[名词解释]
胎盘粘连

脐带过长产后出血(postpartum hemorrhage) 关食管癌的描述中，错误的是() ["A．食管上段最常见","B．可见原位癌","C．亚硝胺与食管癌发生有关","D．可以多中心发生","E．鳞状细胞癌多见"] 病理缩复环(pathologic retraction ring) 脐带过短