Menstrual blood is known to contain flakes of clotted blood among other bits that will form flakes once dry.
To say you need a scientist with a PHD is nonsense.
What do you believe to be the source of the blood?
Mmm. Blood of any description can't, because it's liquid, strictly be said to contain "flakes" which are, by definition, unless they're of the chocolate variety that melt in the mouth anyway, dry. Whilst it's true that the uterus will expel other materials, they are not necessarily clots. The inclusion of such -and the causation- is due to many variables. As we're not privy to Sheila's gyneacologic history, we can only hazard guesses. However, I can't recall reading that she had any problems. This belief is backed up by the fact of her being fitted with an IUD which wouldn't have occurred had she ever had menstrual problems. We are left with the certain knowledge that HAD clots been present, soaking in water alone would be enough to disperse them. Water to which detergent had been added would have broken them down ever further.
Whilst the need for a Phd is probably overstepping the mark, I stand by my claim that some scientific knowledge of 'how to......' would have been necessary, rather than a WI mentality and a large helping of wishful thinking which likened a blood droplet to "a blob of jam". I do not believe that rank amateurs, armed with a pipette and an eye-dropper, could have extricated anything like enough useful material from blood-stained water.
I imagine the actual source of blood is as open to speculation now as when it was last discussed here, but for me, the most obvious, although not necessarily correct, is that it would have come from drawback in a close contact shot.