they seem to have sorted out what the problem is, though not what to do about it. During the op they managed to rupture a vein, so they had to transplant one from a, er, cadaveric donor.
(This is one reason OH is wary of doctors, the rupture means a lifetime of warfarin, except when having chemo, which doesn't work with warfarin so it has to be replaced by daily self-injections of anticoagulants, which OH loathes doing.)
Anyway, it's getting clotted and not doing its job properly, so fluids are getting fuddled. It should sort itself out but they have to find out how to manage it in the meantime.
Bodies, eh?