tilly.........the information is scarce and I can only comment on what you have told me.
He clearly has problems with his veins and the question seems to be, is whether it is a long standing condition in which there is very little danger of a clot moving to his lungs (Pulmonary Embolus) or whether this is an acute situation of a DVT in which case there is a very real chance of a life threatening pulmonary embolus.
The fact that the Popliteal veins are clear is a good sign as in a DVT, the Popliteal veins are invariably blocked.........but your friends are clear, making DVT unlikely which is good news.
The Femoral Vein thrombosed with patent (clear Popliteal Veins) would indicate a long standing non life threatening condition as the thrombus would be stuck hard to the vein wall and unlikely to dislodge and go to the lungs.
I am surprised however that your friend has not got a swollen leg.
Interesting post, keep me informed and remember my comments are based entirely upon the information in your post.