- Hartrampf divided the abdominal tissues into distinct perfusion zones I-IV based upon their location to the perforating artery. Zone I overlies the perforating vessel, Zone II is across the midline adjacent to perforating vessel. Zone III is on the ipsilateral periphery to the perforating vessel and Zone IV is on the furthest periphery on the contralateral side from the perforator. Over the years this has undergone debate and many have advocated that zones II-III (according to Hartrampfs original classification) should be switched. However everyone remains clear on the term Zone IV. Zone IV is classically the area of the flap which receives least perfusion/drainage from the perforating vessels and as such is most liable to undergo congestion and tissue ischaemia leading to fat/skin necrosis. As such many surgeons routinely excise zone IV from the DIEP flap prior to transfer to the chest defect. This obviously leads to a reduction in the volume of tissue available for reconstruction.