chroot said:
In before Moonbear's scorn and a flurry of journal references.
Sperm living for seven days on the dry skin on the outside of the penis?

Where
do you morons come up with this stuff?
- Warren
Thanks, I think you've already addressed the point of sperm living externally, but I'm afraid there's no flurry of journal references on this one.
There seems to be a grand total of 3 references, two recent enough to actually be accessed, and you'll quickly see why none is conclusive. The first is an old study (before or near the turn of the century) that's the original basis of the information, in which someone basically had a few male volunteers collect "pre-orgasmic" fluids, and found that some of them contained sperm while others did not. That's all I know on that. A more recent study in the Lancet 1992 (the relevant pages are missing from the online version, so I'm not sure if it's just a letter, so will have to locate the paper copy to verify) apparently was examining pre-ejaculatory fluids for presence of HIV in HIV-infected men, and found no sperm. I need to verify this, but from other sources that cite it, it sounded like it too only included a very small population, and of course, they had HIV, so were not necessarily healthy and producing normal sperm in the first place. A third paper is a short communication, also with only a handful of subjects (12), and only 4 of them were normal, healthy volunteers. The other 8 were reporting due to other reproductive abnormalities (excessive fluid secretion during foreplay and premature ejaculation). The subjects were asked to collect a drop of pre-ejaculatory fluid on a slide and allow it to dry. Nothing is indicated about when they collected (my guess is it would be the first drop, because after that, they'd be too busy with intercourse to stop to collect a specimen on a slide, but this is not described, so I guess nobody thought to ask that question). This third paper makes it clear it is only preliminary data, and far from conclusive (4 normal subjects with a drop of fluid each is not really representative of much, especially if it was collected very early during intercourse).
Journal of Assisted Reproduction and Genetics, Vol. 20, No. 4, April 2003
But, based on those two more recent papers with very limited subjects, there's a flurry of sites now saying that the pre-ejaculatory emissions don't contain sperm, and the withdrawal method is safe. Do you really want to gamble your future based on just 2 limited studies with a grand total of 4 normal, healthy subjects when nobody has said that every male will have sperm in every drop of their pre-ejaculatory emissions every time they have intercourse?
The further problem with extrapolating anything from those couple of studies is that the withdrawal method doesn't rely on stopping when that first drop from the bulbo-urethral gland is secreted, indeed, you'd never notice those few drops during intercourse. Instead, withdrawal is done just prior to ejaculation. Prior to ejaculation is an emission phase in men, where the sperm are released into the vas deferens in preparation for ejaculation, and it is probably this emission phase that provides the sensation warning of the impending ejaculation that is used for timing withdrawal. Usually, the emission and ejaculation phase follow one another very rapidly, but that does not preclude some emission starting sufficiently early for sperm to escape before the sensation of impending ejaculation becomes evident.