作者单位:Univ Autonoma Nuevo Leon, Human Anat Dept, Fac Med, Monterrey, Mexico[1]Univ Autonoma Nuevo Leon, Dept Introducc Clin, Fac Med, Monterrey, Mexico[2]Hosp Univ Dr Jose Eleuterio Gonzalez, Univ Autonoma Nuevo Leon, Obstet & Gynecol Dept, Monterrey[3]