A surgical device for use in minimally invasive surgery in which body cavity is accessed by a surgeon though an access port defined by the device, the device including a body cavity engagement feature for insertion into the incision to locate the device in position, fixing feature with a ring that attaches the device to the patient's skin, and a toroid cell having a bladder filled with a liquid or a gel to prevent substantial leakage of gas from the body cavity and formed to mould about a substantial portion of a surgeon's hand or surgical instrument on insertion.