The reason why frogs ligate both sides before cutting rectus abdominis is is to prevent the abdominal vein located in the midline of the abdomen from being damaged. Cut the abdominal wall slightly to the left along the midline of the abdomen with scissors (to avoid damaging the abdominal vein located in the midline of the abdomen), and then cut diagonally along the left and right sides of the xiphosternum to cut the coracoid and scapula.