Hardening of vein on elbow

A portacath should solve the problem! My veins lasted long enough, so I didn’t have one but that should give your vein some serious recovery time. 

@Afraser yes my is quite battered too. So I had portacath insertion surgery done. Hopefully, it's ok to draw blood from portacath weekly instead of my elbow vein, Thanks for your response.

Dear @Siewli

Very likely to be scar tissue - although the needle prick is small, it still has to heal and will cause scar tissue which is tougher and thicker. The blood’s still flowing through the vein but it’s a lot less accessible. Best to give it a break, as long as possible. I could only use one arm for blood and related tests and my favoured elbow vein got pretty battered. Now that I have tests much less frequently, the vein is serviceable but scar tissue is still detectable. Best wishes.