There’s no simple referral rule that says when to see a vascular specialist. What matters is the point at which blood flow, rather than dressings, becomes the question. In practice, that is the same point.
For an arterial wound, the answer is direct. To treat an ischemic ulcer, blood flow to your legs needs to be restored. You may need to take medicine. In some cases, you may need surgery. That puts the decision outside wound care in the ordinary sense.
For peripheral artery disease, surgery may be performed if the condition is severe and is affecting your ability to work or do important activities, you are having pain at rest, or you have sores or ulcers on your leg that do not heal. The options include a procedure to open narrowed or blocked vessels — balloon angioplasty — and surgery to reroute the blood supply around a blocked artery. A leg sore that will not heal is on that list.
The same logic applies to veins. If venous ulcers do not heal well, your provider may recommend certain procedures or surgery to improve blood flow through your veins. Different vessels, same question.
There is one timing benchmark, and it is a general one. A wound is considered non-healing if it has not started to heal in 2 weeks or has not completely healed in 6 weeks.
Put together, it works like this. A leg wound that has passed those marks, or a leg wound with the arterial signs — a foot that is cool, pale or blue, pain at rest, weak or absent pulses — is a wound where the blood-flow question should have been asked and answered. Who you are referred to is your provider’s decision. What is in your hands is making sure the question has been asked at all.