Suture materials classification

Sutures are also classified according to size. Currently, two standards are used to describe size USP (United States Pharmacopeia) and EP (European Pharmacopeia) (Chu et al., 1997). Appendix 2 at the end of this chapter provides a summary of these. In the USP standard, which is used most commonly, the size is represented by a series combination of two Arabic numbers a zero and any number other than zero, for example, 2-0 (or 2/0). The higher the first number, the finer is the suture material. Sizes larger than 0 (1/0) are denoted by 1,2,3 etc. This standard also varies with the type of suture material. In the EP standard, the code ranges from 0.1 to 10. The corresponding minimum diameter (mm) can be easily calculated by taking the code number and dividing it by 10. The EP standard does not separate natural from synthetic absorbable sutures as does USP. Table 10.A.2 in the Appendix at the end of this chapter outlines USP and EP suture size classification... 

The size of Gore-Tex sutures does not follow USP size classification but is designated by CV (i.e., cardiovascular). The diameter is measured in the material s pre-expanded form and the actual value of the suture is obviously larger because it contains >50% air by volume. For example, CV-4 Gore-Tex suture has a similar diameter (0.35 mm) to a 2-0 Prolene (0.303 mm). 

---