Permanent<unk> <unk> occurs as a consequence of: * Repeated injections, especially with blunt needles. * Poor injection technique. * Injection of substances which irritate the<unk> s; in particular, injection of liquid methadone intended for oral use. Smaller<unk> s may<unk> as a consequence of too much suction being used when pulling back against the plunger of the syringe to check that the needle is in the<unk> . This will pull the sides of the<unk>  together and, especially if they are inflamed, they may stick together causing the<unk>  to block. Removing the needle too quickly after injecting can have a similar effect.
Collapsed vein
Dural ectasia
Varicose veins
Arteriovenous fistula
Pump thrombosis
Necklace of Venus
Venous cutdown
Dural arteriovenous fistula