An understanding of the blood supply of the abdominal wall is essential in planning of second abdominal incisions. Parallel incisions, angles between vertical and transverse or subcostal incisions, and incisions in irradiated tissues should be avoided. If possible, a pre existing incision should be extended or reused. Wide undermining of skin flaps is of doubtful value, and should be avoided, as should medial retraction of the rectus muscle with paramedian incisions.
