Final answer:
In venipuncture using the butterfly method, rolling veins can present difficulties, especially in patients with varicose veins which are prone to complications like thrombosis. Care must be taken to stabilize the vein during the procedure.
Step-by-step explanation:
When performing venipuncture using the butterfly method, one common problem encountered is rolling veins. Rolling veins are more likely to occur in patients with fragile, superficial veins or those with varicose veins, which are prone to complications such as thrombosis. The practitioner must stabilize the vein to prevent it from moving during venipuncture. While anastomoses ensure that the removal of blood from smaller veins does not typically impair circulation, the presence of varicose veins can increase the risk of thrombus or clot formation, necessitating careful consideration and technique by the healthcare provider.