Histopathologic changes of porcine dermis xenografts for transvaginal suburethral slings

Objective: The purpose of this study was to examine the histopathologic changes of HMDI (Hexamethylene di-isocyanate) cross-linked porcine dermis grafts used for suburethral sling surgery. Study design: Twelve patients underwent reoperation with graft removal for urinary retention or recurrent stress urinary incontinence after transvaginal sling surgery. Tissue specimens were available for pathologic evaluation in 7 patients. Graft specimens underwent histologic preparation including hematoxylin and eosin staining. A single pathologist reviewed the slides blinded to clinical outcomes. Results: Histopathologic analyses revealed only limited collagen remodeling, and evidence of a foreign body type reaction was present in some specimens. In cases of recurrent stress incontinence, implants appeared to be completely replaced by dense fibroconnective tissue and moderate neovascularization without evidence of inflammation or graft remnants. Conclusion: HMDI cross-linked porcine dermal collagen implants result in variable tissue reactions that may have unpredictable clinical outcomes in different patients, raising questions about the overall tolerability and efficacy of these grafts in pelvic reconstructive surgery.