En blodprop i lungen opstår, når noget størknet blod sætter sig fast i et blodkar i lungen. Det størknede blod, blodproppen, kommer ofte fra blodkarrene i benet eller bækkenet, hvor man måske har en dyb årebetændelse.
It's not quite correct. Coagulated blood consists of more then one blood cell. But I must confess the error is mine. It should have been "a little bit of coagulated blood".
But maybe it's still better to say it like this :
"A blood clot in the lung develops when a small amount of coagulated blood gets attached (or attaches itself) to a vessel in the lung."
What do you think ?