Red rash behind knee; blood vessel?

Doubtful. A rash probably is not a blood vessel unless you have a group of spider veins in that area which would give the appearance of spider legs. Varicose veins would be raised, blue and grape-like in appearance. A red rash doesn't sound like veins. You should see a vein specialist for an evaluation.

Related Questions

I popped a blood vessel behind my knee after doing a leg curl. What should I do?

Ouch! I'm guessing you probably have a bruise, and you may be a bit sore. But, overall, your exercise is probably doing you far more good than harm! you may want to hold off on the leg curls until you're less sore (if it hurts), or try a different exercise to work your hamstrings. Btw, it might be time to mix it up a little and do something different: swimming or a spin class, for example. Good luck. Read more...

Leg in pit behind knee felt bruised looked n see blue bulging blood vessels extending from there to front should I worry? Busted vessel or clot?

Difficult. This is difficult to answer without being able to see the lesion but it could be a burst varicose vein or could also be a ruptured cyst behind the knee. You should be examined by your doctor. Read more...

How long should pain last if it is muscle pain? Blood test ruled out DVT & told likely muscle pain behind leg with varicose veins? Leg not red or warm

highly variable. Muscle pain can last moments or months. The hallmark of DVT is asymmetric swelling. Get a tape measure and carefully determine the diameter of your calf at the same level on both sides - if they're not about the same, you need an ultrasound. Read more...
Probably not muscle. If you have a varicose vein there, that may be the cause of the pain and this is more persistent than simple muscle pain. This can be treated with endovenous ablation or sclerotherapy. Talk to a vein specialist or phlebologist. Read more...

Would knee high compression socks help varicous veins behind the knee? And blood pooling due to pots and eds? Or do I need thigh highs?

Vascular surgeon. I feel that knee high compression stockings would not be helpful in your case and that thigh high ones are indicated. A vascular surgeon with special interest in chronic venous insufficiency would be best qualified to evaluate you and prescribe the type and specific strength of compression stockings most appropriate for you. Read more...