A separation vessel (1, 2) is provided for collecting fluid compositions under sterile conditions and for processing under non-sterile conditions. An inner vessel (11, 21) is enclosed within an outer vessel (10, 20), each of the vessels (11, 21, 10, 20) having a sealable closure (14, 13, 23, 24) arranged such that the composition can be introduced into the inner vessel (11, 21) from outside the outer vessel (10, 20) through both the sealable closures (14, 13, 23, 24) without allowing the ingress of air or contaminants from outside each respective sealable closure (14, 13, 23, 24). A method for using the separation vessel (1, 2) is also provided, which enables a composition introduced into the inner vessel (11, 21 ) in a sterile environment to be removed from the sterile environment for separation, for example by centrifuge. The upper portion of the centrifuged composition may then be removed through the sealable closures (14, 13, 23, 24), while still maintaining the sterility of the composition in the substances in the inner vessel (11, 21), whereupon the inner vessel (11, 21) can be returned to the sterile environment, removed from the outer vessel (10, 20), and the separated contents removed and used. One application for the device and method is the extraction of platelet concentrate from a patient's blood by centrifuge during a reconstructive surgical procedure, however the device and method are also applicable in other circumstances where a sterile sample is to be processed in a non-sterile environment and then returned to the sterile environment.La présente invention concerne une cuve de séparation (1, 2) pour la collecte de compositions fluides dans des conditions stériles et pour leur traitement dans des conditions non stériles. Une cuve interne (11, 21) est encapsulée dans une cuve externe (10, 20), chacune des cuves (11, 21, 10, 20) comportant une fermeture scellable (14, 13, 23, 24) disposée de sorte que la composition puisse être introduite dans la cuve i
