Synthetic material for a PVS

The classification by Amid (1997) used for synthetic materials in hernia surgery may be practically applied to urology as well (Table 1).

Table 1.

Amid Classification for Synthetic Materials

TYPE	DESCRIPTION	BRANDS  العلامات التجارية
I	Pores >75 μm; macroporous	Atrium, Trelex, Marlex, Prolene
II	Pores <10 μm; microporous	PTFE: GORE-TEX, Surgical Membrane, Dualmesh
III	Macroporous with multifilamentous or microporous components	PTFE: Teflon, braided Dacron mesh (Mersilene), braided polypropylene mesh (Surgipro), perforated PTFE patch (MicroMesh)
IV	Submicronic pore size	Silastic, Cellcard (polypropylene sheeting)

Adapted from Amid PK. Classification of biomaterials and their related complications in abdominal wall hernia surgery. Hernia 1997;1:15–21.

The most frequently used materials are grouped into four types.

Type I are totally macroporous prostheses (Atrium, Trelex, Marlex, Prolene) containing pores larger than 75 μm, which is the pore size for admission of macrophages, fibroblasts, blood vessels, and collagen fibers (White et al, 1981; Bobyn et al, 1982; White, 1988).

Type II includes totally microporous prostheses (polytetrafluoroethylene [PTFE]: GORE-TEX, Surgical Membrane, and Dualmesh) containing pores less than 10 μm in at least one of their dimensions.

Type III includes a macroporous prosthesis with multifilamentous or microporous components (PTFE: Teflon; braided

Dacron mesh: Mersilene; braided polypropylene mesh: Surgipro; and perforate PTFE patch: MycroMesh).

Lastly, type IV includes biomaterials with submicronic pore size (Silastic, Cellgard (polypropylene sheeting). Type IV is not appropriate for hernia surgery unless used in combination with type I (Amid, 1992).

The most commonly utilized synthetic material for a PVS is polypropylene mesh (Table 2). It is composed of loosely woven strands of synthetic material, with a pore size greater than 80 μm, permitting passage of  macrophages that may allow better host tissue ingrowth compared with the smoother, more tightly woven counterparts (Kobashi et al, 2005). This represents type I among the Amid classification. In fact, Amid (1997) concluded that the risk of infection and seroma formation was avoided by utilization of type I prostheses.

Historically, sling techniques have changed to limit the associated morbid complications. Synthetic material is no longer utilized in a PVS graft to pull the bladder neck into a high retropubic position owing to high erosion rates. Instead, newer approaches position a sling at the midurethra (Niknejad et al, 2002).

Table 2.

Synthetic Sling Materials

TRADE NAME	COMPOSITION	DETAILS
Mersilene	Polyethylene terephthalatae	Multifilament fibers Very porous, becomes firmly embedded in native tissues
Teflon	Polytetrafluoroethylene (PTFE)	Multifilament
GORE-TEX	Expanded PTFE	Very flexible
Silastic	Silicone plus woven polyethylene terephthalate	Minimal tissue reaction, which facilitates removal or revision if necessary
ProteGen	Synthetic mesh impregnated with collagen matrix	Removed from market secondary to high rate of vaginal extrusion
Marlex, Prolene	Polypropylene	Monofilament with open-weave pattern

Adapted from Niknejad K, Plzak LS, Staskin DR, Loughlin KR. Autologous and synthetic urethral slings for female incontinence. Urol Clin North Am 2002; 29:597–611.