Bruising from sclerotherapy still prominent 12/13 weeks later, advice? (photos)

Hello. Sclerotherapy involves the injections of a solution that irritate the lining of the vessel walls. Reticular veins are larger than small spider veins so usually more solution is needed and may then have more inflammation. It also depends on the type of solution used. After such inflammation, hemosiderin deposition can stimulate pigment cells in the skin to produce superficial pigmentation, known as "Post Inflammatory Hyperpigmentation". This can occur in up to 30% of patients who have sclerotherapy. It may take up to a year to resolve. 99% pf patients do experience full resolution. Patients with darker skin types are more prone to having this occur as well. Avoid sunlight on this area and still a good idea to wear your support hose daily. Best of luck.

Sometimes a combination of other minimally invasive procedure is needed to treat underlying medical condition if present depending on your medical evaluation, venous reflux ultrasound results, and diagnosis. For that it is recommended to a see a board certified specialist in Venous and Lymphatic medicine to decide on the best treatment plan for your case, same specialist can also do your follow up on prior treatment complication. All the best, 

The photos and your history are consistent with hemosiderin staining.  These will typically resolve with time but can take up to a year to fade.  This is best avoided by evacuating any retained coagulum or hematoma after sclerotherapy.  I doubt you will be able to extract any significant clot at this time as this far out from the procedure it is probably fibrotic. An ultrasound would let you know if there was blood that could be drained or not.  A topical cream such as Dermaka may help resolve the staining sooner and you can also try adding a drop or two of licorice root extract to the Dermaka when applying it as licorice root extract can act as a natural whitener.