Perhaps Himes, N.E. (1936) _Medical History of Contraception_, Allen and
Wnwin, would be of assistance.  Mind you, I haven't read it, only saw it
cited in James, Peter and Nick Thorpe (1994) _Ancient Inventions_,
Ballantine Books, NY.  They agree that the earliest description of a
condom was by Fallopius in 1564.  They think his was "a refinement of an
earlier device" (p.191) and give various theories about condoms used by
Romans and earlier.