Okay, I know this is probably a bit late, but I have a couple of actions I'd like to throw out there just to see what responses I get. There's several things that I would (off the cuff and with "no
medical training") have done as well.
The first one is a word association test, or other form of testing for a clear ability to think. I've been sailing with Ms. Chris for awhile, I've (knowing me) probably attempted to have some intellectual conversations - I should have a decent baseline of how she responds in certain conversational situations. It should be possible to turn a conversation back into one of those areas and compare her responses now with regard to the responses earlier. Including keeping an eye out for inappropriate responses. I also would have probed further into why she thought she was pregnant - This could be completely valid, however it could equally be a mild form of dementia, which would indicate some form of at least semi-permanent damage has occurred - At which point, despite what she says, my overriding concern would be to get her to
medical attention as soon as possible.
Secondly, I would have recommend a more detailed check of the skull. Besides swelling, are there any other sore spots, is the swelling hard (like an egg) or soft? I would assume those are important indicators.
Also I would want to know what the last thing she remembers is - If she's
lost more than five minutes of time, then we're looking at something is going on besides simply a
single failure to convert short term to long term memory.
Also, I would have insisted on
bed rest. If she absolutely would not and continued to insist she was fine, I would have her sign a document stating what happened and that she wished to return to duty in spite of my objections, as well as an account (signed by both parties) of what occurred.
The
documentation simply because of the fact that in the past some-odd years I've developed a habit of document, document, document. Also because of the fact that I want to avoid any possible lawsuits, including the one where she survives and decides to bring
legal action against me for allowing a preventable
accident to occur, or not insisting on medical attention ASAP.
Head injuries are nasty, inherently.
(Also, I've added these preventers to things to
research, since I'm new to all this sailing stuff.)
You've also got me considering that a good DSM-IV and some general medical reference texts would be a good idea to have onboard. I don't have to know it all, I just have to be able to reference it. With digital
storage these days, in fact, it should be possible to carry around a decent medical library, actually, that is searchable. (This would easily get to be very expensive. Textbooks and/or
references are NOT
cheap.)
Also, since I have a retired doc for a father, I asked him what he would do - His response was, still being a licensced physician, he would have an
Opthalmoscope in his kit, which he would use to look for signs of ICP where the optical nerve enters the eyeball - brilliant. This is the only response from him, all the other paragraphs are mine.
Other than that, it seems to me almost like a sudden fatal aneurysm. My diagnosis of course is not based on
advice from a professional (except for the disclaimed paragraph above) and could very, very easily be wrong.

Also, aneurysms generally don't show symptoms, afaik, that are observable without lots of expensive
equipment before you run into the "Poof, stuff in your
head goes boom!" problem.
It should be noted, I think, that to the best of my memory, aneurysms can develop from blood clots in that area, which could have been caused by the blow to the head. In this case, actually, asprin (or warfarin in a controlled dose, aka rat poison) would have been indicated. However, after ruling out ICP, you have no way of knowing if there IS a blood clot you need to worry about, and if there's something else wrong (or she IS pregnant and not suffering mild dementia) then giving her warfarin would be a very, very bad idea....
If you're looking at a major head trauma, I think the safe course it to set out a nice reclining folding chair on the
deck and give her a book. Tell her she's on strict
bed rest and relaxation therapy until you can get a doctor involved.
Okay, that's a bit more than my two cents worth.
Ah, see the following information for
aneurysm - They do include "sudden death" as one of the things that can happen.