Transgastric abdominal access methods and apparatus are described herein. A shape-lockable elongate body can be advanced endoluminally in a flexible state into the stomach, where an opening is created through the stomach wall. The opening can be created endoluminally or by incising instruments placed through the abdominal wall. The elongate body can be transitioned to a rigid state prior to, during, or after advancement into the patient and is passed through the opening into the peritoneal cavity. A dilation balloon can be positioned simultaneously within the elongate body and within the tissue opening such that the elongate body can be advanced through the tissue opening. A flexible needle catheter can also be delivered through the elongate body or an endoscope to provide for insufflation prior to cutting or piercing through the stomach wall. Also, tissue closure devices and methods to close the opening created through the stomach wall.