Mr Ms

Can anybody think of a way to find out what gender somebody is while taking their medical history?  It came up the other day while an Esteemed Colleague and I were looking at some medical records and we couldn't see where the person's gender was recorded.  We thought about how awkward it would be to have to ask someone their gender (believe me, I've been there when someone was asked and it was very awkward) and so started wondering if there was a way you could figure it out indirectly.

It isn't always obvious from their name.  Some people have either gender-neutral names (eg Ricky Ponting) or are from an unfamiliar cultural context (eg: Ricky Lake).

There's obviously no point in asking questions concerning preferred sexual partner(s) since that's actually not helpful at all.

It's no use to ask gender-specific questions (eg: how's your prostate? when did you have your last period?) because if you guess wrong you'll look like an idiot which is what you're trying to avoid.

Perhaps you could measure their height and weight and then hand them a double-sided set of gender-specific growth charts and ask them to plot themselves while you do some writing on your blog.

Or perhaps you could take some blood to check their thyroid function (because everyone needs their thyroid checked, right?) and secretly order a karyotype to determine their XY/XX status.

Hmm.  Seems that I might be better off just asking them directly.  Any other ideas?