Conclusion : The presacral veniplex has wide sources and is full of anastomasis thin wall most with no valves and this is the anatomical basis of massive hemorrhage during the surgery of rectal carcinoma

结论：骶前 静脉 丛来源广泛，吻合丰富， 变异 突出，管壁薄，大多无瓣膜，是手术误伤 引起骶前 静脉 丛大出血的解剖学基础

Results : ① The branches of sacral veniplex shaped like earthworm and anastomosed to nets .

结果：①骶 静脉 丛吻合 丰富， 呈网状 弯曲如蚓。