Objetive: Develop a review of the pathophysiology, diagnosis, treatment and management of reversed arterial perfusion.The reversed arterial perfusion sequence, known in English literature as TRAP sequence (twin reversed arterial perfusion (1), pathology associated with complications of monochorionic twin pregnancy, (2) is the absence of a well-defined cardiac structure on a twin (the acardiac twin), which is kept alive by his co-twin (the pump twin) through an arterial-arterial surface placental anastomosis. (3) the normal twin accompanying the acardiac has a mortality of 60% ; morbidity is mainly associated with congestive heart failure (4) while the acardiac twin has a mortality of 100% Apropos of a case reversed arterial perfusion syndrome TRAP diagnosed in the second trimester of pregnancy will be displayed and evaluate it. Management made in the service of Gynecology, service image and Pathology service and the associated perinatal outcomes. Keywords: acardic Fetus, perfusion sequence reversed arterial, sequence TRAP, monochorionic pregnancy twin