A tissue containment bag, comprising a first opening and a second opening interconnected by a sidewall of flexible material, the sidewall defining a first interior compartment configured for receiving a tissue specimen through the first opening into the first interior compartment; the sidewall forming an elongated hollow, sleeve-like neck extension defining a second interior compartment having a proximal end interconnected with the first interior compartment and a distal end interconnected with the second opening; the second opening being in fluidic communication with the second interior compartment; the second interior compartment being in fluidic communication with the first interior compartment and the first interior compartment being in fluidic communication with the first opening; the sidewall at the first interior compartment having a width perpendicular to a first longitudinal axis defined by a radial plane of the first opening when the bag is in undeflected configuration and a length along the first longitudinal axis; the neck extension having a width perpendicular to a second longitudinal axis defined by a radial plane of the second opening when in undeflected configuration and a length along the second longitudinal axis; and the width of the neck extension being smaller than the width of the first interior compartment, the tissue containment bag being characterized in that the neck extension includes a sealing mechanism for sealing off the second opening when the tissue containment bag is ready for removal from an incision or a body orifice; the sealing mechanism comprising a first pocket having a first pocket mouth and a second pocket having a second pocket mouth, wherein the first and second pockets (52, 54) are connected to an outer surface of the neck extension such that the first pocket mouth faces the second pocket mouth. the sidewall defining a first interior compartment configured for receiving a tissue specimen through the first opening into the first interior compartment; the sidewall forming an elongated hollow, sleeve-like neck extension defining a second interior compartment having a proximal end interconnected with the first interior compartment and a distal end interconnected with the second opening; the second opening being in fluidic communication with the second interior compartment; the second interior compartment being in fluidic communication with the first interior compartment and the first interior compartment being in fluidic communication with the first opening; the sidewall at the first interior compartment having a width perpendicular to a first longitudinal axis defined by a radial plane of the first opening when the bag is in undeflected configuration and a length along the first longitudinal axis; the neck extension having a width perpendicular to a second longitudinal axis defined by a radial plane of the second opening when in undeflected configuration and a length along the second longitudinal axis; and the width of the neck extension being smaller than the width of the first interior compartment, the tissue containment bag being characterized in that the neck extension includes a sealing mechanism for sealing off the second opening when the tissue containment bag is ready for removal from an incision or a body orifice; the sealing mechanism comprising a first pocket having a first pocket mouth and a second pocket having a second pocket mouth, wherein the first and second pockets (52, 54) are connected to an outer surface of the neck extension such that the first pocket mouth faces the second pocket mouth.