Providing a vascular anastomosis instrument capable of performing an anastomosis of blood vessels with a diameter difference well. And two of the pin with a ring 21 made of a flexible material, two of a pair of ring retainer 22 of freely opening and closing to removably hold the pin with a ring 21, ring retainer 22 pin with ring and a deforming means, by inserting the ends of the vessel towards caliber is large at one of the pins with the ring 21, pierce the vessel wall to the pin to expand the blood vessel wall 90 Dosotogawa, vessels towards diameter is small and inserting the end into the other pin Ring 21, after performing an incision from the end face of the vessel towards diameter is smaller in the longitudinal direction, so as to match the minor diameter of the ellipse to the diameter of the vessel towards diameter is small above by a pin with ring deformation means to deform the two pins with a ring 21 in the same elliptical shape, open the blood vessels of more caliber is small elliptical shape, pin the vessel wall by expanding the blood vessel wall in 90 Dosotogawa to The stab in, to bind both the pin with ring by piercing a pin of two of the pin with a ring 21 to the other side of the ring.口径差のある血管の吻合を良好に行うことができる血管吻合器を提供する。可撓性の材料からなる2個のピン付きリング21と、2個のピン付きリング21を脱着可能に保持する開閉自在の一対のリング保持具22とを備え、リング保持具22はピン付きリング変形手段を有し、一方のピン付きリング21に口径が大きい方の血管の端部を挿通して、該血管壁を90度外側に拡げて血管壁をピンに刺し、口径が小さい方の血管の端部をもう一方のピン付きリング21に挿通し、口径が小さい方の血管の端面から長軸方向に切開を施した後、口径が小さい方の血管の直径に楕円の短径を合わせるように上記ピン付きリング変形手段によって2個のピン付きリング21を同じ楕円形状に変形させ、口径が小さい方の血管を楕円形状に開いて、該血管壁を90度外側に拡げて血管壁をピンに刺し、2個のピン付きリング21のピンを相手側のリングに突き刺すことによって両ピン付きリングを結合させる。
