Our experience of suburethral tapes is that monofilament prostheses are rigid, which is why we have favoured multifilament prostheses. As Richardson et al. point out, these prostheses are less elastic and therefore can be inserted tension free more easily. However, we rapidly observed postoperative vaginal erosions (on average 9 months) worth reporting to the BJOG readers to discuss their aetiologies: are these erosions infections or foreign body–tissue reaction?
Infection is the first aetiologic factor that has to be considered when foreign material placed in the tissues causes complications. Indeed, the main risk factor associated with such biomaterial is infection. The degree of risk depends on the nature of prosthesis and its manufacturing type.1 Thus, in vitro studies show that polypropylene multifilament tapes are more prone to infections than polypropylene monofilament tapes.1 Moreover, late infections prior to slime production are well known in other specialties such as orthopaedics.2 Patients presenting with this type of infection often present with an abscess, as is the case in our series, without any prior symptoms of infection.
We think, as do Richardson et al., that foreign body–tissue reaction can probably account for all the erosions we observed. However, such a theory has first to be tested by in vivo or in vitro studies rather than speculating that they are due to a simple mistake in operative technique. For comparison, we have studied a further 313 patients to assess the efficacity and the complications of monofilament and multifilament polypropylene tapes, inserted by the same surgeons with the same technique in the same operating room.3 That study showed a 9% erosion rate for multifilament prostheses compared with 0% for monofilament prostheses.3 Moreover, multifilament prostheses appear to be less efficient than monofilament prostheses (73% of patients were cured against 88%).3
So far, the ideal prosthesis for vaginal surgery has not been found. Yet, clinical and in vitro studies seem to suggest that some prostheses appear to be less appropriate in this type of surgery, particularly polypropylene multifilament prostheses. Richardson et al. speculate on the mechanisms causing these erosions, but whatever their aetiology, our experience suggests a higher rate of vaginal erosion even when the operative procedure is carried out by the same surgeon with the same technique. It would be interesting for these authors to publish their results so as to help us not to expose patients to further complications.