Title : Adverse events following transvaginal polypropylene mesh implantation to treat pelvic floor disorders: An explanatory study of explanted devices
Abstract:
Transvaginal Transvaginal polypropylene meshes used to treat pelvic floor disorders have been a significant concern in recent years due to adverse events. There is still considerable uncertainty about the causes of these complications. We aim to identify histological patterns that could contribute to adverse events associated with polypropylene meshes in the surgical treatment of POP and SUI.
Eight explants were retrieved from seven patients (pelvic organ prolapse: four; stress urinary incontinence: three). Indications for explantation included vaginal mesh exposure (five), bladder mesh exposure (one) and recurrent prolapse (one). The explants were processed for histological investigations in scanning electron microscopy, light microscopy after different stainings (hematoxylin-eosin, Masson’s trichrome, Weighert, red picrosirius) and transmission electron microscopy.
Eye naked observation revealed multiple small tissue fragments and chunks interspersed with fabrics, with loose polymer threads observed at the edges. Scanning electron microscopy showed varying levels of tissue encapsulation: from proliferative tissue in the absence of bacterial colonization to inconsistent debris in the presence of infection. Damage to the polypropylene filaments included perpendiculars cracks, uplifted oxidized layers, and longitudinal fragmentation. Light microscopy identified inflammatory cells along the polypropylene surface, surrounded by concentric scar tissue layers primarily composed of collagen. The fibers appeared stretched without noticeable undulation. In cases of bacterial colonization, the encapsulation was made up of cellular debris. Transmission electron microscopy confirmed the absence of sinusoidal collagen fibers. In the absence of bacteria, the filaments were distinctly individualized and aligned in parallel with regular banding. Bacterial colonization was associated with the lysis of encapsulation, though individual collagen filaments retained their structure.
The polypropylene fibers exhibited a lack of biostability, likely to exacerbate a chronic inflammatory response. Mishandling of the polypropylene mesh might further accelerate its degradation. In the absence of bacteria, scar tissue formation consisted of stretched collagen fibers, which were well-defined and exhibited extensive stretching. When implanted, the polypropylene mesh is unable to form a soft bio-reconstruction. Ideally, such a device should be encapsulated by parallel sinusoidal collagen fibers with regular banding to prevent contraction and resist bacterial hospitality.
