Ashton wonders: Why could not a simple thin-wall, sharp-edged catheter with available light suction - be used to slowly suck the little bugger into tube -?- then withdraw catheter? (suction might even.. sorta "reverse the direction of" the spines - with perhaps a bit of distress to wall of urethra? Small collateral damage, considering the alternative)

You mean withdraw the catheter the same way Fishy entered (which would imply entering it that way too)? I don't think that would work -- if it did, then one would have been able to do it with tweezers (or some similar implement) too. And I think the reason is...

Were there some slight lacerations made by the tips of its spines: well, that would be like other internal damage - treat via the fav nostrum.. and a different catheter, possibly left in for a time, to bypass the wounded area while it heals.

...that this isn't a matter of "some slight lacerations". How long, exactly, are those spines? Remember, the total maximum diameter when you "reverse the direction of" would be two spine lengths, plus the thickness of Fishy's body.

So I think the only way to do it would be to catch it in the catheter from in front... Which would, yes, require a sharp-edged one -- because that means you'll have to pass through the wall of the, ahem, organ.

"Will this hurt, Doctor?" (You fucking betcha it will...!)