) and cruciate vs circular (p=0.0024). This ex-vivo study suggests incision type/size have predictable influences on ATF for herniation. En-bloc human studies are underway to assess these factors in more clinically optimized models. If confirmed, these data can help to standardize urostomy creation, reducing PSH risk.